No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Assessment of grey mould (Botrytis cinerea) impact on phenolic and sensory quality of Bordeaux grapes, musts and wines for two consecutive vintages
Australian Journal of Grape and Wine Research
Abstract
Background and Aims: The impact of grey mould (Botrytis cinerea (B. cinerea)) was quantified on chemical, phenolic and sensory qualities of grapes, derived musts and wines.
Methods and Results: Analyses were carried out by using naturally or artificially infected grape berries at ripeness or overripeness. In grape seeds, chemical analyses revealed no major differences between healthy and rotten grapes. In grape skins of Botrytis-affected berries, concentrations of all the phenolic compounds (anthocyanins and proanthocyanidin monomers, dimers and trimer) decreased drastically. Mean degree of polymerization of the proanthocyanidin polymeric fraction was also affected in skins. Chemical analyses of musts and wines made with different percentages of rotten berries showed a moderate impact of the pathogen on their phenolic composition. Nevertheless, sensory analyses underlined a loss of wine sensory quality perceptible from a threshold as low as 5% of Botrytis-affected grapes onwards.
Conclusion: Phenolic variations and the associated negative impact in grapes, derived musts and wines may be related to oxidation phenomena from B. cinerea. The main effects of severity/age of grey mould and the level of berry maturity are also discussed.
Significance of the Study: B. cinerea drastically affects the phenolic and organoleptic properties of grape skins and derived wines. Therefore, prophylactic actions early in the vineyard, evaluation of the sanitary status of the harvested grapes and berry sorting are primordial even under low disease pressure.
... In addition to the thermal stability, the antioxidant properties of the mill-dried WP-fillers are important for their use . 9 Linear correlation between the Δm cellulose and the thermal stability (T 10% ) of the mill-dried WP-filler powders wine grapes led to a decrease in total anthocyanin content by 46% [88]. Respectively, the TPC of RWP-P-23 in the present study might have been reduced because of Botrytis cinerea negatively affecting the phenolic composition of the wine grapes by phenols oxidation [88]. ...
... 9 Linear correlation between the Δm cellulose and the thermal stability (T 10% ) of the mill-dried WP-filler powders wine grapes led to a decrease in total anthocyanin content by 46% [88]. Respectively, the TPC of RWP-P-23 in the present study might have been reduced because of Botrytis cinerea negatively affecting the phenolic composition of the wine grapes by phenols oxidation [88]. However, focusing on the influence of the climate conditions, a positive linear correlation between the sunshine hours and the TPC of WWP-P (y = 0.0282x -28.274; ...
... That the RWP-P from 2023 showed a lower TPC could be attributed to the infestation of the red wine grapes with noble rot caused by the fungus Botrytis cinerea (grey mould) in 2023, since exposure to diseases is known to alter the phenolic content in wine grapes, in addition to other factors such as variety, climate, and geographic origin [28]. Ky et al. [88] investigated the impact of Botrytis cinerea on the TPC of wine grapes of Merlot Noir variety cultivated near Bordeaux (France) by analyzing healthy and botrytized grapes. The authors found a significant decrease in TPC from 51.1 to 42.6 mg GAE/g dwb and from 24.6 to 4.0 mg GAE/g dwb for the wine grape seeds and skins, respectively [88]. ...
Biopolyesters such as poly(butylene succinate) (PBS) show great potential to be used as biobased alternatives to conventional petroleum-based polyolefins. To access technical applications, biobased materials are mostly stabilized using conventional additives, which impair their biobased character. Wine grape pomace (WP), a largely unused, low-value by-product of winemaking, shows great potential to improve the thermo-oxidative stability. Since WP is a natural material, annual variations must be considered for its use as stabilizing bio-filler on an industrial scale. This study investigates the impact of annual variations of WP on the stabilizing effects in PBS. WP of two different varieties and three vintages were studied. The composition and properties of the native by-products were analyzed, and WP-based functional fillers were prepared by industrial mill-drying. The bio-fillers obtained were analyzed regarding their physical, thermal, biochemical, and antioxidant properties and blended into PBS with filler contents up to 20 wt.-% by twin-screw extrusion. The biocomposites’ thermal and thermo-oxidative properties were investigated subsequently. All WP varieties and vintages increased the thermo-oxidative stability of PBS by at least 24% at a filler content of 3 wt.-%, demonstrating the potential of WP as a reliable stabilizer. However, the maximum stabilization effect achieved varied slightly. The results of this study showed that minor differences in the bio-filler properties can be related to meteorological data, while the antioxidant activity, pH, and fat content could be used as bioanalytical indicators to evaluate the thermo-oxidative stabilization effects of WP-based functional fillers to enable reliable industrial applications of WP as a polymer stabilizer.
... This is probably the worst plague affecting vine culture since it causes huge economic losses each year for agriculture, especially in grape and wine production (Steel et al., 2013). In addition to the release of laccase, which seriously affects wine colour (La Guerche et al., 2007;Ky et al., 2012;Vignault et al., 2019;Giménez et al., 2022), Botrytis cinerea causes several other problems, such as contamination with non-desirable microorganisms (Barata et al., 2008;Lleixà et al., 2018), problems of settling and filtration (Villettaz et al., 1984;Jadhav and Gupta, 2016), presence of ochratoxin A (Ponsone et al., 2012;Valero et al., 2008) and mouldy odours Meistermann et al., 2021). ...
... For this reason, the presence of laccase from Botrytis cinerea in red grapes poses a serious problem since it typically makes those wines have a less intense and less stable red colour. Several studies about the effect of laccase on the browning of white grape must and wines (Gómez et al., 1995;La Guerche et al., 2007;Li et al., 2008;El Hosry et al., 2009;Oliveira et al., 2011;Ky et al., 2012;Zimdars et al., 2017;Vignault et al., 2019;Giménez et al., 2022) have been reported, but only very little information exists about the effects of laccase on red wine colour (Ky et al., 2012;Steel et al., 2013;Vignault et al., 2019;Kelly et al., 2022) and to our knowledge even less about the effect of laccase on grape anthocyanins (Ky et al., 2012;Fang et al., 2015;Detering et al., 2018). Pol Giménez et al. ...
... For this reason, the presence of laccase from Botrytis cinerea in red grapes poses a serious problem since it typically makes those wines have a less intense and less stable red colour. Several studies about the effect of laccase on the browning of white grape must and wines (Gómez et al., 1995;La Guerche et al., 2007;Li et al., 2008;El Hosry et al., 2009;Oliveira et al., 2011;Ky et al., 2012;Zimdars et al., 2017;Vignault et al., 2019;Giménez et al., 2022) have been reported, but only very little information exists about the effects of laccase on red wine colour (Ky et al., 2012;Steel et al., 2013;Vignault et al., 2019;Kelly et al., 2022) and to our knowledge even less about the effect of laccase on grape anthocyanins (Ky et al., 2012;Fang et al., 2015;Detering et al., 2018). Pol Giménez et al. ...
This work aimed to study the degradation kinetics of five grape anthocyanins caused by laccase from Botrytis cinerea. In individual solutions, the anthocyanins with three substituents in the B-ring—petunidin, delphinidin and malvidin 3-O-glucosides—were degraded much faster than those with two substituents. In the latter case, cyanidin 3-O-glucoside did not degrade as quickly, and peonidin-3-O-glucoside, in particular, was not degraded by laccase at all. In contrast, when an equimolar solution of the five anthocyanins was used, the differences in the degradation kinetics of all anthocyanins were lessened, probably because the less reactive anthocyanins were able to polymerise with the quinones formed by the laccase action on the more reactive anthocyanins. Finally, supplementation with (-)-epicatechin, glutathione and especially seed tannins seemed to protect the red colour from laccase.
... [9]. Other authors have stated that even low levels of infection can have a detrimental effect on wine quality [10]; indeed, this problem could be more pronounced in the case of red winemaking because of the longer skin contact time during maceration. ...
... Some studies have shown that wines made from partially rotten grapes exhibit an altered colour resulting from the activity of oxidase enzymes, together with higher dry extract due to the formation of glycerine, polysaccharides, uronic acids and aldonic acids, and a substantially increased volatile acidity [11]. However, how the wine quality is affected may be linked to the extent of infection and it may exist a limit on the percentage of bunch infection over which the final wine quality is clearly affected [10,12]. Rotten grapes present a more degraded skin due to the enzymatic action of microbes, which, while facilitating phenolic extraction, may also be accompanied by the extraction of microbial enzymes capable of oxidating and degrading grape phenolic compounds, especially anthocyanins. ...
... Table 3 Volume of lees and wine turbidity measured at the end of alcoholic fermentation CW 12, control wine from grapes harvested at 12ºBaume; SW 12, wine from grapes harvested at 12ºBaume and sonicated; CW 13.5S, control wine from healthy grapes harvested at 13.5ºBaume; SW 13.5 S, wine from healthy grapes harvested at 13.5ºBaume and sonicated; CW 13.5PR, control wine from partially rotten grapes harvested at 13.5ºBaume; SW 13.5 PR, wine from partially rotten grapes harvested at 13.5ºBaume and sonicated. Different letters within the same column indicate significant differences (p < 0.05) Several authors have described a loss of phenolic compounds in wines made from rotten grapes due to the action of microbial oxidase enzymes, especially those of anthocyanins [9,10]. However, in agreement with our results, Barata et al. [12] found that wines made with grapes presenting sour rot have a higher level of anthocyanins and total phenols, and a more intense colour as a consequence of the higher skin to free juice ratio. ...
Several studies have demonstrated that the application of ultrasounds to crushed grapes improves the chromatic and sensory characteristics of the resulting wines by facilitating the extractability of compounds from grapes to the must-wine. The objective of this work was to determine whether the application of ultrasounds to grapes of different maturity levels or different sanitary status leads to the same positive outcome as regards chromatic characteristics, phenolic and aroma compounds as well as sensory properties. The results showed that, independent of grape ripening or sanitary status, the application of ultrasounds to Syrah crushed grapes leads to wines with better chromatic characteristics at the moment of bottling, increasing colour intensity, total phenol content and tannin concentration up to 12%, 18% and 43%, respectively, in the wines from less ripen grapes and 13%, 23% and 30% in the wine from partially rotten grapes. The concentration of volatile compounds was less affected by sonication than the chromatic characteristics, with small decreases in the main families of volatile compounds, although the sensory analysis showed clear differences between control wines and those made from sonicated grapes, which were generally preferred and score higher for most of the sensory parameters evaluated.
... flavanols, flavonols, anthocyanins, stilbens) (Ahmed et al., 2017). In grapes, phenolic compounds are found mainly in skins and seeds (Ky et al., 2012). In response to B. cinerea antibacterial (Nechita et al., 2017a) and antitumoral activities of the new bioproduct. ...
... Recent studies suggest that plant proanthocyanidins maintain B. cinerea in a quiescent stage, leading to delayed development of the symptoms (Van Baarlen et al., 2007). Moreover, plant proanthocyanidins may act as competitive inhibitors of B. cinerea laccase, thereby preventing detoxification of the phenolic phytoalexin (Goetz et al. 1999;Ky et al., 2012). Mendoza et al. (2013) demonstrated in vitro inhibitory effect of polyphenols extracted from Cabernet Sauvignon grape pomace (skins and seeds) on B. cinerea mycelium growth and germ tube elongation. ...
... extracellular enzymes that catalyse the oxidation of phenolic compounds (Bollag and Leonowickz, 1984;Oszmianski et al., 1985;Pezet, 1998;Osman et al., 2007). Ky et al. (2012) evaluated the impact of B. cinerea infection on phenolic compounds concentration, in healthy and naturally or artificially infected grape skins, and found a severe decrease in phenolic compounds in infected grapes. Antifungal activity of the bioproduct on Botrytis cinerea spore germination Spore germination of BC5, BC6 and BC8 strains started after 20 hours, in the case of control (PDA without bioproduct). ...
Botrytis cinerea is a necrotrophic fungus that affects over 200 plant species. In vineyards, this pathogen is responsible for one of the most important diseases, commonly known as botrytis bunch rot or grey mould. Keeping infection under control with synthetic fungicides leads to an increased biological resistance of pathogen populations. An alternative way to synthetic products is to obtain natural fungicides by using bioactive compounds of plants. This study focuses on the antifungal properties of a new bioproduct obtained from polymeric proanthocyanidins extracted from grape seeds of 'Fetească neagră' variety. The bioproduct in solid state presented a total content of polyphenols of 0.625 mg GAE mg-1 , a polyphenolic index of 17.40 and an antioxidant activity of 91.27% scavenged DPPH. The bioproduct with polyphenolic structure showed a moderate effect on the radial growth of fungal mycelium, at EC50 values between 11.23 and 12.15 mg mL-1. Effective antifungal activity was showed in the inhibition of spore germination, where the EC50 values varied from 1.14 to 1.47 mg mL-1. These in vitro results sustain the possibility of including the bioproduct in the category of natural fungicides for biological control against Botrytis cinerea fungus.
... It is the agent responsible for the disease known as 'grey mould', as it produces a grey powdery mould on the crops infected. When infecting winegrapes, grey mould reduces yield at harvest, and negatively alters constituents important to wine quality, including sugar, organic acids and aroma compounds (Ky et al. 2012). Alternatively, B. cinerea may manifest as the desirable noble rot, historically used to produce late-harvest specialised dessert wines such as Tokaji and Sauternes since the 16th century (Jackson 2008, Negri et al. 2017. ...
... The concentration of primary amino nitrogen was higher in Bot10% wines, in conflict with other literature that has found a low concentration of yeast-assimilable nitrogen associated with B. cinerea infection (Magyar and So os 2016). Our data, however, agrees with other findings of elevated concentration of acetic acid that is correlated with the presence of B. cinerea infection (Ky et al. 2012), as well as in wines made from withered grapes (Kelly et al. 2018). When yeast cells are exposed to high sugar environments, they produce a higher concentration of glycerol and acetic acid in wine (Erasmus et al. 2004). ...
... An infection rate of 29% has been indicated as sensorially discernible in wines made with non-botrytised red grapes (Zapparoli et al. 2018). Contrary to these findings, Ky et al. (2012) reported a negative sensory impact on wines, by way of off-flavour descriptors such as Damp earth and Mushroom, from 5% botrytised Merlot (nonappassimento) berries. The differences in impact may be because of the different wine styles and cultivars in these studies. ...
Modification of important odorants induced by Botrytis cinerea has been reported in dry red wine (Amarone) made from withered grapes, but the impact on wines produced in other regions remains to be elucidated. Cabernet Franc grapes from Ontario were dried to 28.0°Brix and fermented with either non‐botrytised grapes or a combination of non‐botrytised and botrytised grapes (10% infection). The metabolites, including volatile compounds, were analysed and sensory evaluation including consumer preference were assessed. Gluconic acid, glycerol and acetic acid were significantly higher in the B. cinerea wines. Differences in some ethyl esters, isoamyl acetate and hexanol were observed between the Control and botrytised wines. These wines were differentiated by only one sensory attribute. A consumer preference test (n = 153) comparing liking scores of wines from this study to wines previously made from withered grapes fermented with an autochthonous yeast showed no difference in preference. Inclusion of 10% B. cinerea infection in wines vinified from withered Cabernet Franc grapes makes little chemical or sensory difference, suggesting culling at this infection rate may be unnecessary and does not negatively impact consumer liking. Red wine made from withered grapes may tolerate 10% botrytised fruit without adversely affecting consumer liking.
... Hill et al. (2019) have reported that this fungus causes annual crop losses in New Zealand of up to NZ dollars 2578 per hectare (around 1509 euros or 1855 US dollars). It is responsible for probably the worst blight affecting viticulture because it gives rise to several serious problems such as contamination with non-desirable microorganisms (Barata et al., 2008(Barata et al., , 2012Lleixà et al., 2018), problems of settling and filtration (Villettaz et al., 1984;Jadhav & Gupta, 2016), presence of ochratoxin A (Ponsone et al., 2012;Valero et al., 2008), mouldy odors (La Guerche et al., 2007;Steel et al., 2013) and a worsening of the foaming properties of sparkling wines (Cilindre et al., 2007), which cause the quality of the wine to deteriorate (Ky et al., 2012;Lopez-Pinar et al., 2017). Nevertheless, the damage that laccase causes to the color of the wine is undoubtedly one of the greatest concerns (La Guerche et al., 2007;Ky et al., 2012;Steel et al., 2013;Vignault et al., 2019). ...
... It is responsible for probably the worst blight affecting viticulture because it gives rise to several serious problems such as contamination with non-desirable microorganisms (Barata et al., 2008(Barata et al., , 2012Lleixà et al., 2018), problems of settling and filtration (Villettaz et al., 1984;Jadhav & Gupta, 2016), presence of ochratoxin A (Ponsone et al., 2012;Valero et al., 2008), mouldy odors (La Guerche et al., 2007;Steel et al., 2013) and a worsening of the foaming properties of sparkling wines (Cilindre et al., 2007), which cause the quality of the wine to deteriorate (Ky et al., 2012;Lopez-Pinar et al., 2017). Nevertheless, the damage that laccase causes to the color of the wine is undoubtedly one of the greatest concerns (La Guerche et al., 2007;Ky et al., 2012;Steel et al., 2013;Vignault et al., 2019). ...
... The B. cinerea single-spore isolate 213, originally isolated from grapevine leaf in 1998, was selected from the collection of UMR SAVE, Bordeaux (Martinez et al., 2003). It was chosen because of its virulence on grapevine leaves and berries and because it is a transposa type strain (Ky et al., 2012;Martinez et al., 2005). The pathogen was cultured on Yeast Peptone Dextrose Petri plates (YPD: 20 g/L of peptone and glucose; 10 g/L of yeast extract and 17 g/L of agar in distilled water) and incubated for about 1 week at 20 • C before use. ...
The aim of this paper is to develop a synthetic model reproducing more realistically the conditions of grape juice to study browning caused by laccase from Botrytis cinerea. The laccase browning kinetics were measured by monitoring the increase in absorbance at 420 nm over time in the presence of different substrates – one monophenol: 4-hydroxybenzoic acid; three orthodiphenols: caftaric acid, (+)-catechin and (−)-epicatechin; and one triphenol: gallic acid. The results indicate that orthodiphenols are better substrates than triphenols and that monophenols do not appear to be reactive. Of the orthodiphenols, (+)-catechin showed the greatest browning intensity, followed in decreasing order by (−)-epicatechin and caftaric acid. These results confirm that sulfur dioxide, ascorbic acid and glutathione really do protect grape juice against laccase browning. The effectiveness of ascorbic acid and glutathione also confirm that both antioxidants can be useful tools for reducing doses of sulfur dioxide in winemaking, especially when grey rot is present.
... These compounds have been linked to the musty aroma of wine (Darriet et al., 2000;Lopez Pinar et al., 2016;Nauer et al., 2022). Moreover, grape infection with fungi can also lead to an altered carbohydrate metabolism (leading to an increase of high molecular weight polysaccharides), laccase synthesis (leading to lower concentrations of phenolic compounds, loss of aromatic terpenes by transformation and hydrolysis of fatty acid ethyl esters) as well as lower organic acid and varietal aroma compound concentrations (Ky et al., 2012;Steel et al., 2013). ...
... The rapid development and improvement of 'omics' tools continues to increase our understanding of plant/berry-fungi interactions (Song, Canellas, Dreolin, Nerin, & Goshawk, 2021). Both targeted and non-targeted metabolomics have been used for the analysis of grape and wine metabolites, and for studying metabolic changes initiated during grape infection and wine production (Darriet et al., 2000;Ky et al., 2012;Nauer et al., 2022). The most important analytical methods used for metabolome analysis of grapes and wine are high-performance liquid chromatography with spectrophotometric detection (e.g. ...
... HPLC-MS, HPLC-MS/MS, GC-MS), and olfactometry (e.g. GC-O) (Darriet et al., 2000;Ky et al., 2012;Landrault et al., 2002). In addition to these well-known analytical approaches, new emerging tools can also offer new levels of information for non-targeted metabolomics approaches. ...
An exploratory study for verifying regional geographical origin of carrots from specific production regions in Austria (“Genussregionen”) was performed by combining chemical fingerprinting methods, namely n(⁸⁶Sr)/n(⁸⁷Sr) isotope amount ratios, multi-elemental and metabolomic pattern. Chemometric classification models were built on individual and combined datasets using (data-driven) soft independent modelling of class analogies and (orthogonal) projections to latent structures-discriminant analysis to characterise and differentiate carrots grown in five regions in Austria. A predictive ability of 97% or better (depending on the classification technique) was obtained using combined Sr isotope amount ratios and multi-elemental data. The use of data fusion strategies, in particular the mid-level option (fusion of selected variables from the different analytical platforms), allowed highly efficient (99-100%, except soft independent modelling of class analogy with 97%) and correct classification of carrot samples.
... B. cinerea is a crucial pathogen that annually results in substantial yield losses grape cultivation globally [32]. Additionally, the oxidation triggered by B. cinerea neg tively impacts not only the quality of grapes but also the taste and character of the resu ing grape musts and wines [33]. Natural products are widely recognized for their en ronmentally friendly nature and minimal toxicity, making them a preferred choice managing postharvest fungal decay [34]. ...
... B. cinerea is a crucial pathogen that annually results in substantial yield losses in grape cultivation globally [32]. Additionally, the oxidation triggered by B. cinerea negatively impacts not only the quality of grapes but also the taste and character of the resulting grape musts and wines [33]. Natural products are widely recognized for their environmentally friendly nature and minimal toxicity, making them a preferred choice for managing postharvest fungal decay [34]. ...
Gray mold, caused by Botrytis cinerea, is the primary factor contributing to postharvest losses in table grape fruit. In this study, we have identified amphotericin B (AMB), a natural compound originating from Streptomyces nodosus, as a promising agent in managing postharvest gray mold in table grapes. In vitro experiments demonstrated that 0.2 mg/L AMB achieved an inhibition rate of over 90% against B. cinerea in PDA medium, and in vivo assays on grape berries showed that 200 mg/L AMB treatment could completely suppress the occurrence of gray mold disease. A mechanism analysis found that AMB treatment disrupted the plasma membrane structure, which consequently triggered cellular leakage and induced cell death. Furthermore, AMB application effectively modulated the transcriptional profile of genes related to redox homeostasis, transmembrane transport, and peroxidase functions in B. cinerea, thereby reducing the virulence of the fungus. In addition, AMB treatment had the potential to activate defense mechanisms in table grapes by enhancing the activities of ROS-scavenging enzymes and defense-associated enzymes. Collectively, AMB can be regarded as a natural antifungal agent that effectively combats B. cinerea, thereby extending the postharvest shelf life of table grape fruit.
... 10.94 ± 1.06a 8.38 ± 0.58b *TAE: tartaric acid equivalents contained higher quantities of total phenols, total anthocyans (total red pigments, including anthocyanins, anthocyanins derivatives, such as pyranoanthocyanins, and red polymers formed by condensation of anthocyanins with favan-3-ols), total anthocyanins and total tannins than C wine; contents of total anthocyans and total anthocyanins were significatively different (p < 0.05). These results agree with those obtained by Ky et al. (2012) for Merlot red wines made with a different proportion of botrytized grapes. Moreover, as it is well known (Jackson, 2020), the extraction of anthocyanins and condensed tannins (proanthocyanidins) from grape skins is related to the fracture of cell walls during grape crushing before the alcoholic fermentation, and the intensity of that fracture is related to the stiffness of cell walls; it may be supposed that the integration of Si in the cell walls should increase rigidity, helping their fracture during crushing. ...
... The content of those pigments, displayed in Table 3, usually is higher in Si wine than in C wine, except Pn-Gl; differences observed (but not in the case of Pn-Gl) are significantly different (p < 0.05). These results agree with those obtained by Ky et al. (2012) for Merlot red wines made with a different proportion of botrytized grapes. Our results should be expected if data obtained for hue and chemical age index (Table 2) are considered, because Si wine is a less evolved wine than C wine, and polymerization of anthocyanins onto polymeric pigments should have been less intense in Si wine than in C wine, leading to a decrease in the content of free anthocyanins in C wine. ...
Impact of applying monosilicic acid to grapevines during ripening on chemical composition of Mencía red wines in an area where fungal diseases during summer are common was examined. The foliar application of monosilicic acid to grapevines led to a less oxidized wine, with lower levels of acetic acid, acetaldehyde, ethyl acetate and diacethyl; this should be considered as positive from a sensory point of view. Wines made with silicon-treated grapes also contained lower levels of gluconic acid and glycerol, which are chemical markers of wines made with botrytized grapes, as well as higher contents of total phenols, anthocyanins and tannins. Furthermore, the contents of several mid-chain alcohols were higher (p<0.05) in wines made with grapes from silicon-treated plants.
... Sporulation was clearly noticed in the highly compact Trincadeira clusters. As the content of secondary compounds such as phenols and anthocyanins indicate ripening stage and may play a role in plant defence against pathogens [30,31], both were extracted and quantified. Total phenolic content (TPC) extracted in methanol, a less hydrophilic solvent and therefore rich in compounds such as hydroxyphenylacetic acids or stilbenes, shows no changes upon infection, though a tendency for a potential decrease upon infection can be seen. ...
... Both compounds, when present in specific quantities, may reduce susceptibility to B. cinerea [30,46]. It has also been described that B. cinerea infection leads to degradation of anthocyanins, usually through laccases secretion [31,33,47]. The trans-2-Hexenal as also been associated with defence by inducing the expression of genes involved in resistance to B. cinerea [48]. ...
The aroma of grapes is cultivar dependent and is influenced by terroir, vineyard practices, and abiotic and biotic stresses. Trincadeira is a non-aromatic variety associated with low phenolic content and high sugar and organic acid levels. This cultivar, widely used in Portuguese wines, presents high susceptibility to Botrytis cinerea. This work aimed to characterise the volatile profile of Trincadeira grapes and how it changes under infection with B. cinerea. Thirty-six volatile organic compounds were identified, from different functional groups, namely alcohols, ester acetates, fatty acid esters, fatty acids, aldehydes, and products of the lipoxygenase pathway. Both free and glycosidic volatile organic compounds were analysed by Gas Chromatography and Gas Chromatography coupled to Mass Spectrometry for component quantification and identification, respectively. A multivariance analysis showed a clear discrimination between healthy and infected grapes with 2-trans-hexenal and isoamyl-acetate among the compounds identified as negative and positive markers of infection, respectively. Ester acetates such as 2-phenylethyl acetate, isoamyl acetate, and 2-methylbutyl acetate were present in higher contents in infected samples, whereas the contents of several fatty acid esters, such as ethyl decanoate and ethyl dodecanoate, decreased. These data were integrated with quantitative PCR data regarding genes involved in volatile metabolism and showed up-regulation of a gene coding for Hydroperoxide Lyase 2 in infected grapes. Altogether, these changes in volatile metabolism indicate an impact on the grape quality and may be related to defence against B. cinerea. The presence/absence of specific compounds might be used as infection biomarkers in the assessment of Trincadeira grapes’ quality.
... The lifecycle of the most common fungal diseases is wellcharacterized, as is their negative impact on grapevine physiology; yet, for most diseases, the molecular mechanisms that underpin the deterioration of berry quality remain to be elucidated. Recent advances in metabolomics led to the discovery of new odorous and non-odorous compounds produced either directly by pathogens or released by leaves or berries following infection (Darriet et al., 2002;Ky et al., 2012;Pons et al., 2018;de Ferron et al., 2020). These compounds can be linked to deleterious effects on wine quality. ...
... In particular, phenolic compounds (anthocyanins, hydroxycinnamic acids, and flavanols) are oxidized by the polyphenol oxidase (laccase) activity of B. cinerea (Dubernet et al., 1977), which leads to quinones, that are highly reactive with glutathione and volatile odorous thiols. Ky et al. (2012) showed that all phenolic compounds (anthocyanins and proanthocyanidin monomers, dimers and trimers) decreased drastically in gray mold-infected grape skins as well as the mean degree of polymerization of the proanthocyanidin polymeric fraction. Some aromatic components, like monoterpenes that play a major role in the aromas of Muscat grape cultivars and wines, are transformed into less odorous compounds (Boidron, 1978;Bock et al., 1986). ...
The grapevine is subject to high number of fungal and viral diseases, which are responsible for important economic losses in the global wine sector every year. These pathogens deteriorate grapevine berry quality either directly via the modulation of fruit metabolic pathways and the production of endogenous compounds associated with bad taste and/or flavor, or indirectly via their impact on vine physiology. The most common and devastating fungal diseases in viticulture are gray mold, downy mildew (DM), and powdery mildew (PM), caused, respectively by Botrytis cinerea, Plasmopara viticola, and Erysiphe necator. Whereas B. cinerea mainly infects and deteriorates the ripening fruit directly, deteriorations by DM and PM are mostly indirect via a reduction of photosynthetic leaf area. Nevertheless, mildews can also infect berries at certain developmental stages and directly alter fruit quality via the biosynthesis of unpleasant flavor compounds that impair ultimate wine quality. The grapevine is furthermore host of a wide range of viruses that reduce vine longevity, productivity and berry quality in different ways. The most widespread virus-related diseases, that are known nowadays, are Grapevine Leafroll Disease (GLRD), Grapevine Fanleaf Disease (GFLD), and the more recently characterized grapevine red blotch disease (GRBD). Future climatic conditions are creating a more favorable environment for the proliferation of most virus-insect vectors, so the spread of virus-related diseases is expected to increase in most wine-growing regions. However, the impact of climate change on the evolution of fungal disease pressure will be variable and depending on region and pathogen, with mildews remaining certainly the major phytosanitary threat in most regions because their development rate is to a large extent temperature-driven. This paper aims to provide a review of published literature on most important grapevine fungal and viral pathogens and their impact on grape berry physiology and quality. Our overview of the published literature highlights gaps in our understanding of plant-pathogen interactions, which are valuable for conceiving future research programs dealing with the different pathogens and their impacts on grapevine berry quality and metabolism.
... The intensity (also called severity in the literature) represents the percentage of diseased berries (i.e., the sum of rotten berries per bunch divided by 50), and it is indicative of disease pressure. Disease intensity is a variable with high interest as it reflects the impact on wine yield and gustative quality (Hill et al., 2010;Ky et al., 2012). ...
... Prior to the arrival of biopesticides on the market for controlling B.cinerea, organic vine producers only benefited from prophylactic methods (e.g., leaf or bunch removal). B.cinerea can lead to a strong qualitative depreciation on wines from only 5% of Botrytis-affected grapes that cause degradation of color, aroma, and structure (Ky et al., 2012), which reinforces the need to provide additional and reliable management practice for organic producers. Biopesticides represent a promising tool in Integrated Pest Management as they can be combined with chemical fungicides to reduce the risk of fungicide resistance and high residue levels. ...
An on-farm research network is an organization of farmers that conducts agronomic experiments under local conditions. There is growing interest in on-farm research networks because they provide the infrastructure needed to test new products and management practices in farmers’ fields. Often, the results are usually presented as individual reports (i.e., a report summarizing the outcome for one trial), but this provides limited information difficult to generalize and does not allow presenting, in a synthetic way, all the results collected from the different trials. Moreover, there is an unexplored potential in detecting yield response variability patterns for better decision making. The overall objective of this thesis is to demonstrate the importance of identifying appropriate statistical methods for analyzing and visualizing on-farm research network data. Specifically, I focused on analyzing the on-farm research networks managed by the Iowa Soybean Association, and an adaptation was made with a French case-study. A data-analytics framework was developed to analyze multiple trials that use a common protocol and identify the conditions where an imposed treatment may or may not be effective. This framework used a random-effect model through a Bayesian approach and returned yield response estimates at the network and trial levels. The framework was implemented through a web-application for 51 different management practices on corn and soybean. The web-application includes dynamic data visualization features to enhance communication and information sharing, and is accessible to a broad audience to improve accessibility to on-farm research insights. A random-effects statistical model was used to compute prediction intervals describing a range of plausible yield response for a new (out-of-sample) trial, and compute the probability that the tested management practice will be ineffective in a new field. Depending on the level of between-trial variability, the prediction intervals were 2.2–12.1 times larger than confidence intervals for the estimated mean yield responses (i.e., at the network level) for all tested management practices. Using prediction intervals and the probability of ineffective treatment will prevent farmers from over-optimistic expectations that a significant effect at the network level will lead with high certainty to a yield gain on their farms. The data-analytic framework was adapted to a French on-farm research network focusing on the efficacy of biocontrol agent products against Botrytis cinerea, potassium bicarbonate and Aureobasidium pullulans, on organic vine. The results favored potassium bicarbonate as its efficacy on incidence at the network level is higher for diseased intensities between 0% and 10% than for Aureobasidium pullulans. For both biocontrol agents, the efficacy on incidence for a new trial is highly uncertain for intensity levels higher than 15%. Finally, this research investigated the impact of experimental plot scale (i.e., small-plot scale and field scale) on the effect of management practice on crop yield and identified the cause of potential discrepancies to inform on-farm decision-making better and adapt the extrapolation of the results. Taken together, this research represents the first major effort in consolidating results from on-farm research network and provides insight to make better farming management decisions.
... The severity (also called intensity in the literature) represents the percentage of diseased berries (i.e., the sum of rotten berries per bunch divided by 50) and it is indicative of disease pressure. Disease severity is a variable with high interest as it reflects the impact on wine yield and gustative quality (Hill et al., 2010;Ky et al., 2012). ...
... Prior to the arrival of biopesticides on the market for controlling B. cinerea, organic vine producers only benefited from prophylactic methods (e.g., leaf or bunch removal). B. cinerea can lead to a strong qualitative depreciation on wines from only 5% of Botrytis-affected grapes that cause degradation of color, aroma, and structure (Ky et al., 2012), which reinforces the need to provide additional and reliable management practices for organic producers. Biopesticides represent a promising tool in Integrated Pest Management as they can be combined with chemical fungicides to reduce the risk of fungicide resistance and high residue levels. ...
Botrytis cinerea, a fungal pathogen that causes gray mold on grapes, can decrease yield, substantially reduce wine quality, and therefore cause significant economic losses. In a context of increasing awareness of environmental and human health, biopesticides are a potential alternative to synthetic chemical treatments to produce grapes and wine in compliance with high food standards. However, the effectiveness of biopesticides is not well known and more research is needed to help winegrowers assess their ability to control wine diseases. Our study aims to assess the efficacy of two commercial biopesticides, based on potassium bicarbonate and Aureobasidium pullulans, in reducing the incidence of gray mold (i.e., the proportion of grape bunches that are diseased). We use data from an on-farm trial network managed over 3 years (from 2014 to 2016) in a major wine producing region located in Southwestern France, and fit Bayesian generalized linear multilevel models able to take the variability of treatment effect across trials into account. The fitted models were then used to estimate the efficacy on incidence as a function of the severity (i.e., the proportion of diseased grape berries in a bunch) in an untreated plot in order to determine if the effectiveness of the treatments depends on the disease pressure. At average disease severity (i.e., 3%), the efficacy on disease incidence at the network level was equal to 20% [95% CI = (−0.1; 37.3)] and 13% [95% CI = (0.2; 24.7)] for potassium bicarbonate and A. pullulans, respectively. For both biopesticides, the efficacy on incidence for a new site-year is highly uncertain, but potassium bicarbonate had a lower uncertainty and a lower application cost compared to A. pullulans. Our results confirm that potassium bicarbonate is an interesting biopesticide under farming conditions in organic vineyards in southwestern France, but the amount of uncertainty points to the need for further research.
... Pests and diseases impact in crops production both in terms of quality and quantity, with nefarious effects for agricultural in general, as well as for specific species of high commercial value, such as vineyards [136][137][138] . Moreover, severe pest and disease attacks can limit the normal development of (but not confined to) the grapevine, reducing its ability to create and store biomass and weakening it progressively 139 . ...
Climate change pose significant challenges to modern agriculture management systems, threatening food production and security. Therefore, tackling its effects has never been so imperative to attain sustainable food access and nutrition worldwide. In the case of viticulture, besides jeopardizing grape production, climate change has severe impact in quality, which has becoming more challenging to manage, due to the increasingly frequent fungal contamination, with consequences for relevant quality parameters such as the aromatic profiles of grapes and wines and their phenolic compounds. This has been leading to a reconfiguration of the wine industry geostrategic landscape and economy dynamics, particularly in Southern Europe. To address these and other emerging challenges, in-field deployable proximity-based precision technologies have been enabling real-time monitoring of crops ecosystems, including climate, soil and plants, by performing relevant data gathering and storage, paving the way for advanced decision support under the Internet of Things (IoT) paradigm. This paper explores the integration of agronomic and technological knowledge, emphasizing the proper selection of IoT-capable sensors for viticulture, while considering more general ones from agriculture to fill gaps when specialized options are unavailable. Moreover, advisable practices for sensor installation are provided, according to respective types, data acquisition capabilities and applicability.
... These diseases can infect grapevines and spread to healthy grapevines which may cause significant yield losses if left untreated and can impact to overall loss of income. Managing these diseases is inevitable and it often requires intensive labor, including scouting for symptoms, applying chemicals, and other cultural practices (Calonnec et al., 2004;Ky et al., 2012;Leroy et al., 2013). For these, pesticide use is prevalent, and numerous sprayings are frequently necessary to safeguard the grapevine and successfully produce high-quality grapes at harvest (González et al., 2022). ...
To meet both qualitative and quantitative production standards, pests and diseases in grape cultivation must be actively controlled by an intensive schedule of pesticide applications. The use of pesticides can have both positive and negative effects on grape production and the environment. The harmful effects of pesticides on human health, the environment, and chemical residues in food have sparked this review to focus on the pesticide circumstances in grape production globally. Information reviewed reveals that, the use of pesticides in grape production is the most efficient method for controlling pests and diseases. These agro-chemicals tend to leave poisonous residues that pose serious problems to the environment and human health when applied in inappropriate ways. Furthermore, some fungal pathogens and other grapevine pests develop resistance to pesticides which makes it difficult to control. Additionally, the majority of grape producers’ lack awareness on the impacts of chemical residues in grapes and their products. Grape value chain actors should follow pesticide handling procedures and the instructions available on the labels for effective application of pesticides to reduce contamination of grape products and prevent pesticide residue levels from exceeding the Maximum residue limits (MRLs) which is the standard. Grapevine growers should consider cultural, physical/mechanical, biological, and chemical methods for controlling pests and diseases in grapes.
... A study conducted in France in the late 1990s on Bordeaux varieties demonstrated that 35 % of rotted berries at harvest resulted in a 28.5 % reduction in wine production (Dubos, 1999). Negative effects on wine sensory aspects such as colour, aroma, and taste are already evident when the grapes have reached a 5 % infection threshold, as evidenced by phenol oxidation, colour alteration, unpleasant appearance, and problematic ageing (Ky et al., 2012). The use of anti-Botrytis cinerea products is increasingly being resorted to control disease (Rosslenbroich and Stuebler, 2000), but this leads to the generation of resistant strains on the one hand (Hahn, 2014) and, on the other hand, a more massive use of pesticides with serious repercussions on the environment and human health (Damalas and Eleftherohorinos, 2011). ...
The grapevine (Vitis vinifera L.) cultivar Pinot gris is an international variety that has spread world wide and is oneof the most important in Italy, especially in the northern regions where almost half of the world's total is grown. Over a three-year period (2019–2021), a comparative study was conducted on 17 clones to evaluate their agronomic aptitudes, susceptibility of grapes to Botrytis cinerea, fertility of buds, vigour, and oenological characteristics. We aimed to provide local viticulture with agronomic, sanitary status, and oenological indications that help to choose the genotype that best fits and enhances the clone/environment synergy. This is important given climate change, one of the most significant factors affecting viticulture. Hence, productive, qualitative, and health surveys were conducted on grapes during harvest. Vigour and vegetative/productive balance were also evaluated regarding the weight of the pruned wood. The Ravaz index and fertility of buds were studied when the inflorescences were separated and clearly visible (between DOY 131 and DOY 141 each year). The confirmation of the bunch was also evaluated (shape and number of wings) according to the Organisation Internationale de la Vigne et du Vin (OIV) descriptors. Through the use of digital photogrammetry, some descriptors of the cluster that most correlate with the severity of Botrytis cinerea were identified. In 2020 and 2021, microvinifications were carried out in white and with maceration of skins, respectively, following tested protocols. Sensory analysis of the wines was performed with a trained panel of experts. The study revealed interesting differences between clones concerning grapes' qualitative, productive, and sanitary aspects. Some clones stood out for their sugar accumulation, yield and resistance to Botrytis cinerea, as well as for the oenological olfactory profile. Statistical analysis highlighted that the severity of Botrytis cinerea and bunch rot was not correlated with the vigour of the plant but rather with the hardness of skin, content of soluble solids, soluble solids/total acidity ratio, pH, and total acidity. From the sensory analysis, several clones had a higher score for some descriptors in both study years and were more appreciated than others.
... In the winemaking process, the infection of grapes by Botrytis cinerea (phytopathogenic fungus) leads to high laccase activity in must. Due to its stability in wine conditions [28], laccases can oxidize polyphenols and generate brown compounds that negatively affect the color and organoleptic qualities of red wine [29][30][31]. According to Vignault et al. [32,33], the oenological tannin (gallotannins, grape-skin, and grape-seed tannin) inhibits laccase activity and preserves the color of red wine at low doses (20 g hl −1 ), which is not the case with bentonite that wasn't able to remove laccase proteins. ...
Oenological tannins are extracted from plants and agro-industrial byproducts for application in the wine industry; they are used for their ability to improve the protein stability of wine and also to protect it against negative physicochemical changes and unpleasant sensory attributes. The potential applications of tannin extract are determined by the phytochemical composition and the production cost, which mainly depends on the complexity of the raw material used and the manufacturing process of the tannin extract. In general, tannins are extracted from the lignocellulosic barrier, which limits their release during the diffusion process. Many treatments are used to reduce the recalcitrance of lignocellulosic material and to intensify the tannins extraction yield. This review gives a general description of different classes and properties of oenological tannins, and it elucidates in detail conventional methods for the industrial production of tannins, as well as the emerging extraction techniques and characterization methods developed from previous studies. Indeed, clear interest has been noticed in the extraction of tannin using emerging techniques, and this is linked to their many advantages such as the use of non-toxic solvents, and short extraction time. However, their implementation at the industrial level for oenological tannin content remains a challenge, particularly in terms of installation and equipment costs. Additionally, conventional methods are non-complex processes with higher yields/outcomes than these techniques. Several characterization techniques have revealed the molecular diversity of oenological tannins that influence their proprieties. The botanical origin of the tannins can be identified by spectroscopy, GC-FID/MS, and RP-HPLC. Electrochemical methods (CV and LSV) can be a rapid alternative for classifying tannins.
Graphical abstract
... This process alters the colour of must and wine [13], leading to wine instability and colour degradation. Off-flavours such as geosmin or 1-octen-3-one [14,15] can affect wine quality at concentrations as low as 5% of Botrytis-infected grapes [16]. These compounds result During the 2022 harvest season, various Botrytis cinerea strains were obtained from different regions and grape varieties (Edenkoben, Göcklingen, Mußbach, Bonn, Mutzig, Barsac, Ihrlingen, Freiburg im Breißgau, Heppenheim, Sternenfels, Oestrich-Winkel, Wollmesheim, Mettenheim, Zeltingen-Rachtig, Table 1). ...
Botrytis cinerea is a well-known pathogen that can be challenging to control in crops, such as wine grapes. To adapt to the increasing problems of climate change and strain resistance, it is important to find new methods to detect Botrytis cinerea and differentiate strains. These methods include strain differentiation and classification by simple sequence repeats (SSRs) and early detection of the fungus by qPCR. Various strains were analysed using SSR markers and either agarose gel electrophoresis or capillary sequencing via PCR. A sensitive qPCR method was refined to achieve an early detection method for the pathogen. The results demonstrate promising ways to distinguish between strains using both agarose gel electrophoresis and capillary sequencing as well as to detect infection before it becomes visible on grapes. This can be used to further understand and analyse different Botrytis cinerea strain characteristics such as laccase activity, regional or annual effects. The early detection method can be used to better prepare growers for an impending infection so that targeted efforts can be made.
... The enzymatic browning of grape must is still a major problem in oenology today (Li et al., 2008), being particularly serious when the grapes have been infected by grey rot (Ky et al., 2012). Browning is an oxidation process that causes certain foods to turn brown, which often leads to them being rejected by consumers (Friedman, 1996). ...
In this study, the effectiveness of a selected strain of Metschnikowia pulcherrima (MP1) was compared to that of sulphur dioxide for preventing white grape must from browning. Sulphur dioxide was found to drastically reduce oxygen consumption rate, protect hydroxycinnamic acids against oxidation and prevent grape must from browning, even in the presence of laccase. By contrast, supplementation with the selected strain of Metschnikowia pulcherrima (MP1) drastically increased oxygen consumption rate, thus reducing the amount of oxygen available for polyphenol oxidases. In the absence of laccase, this resulted in a decrease in browning and a certain degree of protection of the hydroxycinnamic acids, but in the presence of laccase it was not effective enough. Consequently, the selected strain of Metschnikowia pulcherrima (MP1) can be considered an interesting alternative to sulphur dioxide for preventing browning in white grape must, but only in conditions of healthy grapes.
... Grapes are particularly vulnerable to Botrytis rot during maturity, but the use of chemical products to control the disease is not feasible due to the risk of contaminating production with chemical residues. Moreover, B. cinerea -induced oxidation has been reported to negatively impact grape quality, musts, and wines (Lorrain et al. 2012 ). Additionally, the troubling development of resistance to chemical fungicides by Botrytis (Leroux 2007 ) emphasizes the urgent need to minimize pesticide effects on the environment. ...
Botrytis cinerea poses a recurring threat to viticulture, causing significant yield losses each year. The study explored the biocontrol capabilities of commercially used winemaking yeasts as a strategy to manage B. cinerea in grape berries. The winemaking yeast strains - Saccharomyces cerevisiae ES181, Saccharomyces pastorianus KBG6, S. cerevisiae BCS103, Lachancea thermotolerans Omega, and Torulaspora delbrueckii TD291 - reduced B. cinerea growth and conidiation in vitro. Furthermore, they demonstrated a decreased disease severity and number of conidia in grape berries. Among these strains, S. cerevisiae BCS103 was the most effective, inducing the expression of the defense-related gene PR4 in berries. Its diffusible compounds and volatile organic compounds also reduced the expression of BcLTF2, a positive regulator of B. cinerea conidiogenesis. The examined winemaking yeast strains, especially S. cerevisiae BCS103, demonstrated effective inhibition of B. cinerea in vitro and in grape berries, influencing key defense genes and reducing BcLTF2 expression, offering potential solutions for disease management in viticulture. The study underscores the promise of commercially available winemaking yeast strains as eco-friendly tools against B. cinerea in viticulture. Leveraging their safety and existing use in winemaking offers a potential avenue for sustainable disease management.
... BOT, caused by the necrotrophic fungal pathogen Botrytis cinerea, infects mostly inflorescences and ripening berries (Martinez et al., 2005). It could be responsible for important crop losses and qualitative oenological damage (Ky et al., 2012;Steel et al., 2013). Finally, BR, caused by the fungi Phyllosticta ampelicida, is a foliar and a cluster disease currently becoming increasingly important in Europe following current efforts to reduce fungicide use (Molitor and Beyer, 2014). ...
Grapevine is subjected to a range of pathogen attacks requiring a sustained phytosanitary protection during the vegetative phase to prevent yield losses and ensure harvest quality. However, the link between disease severities and crop losses has been little studied. We conducted, on two sites near Bordeaux (France) during three years, a field experiment to study the relationship between the severities of mildews and rots (on foliage and cluster) and crop losses (mass of grape clusters harvested and potential alcohol content). As expected under oceanic climate, downy mildew (DM) was the most prevalent disease in all sites and years. The three levels of grapevine phytosanitary protection used in the experiment generated contrasted epidemic situations. This dataset was used to fit phenomenological relationships describing how yield losses (modeled as the difference between the attainable and actual yields) increased with DM severity. We found that yield losses significantly increased with DM severity on clusters regardless of year or site. Yield losses also decreased with DM severity on foliage but to a variable extent depending on years and sites. This suggests that the transfer of DM epidemics from the foliage to the clusters is variable. We further show that such foliage-cluster transfer could relate to an humidity index during the period of major susceptibility of clusters to DM infections, between stages 53 to 79. Finally, we quantified how the severity of DM reduce the potential alcohol content while discussing the mechanisms underlying the annual variability of these relationships.
... One of the major problems in oenology currently is enzymatic browning [1], especially when grapes are affected by the filamentous fungi Botrytis cinerea [2]. Browning is an enzymatic oxidation process in several foods that causes the appearance of a brown colour, which sometimes leads consumers to reject them [3]. ...
One of the problems that most seriously affects oenology today is enzymatic browning, especially when grapes are infected by grey rot. We studied the capacity of glutathione (GSH) and a specific inactivated dry yeast rich in glutathione (IDY-GSH) to protect white grape must from browning compared to that of sulphur dioxide (SO2). The results indicate that SO2 drastically reduces the oxygen consumption rate (by around 72%), protects hydroxycinnamic acids from oxidation and prevents grape must against browning even in the presence of laccase. Specifically, the presence of SO2 reduced the colour’s blue–yellow component (b*) by around 91% in control conditions and around 76% in the presence of laccase. GSH, pure or in the form of IDY-GSH, also reduces the oxygen consumption rate (by 23% and 36%, respectively) but to a lesser extent than SO2. GSH also favours the formation of grape reaction product (GRP) from hydroxycinnamic acids and effectively protects grape must against browning in healthy grape conditions. Specifically, the presence of GSH reduced b* by around 81% in control conditions. Nevertheless, in the presence of laccase, it was not effective enough, reducing b* by around 39% in the case of pure GSH and 24% in the case of IDY-GSH. Therefore, both forms of GSH can be considered as interesting alternative tools to SO2 for preventing browning in white grape must, but only when the grapes are healthy.
... And for another microbial mold, PAs do not seem to exert a significant effect in vivo. Grape skins with high levels of PAs were infested with grey mold (Ky et al. 2012). Whereas in vitro, grey mold is sensitive to PAs, Aspergillus flavus is able to respond to being removed by binding precipitation with PAs (Perret, Pezet, and Tabacchi 2003;Yoshida et al. 2022). ...
Proanthocyanidins (PAs) are a class of polymers composed of flavan-3-ol units that have a variety of bioactivities, and could be applied as natural biologics in food, pharmaceuticals, and cosmetics. PAs are widely found in fruit and vegetables (F&Vegs) and are generally extracted from their flesh and peel. To reduce the cost of extraction and increase the number of commercially viable sources of PAs, it is possible to exploit the by-products of plants. Leaves are major by-products of agricultural production of F&Vegs, and although their share has not been accurately quantified. They make up no less than 20% of the plant and leaves might be an interesting resource at different stages during production and processing. The specific structural PAs in the leaves of various plants are easily overlooked and are notably characterized by their stable content and degree of polymerization. This review examines the existing data on the effects of various factors (e.g. processing conditions, and environment, climate, species, and maturity) on the content and structure of leaf PAs, and highlights their bioactivity (e.g. antioxidant, anti-inflammatory, antibacterial, anticancer, and anti-obesity activity), as well as their interactions with gut microbiota and other biomolecules (e.g. polysaccharides and proteins). Future research is also needed to focus on their precise extraction, bioactivity of high-polymer native or modified PAs and better application type.
... A statistically significant difference (p < 0.05) in the content of phenolic compounds in wine produced from healthy grapes and grapes affected by Botrytis cinerea was shown for all compounds except for p-coumaric acid (p = 0.154) ( Table 5). Grape skin is the main source of phenolic compounds, therefore direct contact of skin with Botrytis cinerea causes a decrease in its content [52]. Our results showed a lower content of phenolic compounds in wines produced from moldy grapes in comparison with the wines produced from healthy ones (Table 5), which is in line with the previously mentioned literature data. ...
The phenolic composition and antioxidant activity of wine and fermented pomace (FP) from Cabernet Sauvignon grapes harvested at three ripening stages were evaluated using LC-MS/MS and spectrophotometric analyses. An investigation of grey mold’s (Botrytis cinerea) influence on wine phenolic content modulation was conducted as well. Finally, the influence of the plant’s ripening stage on the dynamics of the phenolic compounds extracted from wine and FP obtained from fully ripe grapes was evaluated. In this study, the content of catechin, epicatechin, quercetin, and p-coumaric, gallic, and syringic acids was analyzed. Wine and FP were obtained after extended maceration during the spontaneous and inoculated fermentation of fully ripe grapes. When comparing the wine and FP obtained from véraison, fully ripe, and overripe grapes, catechin was the most abundant in wine (40.13 ± 3.25 mg/L) and quercetin in FP (10.96 ± 0.14 mg/kg). A decrease in analyzed phenolic compounds was noticed in wine produced from grapes affected by Botrytis cinerea, and the highest depletion was found for quercetin. The use of a winemaking technique that involved differing maceration periods and inoculation using yeasts as well as spontaneous fermentation significantly modulated the phenolic content of derived wines and FP. The dynamics of the phenolic compounds extracted into wine, evaluated using a principal component analysis (PCA), highlighted contents of catechin and epicatechin. After a decrease in maceration, the PCA revealed a notable content of gallic and syringic acids, as well as quercetin, in samples of FP. This study offers a perspective for future research and the development of functional food with a high content of phenolic compounds originating from red grape products, such as wine and fermented pomace.
... Volatile compounds elicited during fungal growth vary according to abiotic conditions, including nutrient availability, temperature, microbial interactions, and substrate [6,7]. Several volatile compounds have been selected as markers for B. cinerea, including 1-octen-3-ol, 1-octen-3-one, and 3-octanone, which are widely reported to cause mouldy or mushroom odours associated with fungal infections [8] and are therefore ideal targets for pathogen detection. ...
Fungal infection of grape berries (Vitis vinifera) by Botrytis cinerea frequently coincides with harvest, impacting both the yield and quality of grape and wine products. A rapid and non-destructive method for identifying B. cinerea infection in grapes at an early stage prior to harvest is critical to manage loss. In this study, zeolitic imidazolate framework-8 (ZIF-8) crystal was applied as an absorbent material for volatile extraction from B. cinerea infected and healthy grapes in a vineyard, followed by thermal desorption gas chromatography-mass spectrometry. The performance of ZIF-8 in regard to absorbing and trapping the targeted volatiles was evaluated with a standard solution of compounds and with a whole bunch of grapes enclosed in a glass container to maintain standard sampling conditions. The results from the sampling methods were then correlated to B. cinerea infection in grapes, as measured and determined by genus-specific antigen quantification. Trace levels of targeted compounds reported as markers of grape B. cinerea infection were successfully detected with in-field sampling. The peak area counts for volatiles 3-octanone, 1-octen-3-one, 3-octanol, and 1-octen-3-ol extracted using ZIF-8 were significantly higher than values achieved using Tenax®-TA from field testing and demonstrated good correlation with B. cinerea infection severities determined by B. cinerea antigen detection.
... Volatile compounds elicited during fungal growth may vary according to abiotic conditions, including nutrient availability, temperature, microbial interactions, and substrate [6,7]. Several volatile compounds have been selected as markers for B. cinerea, including 1-octen-3-ol, 1-octen-3-one, and 3-octanone, which are widely reported to cause mouldy or mushroom odours associated with fungal infections [8], and are therefore ideal targets for pathogen detection. ...
Fungal infection of grape berries (Vitis vinifera) by Botrytis cinerea frequently coincides with harvest, impacting both the yield and quality of grape and wine products. A rapid and non-destructive method for identifying B. cinerea infection in grapes at an early stage prior to harvest is critical to manage loss. In this study, zeolitic imidazolate framework-8 (ZIF-8) crystal was applied as an absorbent material for volatile extraction from B. cinerea-infected and healthy grapes in a vineyard followed by thermal desorption gas chromatography-mass spectrometry. The performance of ZIF-8 to absorb and trap targeted volatiles was evaluated with a standard solution of compounds and with a whole bunch of grapes enclosed in a glass container to maintain standard sampling conditions. Results from sampling methods were then correlated to B. cinerea infection in grapes as measured and determined by Genus specific antigen quantification. Trace levels of targeted compounds reported as markers of grape B. cinerea infection were successfully detected with in-field sampling. Peak area counts for volatiles 3-octanone, 1-octen-3-one, 3-octanol, and 1-octen-3-ol extracted using ZIF-8 were significantly higher than values achieved using Tenax®-TA from field testing and demonstrated good correlation with B. cinerea infection severities determined by B. cinerea antigen detection.
... BBR is responsible for considerable economic losses in many crops, including grapes, in both field and storage conditions. Specifically, in wine grapes, the disease can result in a decrease in yield and a reduction in wine quality [2,3]. The epidemiology of the disease is mostly determined by factors such as seasonal weather patterns [4,5], cultivar susceptibility [6], genetic structure of pathogen populations [7], host plant ontogenic resistance and vigor [8][9][10], and bunch structure and micro-climatic conditions [11,12]. ...
In organic phytosanitary management of vineyards, it is crucial to understand the available pathogen control alternatives in order to progress towards a more sustainable form of viticulture. The objective of this study was to evaluate the efficacy of seven biofungicides registered in Chile for the prevention and treatment of Botrytis Bunch Rot (BBR), and to test a novel fungicide composed of chitosan and riboflavin (CH-RF). Biofungicides including Trichoderma spp., Aureobasidium pullulans, and Melaleuca alternifolia were evaluated using biotests with grapevine berries. Registered products (specifically biological control agents) significantly reduced the in vitro growth of B. cinerea. However, the degree of pathogen control varied significantly among products in grapevine berries of the Chardonnay cultivar, and disease incidence and severity changed depending on the inoculation time. High control effectiveness was achieved with two biofungicides, A. pullulans (average efficacy 34%) and M. alternifolia oil (average efficacy 29%). In vitro tests showed CH-RF significantly reduced mycelial growth of B. cinerea. Noticeable differences between the new CH-RF fungicide (incidence under 50% and infection score under 1) and A. pullulans- and M. alternifolia-based products were detected in grapevine berries. Therefore, the new experimental formulation CH-RF constitutes a promising alternative for the control of B. cinerea and provides a basis for further research.
... Responsible for grey rot (Botrytis bunch rot BBR) and noble rot in vineyards, B. cinerea is a necrotrophic multihost fungus that is well-known to winegrowers as such (Amiri et al., 2008;Combrinck et al., 2011;Fedele et al., 2020;Olea et al., 2019;Šernaitė et al., 2020;Wang et al., 2010). At harvest, a BBR severity threshold as low as 5 % has been demonstrated to lead to irreversible organoleptic losses in the wine produced (Ky et al., 2012). The decrease in ontogenic resistance of grapevine fruit has been well characterised during berry development and maturation. ...
Eugenol (2-methoxy-4-(2-propenyl)-phenol), widely spread in various plants, notably clove, basil and bay, is a well-known antifungal and antibiotic molecule that is abundant in the hybrid grapevine cultivar Baco blanc (Vitis vinifera × Vitis riparia × Vitis labrusca). This variety, created by François Baco (19th century), is confirmed in this study as highly resistant to Botrytis cinerea by comparing fruit rot incidence and severity with two Vitis vinifera cultivars: Folle Blanche and Ugni Blanc. According to two major antibiosis modes of action, i.e., direct or volatile, this study demonstrated the efficiency of eugenol in vitro by also investigating precisely the effect on B. cinerea of small concentrations of eugenol, 3 to 4 ppm, corresponding to IC10. Moreover, the vapour-inhibiting effect was shown to be highly powerful. The total eugenol concentration peaked at the veraison stage, exceeding 1000 μg×kg-1 in the skin of Baco blanc berry under our conditions. At this point, leaf removal in the bunch zone induced a significant increase in eugenol (32 %), from 1118 to 1478 μg×kg-1, which was also associated with a significant decrease in B. cinerea infection in the vineyard. Thus, for the first time, eugenol, as an endogenous molecule of Baco blanc, was clearly demonstrated to be an inducible compound in the vineyard. Furthermore, significant intravarietal variability in eugenol concentrations according to the Baco blanc clone was demonstrated to be associated with significant differences in fruit susceptibility to the plant pathogen assessed in biotests. Interestingly, in keeping with fruit ontogenic resistance, a significant negative correlation was established between the technological maturity of berries and the total eugenol content in the berry skin. Finally, the time-progress study of the two biochemical forms of eugenol (bound vs. free eugenol) allowed us to hypothesise the effectiveness against the plant pathogen of some precursor forms of eugenol, and the corresponding biochemical structures are currently being investigated. Thus, eugenol appears to be a key biochemical marker of ontogenic resistance in the hybrid cultivar Baco blanc.
... One of the problems that most seriously affects oenology today is enzymatic browning [1], especially when the grapes are infected by grey rot [2]. Enzymatic browning is an oxidation process that occurs in many foods that increases the brown color [3], which often leads consumers to reject them. ...
Sulfur dioxide is the most used additive today for preventing browning in grape musts and wines. However, since wine consumers are increasingly interested in healthier wines, the wine industry is keen to reduce its use. Some promising alternatives to sulfur dioxide have been proposed in recent years, including glutathione, both pure and in the form of inactivated yeasts, and Metschnikowia pulcherrima used as a bioprotective agent. Some information exists about the protective effect against oxidation of glutathione but there is very few about the use of bioprotection for that purpose. Supplementation with glutathione, regardless of the commercial form, reduced oxygen consumption and browning intensity when laccase was not present in the grape juice. Metschnikowia pulcherrima also reduced browning intensity in the absence of laccase but increased the total oxygen consumption. However, in the presence of laccase, glutathione and Metschnikowia pulcherrima were not effective enough to adequately prevent the grape juice from browning. Glutathione, both pure and in the form of inactivated yeasts, and Metschnikowia pulcherrima are interesting tools for protecting grape must against browning, and thus reducing the use of sulfur dioxide.
... Based on our previous results, Botrytis enzymes are able to modify some stilbenes, such as resveratrol and ε-viniferin. The aim could be a detoxication of these molecules to allow for Botrytis development (Goetz et al. 1999, Ky et al. 2012. Hence the presence of oligomerized stilbenes in the SE extract, that prevent laccase production, might reduce the metabolization/degradation of stilbene forms (resveratrol and ε-viniferin) that can be metabolized by Botrytis and thus guarantee their integrity and their antimicrobial activity. ...
La vigne (Vitis vinifera L.) est une des cultures les plus largement répandues dans le monde et présente une importance économique majeure. Elle est sujette à de nombreuses maladies dont les plus répandues sont d’origine fongique. En France, parmi les maladies les plus dommageables nous pouvons citer Plasmopara viticola, agent responsable du mildiou, et Botrytis cinerea, agent de la pourriture grise. Le contrôle de ces maladies est largement effectué par l’application de pesticides issus de synthèse chimique. Or, ces composés présentent des effets néfastes sur l’environnement et la santé humaine. Face à ces problématiques, des solutions alternatives doivent être développées et proposées telle que l’utilisation de produits naturels dotés d’activité antimicrobienne préférentiellement obtenus à partir de co-produits de l’agriculture. Dans cette étude, nous avons considéré la possibilité d’utiliser des extraits enrichis en stilbènes, des métabolites végétaux aux propriétés antioxydantes et antimicrobiennes, comme solution de biocontrôle des maladies. Les stilbènes sont synthétisés par plusieurs espèces végétales dont la vigne qui présente une forte diversité de stilbènes dont des tétramères du resvératrol. Ces dernières molécules sont en quantité importante dans les parties pérennes de la plante (sarments, ceps et racines). De plus, l’efficacité antimicrobienne de tels stilbènes oligomérisés est remarquable. Ainsi, nous avons choisi de produire un extrait enrichi en stilbènes à partir de ceps et de racines de vigne. Une optimisation de la méthode d’extraction des stilbènes complexes a été mise en œuvre. Dans le but de produire un extrait selon une approche durable, nous avons comparé deux solvants dits « verts », l’éthanol et l’acétate d’éthyle. Nous avons retenu l’acétate d’éthyle pour sa plus grande efficacité d’extraction. Deux extractions successives dans les proportions en solvant de 100 puis de 85 % permettent l’obtention d’un meilleur rendement. L’extrait obtenu est riche en stilbènes (50% de l’extrait) et contient des formes complexes (dimères et tétramères). Au laboratoire, cet extrait a démontré une forte activité oomycide contre le mildiou de la vigne, P. viticola. Une formulation a été développée afin d’optimiser l’action de l’extrait et de pouvoir évaluer son efficacité in natura. En serre, l’extrait a montré une capacité de réduction de la sévérité de la maladie de 40 % et jusqu’à 50 % lorsque formulé. De plus, l’application de l’extrait sur les feuilles de vigne déclenche des réponses de défense chez la plante. Concernant l’effet de l’extrait stilbénique envers B. cinerea, une forte activité fongicide a été relevée. Nous avons déterminé les stilbènes responsables de cette activité parmi les stilbènes majeurs de l’extrait : les plus actifs sont la r-viniférine, le resvératrol et l’ε-viniférine. Par ailleurs, informés que certaines enzymes du sécrétome de B. cinerea, les laccases, peuvent dimériser certains stilbènes, nous avons suivi l’action de telles enzymes sur les stilbènes de notre extrait puis déterminé l’activité fongicide de l’extrait biotransformé. Nous avons montré que plusieurs stilbènes de l’extrait, notamment des dimères, sont transformés, alors que d’autres ne peuvent l’être, tel la plupart des tétramères. Ainsi, pour la première fois, par ces travaux, nous avons mis en évidence la formation d’hopéaphénol, de r-viniférine et de r2-viniférine à partir d’ε-viniférine. L’activité anti-Botrytis de l’extrait biotransformé n’est que peu impactée. De plus, nous avons noté que l’extrait de stilbènes agit de façon négative sur la production de laccases. L’ensemble de ces résultats confirment la pertinence de poursuivre le développement d'extraits enrichis en stilbènes oligomérisés pour leur utilisation potentielle comme approche alternative pour la prévention et le contrôle de P. viticola et B. cinerea dans les vignobles.
... Botrytis cinerea is the causal agent of grey mould, which is one of the most important and damaging diseases affecting wine grapes and table grapes worldwide. This agent is a major necrotrophic fungal pathogen of numerous host plants (Elad et al., 2016a;Elad et al., 2016b) and leads to considerable yield and quality losses in the field as well as in wine production and/or storage (Ky et al., 2012;Sharma et al., 2009). Although several anti-Botrytis synthetic fungicides are available, their use in pre-or postharvest conditions is not considered sustainable due to the possible negative consequences, including (i) the appearance of resistant strains (Hahn, 2014;Leroux, 2004) and (ii) the adverse effects of the fungicides on the environment and/or human health (Coleman et al., 2012). ...
In table grapes (cv. Thomson Seedless), the antifungal activity against Botrytis cinerea was further analysed and compared between two high potential bacterial biological control agent (BCA) strains, Bacillus velezensis BUZ-14 and B. ginsengihumi S38. Two commercial biocontrol products (BPs), served as standards of comparison, Amylo-X® and Serenade Max®, also based on Bacillus BCA strains. The main mode of action quantified for all the strains was antibiosis due to hydrosoluble and volatile metabolites and their combinations. The BUZ-14 strain was the most active BCA strain, demonstrating significant disease reduction exceeding 60 % when used in the culture form grown in 863 medium, including living cells (LCs) and cell-free supernatant (CFS). Both BPs exhibited significantly reduced efficacy of their CFS fraction (< 10 %) compared with that of the two BCA strains, confirming their high antibiosis potential. The novel methodology allowed us to demonstrate the significant effect of the BCA culture medium on volatilome (VOC) antagonist efficacy. The S38 strain achieved the highest disease reduction (90 %) owing to the greatest production of VOCs in the richest MOLP (Medium Optimum Lipopetide Production) culture medium, whereas grape juice was the least favourable medium for VOC efficacy for both bacterial strains (BUZ14 and S38). The overall poor activity of living Bacillus cells in all the BCA and BPs tested is discussed based on the low capacity of the BCA strains to grow in the berry. Then, the presence of living cells is also discussed with the possibility that these cells are not required in field applications of such BCA strains in this genus. Moreover, different environmental suboptimal conditions, including temperature (22 and 27 °C) and relative humidity (RH) (100 and 85–95 %), were tested, and BUZ-14 exhibited the highest Botrytis reduction at both temperatures and RH values. However, no significant differences were observed between temperatures or RH values for the same BCA. Further studies in vineyard conditions and applications, such as biofumigation or active packaging, will be performed to confirm the new findings reported in this investigation.
... In warm/hot, dry growing regions, gray mold is more prominent. Gray mold is a necrotrophic fungus ubiquitous to crops and particularly fruit production (Ky et al., 2012). It initially infects fruit from the surface, followed by degradation of subtending tissues, leading to a loss of yield while compromising quality-related metabolites, such as organic acids, phenolics, and volatiles. ...
Wine grape (Vitis vinifera L.) is the most widely cultivated fruit crop in the world. However, the climactic characteristics in some growing regions are suboptimal for grape production, including short season length and excess precipitation. Grape growers can utilize an array of methods to mitigate these issues, including “early leaf removal,” a management practice involving the removal of leaves from selected basal nodes along shoots around bloom. This meta-analysis reviews the extensive literature on this practice, with specific regards to application at “pre-bloom” (PB). One hundred seventy-five publications on the topic of “early leaf removal” were identified using key terms and subsequently narrowed via eight data curation steps. The comparison between treated (PB) and control plants in these studies revealed two important results. First, PB lowered bunch rot disease (−61%), partially through reducing the compactness of clusters. Second, PB promoted a significant increase in fruit total soluble solids (°Brix, +5.2%), which was related to the increase in the leaf-to-fruit ratio. Furthermore, cultivar and rootstock were found to have a large influence on the success of PB, while the contribution of climate was smaller. In conclusion, PB significantly lowers yield and bunch rot disease and increases °Brix, both of which improve grape and wine quality.
... The isolates of P. kudriavzevii L18 (a producer of antifungal VOCs which completely inhibited the incidence of P. glabrum) and Z. meyerae L29 (with pectinase, chitinase and β-glucanase activity and biofilm formation which reduced 70% of the incidence of P. glabrum) are proposed as suitable biocontrol agents against P. glabrum. Foods 2020, 9, 1864 2 of 22 which include reduction of total phenolic compounds of seeds and skin because fungal laccases are well described [9]. Moreover, it is implicated in the production of earthy "off" aromas in wine by geosmin and other volatile compounds synthesis [10]. ...
Biocontrol is one of the most promising alternatives to synthetic fungicides for food preservation. Botrytis cinerea, Alternaria alternata, and Aspergillus section Nigri are the most concerning pathogens for grape development. However, frequently, other species, such as Penicillium glabrum in this study, are predominant in spoiled bunches. In this work, 54 native yeasts from vineyards were screened by direct confrontation in potato dextrose agar plates as antagonists against P. glabrum. Isolates of Pichia terricola, Aureobasidium pullulans, and Zygoascus meyerae were selected for their antagonist activity in vitro, plus isolates of Pichia kudriavzevii, Hormonema viticola, and Hanseniaspora uvarum were used as negative controls. However, in vivo, confrontations in wounded grapes showed disagreement with direct confrontation in vitro. P. terricola, P. kudriavzevii, H. viticola, Z. meyerae, and H. uvarum significantly reduced the incidence of P. glabrum on grapes. Nevertheless, P. terricola, H. viticola, and H. uvarum themselves spoiled the wounded grapes. Inhibitions were associated with different mechanisms such as the production of volatile organic compounds (VOCs), lytic enzymes, biofilm formation, and competition for nutrients. The isolates of P. kudriavzevii L18 (a producer of antifungal VOCs which completely inhibited the incidence of P. glabrum) and Z. meyerae L29 (with pectinase, chitinase and β-glucanase activity and biofilm formation which reduced 70% of the incidence of P. glabrum) are proposed as suitable biocontrol agents against P. glabrum.
... They may cause severe to total loss in grapevine production [8] [27]. Grape moths are a major pest in vineyards: They cause the direct loss of some berries from flowering to harvest [28], while their boreholes in the berries also allow Botrytis infections with numerous qualitative and quantitative consequences [29]. When converting to organic farming, growers are required to stop using all synthetic plant protection products. ...
Given the need to reduce pesticide use and rising consumer demand for healthy food, organic vineyard areas have increased since 2000. Converting to organic farming requires numerous changes in pest and disease management, fertilization and weeding techniques. These changes can lead to difficulties in sustaining yields. Some studies have highlighted higher yields in conventional farming than in organic agriculture, but knowledge on yield dynamics during conversion is lacking. A set of 26 plots, under conventional management and in conversion to organic farming, were monitored from 2013 to 2016 in southern France throughout the three-year conversion phase to investigate the dynamics of grape yield and yield components. The survey showed that the yield and yield components remained similar levels as in conventional farming from the third year of conversion. However, the first two years of conversion were a transitional and less successful period during which yield and yield components decreased. Based on the in-depth analysis of the yield components, we have put forwards hypotheses on the processes at play and technical advice that could support winegrowers as they convert to organic farming.
... Parmi ces trois situations, le dépassement du seuil déclenchant une intervention est apparu 11, 18 ou 40 jours avant récolte. Lorsqu'aucun traitement n'était préconisé, le seuil couramment admis (Ky et al, 2012) de 5 % de dégâts de botrytis n'a pas été atteint, ce qui justifie la préconisation faite. Lorsqu'un traitement était préconisé en plus de l'effeuillage, le seuil de 5 % a systématiquement été dépassé (5,1% ; 5,9% ; 8,5%) mais de peu deux fois sur trois. ...
La double performance, économique et environnementale, constitue un enjeu majeur pour la filièreviticole qui demeure très dépendante de l’utilisation des pesticides. A elle seule, la lutte fongicidereprésente 80% des intrants. Un OAD (DeciTrait®) regroupant l’ensemble des informations nécessairesà la mise en œuvre d’une protection économe en intrants vis-à-vis des principales maladiescryptogamiques (mildiou - oïdium - black-rot - botrytis) a été conçu dans une démarche collaborative ausein d’un projet CASDAR. Cet OAD est simple à utiliser et propose à l’utilisateur une stratégie deprotection personnalisée sur la base des informations et connaissances recueillies. Les essaisbiologiques conduits au sein du projet CASDAR mettent clairement en évidence le potentiel deréduction des intrants phytosanitaires permis par cet OAD, tant sur la réduction du nombre detraitements que sur la dose appliquée.
Botrytis cinerea is a well-known pathogen that can be challenging to control in crops, such as wine grapes. To adapt to the increasing problems of climate change and strain resistance it is important to find new methods to detect Botrytis cinerea and differentiate strains. These methods include strain differentiation and classification by simple sequence repeats (SSRs) and early detection of the fungus by qPCR. Various strains were analysed using SSR markers and either agarose gel electrophoresis or capillary sequencing via PCR. A sensitive qPCR method was refined to achieve an early detection method for the pathogen. The results demonstrate promising ways to distinguish between strains using both agarose gel electrophoresis and capillary sequencing as well as to detect infection before it becomes visible on grapes. This can be used to further understand and analyse different Botrytis cinerea strain characteristics such as laccase activity, regional or annual effects. The early detection method can be used to better prepare growers for an impending infection so that targeted efforts can be made.
Botrytis cinerea is one of the most destructive diseases for Vitis vinifera, and grape bunch morphology plays a crucial role in grey mould infection. However, the common visual evaluation technique for assessing bunch compactness suffers from a lack of sensitivity and objectivity. This study proposes a standardised digital twin shape analysis to evaluate the morphology of grape bunches. Seventeen Pinot Gris and six Pinot Noir clones were considered. The grey mould severity was evaluated in the field. Fully ripened bunches (138) were gathered and then photographed at different angles. Digital twin reconstruction was carried out using the photogrammetry technique. Several measures and indices were extracted from each digital twin. Principal component analysis and multiple linear regression models were applied to identify the descriptors most related to grey mould symptoms. The results revealed that the most significant factors include the berries density, the estimated empty volume, and the bunch width. These results show that digital twins are a suitable tool for estimating grey mould infection risks. Two linear models, divided into 2D and 3D descriptor models, were proposed. The R-squared value and the root mean square error were compared between the models. For Pinot Gris, from the 2D to the 3D models, the R-squared value rose from 0.656 to 0.838, while the error decreased from 1.713 to 1.175. In Pinot Noir, the 2D model did not provide sufficient robustness, while the 3D model had an R-squared value of 0.936 and an error of 0.290.
Wine is a highly complex mixture of components with different chemical natures. These components largely define wine's appearance, aroma, taste, and mouthfeel properties. Among them, aroma is among the most important indicators of wine's sensory characteristics. The essence of winemaking ecosystem is the process of metabolic activities of diverse microbes including yeasts, lactic acid bacteria, and molds, which result in wines with complicated and diversified aromas. A better understanding of how these microbes affect wine's aroma is a crucial step to producing premium quality wine. This study illustrates existing knowledge on the diversity and classification of wine aroma compounds and their microbial origin. Their contributions to wine characteristics are discussed, as well. Furthermore, we review the relationship between these microbes and wine aroma characteristics. This review broadens the discussion of wine aroma compounds to include more modern microbiological concepts, and it provides relevant background and suggests new directions for future research.
Sulfur dioxide is the most used additive today for preventing browning in grape musts and wines. However, since wine consumers are increasingly interested in healthier wines, the wine industry is keen to reduce its use. Some promising alternatives to sulfur dioxide have been proposed in recent years, including glutathione, both pure and in the form of inactivated yeasts, and Metschnikowia pulcherrima used as a bioprotective agent. Some information exists about the protective effect against oxidation of glutathione but there is very few about the use bioprotection for that purpose. Supplementation with glutathione, regardless of the commercial form, reduced oxygen consumption and browning intensity when laccase was not present in the grape juice.
Metschnikowia pulcherrima also reduced browning intensity in the absence of laccase but increased the total oxygen consumption. However, in the presence of laccase, glutathione and Metschnikowia pulcherrima were not effective enough to adequately prevent the grape juice from browning.
Fungal diseases such as powdery mildew and bunch rots reduce yield and quality of grapes and affect chemical and sensory properties of wine. The effects of powdery mildew, downy mildew, botrytis bunch rot, and ripe rot on grape and wine quality are reviewed. Approaches to detection and quantification of fungal contamination are examined, including enzyme, immunological and DNA assays and spectroscopy. Such approaches offer efficient and or objective means of quantifying fungal contamination in the vineyard and at the winery to facilitate quality control and decisions about use of grapes. Alternatives to conventional fungicides for disease management and their effects on quality are examined also.
Botrytis cinerea, one of the most critical diseases in strawberry cultivation, significantly reduces strawberry production worldwide. One of the standard practices for B. cinerea management is chemical fungicides. However, the effects of these fungicides have decreased in time due to fungal resistance. Besides, these fungicides have become increasingly unacceptable because of both public concerns and environmental pollution. So, it is prominent to search for environmentally-friendly control agents to fight against Botrytis cinerea. Phenolic compounds are well known to play a significant role in plant defence mechanisms against plenty of insect pests and plant pathogens. For this purpose, in this study, we determined the effects of grey mould disease on free radical scavenging ability (DPPH), the total phenolic compound, and phenolic contents of detached leaves of different strawberry cultivars. Grey mould resulted in a decrease in free radical scavenging ability (DPPH%) and total phenol content in all strawberry cultivars apart from the ‘Kara’ cultivar. ‘Kara’ had the highest DPPH content (84%) and the entire phenol content (1475 mg GAE 100 g‑1). We also identified the gallic acid, ellagic acid, caffeic acid, p-coumaric acid, myricetin, quercetin, kaempferol in the detached strawberry leaves quantified by HPLC techniques. Grey mould decreased in some of the strawberry leaves’ phenolic content, while it increased in some of the strawberry leaves’ phenolic content. According to the obtained results, ‘Kara’ was more tolerant against Botrytis cinerea than ‘Osmanlı’ and ‘Tüylü’.
Red wines obtained by microvinification in the laboratory and adjusted to three pH values (3.2, 3.6 and 4.0) were examined for the formation of anthocyanin-derived pigments throughout nine months of storage in bottles at 15°C. The formation of the pigments was also followed in aliquots of the wines at pH 3.2 with added acetaldehyde (800 mg/L). Pigment analyses were accomplished by HPLC using double on-line detection by diode array spectrophotometry and mass spectrometry. Two different types of pigments were observed. The first were products derived from the condensation between anthocyanins and flavanols by ethyl bridges. The second corresponded to products showing an additional heterocycle in the anthocyanin structure (vitisin-like pigments); of these, vitisin B, which derives from malvidin 3-monoglucoside, was the most important one. Products similar to vitisin B derived from other anthocyanins were also detected, as well as structurally related pigments containing flavanol moieties. The formation of all these pigments involves the acetaldehyde, since they appeared or were enhanced as a result of its addition, and were also favored in more acidic wines.
Resveratrol (trans-3,5,4'-trihydroxystilbene), a grapevine phytoalexin related to grey mold resistance, is produced by grape berries of Vitis vinifera L. and Vitis labrusca L. in response to UV-irradiation; its production decreases during fruit ripening. In vinifera varieties, the resveratrol content of whole berries steadily declined between the green stage and complete maturity, nearing zero in ripe fruit, while a pronounced decrease was observed in the berries of V. labrusca after veraison. On the other hand, resveratrol synthesis was found to be located in the skin, thus showing that the principal resistance of grapes to fungal attacks takes place at this level. Finally, the decrease of resveratrol production during maturation was also confirmed by the fact that there is a clear negative correlation between the resveratrol content of grape skin and the developmental stage of berries measured by the sugar concentration of juice.
Grape phenolics are structurally diverse, from simple molecules to oligomers and polymers that are usually designated 'tannins,' referring to their ability to interact with proteins. Anthocyanin pigments and tannins are particularly important for red wine quality. Their extraction depends on their location in the berry and their solubility. All phenolic compounds are unstable and undergo numerous enzymatic and chemical reactions. Color and taste changes during red wine aging have been ascribed to anthocyanin-tannin reactions. The structures and properties of tannins and pigmented tannins from these reactions are often misunderstood. Current research on wine phenolic composition is reviewed, with emphasis on the following issues: (1) reactions of tannins yield both larger polymers and smaller species; (2) anthocyanin reactions can generate colorless species as well as polymeric and small various pigments; (3) some polymeric pigments undergo sulfite bleaching while some low molecular weight pigments do not; (4) polymers are both soluble and astringent, so the astringency loss during aging may involve cleavage rather than polymerization; and (5) sensory properties of anthocyanins and tannins are modulated by interactions with other wine components.
The hypothesis that grey mould incidence would be positively correlated to grapevine canopy development was confirmed over a period of 3 years (2004–2006) on Aranel cultivar in an experimental vineyard near Montpellier, south France. Different levels of vine growth were generated by implementing three management schemes: (i) perennial cover crop, (ii) chemical weed control and (iii) irrigation and fertilisation. Grey mould incidence was assessed at harvest, together with various sets of variables linked with canopy microclimate, shoot vigour, vine capacity, cluster architecture, yield components and fruit composition. Significant positive correlations were observed between disease incidence and key variables of shoot vigour and vine capacity: total leaf number, leaf dry matter, leaf layer number, leaf area per metre of row, pruning mass and nitrogen accumulation. In 2004, Botrytis cinerea developed in all experimental plots because climatic and microclimatic conditions were conducive to grey mould. The climatic and microclimatic variables that significantly favoured grey mould development were: precipitation, duration of relative humidity >90% in the canopy and low potential evapotranspiration. However, in 2005 and 2006, under dry summer conditions, disease developed only in the most vigorous vines, which were both irrigated and fertilised. These vines showed a very high canopy growth, very compact clusters and a delayed fruit maturity. This evidenced that unfavourable climatic conditions for the disease development can be counterbalanced by conditions of high vine growth and associated canopy and cluster features.
Grey mould caused by Botrytis cinerea is one of the most important diseases of grapes. Between bloom and veraison, grape berries are resistant to B. cinerea, although they can harbour the pathogen without any visible signs of disease development. After veraison, B. cinerea can produce disease in susceptible grape varieties (e.g. Gamay), but remains quiescent in resistant varieties (e.g. Gamaret). Pathogen resistance in the quiescent stage is not yet fully understood, but is thought to involve multiple parameters including chemical and mechanical factors. The pathogenesis of B. cinerea is essentially linked to excretion of lytic enzymes such as polyphenoloxidases or laccases. One lytic enzyme, stilbene oxidase, can detoxify grape stilbenic phytoalexins, destroying the grapes’ defence mechanisms and allowing the fungus to grow. Some constitutive grape berry phenolic compounds, however, strongly inhibit stilbene oxidase activity. Constitutive berry phenolic compounds were isolated from Gamay and Gamaret varieties and their biological activities, concentrations and chemical structures were comparatively analysed. Catechin, epicatechin-3-O-gallate, trans-caftaric, trans- and cis-coutaric and trans-coumaric acids, taxifoline-3-O-rhamnoside and quercetine-3-O-glucuronide were identified as potent stilbene oxidase inhibitors. High concentrations of some of those compounds could be closely involved in the persistence of the quiescent stage of B. cinerea, between bloom and veraison in all grape varieties and after veraison in resistant varieties.
Red wines obtained by microvinification in the laboratory and adjusted to three pH values (3.2, 3.6 and 4.0) were examined for the formation of anthocyanin-derived pigments throughout nine months of storage in bottles at 15 °C. The formation of the pigments was also followed in aliquots of the wines at pH 3.2 with added acetaldehyde (800 mg/L). Pigment analyses were accomplished by HPLC using double on-line detection by diode array spectrophotometry and mass spectrometry. Two dif ferent types of pigments were observed. The first were products derived from the condensation be tween anthocyanins and flavanols by ethyl bridges. The second corresponded to products showing an additional heterocycle in the anthocyanin structure (vitisin-like pigments); of these, vitisin B, which derives from malvidin 3-monoglucoside, was the most important one. Products similar to vitisin B derived from other anthocyanins were also detected, as well as structurally related pigments con taining flavanol moieties. The formation of all these pigments involves the acetaldehyde, since they appeared or were enhanced as a result of its addition, and were also favored in more acidic wines.
The phytopathogenic fungus Botrytis cinerea is a complex of two main genetic groups, Group-I and Group-II, the latter including different TE types distinguished by the presence or absence of two transposable elements (TE), Boty and Flipper. In populations from Bordeaux vineyards (n = 470), the frequency distribution into these genetic subdivisions showed that Group-I isolates were rare (2.3 %) whereas, within Group-II, four TE types were identified by dot blot in very different proportions: II-transposa (59.8 %), II-boty (21.3 %), II-vacuma (15.5 %) and II-flipper (1.1 %). To distinguish the TE types by PCR, a first primer pair was designed within the Flipper sequence which yielded a not-expected 2287 bp fragment. The 5′ extremity of this fragment was sequenced revealing a potential genomic insertion site of the Flipper element allowing the design of a new overlapping PCR primer. Detection of the Flipper element by two newly developed PCR tests and a published one (F300-F1550) was consistent with dot blot results in Group-I and II-transposa (concordance rates from 94.6 % to 100 %). However, discrepancies between PCR and dot blot were noticeable especially in II-boty, but also in II-vacuma (concordance rates from 33.3 % to 38.0 % and from 62 % to 81.2 %, respectively). On the basis of TE-type identification strengthened by combining different PCR and dot blot results, the spatiotemporal distribution of the Group-II isolates was assessed according to the developmental stage and the host organ of grapevine. In Bordeaux as in Loire valley vineyards, similar distribution patterns were described showing significant differences between the most sampled TE types. The II-transposa isolates predominated on grape berries at the end of the season, whereas the II-vacuma ones were detected mostly at flowering. Lastly, the II-boty isolates were more often detected on grapevine leaves than on flowers or berries.
The trends in changes to berry weight and phenolic concentrations of Cabernet Sauvignon berries during the later stages of berry ripening from different pruning and irrigation treatments were examined. Maturity was defined as total soluble solids (TSS). Berry phenolic concentration was examined using a 50% ethanol extract of grape homogenate, which is commonly used in the Australian wine industry to measure grape anthocyanins. Berry weight and berry composition were examined at three maturity stages over three vintages. Three pruning treatments were established with two irrigation treatments superimposed to provide a wide range of berry sizes and phenolic measures. Increasing maturity had consistent effects on berry weight across vintages and on berry phenolic composition within vintages. In a commercial context, peak total anthocyanin concentration and content might be a useful guide to harvest decisions, but in this study total phenolic and tannin measures did not assist in these decisions, as these measures were highest at higher than commercially acceptable TSS. In a research context, this information can be useful in determining the pattern of anthocyanin, total phenolic, and tannin accumulation and decline and would be useful in conjunction with wine measures of these parameters to determine relationships between berry and wine composition. Pruning treatments were associated with consistent effects on berry weight across vintages and maturity stages and consistent effects on total anthocyanin and total phenolic concentrations, but not on tannin concentrations. Irrigation effects were less consistent within or between vintages and the effects were highly dependent on vintage conditions.
The trends in changes to berry weight and phenolic concentrations of Cabernet Sauvignon berries during the later stages of berry ripening from different pruning and irrigation treatments were examined. Maturity was defined as total soluble solids (TSS). Berry phenolic concentration was examined using a 50% ethanol extract of grape homogenate, which is commonly used in the Australian wine industry to measure grape anthocyanins. Berry weight and berry composition were examined at three maturity stages over three vintages. Three pruning treatments were established with two irrigation treatments superimposed to provide a wide range of berry sizes and phenolic measures. Increasing maturity had consistent effects on berry weight across vintages and on berry phenolic composition within vintages. In a commercial context, peak total anthocyanin concentration and content might be a useful guide to harvest decisions, but in this study total phenolic and tannin measures did not assist in these decisions, as these measures were highest at higher than commercially acceptable TSS. In a research context, this information can be useful in determining the pattern of anthocyanin, total phenolic, and tannin accumulation and decline and would be useful in conjunction with wine measures of these parameters to determine relationships between berry and wine composition. Pruning treatments were associated with consistent effects on berry weight across vintages and maturity stages and consistent effects on total anthocyanin and total phenolic concentrations, but not on tannin concentrations. Irrigation effects were less consistent within or between vintages and the effects were highly dependent on vintage conditions.
Background and Aims: The impact of Esca, a cryptogamic disease affecting woody tissues of grapevines (trunk, branches and shoots), was investigated on phenolic and sensory qualities of Cabernet Sauvignon grapes, derived musts and wines.
Methods and Results: Global phenolic analyses revealed no major difference between healthy and affected grapes whereas high-performance liquid chromatography analyses showed decreases in the skin concentrations of catechin and epicatechin and of anthocyanins for the two vintages assessed. Proanthocyanidin characteristics, and particularly mean degree of polymerisation, were strongly decreased in skin proanthocyanidin polymeric fractions. Chemical analyses of wines made with different percentages of fruit from Esca infected grapevines confirmed the moderate impact of Esca on phenolic composition. Nevertheless, sensory analyses revealed a loss of wine sensory quality perceptible with as little as 5% of affected fruit in wines.
Conclusions: Phenolic variations in grapes and in derived wines may be related to changes to grapevine physiology caused by Esca fungi that impact on flavonoid metabolism. The chemical and sensory variations between wines can also be related to the delayed ripening delay of fruit from Esca infected grapevines.
Significance of the Study: Esca moderately affected the phenolic composition of grapes and decreased the sensory quality of wines, suggesting a dramatic increase in the economic importance of Esca if no control methods are found.
During conservation and ageing of red wines, the grape anthocyanins initially responsible for wine colour are displaced, progressively and irreversibly, by more stable polymeric pigments, which account for up to 50 per cent of colour density within the first year. These new pigment forms are much less sensitive to changes in pH than are the anthocyanins, and are quite resistant to decolorization by sulphur dioxide. Evidence is given in support of the hypothesis that the polymers contain quinonoid anhydrobase chromophores derived from the anthocyanins, and which have been stabilized by substitution with reactive flavans. Some possible structures of these tannin pigment materials are discussed.
PPO-catalyzed oxidation of (+)-catechin was performed in aqueous buffers in the pH range 3-7, using the same level of PPO activity at all pH values. Concentration of (+)-catechin and major oxidation products was monitored by HPLC. The nature and amounts of products formed were highly pH dependent. The solutions oxidized at pH below 4 contained mostly colorless products (lambda(max) 280 nm), whereas yellow compounds (lambda(max) 385-415 nm), eluting later than the colorless ones, predominated at higher pH values. Seven of them were purified by semipreparative HPLC. FAB-MS and acid hydrolysis data indicated they were dimers differing from natural procyanidins.
A direct and general synthesis of procyanidin dimers B1, B2, B3 and B4 (10a–d) is presented. The approach is based on the stoichiometric coupling of two protected monomeric units (the nucleophilic 2a–b and electrophilic 4a–b partners) and deals with the regio- and stereocontrol of the C4–C8 interflavan bond as well as the control of the degree of oligomerization. The synthesis involves a five-step pathway starting from the native catechin (1a) or epicatechin (1b) to the fully deprotected dimers 10a–d. Furthermore, the process appears to be iterative as the coupling intermediates 9a–d themselves can be readily used in further selective syntheses of trimers or higher oligomers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
An in vitro oxidation system containing all the phenolic compounds of an extract of grape seeds and phenol oxidases (catechol oxidase from grapes and laccase from grey mold of grape Botrytis cinerea) was used to determine the effects of enzymic oxidation on seven phenolic compounds: gallic acid, (+)-catechin; (-)-epicatechin and four procyanidins, dimers of (+)-catechin and (-)-epicatechin units. HPLC determinations showed that there was considerable depletion of phenolic compounds in the extract by both enzymes since the quantities of all the compounds fell during enzymic oxidation. When a pure chemical oxidation was compared, the decrease was very much slower.
The syringaldazine assay was adapted for quantitative determination of laccase (EC 1.10.3.2) activity from Botrytis cinerea Pers in musts and new wines. This colorimetric method is fast, specific and sensitive. It makes it possible to assess the level of contamination of crops by Botrytis cinerea.
The assay can be performed in the presence of tyrosinase but the phenolic compounds of the grape must first be eliminated because of their inhibition of syringaldazine oxidation by laccase.
When measured in botrytised grape, laccase activity is related to the stages of development of the fungus.
A 32-kDa laccase-like stilbene oxidase was purified to homogeneity (one single band on SDS-PAGE) from Botrytis cinerea liquid culture medium enriched with pectin. Two major isoforms with pI 4.35 and 4.3 were revealed by isoelectric focusing (IEF). This enzyme oxidizes the grape stilbenic phytoalexins, resveratrol and pterostilbene. Syringaldazine is poorly oxidized by this stilbene oxidase as compared to the rate of stilbene oxidation. This enzyme catalyses the oxidation of resveratrol to ?-viniferin.
Botrytis cinerea (Pers.: Fr), the causal agent of botrytis bunch rot, is an important disease of grapevines worldwide, with canopy management and the prophylactic use of fungicides being the most common control methods. The latter has resulted in fungicide resistance and is increasingly raising concerns regarding residues in wine and effects on human and environmental health. Research-led alternatives to this practice are beginning to emerge, including a range of biotic and abiotic treatments that induce vine resistance to B. cinerea and inundative applications of biological control agents such as Trichoderma, Bacillus, Ulocladium and Streptomyces species. Also, habitat manipulation techniques that aim to improve the effectiveness of naturally occurring biological control are being developed using mulches brought into the vineyard, as well as mulched cover crops. These can accelerate decomposition of botrytis mycelium and sclerotia on the vineyard floor in winter. The challenges of these different techniques and the prospects for habitat manipulation for this fungal disease are discussed. Extensive tables on synthetic fungicides, biofungicides, essential oils and plant extracts effective against B. cinerea are included.
Intensity of astringency and bitterness of seven flavonoid compounds was evaluated by a time-intensity (TI) procedure. Eighteen trained judges rated intensity continuously from ingestion, through expectoration at 10 s until extinction of the sensation. The seven stimuli included two flavan-3-ol monomers, (+)-catechin and (−)-epicatechin, three dimers and two trimers synthesised from catechin or epicatechin by condensation with (+)-dihydroquercitin. As the degree of polymerisation increased, maximum bitterness intensity (Imax) and total duration (Ttot) decreased whereas astringency Imax increased. The monomers were significantly higher in bitterness at Imax than the dimers, which were significantly higher than the trimers. Astringency Imax of the monomers was lower than the dimers or trimers, although no significant difference was found in Ttot among the polymer classes. The bond linking the monomeric units had an influence on both sensory properties. The catechin-catechin dimer linked by a 4→6 bond was more bitter than both catechin-(4→8)-catechin and catechin-(4→8)-epicatechin. Astringency was affected by both the specific linkage and the identity of the monomeric units with the dimer, catechin-(4→8)-catechin, being lower in astringency than either catechin-(4→6)-catechin or catechin-(4→8)-epicatechin. © 1999 Society of Chemical Industry
The chemical and physical basis for red wine astringency is reviewed. Models describing the physiological foundation of astringency are presented and compared. The phenolic and other red wine components that evoke astringency are described, together with their sensory properties and the factors that affect their perception. The paper also presents a detailed account of the chemical properties of saliva and the possible modes of interaction between these and red wine phenolics that lead to the necessary physical changes in saliva required to elicit astringency. Reasons for differences in astringency perception across oral sites and amongst individual tasters are also discussed. It is concluded that whilst great advances have been made in the field of red wine phenolic chemistry in recent years, a better understanding of the effect of wine polyphenol-salivary protein interaction on the rheological properties of saliva is required in order to gain a comprehensive understanding of red wine astringency.
One hundred and twenty-one single-spore strains of Botrytis cinerea isolated from Bordeaux vineyards were molecularly characterized as either transposa or vacuma, two subpopulations of B. cinerea distinguished by the presence of transposable elements. Forty-three vacuma and 68 transposa strains were distributed into two main classes (mycelial or sclerotial) by morphological phenotype according to the organ of origin. Strains isolated from overwintering sclerotia produced exclusively sclerotial colonies. The mycelial growth rate of 21 transposa and 13 vacuma strains was significantly influenced by agar-medium and temperature. The mycelial growth rate was significantly strain-dependent at favourable temperatures (15, 20 and 25 C), but not at limiting ones (5 and 28 C): vacuma strains showed the fastest growth rates. The strains of the two subpopulations were similar in virulence on both host species tested (Vitis vinifera and Nicotiana clevelandii). The grapevine leaves were significantly more susceptible to B. cinerea than those of tobacco. A significant negative correlation was established between virulence and mycelial growth rate. The epidemiological consequences concerning population structure of B. cinerea in vineyards are discussed.
Plants possess a range of tools for combating a Botrytis infection. This chapter will describe three types of pre-formed and induced plant defence compounds and discuss their effectiveness
in restricting Botrytis infection. Case studies are presented on several types of secondary metabolites: stilbenes including resveratrol, saponins
including ??-tomatin, cucurbitacins, proanthocyanidins and tulipalin A. Evidence is presented suggesting that Botrytis species have evolved mechanisms to counteract some of these defence responses. Secondly, we discuss the role of structural
barriers and cell wall modification in preventing penetration. Finally the contribution of PR proteins to resistance is discussed.
The chemical control of Botrytis spp., and especially B. cinerea the causal agent of grey mould on many crops, can be achieved by several families of fungicides. Among those affecting fungal
respiration, the oldest ones are multi-site toxicants (e.g. dichlofluanid, thiram); newer ones are uncouplers (e.g. fluazinam),
inhibitors of mitochondrial complex II (e.g. boscalid) or complex III (e.g. strobilurins). Within anti-microtubule botryticides,
negative-cross resistance can occur between benzimidazoles (e.g. carbendazim) and phenylcarbamates (e.g. diethofencarb), a
phenomenon determined by a mutation in the gene encoding ??-tubulin. Aromatic hydrocarbon fungicides (e.g. dicloran), dicarboximides
(e.g. iprodione, procymidone, vinclozolin) and phenylpyrroles (e.g. fludioxonil) affect the fungal content of polyols and
resistance to these various compounds can be associated with mutations in a protein histidine kinase, probably involved in
osmoregulation. However, dicarboximide-resistant field strains of B. cinerea are sensitive to phenylpyrroles. Anilinopyrimidines (e.g. cyprodinil, mepanipyrim, pyrimethanil) inhibit methionine biosynthesis
but their primary target site remains unknown. In few situations, resistance of commercial significance has been recorded.
Among sterol biosynthesis inhibitors those inhibiting 14??- demethylase (DMIs) which are widely used against many fungal diseases
are of limited interest against Botrytis spp., whereas the hydroxyanilide fenhexamid, which inhibits the 3-keto reductase involved in sterol C4-demethylations, is
a powerful botryticide. Monitoring conducted in French vineyards revealed the presence of multi-drug resistant (MDR) strains,
a phenomenon probably determined by overproduction of ATP-binding cassette transporters. Resistance towards fungicides of
the different groups is described throughout the chapter.
This work investigated the structural and biochemical changes during grape berry development which account potentially for
the onset and increase in susceptibility to Botrytis cinerea. Using the cv. Sauvignon blanc, we quantified at seven developmental growth stages from herbaceous to over-mature berries:
(1) fruit ontogenic resistance using three strains (II-transposa), (2) the morphological and maturity fruit characteristics and (3) preformed biochemical compounds located in the berry skin.
From the mid-colour change stage onwards, susceptibility of unwounded fruit increased sigmoidally in both rot and sporulation
severities at the berry surface. A principal component analysis identified a very close connection between fruit susceptibility
and the level of fruit maturity. Berry susceptibility was significantly and positively correlated with the phenolic compounds
in the skin cell walls and negatively correlated with the total tannin content in the skin and with water activity (Aw) at
the fruit surface. On the berry, Aw decreased from 0.94 at bunch closure to 0.89 at berry maturity, with a relatively low
value (0.90) at the stage of mid-colour change. Using artificial media, different Aw levels led to significant differences
in mycelial growth (Aw ≤0.95 resulted in the lowest growth rate ≤0.34mm day−1). Thus, besides the level of fruit maturity, both water activity on the fruit and the total tannin content in the skin may
affect fungal growth and berry colonisation. The potential of these variables for use as indicators of grape berry susceptibility
as well as associated mechanisms for the development of disease are discussed.
Laccase (EC 1.10.3.2, p-diphenol dioxygen oxidoreductase)-catalysed (+)-catechin oxidation was investigated, both in the presence and absence of the mediator ABTS. The effect of ascorbic acid, a radical scavenger, on the reaction mechanism was also examined. Using reversed-phase HPLC chromatography, UV–vis and HPLC-ESI-MS spectroscopies, we identified the formation of dimers of the type dehydrocatechin B, which are relatively more hydrophilic than the parent substrate, and hydrophobic dimers of type-A, as well as previously not described oligomers, namely, a trimer, tetramer and their oxidized forms. Evidence is presented for the conversion of a hydrophilic dimer via a quinone intermediate to the hydrophobic dimers. The hydrophobic dimers were further oxidized by laccase to o-quinone, which upon condensation with catechin forms the reduced trimer. Both ABTS and ascorbic acid had effect on the overall rate of (+)-catechin oxidation and the proportions of the final oxidation products. ABTS favoured the formation of the hydrophobic products and decreased the hydrophilic dimers. In contrast, at low concentrations, ascorbic acid favoured the formation of hydrophilic products, whereas at higher concentrations the radical scavenger inhibited the laccase-catalysed catechin oxidation reaction, most probably, by reducing the semiquinone and o-quinone back to the parent polyphenol. A nucleophilic rather than radical mechanism accounts for the product formation.
Five tannin fractions were isolated from grape (Vitis vinifera) seeds. HPLC analysis of the degradation products released by thioacidolysis showed that all fractions consisted of catechin, epicatechin and epicatechin gallate units. Epicatechin was the major component in the extended chain. Catechin was more abundant in terminal units than in extension units. The proportion of galloyllated units varied from 13% to 29% as the Mr, increased. Mean degrees of polymerization ranging from 2.3 to 15.1 (by thiolysis) and from 2.4 to 16.7 (by GPC) were determined.
(+)-Catechin oxidation was carried out in aqueous systems using grape polyphenoloxidase as catalyst. Eight fractions corresponding to the major products formed at pH 3 and 6 were purified using HPLC at the preparative and semi-preparative scale. Structural characterization using UV-visible detection and mass spectrometry indicated that they corresponded to (+)-catechin dimers including two yellow pigments. Mono- and bi-dimensional H-1 and C-13 NMR analyses provided structural hypotheses for five oxidation products whereas the other three fractions were mixtures of several isomers. Colourless products, with C-C or C-O interflavan linkages, were dehydrodicatechins of the B-type. One of the two pigments corresponds to dehydrodicatechin A, already identified in other oxidation models, and the other pigment is a new structure of the quinone-methide type.
ABSTRACT Change in relative frequencies of the three main genetic types of Botrytis cinerea (Group I, Group II vacuma, and Group II transposa) were monitored over time from 1998 to 2000 in three Bordeaux vineyards not treated with fungicides. During 2000, Group I isolates, detected mostly at flowering comprised only 2.5% of the entire population. Within Group II, the complementary frequencies of vacuma and transposa isolates differed significantly depending on grapevine phenological stages and organs. Every year and at all sites, including one noble rot site, transposa isolates dominated at every stage, particularly on overwintering canes and at harvest (greater than 86.7% on berries). The complementary frequency of vacuma isolates reached a maximum on senescing floral caps (between 23.5 and 71.4%) and then decreased significantly until harvest on leaves and berries. In pathogenicity tests on grape berries, transposa isolates were significantly more virulent than were vacuma isolates. Mycelial growth rate was negatively correlated with virulence, notably on leaves in transposa and with double resistance to the fungicides carbendazim and vinclozolin. In vacuma, this double resistance was positively correlated with virulence on leaves. Change in the vacuma and transposa frequencies was most likely caused by differences in saprotrophic and pathogenic fitness. Possible interactions between fungicide resistance profiles and fitness are discussed.
Musty, earthy odors are highly detrimental to the aromatic quality of wines. A characteristic aroma of freshly tilled earth, damp cellar was studied in some red and white wines of different origins. The extraction and purification of the wines marked by this odor have shown after analysis by gas chromatography-olfactometry a unique strong odorous zone having the same odor as the one perceived at tasting. The compound responsible for this odorous zone was identified by gas chromatography-mass spectrometry as geosmin (trans-1,10-dimethyl-trans-9-decalol), which possesses a distinctive earthy odor. Geosmin may be present in wines at levels higher than the racemic geosmin olfactory perception threshold, thus suggesting its contribution to their off-aroma. Moreover, the presence of this compound in juice taken from freshly crushed grapes suggests that microorganisms that develop on the grapes may contribute to the presence of this compound in wines.
Various basidiomycetes, ascomycetes, and deuteromycetes, grown in a sugar-rich liquid medium, were compared for laccase-producing ability and for the inducing effect of 2,5-xylidine on laccase production. Clear stimulation of the extracellular enzyme formation by xylidine was obtained in the cultures of Fomes annosus, Pholiota mutabilis, Pleurotus ostreatus, and Trametes versicolor, whereas Rhizoctonia praticola and Botrytis cinerea were not affected by the xylidine, and in the case of Podospora anserina a decrease in laccase activity was observed. The laccases were purified, and electrophoresis on polyacrylamide gels indicated a particular pattern for each laccase. The bands of the induced forms appeared only with basidiomycetes. The optimal pH of R. praticola laccase was in the neutral region, whereas the optima of all the other exolaccases were significantly lower (between pH 3.0 and 5.7). All laccases oxidized the methoxyphenolic acids under investigation, but there existed quantitative differences in oxidation efficiencies which depended on pH and on the nature (noninduced or induced) of the enzyme. The sensitivity of all enzymes to inhibitors did not differ considerably.
Quantitative and qualitative modifications of tannins and anthocyanins in grape skin were investigated at different dates of harvest, from berries sorted on the basis of their density. Free anthocyanins accumulated until 170 g/L of sugars in pulp before undergoing a slight decrease. Changes in anthocyanin composition were observed with increasing sugar levels in the pulp that reflected structural differences between classes of anthocyanins. The proportion of methoxylated anthocyanins continued to increase in the skin as sugar accumulated while the proportion of coumaroylated anthocyanins initially increased (up to 200 g/L of sugars in the pulp) and then rapidly decreased. In comparison, no major quantitative nor qualitative change was observed for tannins, except for a slight increase of the mean degree of polymerization. Whatever the physiological stage of the pulp, the extraction yield of skin phenolics into hydroalcoholic solution for 5 h was lower than 77% for anthocyanins and 38% for proanthocyanidins. For both classes of compounds, no clear evolution in these extraction yields could be observed as sugars accumulated in pulp (from 162.6 to 275.0 g/L). Nevertheless, some structural features within each family of compounds significantly influenced extractability, for example, a lower extraction yield for coumaroylated anthocyanins and for tannins with a high degree of polymerization. Finally, no direct relationship could be found in extraction media between the amounts of all red pigments (measured in acidic conditions) and the color intensity at 520 nm (measured in wine-like model solutions).
Grape rot is one of the major causes of degradation of many grape components and, thus, of deterioration in wine quality. In particular, the association of Botrytis cinerea with other, less visible, fungi frequently leads to the development of organoleptic defects in grapes and sometimes in wines. This study examines the nature of the volatile compounds responsible for mushroom, mossy, or earthy odors detected by gas chromatography-olfactometry in organic extracts of rotten grapes and musts. 2-Methylisoborneol, (-)-geosmin, 1-octen-3-one, 1-octen-3-ol, 2-octen-1-ol, and 2-heptanol were identified or tentatively identified. Their concentrations in musts were determined, and the impact of alcoholic fermentation by the yeast Saccharomyces cerevisiae was studied. The ability of fungi isolated from rotten grapes (Botrytis cinerea; Penicillium species including P. brevicompactum, P. expansum, P. miczynskii, P. pinophilum, P. purpurogenum, and P. thomii; Aspergillus section nigri; Rhizopus nigricans; and Coniothyrium sp.) to produce some of the identified compounds was evidenced.
A method was developed to determine the amount of ethylidene-bridged flavan-3-ols in wine. The method was based upon the analysis of 2,2'-ethylidenediphloroglucinol (EDP), a product formed after acid-catalyzed cleavage of wine flavan-3-ols in the presence of excess phloroglucinol. In the developed analytical method, the wine was purified and concentrated using C18 solid-phase extraction before the phloroglucinolysis reaction was carried out. This procedure was used to quantify ethylidene-bridged flavan-3-ols in wine and the molar ratio between ethylidene-bridged linkages and native interflavan linkages. The method validation showed 9.2% repeatability. The recovery of the ethylidene-bridged flavanols in wine was 90% for concentrations up to 4.5 mg.L-1 of ethylidene-bridged linkages, and it decreases to 83% above and until the concentration reached 7.6 mg.L-1. Initial results showed that the concentration of ethylidene-bridged flavan-3-ols measured in wines was very low (less than 1.3 mg.L-1) and that they represented less than 1.3% of the total interflavonoid linkages on a molar ratio.
Geosmin, an off-flavour of some rotten grapes, has been implicated in wine defects. Botrytis cinerea and Penicillium expansum were the most common among the numerous microorganisms isolated from rotten grapes. P. expansum produces geosmin on model media but not healthy grape juice. However, geosmin synthesis by P. expansum was demonstrated in grape juice and on crushed grapes that had been pre-cultured with certain B. cinerea strains. 34 out of 156 B. cinerea strains ([bot +] phenotype) isolated from the centre of grape bunches were able to induce high geosmin production, up to 494 ng/l, by P. expansum in grape juice. A study of the impact of grape juice composition on geosmin synthesis by P. expansum revealed the importance of nitrogen composition, particularly amino-acid deficiency. Metabolism of amino acids by B. cinerea was shown to be favourable to geosmin synthesis by P. expansum. However, the amino-acid and ammonium concentrations in grape juices pre-cultured with B. cinerea [bot -] and [bot +] strains were very similar implying that other factors are involved as well. Indeed, an ethanol-precipitable fraction, probably a polysaccharide, synthesized by B. cinerea [bot -], but not [bot +] strains, inhibited geosmin production by P. expansum.
La pourriture grise In: Maladies cryptogamiques de la vigne: champignons parasites des organes herbacés et du bois de la vigne
- B Dubos
Dubos, B. (1999) La pourriture grise. In: Maladies cryptogamiques de la
vigne: champignons parasites des organes herbacés et du bois de la vigne.
Ed. E. Féret (Editions Féret: Bordeaux) pp. 55-71.