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Postharvest biological control of gray mold decay of strawberry with Rhodotorula glutinis
Abstract
Rhodotorula glutinis was evaluated for its activity in reducing postharvest gray mold decay of strawberry caused by Botrytis cinerea in vitro and in vivo. In the test on PDA plates, R. glutinis significantly inhibit the growth of B. cinerea. Spore germination of pathogens in PDB was greatly controlled in the presence of living cell suspensions. Rapid colonization of the yeast in wounds was observed during the first 3 days at 20°C, and then the populations stabilized for the remaining storage period. On strawberry wounds kept at 4°C, the increase in population density of R. glutinis was lower than those kept at 20°C, but continued over 8 days after application of the antagonist until it reached a high level. Number of inoculated strawberry fruit treated with 1×108CFU/ml washed cell suspension of R. glutinis was 10% after 2 days at 20°C, compared to 100%, respectively, in the control. Washed cell suspensions of yeast controlled gray mold better than yeast in culture broth. Treatment of wounds with autoclaved cell cultures or cell-free culture filtrate did not prevent decay. The concentrations of antagonist had significant effects on biocontrol effectiveness: the higher the concentrations of the antagonist, the lower the disease incidence regardless of whether the fruit was stored at 20°C for 2 days or 4°C for 7 days. At concentrations of R. glutinis 1×109CFU/ml, the incidence of gray mold was reduced by 94.7 or 95%, respectively, compared with control, after storage at 20°C for 2 days or 4°C for 7 days, respectively. R. glutinis significantly reduced the natural development of decay of fruit following storage at 20°C for 3 days or 4°C for 5 days followed by 20°C for 3 days.
... In this context, prospecting yeasts from the cacao tree phytobiome as biological control agents (BCA) seem to be a promising, less expensive and safe alternative (GRAS (generally recognized as safe)) for humans and animals. Yeasts are safe to manipulate and have great competitive potential (Zhang et al. 2007); they release killer toxins (Platania et al. 2012), produce volatile compounds (Bruce et al. 2003), and secrete hydrolytic enzymes that can degrade the phytopathogen cell wall (Masih and Paul 2002;Urquhart and Punja 2002;Lu et al. 2014). In addition, yeasts can withstand environmental changes and stressful conditions (Sui et al. 2015) are are tolerant to pollutants, essential oils, phytoalexins, and some fungicides (Valdebenito-Sanhueza 2000); they can survive saprophytically (Afsah-Hejri 2013) and tolerate adverse conditions (Hu et al. 2015). ...
... In general, all yeast isolates obtained from the cacao tree phytobiome proved to have one or more of the skills evaluated in the in vitro tests performed to characterize them as antagonists to M. perniciosa (Figs. 1, 2, 3, and 4) (Zhang et al. 2007;Bruce et al. 2003;Platania et al. 2012). They show different levels of competition with the pathogen, ability to produce diffusible and volatile compounds, release killer toxins (with exception of 13 isolates; Fig. 3) and inhibit basidiospore germination. ...
The cacao tree surface is a substrate for various microorganisms. However, the species which live on the surface have hardly been described. The aims of this study were to evaluate the diversity of native cacao yeasts and to investigate their possible interaction with Moniliophthora perniciosa. A total of 225 yeast strains were isolated from the surface of leaves, fruits, and flowers of 20 cacao genotypes selected as carriers of resistance genes to M. perniciosa and M. roreri, which are the causal agents of witches’ broom (WB) and frosty pod rot diseases (FPR), respectively. The yeast isolates were molecularly identified based on sequences of the D1/D2 and ITS1/ITS4 regions of the rDNA. A total of 20 taxa distributed into 11 genera was found: Hannaella (23), Cryptococcus (9), Candida (11), Hanseniaspora (4), Kwoniella (1), Occultifur (3), Rhodotorula (17), Pichia (2), Sporobolomyces (1), Wicherhamomyces (1), and Yamadazyma (1). Phylloplane tissues showed the greatest richness: 55% of species and 81.82% of identified genera. Six yeast strains (Candida orthopsilosis—LEV 225; Hanseniaspora uvarum—LEV 162, 210, 211; and Rhodotorula paludigena—LEV 166, 168) exhibited the desired traits for a BCA agent: antibiosis in cocultivation, antibiosis by volatile compounds, germination inhibition, and production of killer toxins. This study is the first to show the great diversity of yeasts found in the cocoa phytobiome and the discovery of at least six microorganisms with excellent potential as BCA against cocoa witches’ broom disease.
... To date, there is much concern about fungicide residue in agricultural product, and biocontrol has been considered as a more acceptable method for controlling postharvest diseases (Karunaratne, 2011;Kilani-Feki et al., 2016;Mohamed & Saad, 2009;Pretorius, Van, & Clarke, 2015). Multiple biocontrol agents (BCAs) have been isolated from environment, and they were shown to facilitate the control of postharvest decay of strawberry fruit (El Ghaouth & Wilson, 2002;Menel, Faten, & Moktar, 2012;Wei, Mao, & Tu, 2014;Zhang et al., 2007), suggesting possible application of BCAs in strawberry postharvest storage. Some yeast strains with potential biocontrol ability directly inhibit the growth of fungal pathogens on strawberry by antagonism pattern (Wei et al., 2014;Zhang et al., 2007). ...
... Multiple biocontrol agents (BCAs) have been isolated from environment, and they were shown to facilitate the control of postharvest decay of strawberry fruit (El Ghaouth & Wilson, 2002;Menel, Faten, & Moktar, 2012;Wei, Mao, & Tu, 2014;Zhang et al., 2007), suggesting possible application of BCAs in strawberry postharvest storage. Some yeast strains with potential biocontrol ability directly inhibit the growth of fungal pathogens on strawberry by antagonism pattern (Wei et al., 2014;Zhang et al., 2007). Different mechanisms were involved in antagonistic microorganism-mediated fungal pathogen growth inhibition, and volatile organic compounds (VOCs) have been suggested to act as a functional molecular factor to interfere fungal pathogen growth (Asari, Matzén, Petersen, Bejai, & Meijer, 2016;Sánchez-Fernández et al., 2016). ...
Volatile organic compounds (VOCs) of antagonistic yeasts are considered as environmental safe fumigants to promote the resistance and quality of strawberry (Fragaria ananassa). By GC‐MS assays, VOCs of Hanseniaspora uvarum (H. uvarum) fumigated strawberry fruit showed increased contents of methyl caproate (5.8%), methyl octanoate (5.1%), and methyl caprylate (10.9%) in postharvest cold storage. Possible mechanisms of H. uvarum VOCs involved in regulations of the defense‐related enzymes and substances in strawberry were investigated during postharvest storage in low temperature and high humidity (2 ± 1°C, RH 90%–95%). Defense‐related enzymes assays indicated H. uvarum VOCs stimulated the accumulation of CAT, SOD, POD, APX, PPO, and PAL and inhibited biosynthesis of MDA in strawberry fruit under storage condition. Moreover, the expression levels of related key enzyme genes, such as CAT, SOD, APX42, PPO, and PAL6, were consistently increased in strawberry fruit after H. uvarum VOCs fumigation. Hanseniaspora uvarum volatile organic compounds (VOCs) increase specific esters in strawberry volatile emissions during postharvest storage. It also enhances the activity of defense‐related enzymes and inhibits the accumulation of MDA content and the production rate of superoxide anion. This study also showed that these VOCs maintain the strawberry quality via inducing the expression of defense‐related enzyme genes.
... The evolution of total soluble solids of strawberry fruits during storage is shown in table 4. TSS decreased slowly in the first 14 days in all treatments, followed by a sudden decline in the last 7 days of fruits storage. This evolution may be related to the high physiological activity and respiration in the last 7 days of storage, resulted in fast hydrolysis of sucrose (Zhang et al., 2007). Strawberries dipped in citric acid recorded the lowest TSS content while fruits dipped in acidic electrolyzed water, benzoic acid and sorbic acid presented significantly higher values of TSS than controls. ...
The present research was conducted to evaluate the effect of dipping treatments with 2% citric acid, 0.2% benzoic acid, 0.2% sorbic acid and acidic electrolyzed water on the quality of strawberries ("Malvina" cultivar) during 21 days storage at 8 °C. The following analyses were performed on the control and sanitized strawberry fruits at 1, 7, 14 and 21 days of storage: weight loss, firmness, decay incidence, soluble solids content, titratable acidity, total phenolics content, total anthocyanins content and DPPH antioxidant activity. All sanitizing treatments significantly (P<0.05) reduced weight loss and fruit decay during strawberry storage. Dipping strawberries in 0.2% sorbic acid or 0.2% benzoic acid aqueous solutions were the most effective treatments for maintaining firmness and phytochemical content and for delaying the decay of strawberries during cold storage.
... Among all the tested fitness parameters, no significant differences were observed except for osmotic sensitivity (procymidone) and sporulation (zoxamide). Otherwise, all B. cinerea resistant isolates showed similar fitness as sensitive ones, which is in line with previous studies (Moyano et al. 2004;Zhang et al. 2007;Sun et al. 2010;Liu et al. 2016;Rupp et al. 2017). Procymidone-resistant isolates were sensitive to fludioxonil (PPs) in this study, which confirms previous reports that no cross-resistance existed between DCFs and PPs in B. cinerea field isolates (Faretra and Pollastro 1993;Hilber et al. 1995;Ziogas and Kalamarakis 2001;Vignutelli et al. 2002;Amiri et al. 2013;Li et al. 2014;Fernández-Ortuño et al. 2015;Yin et al. 2015). ...
Gray mold, caused by Botrytis cinerea, is one of the most destructive diseases of strawberry in China. For resistance monitoring, 198 B. cinerea isolates were collected from strawberry greenhouses at 10 locations in Hubei Province. The isolates were screened for resistance to fungicides procymidone and zoxamide. In mycelium growth assays for procymidone, the mean values of effective concentration at which mycelium growth is inhibited by 50% (EC50) for sensitive (ProS) and resistant (ProR) isolates were 0.25 μg/mL and 2.21 μg/mL, respectively. The frequency of ProR isolates was 14%, and the highest frequency (48%) was observed in Yichang. Positive cross-resistance was detected for ProR isolates to other dicarboximide fungicides, but not to phenylpyrroles. Comparative analysis of fitness parameters revealed increased osmotic sensitivity of ProR isolates compared to ProS ones. Sequence analysis of the dicarboximide target gene BcOs1 revealed that ProR isolates carried either a single point mutation at codon 365 (I365S) or a pair of point mutations (Q369P and N373S). The mean EC50 values for zoxamide sensitive (ZoxS) and resistant (ZoxR) isolates were 0.31 μg/mL and 7.76 μg/mL, respectively. Only six (3%) isolates from three locations were found to be resistant to zoxamide. All ZoxR isolates were found resistant to carbendazim. Fitness parameters did not show significant difference between ZoxR and ZoxS isolates. Sequence analysis of the beta-tubulin gene in resistant isolates revealed four previously reported point mutations (E198A, E198K, F200Y and T351I). The mutation T351I was detected only in the isolates possessing E198K point mutation. Mutation F200Y was detected in a highly resistant isolate. Results of this study will be helpful for the management of fungicide resistance in B. cinerea.
... This process has been studied in Botrytis cinerea, a necrotrophic fungus of global importance that causes grey mold disease and infects >1000 species worldwide, including >200 crop species [3,4], such as grapes and strawberry. In hot, humid environments, conidia of B. cinerea invade through stomata, hydathodes, or wounds [5], and early disease diagnosis may protect plants from damage [6]. In recent years, mechanisms of strawberry defense against the early stage of gray mold disease have been studied by various omics approaches [7][8][9], and conventional omics have been used to characterize the response to B. cinerea at the whole-organ level. ...
Pathogen invasion leads to fast, local-to-systemic signal transduction that initiates plant defense responses. Despite tremendous progress in past decades, aspects of this process remain unknown, such as which cell types respond first and how signals are transferred among cell types. Here, we used single-cell RNA-seq of more than 50 000 single cells to document the gene expression landscape in leaves of woodland strawberry during infection by Botrytis cinerea and identify major cell types. We constructed a single-cell atlas and characterized the distinct gene expression patterns of hydathode, epidermal, and mesophyll cells during the incubation period of B. cinerea infection. Pseudotime trajectory analysis revealed signals of the transition from normal functioning to defense response in epidermal and mesophyll cells upon B. cinerea infection. Genes related to disease resistance showed different expression patterns among cell types: disease resistance-related genes and gene encoding transcription factors were highly expressed in individual cell types and interacted to trigger plant systemic immunity to B. cinerea. This is the first report to document the of single-cell transcriptional landscape of the plant pathogenic invasion process, it provides new insights into the wholistic dynamics of host-pathogen interactions and can guide the identification of genes and the formulation of strategies for resistant cultivar development.
... After incubation, a volume of 5 ml of bacterial suspension is centrifuged at 4000 rpm for 10 min. The cells were washed, in the same volume of 5 ml of sterile distilled water, twice, using the centrifuge at the same conditions mentioned above [16]. The bacterial cells were then suspended in 5 ml of sterile physiological saline, and the suspension was adjusted to 3 × 10 8 cell/ml according to the Mac Farland scale [17]. ...
The effect of nine isolates of Bacillus amyloliquefaciens and one strain of Trichoderma harzianum, TR, on mycelial growth and germination of Colle-totrichum acutatum were studied. The nine isolates were identified as Ba-cillus amyloliquefaciens. The efficacy of isolates was tested, at different concentrations. Results showed that one Bacillus isolates (Bc2) and TR were more effective at the lower concentration tested (3 × 105 CFU/ml and 105 conidia/ml).
... An antagonistic Rhodotorula strain has been reported as an effective biocontrol agent against postharvest decay of apples, pears, sweet cherries, and oranges. Rhodotorula glutinis is an effective biocontrol agent against postharvest fungal spoilage of apples [16] pears [17] oranges [18] sweet cherries [19] as well as strawberries [20]. ...
... The application of BCAs in the field can be made with the BCA alone or in combination with other means of control. For example, after Zhang and co-workers confirmed the effectiveness of BCAs in the genus Rhodotorula to reduce postharvest gray mold of strawberry (Zhang et al., 2007), they combined their application with phytic acid (Zhang et al., 2013), salicylic acid (Zhang et al., 2010), and edible coatings (Zhang et al., 2014). ...
Contents
1. Introduction
2. Table grapes
2.1. Botanical classification
2.2. Postharvest diseases of table grapes
3. Kiwifruit
3.1. History, species, and cultivars
3.2. Postharvest diseases of Actinidia spp.
3.3. Psa and postharvest rot relationships
3.4. Conclusions
3.5. Looking forward
4. Strawberry
4.1. Botanical classification
4.2. Postharvest diseases of strawberry
5. Concluding remarks
Acknowledgments
References
Abstract
Table grapes, kiwifruit, and strawberries are highly susceptible to postharvest decay caused by a range of pathogenic fungi. They are generally stored for short (strawberries, up to 1 wk), medium (table grapes, a few weeks to 2 mon), or long (kiwifruit, up to 6–9 mon) periods, and during their storage and shelf life, they are susceptible to several postharvest diseases. Grey mold, caused by Botrytis cinerea, is usually the most important of these. Grey mold control requires specific fungicide treatments applied at different times before harvest in the field to inhibit infections and reduce inoculum. Their timing depends on the species and cultivar, although in all cases, it is important to target latent infections, as these are often established early in the growing season and then frequently expressed after harvest, during storage, and especially during the shelf-life period. Control of other diseases rarely requires specific fungicide applications in the field. Therefore, it is important to manage these pathogens after harvest. For table grapes, sulfur dioxide fumigation or in-package generators control postharvest grey mold, while for kiwifruit and strawberries, preharvest canopy management is essential. Moreover, for kiwifruit, postharvest curing practices are effective. For these crops, grey mold control is based on pre- and postharvest practices. Other strategies (e.g., low temperature, modified atmosphere, and ozone) can be applied to manage postharvest diseases of fruit that are susceptible to these pathogens.
Abbreviations
BCAs Biological control agents
CA Controlled atmosphere
GRAS Generally recognized as safe
MA Modified atmosphere
PAL Phenylalanine ammonia-lyase
RH Relative humidity
SO2 Sulfur dioxide
TA Titratable acidity
TSS Total soluble solids
UV-C Ultraviolet C
... It also produces long-lived structures called sclerotia which are able to survive in the absence of a host plant [3]. For this reason, B. cinerea may cause serious pre-and post-harvest diseases and can be one of the most difficult plant diseases to prevent or control [4][5][6]. Control of grey mould disease is usually carried out by the application of chemical fungicides, which are generally not effective and lead to contamination of the environment, accumulation of toxic residues in fruits, and can cause toxic effects on human health [2,7,8]. ...
The purpose of this study was to assess the activity of Bacillus subtilis BS-2 and peppermint oil against Botrytis cinerea . In this study parameters such as the age and the density of the bacterial culture and the incubation temperature were taken into consideration. Furthermore, the cellulolytic activity of the bacterium was determined. The effect of peppermint oil was evaluated at a concentration range of 0.5-4.0 %. The research was conducted with a dual culture plate method. The influence of B. subtilis BS-2 and peppermint oil on the growth of B. cinerea was evaluated based on the growth rate index. It was noted that the bacterial culture occurred at an initial density of OD560 = 1.0, cultivated at 30 °C for 48 hours demonstrated the strongest antagonistic effect (57.07 % inhibition). Furthermore, it was observed that the highest cellulolytic activity occurred on the bacteria incubated for 48 hours at 37 °C. The effect of mint oil, at the lowest concentration of 0.5-1.0 %, was much weaker on bacterial activity (1.1-12.1 % inhibition). The highest concentration (4.0 %) of mint oil caused the maximum inhibition (31.9 %) of the mycelial growth. B. subtilis BS-2 may be environmental-friendly alternatives for protecting plants against B. cinerea
... The treatment of those fungiis based by the conventional chemical control through repeated foliar or fruit applications of a combination of protectant and systemic fungicides.However, the growing demand of consumers worldwide for a reduction of pesticide, used on fresh fruits and vegetables, force the farmers to look for another ways. In response to this trend, physical and biological approaches have been evaluated as safer alternative to the use of chemical fungicides (Drobyet al., 2002;Zhang et al., 2007). Biological approaches, including the use of antagonistic organisms, natural compounds, cultural practices, and biotechnology, will be used to develop new methods for managing diseases of fruit crops (Wisniewski et al., 2003). ...
The green mold and the grey mold, caused by Penicillium digitatum and Botrytis cinerea
respectively, are the major postharvest diseases of tomatoes and citrusand other species as well. Synthetic fungicides are the primary means to control these diseases. However, the chemical residues in the food and environmental safety make it unwanted. Biological control using microbial antagonists is one of the most promising alternatives to chemical fungicides. Pseudomonas spp. produce many antifungal metabolites, previously shown to be effective against a wide range of fungi. In this study, the inhibitory effects of Pseudomonas putida Q172B, P. fluorescens Q110B and P. fluorescens Q036B, isolated from tomato roots in Agadir-Morocco, on B.cinerea and P. digitatum were examined. The effect of Pseudomonas strains was observed on the inhibition of mycelium elongation by
production of soluble and volatile metabolites. The results showed the antagonism effect of three strains. The inhibition rate ranged from 39 to 54% for P. digitatum, and 66% for B.cinerea for all three strains. For volatile metabolites,100% of mycelium inhibition was recorded in B.cinerea for all three strains, but 44% was the maximum mycelium inhibition recorded in P. digitatum. Our result highlights that the P. putida Q172B and P. fluorescens(Q110B and Q036B) can be used as a non-chemical alternative treatment to control postharvest diseases of fruits.
Key words: Biological control, Botrytis cinerea, Penicillium digitatum, Pseudomonas fluorescens, Pseudomonas putida.
... Per other industrial applications, R. glutinis has been evaluated as a biocontrol agent for post-harvest microbial diseases of fruit (US patent US5525132A). To this end, it has been shown to significantly reduce the incidence of the gray mold, Botrytis cinerea on strawberries and apples [70,71] possibly due to the attachment capability of the antagonistic R. glutinis to B. cinerea [72]. R. glutinis was also used in combination with rhamnolipids to be more efficacious against Alternaria alternata infection in cherry tomato fruit than either agent alone [73]. ...
... Fruits from the different treatments, as well as controls were collected 1, 3, 7, 10 and 15 days after the second spray application at random from sampling, and placed in sterilized plastic container contained ice packages. Fruits were incubated at 5˚C for 7 days and observed daily for Botrytis fruit rot development (Hongyin et al., 2007). Activities of pectinase (PC) and cellulase (CX) enzymes produced by B. cinerea in stored strawberry fruits were determined under laboratory conditions according to methods described by Talboys and Busch (1970) in fruit tissue extract prepared by Luke et al. (1981) The reduction in viscosity of the reaction mixtures containing 2 ml of crude enzyme (tissue extract), 5ml, 1.5% citrus pectin solution in 0.1 M phosphate buffer at PH 5 adjusted by 0.3 M Na OH or HCl. ...
... The results suggested that Y. lipolytica significantly inhibited spore germination rate and germ tube length of P. rubens in PDB media. Similarly, results have been reported that spore germination rate of B. cinerea in PDB media was significantly inhibited by Rhodotorula glutinis (Zhang et al., 2007). ...
Table grapes are one of the most common fruits throughout the world. Decay of grapes caused by pathogenic fungal infections results in tremendous economic losses. The aim of this study was to evaluate the effect of Yarrowia lipolytica on the control of postharvest decay of grapes caused by Penicillium rubens and the possible mechanisms involved. The results showed that Y. lipolytica provided significant inhibition of the postharvest decay of grapes by P. rubens compared with the control. When the concentration of Y. lipolytica was 1 × 10⁹ cells/mL, decay incidence and decay diameter of grapes were 12.45% and 6.19 mm, respectively. Y. lipolytica reduced spore germination and germ tube length of P. rubens. Moreover, the results also showed that the activities of defense-related enzymes, including polyphenoloxidase (PPO), peroxidase (POD), catalase (CAT), phenylalanine ammonialyase (PAL), ascorbate peroxidase (APX) and β-1,3 glucanase (GLU),were significantly enhanced in grapes treated with Y. lipolytica. Similarly, the expression levels of these genes were also increased in grape fruits treated with Y. lipolytica. The results suggested that the possible resistance mechanism of Y. lipolytica was to enhance the defense-related enzymes and genes, ultimately reduce postharvest decay caused by P. rubens in grapes. Altogether, the research work confirmed that Y. lipolytica has potential biocontrol efficacy and could be used as a biocontrol agent to prevent the postharvest decay of grape fruits.
... Previous studies showed that MAP delay senescence of strawberry fruits Besides, MAP can effectively inhibit the cell permeability increasing. Therefore, the shelf life of strawberry was increased accordingly (Zhang et al 2007) The interaction between MAP treatments and storage period was significant, however, strawberry fruits packed in polypropylene film with active MAP1 showed the best appearance, and they did not exhibit any changes in their appearance till 12 th days at 0˚C +2 days at 10˚C and gave product with good appearance after 15 days of storage at 0˚C + 2 days at 10˚C, while MAP2 treated fruits had good appearance until 12 days at 0˚C +2 days at 10˚C then dropped to fair level at the end of storage period. On the other hand, untreated MAP (control) resulted in poor appearance after 15 days of storage at 0˚C + 2 days at 10˚C.These results were true in the two seasons and agreed with those of Concerning the effect of MAP; data revealed that all treatments had significantly greater fruit texture as compared with untreated MAP (control). ...
... L'efficacité des agents de biocontrôle est néanmoins variable et dépend notamment de leur stabilité dans le temps. Cette stabilité peut être influencée par le microclimat, ainsi certains agents de biocontrôle ne se maintiennent pas lors de fluctuations de température ou d'humidité, tandis qu'au contraire, d'autres microorganisme tel que Rhodotorula glutinis, restent efficaces contre B. cinerea après d'importantes variations de température (Zhang et al., 2007). L'efficacité des agents de biocontrôle dépend également du stade d'infection au moment de l'application de ces derniers ainsi que des plantes infectées (Nicot et al., 2016). ...
La perception et l’adaptation à l’environnement sont des processus indispensables pour la survie des organismes vivants. Le champignon phytopathogène Botrytis cinerea peut ainsi percevoir différents types de signaux qu’ils soient chimiques ou physiques. La voie de signalisation de la MAPK Sak1 est impliquée dans l’adaptation au stress osmotique, oxydatif et pariétal, mais aussi dans la sporulation et le pouvoir pathogène en régulant la pénétration de la plante et le développement des nécroses. Afin d’approfondir les connaissances existantes sur la voie de Sak1, nous avons réalisé des études globales basées sur des techniques de protéomique et phosphoprotéomique. L’analyse de protéomique comparative entre la souche sauvage et les mutants de signalisation ∆bos1 et ∆sak1 a notamment mis en évidence que la MAPK Sak1 régule l’abondance de protéines impliquées dans la voie des protéines G et la voie calcique. Cette connexion avec les protéines G a été confirmée par une baisse de la concentration en AMPc chez le mutant ∆sak1. L’utilisation du fludioxonil comme signal de l’activation de la MAPK Sak1 pour l’analyse par phosphoprotéomique a mis en évidence des modifications de l’état de phosphorylation de protéines. Parmi ces protéines différentiellement phosphorylées, la présence de PKAR (sous-unité régulatrice de la protéine kinase A) et du facteur de transcription CRZ1, indiquent respectivement une action sur la voie via protéines G et la voie calcique, validant les résultats obtenus par protéomique. Le phosphoprotéome a révélé une « phosducin-like protein », PhnA. Sa caractérisation fonctionnelle montre son rôle dans l’adaptation aux stress, la sporulation et la germination, ainsi que dans le pouvoir pathogène mettant ainsi en évidence un nouveau facteur de pathogénicité chez B. cinerea. Notre étude a permis de révéler des interactions entre Sak1 et d’autres voies de signalisation non suspectées, agissant aussi bien sur la production de certains composants (régulations transcriptionnelles et traductionnelles) que sur la phosphorylation (modifications post-traductionnelles). Nos résultats constitueront la base de nouvelles recherches pour compléter nos connaissances sur ces interactions impliquant l’adaptation au stress et la pathogénie de B. cinerea.
... Compared with bacteria, the genome of yeasts is more stable. Some yeast species have been reported to be effective agents for the suppression of gray mold on strawberry [20,21]. Several mechanisms have been proposed for the biological control of pathogenic fungi [22]. ...
Gray mold (Botrytis cinerea) is one of the most common diseases of strawberries (Fragaria × ananassa Duchesne) worldwide. Although many chemical fungicides are used for controlling the growth of B. cinerea, the risk of the fungus developing chemical resistance together with consumer demand for reducing the use of chemical fungicides have necessitated an alternative method to control this pathogen. Various naturally occurring microbes aggressively attack plant pathogens and benefit plants by suppressing diseases; these microbes are referred to as biocontrol agents. However, screening of potent biocontrol agents is essential for their further development and commercialization. In this study, 24 strains of yeast with antagonistic ability against gray mold were isolated, and the antifungal activity of the volatile and diffusible metabolites was evaluated. Putative mechanisms of action associated with the biocontrol capacity of yeast strains against B. cinerea were studied through in vitro and in vivo assays. The volatile organic compounds produced by the Galactomyces candidum JYC1146 could be useful in the biological control of plant pathogens and therefore are potential alternative fungicides with low environmental impact.
... Biocontrol by yeast has similarly been described in stone fruits against B. cinerea, Monilinia fructicola, Rhizopus stolonifer, and P. expansum (Qin, Tian, Xu, Chan, & Li, 2006;Qing & Shiping, 2000;Yao & Tian, 2005;Zhang, Zheng, & Yu, 2007b). Studies with other fruits such as banana (Lassois, de Lapeyre de Bellaire, & Jijakli, 2008), papaya (Lima et al., 2013), strawberry (Cai, Yang, Xiao, Qin, & Si, 2015;Zhang et al., 2007a), grapes (Masih & Paul, 2002;Parafati et al., 2015;, kiwi (Batta, 2007), and pineapple (Reyes, Rohrbach, & Paull, 2004) and vegetables as tomatoes (Kalogiannis et al., 2006;Saligkarias, Gravanis, & Epton, 2002), chillies (Chanchaichaovivat, Ruenwongsa, & Panijpan, 2007), and potatoes (Schisler, Slininger, & Bothast, 1997) also demonstrated the potential of yeasts as antagonists. ...
Edible films and coatings have been extensively studied in recent years due to their unique properties and advantages over more traditional conservation techniques. Edible films and coatings improve shelf life and food quality, by providing a protective barrier against physical and mechanical damage, and by creating a controlled atmosphere and acting as a semipermeable barrier for gases, vapor, and water. Edible films and coatings are produced using naturally derived materials, such as polysaccharides, proteins, and lipids, or a mixture of these materials. These films and coatings also offer the possibility of incorporating different functional ingredients such as nutraceuticals, antioxidants, antimicrobials, flavoring, and coloring agents. Films and coatings are also able to incorporate living microorganisms. In the last decade, several works reported the incorporation of bacteria to confer probiotic or antimicrobial properties to these films and coatings. The incorporation of probiotic bacteria in films and coatings allows them to reach the consumers’ gut in adequate amounts to confer health benefits to the host, thus creating an added value to the food product. Also, other microorganisms, either bacteria or yeast, can be incorporated into edible films in a biocontrol approach to extend the shelf life of food products. The incorporation of yeasts in films and coatings has been suggested primarily for the control of the postharvest disease. This work provides a comprehensive review of the use of edible films and coatings for the incorporation of living microorganisms, aiming at the biopreservation and probiotic ability of food products.
... Hal. [59][60][61][62][63][64][65][66][67][68][69][70] tambahan oleoresin 0%, 4%, dan 6%. Karakteristik kertas aktif terbaik adalah kadar air 9,93±0,30%; ketebalan 0,81±0,00 mm; ketahanan tarik 0,54±0,04 N/mm; dan ketahanan lipat 0,30. ...
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Strawberries (Fragaria x ananassa) are one of the horticultural commodities which have a high production and nutritional value. However, strawberries susceptible to loss of quality during postharvest. Changes in the quality of strawberries among others physical, chemical, and microbiological. Therefore, strawberries are required handling during storage with packaging. Active paper packaging based on oleoresin of ginger dreg 2% containing active substances that inhibit the growth of microbes. This research uses current active paper packaging based on oleoresin ginger dreg as a packaging of strawberries. The purpose of this research was to determine the effect of using active paper packaging based on oleoresin of ginger dreg on the quality of strawberries during 12 days of storage at 10 ± 2 ºC. Results of ANOVA analysis with 5% significance shows that the use of active paper packaging based on oleoresin ginger dreg effect on weight loss strawberries for 12 days of storage, color of red on the 3rd, 9th, and 12th day of storage, total acid titration on the 12th day of storage, total dissolved solids on 9th and 12th day of storage, and vitamin C on the 12th day of storage. The hardness and pH value are not affected by the current active paper packaging based on oleoresin ginger dreg during 12 days of storage. Total microbial of strawberries with active paper laying variation has a total microbial lower than strawberries control.
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... Previous reports of fitness studies also reveal that there was a significant difference for DC but no significant difference between benzamide-sensitive and resistant field isolates of B. cinerea, which is in line with our findings Moyano et al. 2004;Sun et al. 2010;Zhang et al. 2007). Fitness assessment suggested a high risk for the use of zoxamide because the R isolates have comparable contestability with S isolates in the field. ...
Altogether, 192 Botrytis cinerea isolates collected from tomato greenhouses at different locations in Hubei Province were evaluated for their sensitivity to fungicides procymidone and zoxamide. The mean effective concentration to cause 50% growth inhibition (EC50) values of procymidone for sensitive and resistant isolates were 0.25 and 3.60 μg/ml, respectively. The frequency of procymidone-resistant (ProR) isolates was 18%, and the highest frequency was recorded in Jingmen. Positive cross-resistance was observed for ProR isolates to other dicarboximide fungicides but not to phenylpyrroles. Significant differences were observed for fitness parameters (i.e., mycelial growth, osmotic sensitivity, and virulence between sensitive and resistant isolates). Amino acid sequence of the Bos1 gene revealed that ProR isolates carried either point mutations at codon 365 (I365S) or a pair of point mutations at codons 369 (Q369P) and 373 (N373S). For zoxamide, the mean EC50 values for sensitive and resistant isolates were 0.22 and 5.32 μg/ml, respectively. Approximately 14% of the isolates were found to be resistant to zoxamide, and the highest frequency of resistance was also observed in Jingmen. There was positive cross-resistance for zoxamide-resistant (ZoxR) isolates to carbendazim. No significant differences were observed for fitness parameters between zoxamide-sensitive and ZoxR isolates. Sequence analysis of the β-tubulin gene of Botrytis cinerea revealed two previously reported point mutations (E198A and E198K) and one new point mutation (T351I). This new mutation was detected in only those isolates which possessed the E198K but not E198A substitution. This study allows for a better understanding of the resistance development profile in Hubei Province. Results will be useful for the improvement of fungicide resistance management strategies.
... For example, a recent taxonomic reclassification based on a number of morphological traits combined with molecular analyses was performed for Pucciniomycotina yeasts ). The family Sporidiobolaceae, which originally included the genera Rhodotorula, Rhodosporidium, Sporobolomyces, and Sporidiobolus, is of interest in this work because it includes several red yeasts that are reported to be BCAs of plant pathogenic fungi (Castoria et al. 2003(Castoria et al. , 2005Cheng et al. 2016;Ianiri et al. 2013;Pinedo et al. 2018;Yan et al. 2014;Zhang et al. 2007;Zheng et al. 2005Zheng et al. , 2017. Reclassification placed Rhodosporidium and Sporidiobolus in the novel genus Rhodosporidiobolus, with consequent name changes in several species. ...
The field of plant protection is steadily reducing the use of chemicals by increasing the use of microbial biocontrol agents. At present, several microorganisms are active ingredients of the so-called biofungicides and some of these are based on yeasts. Molecular techniques applied in microbial taxonomy are leading to extensive revisions of the classification of many microbial groups, including various yeasts used for biocontrol. Recent taxonomic revision of the basidiomycete genus Cryptococcus resulted in C. laurentii (Kufferath) Skinner (Tremellales) being renamed as Papiliotrema laurentii, including strains displaying biocontrol activity, such as strain LS28. In this study, we performed comparisons of ITS, D1D2, TEF1, and RPB1 nucleotide sequences of LS28 with the corresponding genes of the type strains of taxonomically related species. We found that the yeast strain LS28 belongs to the species P. terrestris (Tremellales) (Crestani et al. Int J Syst Evol Microbiol 59:631–636, 2009) rather than P. laurentii. We encourage other groups working on biocontrol to perform molecular characterization of their yeast(s) of interest to identify the species that have the highest potential for practical applications and facilitate possible commercial registration.
... The average disease incidences of A. tenuis and B. cinerea were 100% and 96.17% after inoculation onto the wounded and intact fruits, respectively. The difference from the previous studies may due to the relationship between the pathogenicity of microbial isolates and the ripening index of peach fruits at harvest [39,40]. ...
Postharvest fungal disease is one of the significant factors that limits the storage period and marketing life of peaches, and even result in serious economic losses worldwide. Biological control using microbial antagonists has been explored as an alternative approach for the management of postharvest disease of fruits. However, there is little information available regarding to the identification the fungal pathogen species that cause the postharvest peach diseases and the potential and mechanisms of using the Bacillussubtilis JK-14 to control postharvest peach diseases. In the present study, a total of six fungal isolates were isolated from peach fruits, and the isolates of Alternaria tenuis and Botrytis cinerea exhibited the highest pathogenicity and virulence on the host of mature peaches. In the culture plates, the strain of B. subtilis JK-14 showed the significant antagonistic activity against the growth of A. tenuis and B. cinerea with the inhibitory rates of 81.32% and 83.45% at 5 days after incubation, respectively. Peach fruits treated with different formulations of B. subtilis JK-14 significantly reduced the mean disease incidences and lesion diameters of A. tenuis and B. cinerea. The greatest mean percent reduction of the disease incidences (81.99% and 71.34%) and lesion diameters (82.80% and 73.57%) of A. tenuis and B. cinerea were obtained at the concentration of 1 × 107 CFU mL-1 (colony forming unit, CFU). Treatment with the strain of B. subtilis JK-14 effectively enhanced the activity of the antioxidant enzymes-superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in A. tenuis and B. cinerea inoculated peach fruits. As such, the average activities of SOD, POD and CAT were increased by 36.56%, 17.63% and 20.35%, respectively, compared to the sterile water treatment. Our results indicate that the isolates of A. tenuis and B. cinerea are the main pathogens that cause the postharvest peach diseases, and the strain of B. subtilis JK-14 can be considered as an environmentally-safe biological control agent for the management of postharvest fruits diseases. We propose the possible mechanisms of the strain of B. subtilis JK-14 in controlling of postharvest peach diseases.
... The application of synthetic fungicides for the control of grey mould decay in strawberry fruit during postharvest life convey impending food and environmental safety jeopardies. Hence, developing safe and ecofriendly procedures for the control of grey mould decay is an economically interesting challenge for the strawberry industry (Aghdam & Fard, 2017;Jannatizadeh, Aghdam, Farmani, Maggi, & Morshedloo, 2018;Liu, Zheng, Sheng, Liu, & Zheng, 2018;Zhang, Wang, Dong, Jiang, Cao, & Meng, 2007). In recent years, great efforts have been made by researchers for delaying senescence and reducing decay in strawberry fruits during postharvest life (Li et al., 2018;Li, Ye, Jiang, & Luo, 2017). ...
Herein, we employed exogenous phytosulfokine α (PSKα) for delaying senescence and lessening decay in strawberry fruits during storage at 4 °C for 18 days. Our results showed that the strawberry fruits treated with 150 nM PSKα exhibited lower expression of poly-ADP-ribose polymerase 1 (PARP1) gene, leading to a higher intracellular NAD⁺ availability, beneficial for a sufficient provision of intracellular NADP⁺ with the activity of NAD kinase (NADK). Moreover, higher activities of glucose 6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), and methylenetetrahydrofolate dehydrogenase (MTHFD) may be the reason for the sufficient intracellular availability of NADPH in strawberry fruits treated with 150 nM PSKα. In addition, strawberry fruits treated with 150 nM PSKα exhibited a sufficient availability of ATP resulted from higher activities of succinate dehydrogenase (SDH) and cytochrome c oxidase (CCO). Therefore, our results indicate that exogenous PSKα could be beneficial for delaying senescence and reducing decay in strawberry fruits during cold storage.
... Cryptococcus laurentii (Kuffer.) Rhodotorula glutinis (Fresenius) (Tian et al., 2004), Trichoderma harzianum (Zhang et al., 2007) and Epicoccum nigrum (Larena et al., 2005) have proved postharvest control of strawberries where synthetic fungicides proved ineffective. In a different study, the preharvest application of Aureobasidium pullulans reduced significantly the storage rots in strawberry (Lima et al., 2003), grapes and cherries (Schena et al., 2003), and apples (Leibinger et al., 1997). ...
Crop protection is vital to maintain high productivity and high quality of crops. Over the past years, people used different fungicides, herbicides and good agronomical practices to control fungal diseases and pests to increase productivity. However, extensive use of chemicals in controlling pests and diseases resulted in negative impacts on the environment, producing inferior quality and harming consumer health. In recent times, diverse approaches are being used to manage a variety of pathogens for control of plant diseases. Biological control is the alternative approach for disease management that is eco-friendly and reduces the amount of human contact with harmful chemicals and their residues. A variety of biocontrol agents including fungi and bacteria have been identified; In this regard, yeast and trichoderma species are the most researched microbes in biocontrol research area. But, despite the presence of many reports on biocontrol, practicability of the biocontrols requires effective adoption and a better understanding of the intricate interactions among the pathogen, plants and environment towards sustainable agriculture. To this end, this review attempts to find and compile previous works done on the role of trichoderma and yeast as a biocontrol agent against postharvest fungal pathogens. Moreover, this review analyzes the mechanisms of biocontrol activity, their means of application and future prospects on the use biogents and the challenges that encounter during the commercialization process.
... Due to the absence of antibiotics or mycotoxins production in yeast, yeasts have been used alone or integrated with other control methods in the biological control of some fungal diseases in fruits. [12,[48][49][50]. It is important to determine yeast diversity which including potential yeast strains for the biological control, of fruits. ...
Since yeasts can survive under variable environmental conditions using different food sources they have a wide distribution in nature. Fruits are suitable living spaces for yeasts and other microorganisms due to their high and different sugar contents. Strawberry fruit as well as other fruits are very sensitive to pathogenic fungi. Due to their residues on fruits, limitations on the use of fungicides have led to increased use of microorganisms with antagonistic effects as biological control agents. The biological agents to be used are selected mainly from the microorganisms found in the natural microbiota of the fruit. Therefore, in this study yeast biota on strawberry fruit collected from fungicide treated (Klorzon and Topas) and organic fields was determined using molecular identification methods. In addition, extracellular enzyme profiles of the identified yeast species were determined by the APIZYM-based system. There was no difference in the diversity of yeast species on strawberries collected from fungicide treated and organic fields, but the yeast density on organic strawberries was greater than fungicide treated fruits. The identified yeast species on fruits were determined as Metschnikowia pulcherrima (61.7%), Hanseniaspora uvarum (34.0%) and Wickerhamomyces pijperi (4.3%). W. pijperi yeast species was reported on strawberry fruit in our study first time. It was determined that H. uvarum and W. pijperi yeast species showed no α-glucosidase enzyme activity. All yeast strains showed industrially important β-glucosidase enzyme activity.
... The ClO 2 and O 3 pre-treatments also exhibited higher SSC than the control, the hot NaClO and UV-C pre-treatments, in agreement with the results that the gaseous phase of O 3 maintained higher SSC likely due to the inhibition of the respiratory response (Chen, Zhu, 2011), and the ClO 2 pretreatment was more beneficial for total SSC in strawberry (Aday, Caner, 2014). The high physiological activity and respiration rate possibly resulted in the fast hydrolysis of soluble solids (Zhang et al., 2007), the effectiveness of chemical sanitisers could slow down the metabolic activity, and the sterilization efficiency of chemical sanitisers is enhanced by the cavitation activity of ultrasound (Maslak, Weuster-Botz, 2011;Aday, Caner, 2014). Surface sterilisation using chemical or physical methods influence microbial growth and quality of green asparagus ISSN 1392-3196 Zemdirbyste-Agriculture Vol. ...
... The use of synthetic fungicides applied for relieving grey mold decay in strawberry fruit during postharvest life is limited because of food and environmental safety regulations. Hence, developing safe and eco-friendly procedures for relieving grey mold decay would be of great economic interest for the strawberry industry (Aghdam and Fard, 2017;Jannatizadeh et al., 2018;Liu et al., 2018;Zhang et al., 2007). ...
During postharvest life, strawberry fruit as a perishable commodity exhibiting short shelf life suffers from fungal decay that severely limits its marketability and nutritional value. Herein, we investigated the mechanisms activated by exogenous phytosulfokine α (PSKα) application at 150 nM to delay senescence and relieve decay in strawberry fruit during storage at 4 • C for 18 days. Our results showed higher extracellular adenosine triphos-phate (ATP) accumulation arising from lower apyrase 1 (APY1) gene expression in strawberry fruit treated with 150 nM PSKα during storage at 4 • C for 6 days may serve as a signaling molecule to promote NADPH oxidase activity to trigger signaling H 2 O 2 accumulation giving rise to higher SUMO E3 ligase (SIZ1) gene expression during 18 days of storage at 4 • C. Also, higher superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) genes expression and enzymes activity associated with higher methionine sulfoxide reductase (MSR) and peroxiredoxin (Prx) genes expression in strawberry fruit treated with 150 nM PSKα during storage at 4 • C for 18 days may be ascribed to extracellular ATP signaling. As a result, promoting ROS scavenging systems activity by triggering extracellular ATP signaling in strawberry fruit treated with 150 nM PSKα may be responsible for higher maintenance of membrane integrity as shown by lower malondialdehyde (MDA) accumulation during 18 days of storage at 4 • C. Besides, strawberry fruits treated with 150 nM PSKα exhibited lower weight loss, total soluble solids, and chroma value concurrent with higher firmness, titrable acidity, L* value, and hue angle as quality attributes, which indicated delayed fruit senescence. Based on our findings, exogenous PSKα application unveils its potential to be used as a promising signaling biopeptide for senescence delay and decay alleviation in strawberry fruit during its postharvest life.
... The most commonly used yeast species against B. cinerea is Aureobasidium pullulans due to its ability to compete effectively for space and nutrients, both on the plant surface and in wounds, and for the release of different antifungal compounds, with successful applications in the post-harvest industry in grapes and kiwifruits [25][26][27]. In this regard, effective antagonism has also been described through the release of VOCs in strawberries by Galactomyces candidum [28] and the competition for space in wounds by Rhodotorula glutinis [29]. In addition, in planta, for both tomato leaves and post-harvest grapes, it has been possible to significantly inhibit the development of the fungus and the appearance of the disease, thanks to the ability of Candida oleophila and Pichia membranifaciens, respectively, to produce chitinase and glucanase enzymes that degrade the fungal cell wall [30,31]. ...
Botrytis cinerea is a polyphagous necrotrophic fungus and is the causal agent of grey mold diseases in more than 1400 different hosts. This fungus causes serious economic losses in both preharvest and post-harvest—mainly in grape, strawberry, and tomato crops—and is the second most important pathogen worldwide, to our knowledge. Beneficial bacteria and fungi are efficient biocontrol agents against B. cinerea through direct mechanisms, such as parasitism, antibiosis, and competition, but also indirectly through the activation of systemic plant resistance. The interaction between plants and these microorganisms can lead to the development of defensive responses in distant plant organs, which are highly effective against foliar, flower, and fruit pathogens, such as B. cinerea. This review aimed to explore the systemic plant defense responses against B. cinerea by compiling all cases reported (to the best of our knowledge) on the use of beneficial bacteria and fungi for agriculture, a subject not yet specifically addressed.
... R. glutinis is also an effective biocontrol agent. The yeast cells were able to colonize rapidly the wounded fruits and inhibited the growth of B. cinerea and P. expansum on strawberries and apples by affecting spore germination (Zhang et al., 2007;Zhang et al., 2009). The rhodotorulic acid produced by Rhodotorula species is a hydroxamate-type siderophore with high affinity for the Fe 3+ ions from the environment. ...
Currently postharvest loss of food commodities is a global challenge and it has been estimated that
nearly 30%–50% of the fresh products were lost during the postharvest storage due to pathogenic attack,
improper storage, transportation, or packaging. The pathogenic attack during postharvest storage is
considered as the prime factor for postharvest loss. Conventionally, breeders frequently utilized chem-
ical pesticides or fungicides to manage pathogenic attack and enhance the shelf life of food products.
However, inappropriate and continuous use of chemical pesticides lead to adverse impacts such as chemical residue, low-quality product, and environmental contaminants, or phytopathogens resistance.
Thus, there is a need to search for an alternative, that must be eco-friendly, cost-effective, and free from chemical residue. The microbial antagonism is an emerging approach and is broadly utilized in man-aging the growth of pathogens during pre- or postharvest storage. This chapter summarizes the latest approach and mode of action of microbial antagonistic in managing the pathogens of fresh products
during postharvest storage.
Fresh apple market is affected every year by losses caused by fungi invasion and spoilage, with Botrytis cinerea one of the main responsible pathogens. The objective of this study was the characterization of the in vitro antagonistic activity of Metarhizium anisopliae Ma70 against Botrytis cinerea and its trial on apple fruit. The antagonism was tested by dual cultures, cellophane membrane assay and the effect of M. anisopliae crude extract over conidia germination and mycelium growth of B. cinerea. The trials on apple fruit evaluated crude and semi purified extracts activity against apple gray mold. Antifungal volatile organic compounds produced during the process were determined using GC-MS. We observed that M. anisopliae (Ma70), reduced the B. cinerea growth by 60-63% (P< 0.01). Pathogen’s mycelium is degraded, even without physical contact. Cellophane tests showed that growth inhibition by antibiosis reach a 88%. The Ma70 extracts affects conidia germination (92%) and mycelial growth (50-80%) of B. cinerea. The phytopathogen suffers membrane lipoperoxidation by the effect of antagonist extracts, the malondialdehyde production was increased by a factor of two, in mycelium and in the culture medium. We observed that crude (CE) and semi-purified (SPE) MA70 extracts reduced the damage caused by B. cinerea in apple. The B. cinerea growth inhibition by the VOCs produced by Ma70 was different depending on the culture media, with the highest inhibition effect (75%) seen in sabouraud dextrose agar plus yeast extract. Twenty-eight volatile organic compounds (VOCs) were identified in CE (mainly oxalic acid) and 13 in SPE (mainly octane,1-methoxy). Only 1-Octanol appears in both CE and SPE. M. anisopliae Ma70 can be an effective treatment for biocontrol of the apple gray mold disease, producing compounds that inhibited conidia germination and mycelium growth of B. cinerea.
Morphological and molecular identification of Botrytis cinerea the causal agent of grey mold isolated from strawberry fruits. Arab Journal of Arid Environments. 12 (1-2):8-17 (2019).
Botrytis cinerea is an economically important plant pathogen that infects more than 200 plant species in the field, greenhouses and storage. In present study, strawberry fruits infected by grey mold were collected from local markets. The pathogen was isolated on PDA, and morphologically identified basing on the colony morphology, s, conidiophore shape, conidia size and sclerotia formation. The results showed that the fungal growth on PDA was in many patterns. The conidiophores were more or less straight, septate and branched at the apex. Sizes of the conidia were 8.2–10 X 9–15 μm. The sclerotia were observed on 30 days old colonies as ring along the edge of the Petri dish. Pathogen taxonomy was further confirmed by PCR using two specific primers, C729+/C729_. Results indicated that the isolates were Botytis cinerea as they produce bands of 700 bp. The closet phylogenetic neighbours according to this DNA fragment sequence data was Botrytis cinerea with 99% of similarity.
Methylated vegetable oil adjuvants can enhance initial deposition and decrease the required dosages of pesticides sprayed on plants, so an oil adjuvant mixed with fungicides were used to prevent and control gray mold in greenhouse strawberry. As the persistence and dietary exposure risks from fungicides on strawberries after using adjuvants have not been assessed, the efficacy, dissipation and safety of pyrimethanil and boscalid in the presence and absence of a methylated vegetable oil adjuvant were evaluated. To better describe the actual use of fungicides in greenhouse strawberry, twice repeated application of fungicides were conducted follower by an optimized QuEChERS pre-treatment method.
When applied at 60% of their recommended dosages with the adjuvant, the efficacy of pyrimethanil and boscalid for gray mold was similar to that shown by the treatment of 100% fungicides in absence of the adjuvant based on Duncan’s Multiple-Range test, and their average residues increased to 89.0% and 89.3%, respectively. The adjuvant enhanced the accumulation effect of pyrimethanil residue by 31.7% after repeated applications, and the half-lives were similar (5.2 and 4.2 d). The adjuvant had comparable accumulation effects (1.75 and 1.83) and similar half-lives (5.4 and 5.5 d) for boscalid. In absence of adjuvant, the risk quotients (RQs) of pyrimethanil (0.41 and 0.33) and boscalid (0.49 and 0.63) after twice applications at pre-harvest interval were lower than 1. Adding the methylated vegetable oil adjuvant to fungicides would result in unprolonging half-life and acceptably low dietary exposure risk on strawberries, but lower dosage of fungicides were used.
The effectiveness of Rhodotorula mucilaginosa in combination with salicylic acid (SA)was explored for the control of green mold decay of oranges and the mechanisms involved. The results of the study showed that treatments with the diverse concentrations of SA was remarkable in reducing the disease incidence of oranges and that SA at a concentration of 0.2 mM reduced the decay of oranges from 93.06% to 61.12%. At an incubation temperature of 20 °C and RH of 95% the disease incidence and lesion diameter in fruit treated with R. mucilaginosa enhanced with or without SA were significantly reduced compared to that of the control (P < 0.05). Moreover, the growth of the antagonist was enhanced in vivo by the combination of SA (0.2 mM)at both 20 °C and 4 °C, whiles it did not have any influence on the antagonist in vitro. Mycelia growth and spore germination of P. digitatum in orange wounds were found to be significantly inhibited by the combination of R. mucilaginosa and SA (0.2 mM)from the scanned electron micrographs. Postharvest qualities of orange fruit were not impaired by the combination of the antagonist with SA. Additionally, the combination of the antagonist with SA (0.2 mM)led to an upsurge in polypenoloxidase (PPO), peroxidase (POD), phenylalanine ammonia lyase (PAL), catalase (CAT), ascorbate peroxidase (APX)and β-1,3-glucase (GLU)activities. The improved control via SA could be ascribed either to direct effect or induce resistance of this organic chemical. Thus, the proper combination of R. mucilaginosa and SA can offer a vigorous approach to lessen postharvest decay of oranges.
Brown rot caused by Monilinia fructicola has led to considerable preharvest and postharvest losses in all major nectarine fruit-growing areas. In our previous study, we successfully identified a biocontrol strain of bacteria, Bacillus licheniformis W10, that can be used to control brown rot. However, the possible mechanism of the control of brown rot by B. licheniformis W10 is still unclear. Therefore, the objectives of this study were to determine whether B. licheniformis W10 induces resistance by activating defense-related enzymes including antioxidant enzymes in nectarine. Treatment of nectarine fruit with B. licheniformis W10 reduced both M. fructicola-induced oxidative damage and reactive oxygen species (ROS) production. Furthermore, application of B. licheniformis to nectarine fruit resulted in a significant increase in the activity of antioxidant and defense-related enzymes and increase in the expression of the corresponding genes. Overall, our results verified the proposed mechanism of B. licheniformis W10 in controlling M. fructicola via regulation of ROS levels and activation of antioxidant and defense-related enzymes.
Çilek karakteristik özellikleri ile tüm dünyada en çok tercih edilen meyveler arasında yer almaktadır. Taze çileğin morfolojik yapısı gereği hasat işleminden sonra soğukta depolama esnasında üründe kalite kayıpları gözlenmektedir. Bu nedenle, taze çileklerde yıkama işlemi özellikle mikrobiyal yükün azaltılması ve raf ömrünün artırılması adına önem arz etmektedir. Tüketici kaynaklı sağlık endişelerinden dolayı meyve ve sebzelerin endüstriyel yıkama işleminde kimyasal kullanımına alternatif olarak geliştirilen yöntemlere talep giderek artmaktadır. Ultrases yıkama, kimyasal yıkama işlemlerine kıyasla mikrobiyal yükün azaltılmasının yanında kalite özelliklerinin korunması açısından tercih edilmeye başlanan yenilikçi bir yöntem olarak karşımıza çıkmaktadır. Bu çalışma kapsamında hasat sonrasında taze çileklere ultrases (550 W/35 kHz) ve peroksiasetik asit (40 ppm) ile yıkama işlemleri uygulanmıştır. Yıkama işlemleri gerçekleştirilen çileklere soğukta depolama esnasında 14 gün boyunca pH, toplam asitlik, suda çözünür kuru madde (briks), C vitamini, toplam fenolik madde, antioksidan kapasite, toplam canlı mikroorganizma, küf ve maya sayısı analizleri uygulanmıştır. Ultrases yıkamanın, kavitasyon etkisi sayesinde çileklerde mikrobiyal yükün azaltılması ve biyoaktif özelliklerin korunumunda diğer yönteme kıyasla daha etkili olduğu belirlenmiştir.
Grey mould and Rhizopus rot are diseases of numerous food crops such as strawberry. Composts are sources of beneficial microorganisms, including bacteria that may help control plant disease. The present study evaluated compost bacteria efficacy in inhibiting growth of Botrytis cinerea and Rhizopus stolonifer and in controlling strawberry fruit grey mould and Rhizopus rot. Bacterial antagonists inhibited mycelial growth of B. cinerea and R. stolonifer by as much as 44% and 43%, respectively. The culture filtrates of many bacterial antagonists showed similar inhibitory effects on the growth of the two moulds. Various bacteria showed suppression of grey mould, decreasing disease severity by up to 71%. Different bacteria also provided inhibition of Rhizopus rot, reducing disease incidence and severity by up to 67% and 91%, respectively. Bacillus spp. were particularly suppressive to grey mould, whereas Arthrobacter spp. only suppressed Rhizopus rot. Pseudomonas spp. suppressed both diseases. Antibiosis seemed to be an important component of the activity of the most suppressive bacterial isolates against strawberry grey mould. Results of this study indicate that compost bacteria could aid in the control of strawberry fruit rot.
This study determined the competitive saprophytic ability (CSA) of the hypovirulent isolate QT5-19 of Botrytis cinerea on potato dextrose agar (PDA) at 20°C. Meanwhile, importance of the QT5-19 CSA in biocontrol against virulent isolates of B. cinerea and Sclerotinia sclerotiorum (a close relative of B. cinerea), and the mechanisms for the QT5-19 CSA were elucidated. The results showed that QT5-19 had higher CSA than the virulent isolates 08168 (B. cinerea) and EP-1PNA367 (S. sclerotiorum) on potato dextrose agar. The hyphal fragments of QT5-19 exhibited an effective suppression against infection of leaves of oilseed rape by the hyphae of the two virulent fungal pathogens through competition. QT5-19 was detected to be able to produce volatile organic compounds (VOCs) with antifungal activity against B. cinerea and S. sclerotiorum, whereas the VOCs from the virulent isolate RoseBc-3 of B. cinerea had no detectable antifungal activity. The QT5-19 VOCs effectively reduced disease severity of strawberry fruit rot caused by two virulent fungal pathogens. These results suggest that QT5-19 may achieve success of competition through extensive mycelial growth and production of antifungal volatiles. This study provided an example of using hypovirulent isolates to control virulent isolates of B. cinerea and S. sclerotiorum.
Blackberry (Rubus glaucus Benth.) is perishable fruit with high susceptibility to soft mold which reduces its marketability. The antifungal chitosan action has been studied to maintain blackberry quality during postharvest. However, this biopolymer needs to be dissolved in organic acid to be able to perform correctly as a coating. In this work, the effectiveness of different chitosan concentrations prepared with either lactic or acetic acid was evaluated, for controlling Mucor racemosus in blackberries stored at 4 °C for 14 d. Fruit decay treated with chitosan was compared with the one obtained in blackberries treated with the chemical fungicide imazalil (0.4 g L⁻¹) and with that one obtained in untreated fruit. The treatment with chitosan 17.5 mg mL⁻¹ - lactic acid (LA-17.5) was the most effective (p < 0.05) in the control of soft mold. Blackberry physicochemical properties and its sensory quality were not negatively affected by the treatment with chitosan 17.5 mg mL⁻¹- lactic acid (LA-17.5). The results obtained suggested that the coating with chitosan could be used for the control of soft rot in blackberry during postharvest period.
The treatment of seeds is important to ensure the health of those seeds and the seedlings they generate, allowing full expression of the genetic and physiological potential of the crop. Furthermore, seed treatments can be useful in reducing the amounts of pesticides required to manage a disease, because effective seed treatments can eliminate the need for foliar application of fungicides later in the season. Although the application of fungicides is almost always effective, their non-target environmental impact and the development of pathogen resistance have led to the search for alternative methods, especially in the past few years. In this work, two bacterial isolates of Bacillus amyloliquefaciens (B3 and B24) selected as antagonistic strains of Botrytis cinerea in previous study were used for strawberry seed treatments. The efficacy of seed treatments with B. amyloliquefaciens strains against the B. cinerea pathogen was evaluated based on germination proportion of seeds. When applied as seed treatments, the percentage of germination of seeds treated with B. amyloliquefaciens B3 and B24 was much higher than that of seeds treated with the conidia of the pathogen B. cinerea, and it approaches that of control seeds.
Chapter 5 Appendix 1-6: pages 72-138
Antifungal metabolites produced by Bacillus sp. W10, which was previously isolated from the tomato rhizosphere, were investigated. Strain W10 was identified as Bacillus amyloliquefaciens by analysis of its 16S rDNA and gyrB gene partial sequences. PCR analysis showed the presence of fenB, sfp, and ituD genes, coding for fengycin, surfactin, and iturin, respectively. A novel small antifungal peptide, designated 5240, produced by this strain was isolated by ammonium sulfate precipitation and Superdex 200 gel filtration chromatography. The 5240 peptide was stable at 100 °C for 20 min and remained active throughout a wide pH range (4–10). The antagonistic activity was not affected by protease K and trypsin. The purified 5240 peptide exhibited a broad inhibitory spectrum against various plant pathogenic fungi and was identified as iturin A (C14-C16). Moreover, matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry indicated the presence of fengycin A (C14-C15), fengycin B (C16-C17), and surfactin (C13-C16) isoforms in supernatants from strain W10. These results suggest that B. amyloliquefaciens W10 has significant potential as a biocontrol agent.
Losses are generally determined at a single point in the postharvest food pipeline and accumulated losses while food is being transported and processed are seldom calculated. We fail to consider postharvest disease losses in grocery stores, restaurants, fast food outlets, and kitchens. Also, losses in the nutritional value and quality of food are generally overlooked. In less de veloped countries, postharvest losses are even greater because of the lack of adequate refrigeration and poor sanitation. Worldwide, postharve st losses have been estimated to be 50% of the harvested crop (20) and much of this is due to rots caused by microorganisms. Fungicides are a primary means of controlling postharvest diseases (26) and they have recently come under special scrutiny as posing potential oncogenic risks when applied to processed foods. A 1987 U.S. National Academy of Sciences (NAS) report (41a) states, "As a class the fungicides present special difficulties because nine oncogenic compounds account for about 90% of all fungicide sales." The report indicates that fungicides constitute 60% of the
Mycelial fungi, yeasts, and bacteria were isolated from strawberry plants and evaluated for biocontrol of Botrytis cinerea in strawberry. Comparative tests were done on leaf discs and detached petals in the laboratory and on attached leaves and flowers in the growth room, greenhouse, and field plots. In the various controlled environments, strawberry tissues were inoculated with the microorganisms (107 fungal spores or yeast cells, and 108 bacterial cfu/mL) and challenge-inoculated with the pathogen (106 spores/mL) after 24 h. After a further 24 h, inoculated tissues were transferred to an agar medium containing paraquat to kill the tissues and allow B. cinerea to sporulate within 5-7 d; sporulation density was estimated after 7 d for indirect quantification of infection and colonization. Biocontrol effectiveness of 230 isolates on leaf discs ranged from 0 to 100%; the organisms were grouped into five categories using cluster analysis of the observations, Eleven organisms, including representatives of each biocontrol category, ranked similarly in effectiveness against B. cinerea in the various tests in the laboratory, growth room and greenhouse according to Pearson's correlation analysis (coefficient r = 0.84 to 0.96. P ≤ 0.01). The eleven organisms plus three others were evaluated also in four field tests. Inocula (106 fungal spores/mL; 107 yeast cells or cfu bacteria/mL) or caplan (6.75 kg/ha) were applied three to six times at 5- to 7-d intervals from the green flower-bud stage to the white-pink fruit stage. At the second time of inoculations, B. cinerea (2 x 103 conidia/mL) also was applied. Isolates of Gliocladium roseum, Penicillium sp., Trichodenna viride, Colletotrichum gloeosporioides, Epicoccum purpurascens, and Trichothecinm roseum were among the more effective organisms and suppressed incidence of B. cinerea on stamens and fruits by 79-93% and 48-76%, respectively. Several mycelial fungi were at least as effective as captan. Relative effectiveness of the organisms correlated significantly among the field tests (r = 0.53 - 0.89, P ≤ 0.10 - 0.01) and among the field and controlled tests (Spearman's ranking coefficient = 0.48 - 0.82, P ≤ 0.10 - 0.01, in most instances). It was concluded that the tests in the various controlled environments were effective for identifying organisms of high potential for suppressing B. cinerea in the field.
Antagonistic bacteria and yeasts were isolated from the epiphytic flora of stored strawberry fruits and evaluated for their ability to protect strawberry fruit wounds after harvest against Botrytis cinerea. Among selected potential antagonists, three strains of Candida reukaufii (5L3, 10CL4, 10L2) and one strain of Candida pulcherima (10L8) still protected fruit wounds when applied at 10(3) CFU/wound, reducing lesion or conidiophore development. In the same conditions, two Enterobacteriaceae (10B1, 5B4) highly reduced pathogen development. Strain 5B4 was still highly inhibitory when inoculated at 10(2) CFU/wound. The six strains applied on fruits did not produce any significant change in color, brightness, and firmness of fruits. The two yeasts, 5L3 and 10L8, and particularly the two bacteria, 5B4 and 10B1, were selected for further studies. The four antagonists effectively colonized fruit wounds and strongly inhibited spore germination of B. cinerea in vitro. The bacterial cells surrounded the germinating spores of B. cinerea and attachment of 5L3 cells on germinating spores were additionally observed. Bacterial antagonists, particularly the strain 5B4, multiplied and rapidly used carbohydrates in strawberry fruit juice despite the low pH (pH 3.5). The efficiency of the bacterial antagonists on fruit wounds was related to their growth and nutritional properties.
Losses from postharvest fruit diseases range from 1 to 20 percent in the United States, depending on the commodity. The application of fungicides to fruits after harvest to reduce decay has been increasingly curtailed by the development of pathogen resistance to many key fungicides, the lack of replacement fungicides, negative public perception regarding the safety of pesticides and consequent restrictions on fungicide use. Biological control of postharvest diseases (BCPD) has emerged as an effective alternative. Because wound-invading necrotrophic pathogens are vulnerable to biocontrol, antagonists can be applied directly to the targeted area (fruit wounds), and a single application using existing delivery systems (drenches, line sprayers, on-line dips) can significantly reduce fruit decays. The pioneering biocontrol products BioSave and Aspire were registered by EPA in 1995 for control of postharvest rots of pome and citrus fruit, respectively, and are commercially available. The limitations of these biocontrol products can be addressed by enhancing biocontrol through manipulation of the environment, using mixtures of beneficial organisms, physiological and genetic enhancement of the biocontrol mechanisms, manipulation of formulations, and integration of biocontrol with other alternative methods that alone do not provide adequate protection but in combination with biocontrol provide additive or synergistic effects.
The effectiveness of using honey bees and bumble bees to vector a commercial formulation of Trichoderma harzianum 1295-22 for the control of Botrytis cinerea on strawberries was evaluated from 1994 to 1997 in 2 strawberry fields at the New York State Agricultural Experiment Station in Geneva, New York and in 10 grower fields in eight counties of New York. Commercial bumble bee colonies were used to deliver the biocontrol agent in 1994 and 1995 and five-frame nuclear honey bee hives were used in 1995–1997. Each honey bee exiting the hive carried about 1 × 105 colony-forming units of T. harzianum, with the majority found on the bees' legs (58%). Flowers collected from the bee-delivered treatment generally had half the density of T. harzianum as those from the sprayed treatment. However, during the 4 years of this study, T. harzianum delivered by bumble bees or honey bees provided better Botrytis control than that applied as a spray. In addition, the bee-delivered T. harzianum provided the same or a better level of control of Botrytis as commercial fungicides applied at bloom. Strawberries collected from the bee-visited treatments averaged 22% more seeds and weighed between 26 and 40% more than berries in nonvisited treatments. The number of seeds per berry and berry weight were reduced by 7–12% in plots treated with fungicides and visited by bees, indicating that the use of some commercial fungicides at bloom may impact pollination and yield. Bee delivery of T. harzianum 1295-22 is a viable option for strawberry growers interested in controlling Botrytis with minimal fungicide use.
Mertely, J. C., MacKenzie, S. J., and Legard, D. E. 2002. Timing of fungicide applications for Botrytis cinerea based on development stage of strawberry flowers and fruit. Plant Dis. 86:1019-1024. During the 1999-2000 and 2000-2001 growing seasons, field experiments were conducted to identify the developmental stage(s) of strawberry flowers and fruit that requires fungicide ap- plications to control Botrytis fruit rot. Fenhexamid, a protectant fungicide, was applied to indi- vidual newly opened flowers or fruit of cultivar Sweet Charlie at defined intervals after anthe- sis. In 1999-2000, a single application of fenhexamid at anthesis controlled Botrytis fruit rot as well as multiple weekly applications beginning at anthesis. During both seasons, disease control deteriorated as applications were delayed 7 and 14 days after anthesis. This trend was described by linear regression equations relating the time of application to Botrytis fruit rot incidence. Additional treatments tested the effects of emasculation and petal removal 3 to 7 days after anthesis. Emasculation significantly reduced disease incidence in 2000-2001. Petal removal produced modest but significant reductions in 1999-2000, but not in 2000-2001. These results demonstrate that strawberry flowers are more susceptible to Botrytis cinerea than green fruit, and suggest that stamens are the principal infection court. Fungicide applications should focus on peak bloom periods to minimize fungicide use and optimize control of preharvest Botrytis fruit rot. During these periods, applications should be made at close intervals ( 7 days) to minimize losses to Botrytis.
A screening programme is described for the assessment of the potential of biocontrol agents to control grey mould of strawberries caused by Botrytis cinerea. Bacteria were isolated from strawberry fruits, leaves and flowers from a commercial field site and screened for antagonism towards B. cinerea using two in vitro and one in vivo screening techniques. From 559 microorganisms isolated, 108 inhibited pathogen growth on agar plates and 27 of these prevented spore germination on Cellophane membranes. The ability of these 27 isolates to inhibit infection of young strawberry leaves by B. cinerea on whole plants under glass was then tested. Seven isolates reduced grey mould development and were subsequently assessed in a field trial. Two isolates, one of Bacillus pumilus and one of Pseudomonas fluorescens, were as effective or more effective than standard dichlofluanid sprays and may therefore be of potential value as antagonists of B. cinerea.
Many yeasts, including yeast-like fungi, were selectively isolated from fruits and vegetables. In several assays performed on strawberries, table grape berries and kiwifruit, the yeast-like fungus Aureobasidium pullulans L47 and the yeasts Candida vanderwaltii L60 and C. oleophila L66 were the most effective antagonists of Botrytis cinerea and Rhizopus stolonifer. Isolates L47 and L66 were utilized in trials on strawberries grown under plastic tunnels. They were applied at flowering (full bloom and late petal fall) and at fruit maturity (just before or after harvest). Isolate L47 was the most effective against both B. cinerea and R. stolonifer. Both antagonists were more active when applied at the flowering stage, with isolate L47 more effective than vinclozolin. The antagonist population was consistently high on flowers and developing fruits, and on cold-stored strawberries. Isolates L47 and L66 showed a low sensitivity towards some fungicides in culture and were able to grow at temperatures between those of cold storage and 33 °C. Competition for nutrients seems to be the main mode of action.
The effectiveness of short hypobaric treatments against postharvest rots was investigated by exposing sweet cherries, strawberries and table grapes to sub-atmospheric pressures (0.25, 0.50, and 0.75 atm) for different times (from 1 to 24 h). Postharvest rots of sweet cherries and strawberries arose from natural infections, whereas small table grape bunches and artificially wounded single berries were inoculated with Botrytis cinerea after hypobaric treatment. Sweet cherries exposed to 0.50 atm for 4 h had the lowest incidence of gray mould, brown rot and total rots, while a 1 h treatment was not effective. On strawberries, the greatest reductions of gray mould and Rhizopus rot were observed on fruits treated for 4 h at 0.25 and 0.50 atm, respectively. On table grape bunches treatment with 0.25 atm applied for 24 h significantly reduced the incidence of gray mould. In experiments performed with artificially wounded single table grape berries exposed to 0.50 atm for 24 h and then inoculated, the percentage of infected fruits and the diameter of the lesions were significantly reduced, in comparison with the controls. As a sub-atmospheric pressure of 0.25 atm did not affect radial growth of B. cinerea and Monilinia laxa, induced resistance was likely to be responsible for the observed reduction in decay.
The efficacy of hot water, biological control and controlled atmospheres (CA), alone and in combinations, in controlling gray mold on harvested strawberry fruit was tested. All fruit were wound inoculated with Botrytis cinerea Pers.:Fr. Inoculated fruit were subsequently dipped in hot water at 63 °C for 12 s, inoculated with a biological control yeast, Pichia guilliermondii Wickerham, and/or immediately stored at 5 °C under air or 15 kPa CO2 for 5 and 14 days followed by 2 days at 20 °C to simulate market conditions. Fruit treated with the combination of heat, biocontrol, and CA had significantly less decay than those in all of the other treatments after 5 days at 5 °C plus 2 days at 20 °C. After 14 days at 5 °C and 14 days at 5 °C plus 2 days at 20 °C, the heat+biocontrol+CA treatment continued to control decay though not significantly more than CA alone, biocontrol+CA, or heat+CA treatments. Some damage occurred following heat treatment; however, quality parameters did not differ between treatments. Overall, the combination treatments did not provide better control than the current commercially used treatment of 15 kPa CO2.
ABSTRACT Interactions between CaCl(2), grapefruit peel tissue, Penicillium digitatum, and the yeast antagonist Pichia guilliermondii strain US-7 were investigated. Application of 68 or 136 mM CaCl(2) to grapefruit surface wounds reduced the incidence of green mold caused by Penicillium digitatum by 43 to 52%. In laboratory tests, a cell suspension (10(7) cells/ml) of Pichia guilliermondii containing either 68 or 136 mM CaCl(2) reduced the incidence of green mold from 27 to 3%. In large scale tests, dip application of 136 mM CaCl(2) with US-7 (10(7) cells/ml) significantly decreased the number of wounds infected by Penicillium digitatum. CaCl(2), with or without yeast cells, stimulated ethylene production in grapefruit tissue. Increasing concentrations of CaCl(2) resulted in decreased spore germination and germ tube elongation of Penicillium digitatum. Pectinolytic activity of crude enzyme preparations of Penicillium digitatum was also inhibited by the presence of increasing concentrations of CaCl(2). US-7 exhibited a strong ability to maintain cytosolic Ca(2+) homeostasis at levels that did not exceed 1.4 muM when exposed to 150 mM CaCl(2). On the other hand, strain 114 of Debaryomyces hansenii, which failed to give any protection against infection by Penicillium digitatum, showed reduced capacity to maintain Ca(2+) homeostasis. The effect of calcium in reducing infection of grapefruit wounds by Penicillium digitatum could be due to direct effects on host tissue (making cell walls more resistant to enzymatic degradation) or the pathogen (interfering with spore germination, growth, and inhibition of fungal pectinolytic enzymes). Alternatively, the ability of US-7 to maintain calcium homeostasis may allow it to grow or assist in its competitive ability in a microenvironment that, because of high levels of calcium ions, is inhibitory to growth of the green mold pathogen.
Epiphytic microorganisms isolated from apples, pears and the surfaces of apple leaves were screened for antagonistic activity against Penicillium expansum (blue-mold), Botrytis cinerea (gray-mold) and Rhizopus nigricans (Rhizopus rot) on apple (Malus domestica). A total of 933 bacteria and yeasts were tested in primary screening against P. expansum. Ninety-two strains reduced the lesion size on apples by more than 50%, 72 of which were isolated from the surface of apples. For secondary screening against P. expansum, B. cinerea and R. nigricans, 31 strains were selected. The most promising isolate, CPA-1, was identified as Candida sake. This yeast, isolated from apples in storage season was very effective against all three diseases. Wounded Golden Delicious apples protected with the yeast suspension at a concentration of 2.6 x 10(6) CFU/ml and inoculated with conidia of B. cinerea and R. nigricans of 10(5) and 10(4) conidia/ml, respectively, did not develop rot. Complete control of P. expansum was obtained at the same concentration of the antagonist with a pathogen inoculum concentration of 10(3) conidia/ml. This strain, also provided excellent control of rot development under cold storage conditions. The strain of Candida sake can grow actively in aerobic conditions. In drop-inoculated wounds of apples, the populations of C. sake increased by more than 50-fold during the first 24 h at 20 degrees C. The maximum population of C. sake on apple wounds was the same at 20 as at 1 degrees C and was recovered after three and twenty days, respectively.
Strategies for the isolation and testing of biocontrol agents Isolation of microbial antagonists for bio-control of grey mould disease of strawberries
- J L Smilanick
Smilanick, J.L., 1994. Strategies for the isolation and testing of biocontrol agents. In: Wilson, C.L., Wisniewski, M.E. (Eds.), Biological Control of Postharvest Diseases, Theory and Practice. CRC Press, Boca Raton, FL. Swadling, I.R., JeVries, P., 1996. Isolation of microbial antagonists for bio-control of grey mould disease of strawberries. Biocontrol Sci. Technol. 6, 125–136.
Isolation of microbial antagonists for biocontrol of grey mould disease of strawberries
- J L Smilanick
- I R Swadling
- P Jevries
Smilanick, J.L., 1994. Strategies for the isolation and testing of biocontrol
agents. In: Wilson, C.L., Wisniewski, M.E. (Eds.), Biological Control of
Postharvest Diseases, Theory and Practice. CRC Press, Boca Raton, FL.
Swadling, I.R., JeVries, P., 1996. Isolation of microbial antagonists for biocontrol of grey mould disease of strawberries. Biocontrol Sci. Technol.
6, 125-136.
Strategies for the isolation and testing of biocontrol agents
- Smilanick