[Show abstract][Hide abstract] ABSTRACT: Objective. Plant cell culture is an innovative technology to produce a variety of substances. Numerous plants synthesize among their secondary metabolites phenolic compounds which possess antioxidant and antimicrobial effects. Hawthorn (Crataegus) is one of these plants which has long been used in folk medicine and is widely utilized in pharmaceutical preparations mainly in neuro- and cardiosedative actions. Methods and Results. The production of polyphenol by fifty-two-week-old Crataegus azarolus var. aronia calli was studied in relation to growth variation and antioxidant and antimicrobial capacity within a subcultured period. The DPPH and ABTS+ assays were used to characterize the antioxidant actions of the callus cultures. Antimicrobial activity was tested by using disc diffusion and dilution assays for the determination of the minimal inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC) values of each active extract. High TEACDPPH, TEACABTS, and antimicrobial activity was observed when maximal growth was reached. An optimum of total phenol, proanthocyanidins, flavonoid, (−)-epicatechin, procyanidin B2, chlorogenic acid, and hyperoside was produced during this period. Conclusion. Antioxidant and antimicrobial activities were strongly correlated with total phenols and total flavonoids. Crataegus azarolus var. aronia cells culture represents an important alternative source of natural antioxidants and antimicrobials.
[Show abstract][Hide abstract] ABSTRACT: Fusarium wilt of melon, caused by Fusarium oxysporum f.sp. melonis (Fom), is an important disease; races of the pathogen were identified by inoculating differential standard host cultivars. A total of ten isolates that were obtained from 23 fields located in four different geographical regions were identified as pathogenic. Results indicate that all four known Fom races, namely, 0, 1, 2 and 1.2, were found in north and middle Tunisia. Race 1.2 was the most prevalent.
[Show abstract][Hide abstract] ABSTRACT: Three Monosporascus eutypoides-like isolates recovered from cucurbit plants with symptoms of Monosporascus root rot and vine decline in Tunisia were compared to 28 isolates of M. cannonballus from 12 countries for phenotypic, genomic, and pathogenicity characteristics. Morphologically, M. cannonballus and M. eutypoides-like cultures were similar, each producing fertile perithecia in culture containing globose, smooth, dark brown to black ascospores. Nevertheless, all M. cannonballus isolates had one ascospore per ascus, while M. eutypoides-like isolates had mainly two to three ascospores per ascus (rarely one). The employment of the internal transcribed spacer (ITS) of nuclear ribosomal DNA, the elongation factor 1-alpha (EF-1 alpha), and the beta-tubulin (beta-tub) gene sequence diversity analyses and the resulting phylogenies identified a level of polymorphism that enabled separation of M. cannonballus and M. eutypoides-like isolates. All isolates of M. cannonballus had identical EF-1 alpha and beta-tub sequences irrespective of very diverse geographic origins, which were different from the EF-1 alpha and beta-tub sequences of the M. eutypoides-like isolates (96 and 97% similarity, respectively). Similar results were obtained for the ITS region of rDNA. In addition, of three M. eutypoides-like isolates tested for pathogenicity, all three were pathogenic on watermelon, two were pathogenic on muskmelon, but only one was pathogenic on cucumber. The results demonstrate that the M. eutypoides like isolates belong to the species M. eutypoides, and that M. cannonballus and M. eutypoides are distinct species.
[Show abstract][Hide abstract] ABSTRACT: In the present study, the potato cultivar 'Desirée' was transformed via Agrobacterium tumefaciens strain LBA4404 containing the plasmid pBIN19 which harbors the Ribosome Inactivating Protein (rip30). The potato leaf discs were used as an explant for transformation. The in vitro regeneration parameters (percentage of callus regenerated, number of shoots per callus, percentage of regenerated roots and percentage of the transgenic plants) were evaluated. The PCR technique was used for identification of transformed plants. Southern and Western blot analyses were applied for molecular characterization of the transgenic clones. A greenhouse assay was carried out to evaluate the resistance to Rhizoctonia solani pathogen of transgenic clones expressing the rip30 gene. The results revealed that not all the plants developed in selective medium were positive for the corresponding gene using the PCR technique. Southern blot analysis demonstrated that the tested transgenic plants integrated three copies of rip30 gene into their genome. The expression of the RIP30 protein was confirmed in the leaf extracts of the transgenic clones by Western blot analysis. Resistance evaluation of the transgenic plants in greenhouse conditions showed that disease incidence and severity were reduced for R. solani.
Full-text · Article · Jan 2013 · Biotechnology, Agronomy, Society and Environment
[Show abstract][Hide abstract] ABSTRACT: The effect of double stranded RNA (dsRNA) infection on growth rate and the reproductive potential of Monosporascus cannonballus was studied in 21 isolates collected in cucurbit growing areas of Spain and Tunisia. The isolates were incubated on potato dextrose agar (PDA) under different conditions of temperature, pH, and water potential (Ψ(s)). They showed optimal growth temperatures over the range of 27-34°C and perithecia formation was obtained mainly at 25 and 30°C, although some isolates were able to produce perithecia at 35°C. All isolates were able to produce perithecia in a broad range of pHs (4-8). Regarding the effect of Ψ(s,) the isolates were more tolerant to grow on KCl than on NaCl. For each solute, radial growth decreased progressively as Ψ(s) decreased and was severely limited at -5.0 to -6.0MPa. Perithecia formation was highest at -0.5MPa, decreased at -1.0MPa and occurred just in some isolates at -2.0MPa. Nine of the M. cannonballus isolates harboured dsRNA with 2-6 bands each and a size range of 1.9-18.0Kb. Phenotypical data were subjected to multivariate factorial analysis. Most of the isolates clustered in two groups corresponding with the presence/absence of dsRNA elements. Isolates without detectable dsRNA produced more perithecia. However, isolates with dsRNA produced lower number of perithecia depending on the pH, Ψ(s,) or solute used. These results improve our understanding of the behaviour and growth of this pathogen in soil, and can be useful to implement effective disease control.
[Show abstract][Hide abstract] ABSTRACT: The chemical composition of the volatile fractions obtained from distilled woody terminal branches and roots of Tetraclinis articulata (Vahl.) Masters was identified by Gas Chromatography- Flame ionization detectors (GC-FID) and Gas Chromatography-Coupled with Mass Spectrometry (GC-MS). Twenty compounds represented 83.7% of the essential oil from woody terminal branches and 29.2% from the roots. Nonan-1-ol was the main constituent present in the second fraction of the essential oil from woody terminal branches with the highest percentage of 75.22. Monoterpene hydrocarbons viz: α-terpinene (3.04), δ-carene (1.17) and β-ocimene (1.09) were the main compounds. In the fourth fraction of the essential oil from roots, the major compounds detected were Bornyl acetate (16.63), Camphene (1.59) and γ-cadinene (2.86). This fraction was mainly rich in oxygenate compounds (20.25) and sesquiterpene hydrocarbons (6.84). Furthermore, the oils were tested for their antifungal activity against five phytopathogenic fungi. These oils from woody terminal branches and roots of T. articulata (Vahl.) Masters were found to possess antifungal activity.
[Show abstract][Hide abstract] ABSTRACT: Pythium indigoferae and Pythium irregulare, identified based on morphological and physiological characteristics, were isolated from necrotic roots, crown tissues and the rhizosphere of apple trees in Tunisia from 23 apple orchards in spring and autumn 2007–2009. The virulence assays on excised twigs, using different Pythium species isolated demonstrated that these oomycetes were pathogenic on the Anna, Lorka and Meski varieties and the MM106 rootstock. However, the biggest lesion area was noted on MM106 rootstock. Thus, it appeared that this rootstock is more susceptible to Pythium infections than Anna, Meski and Lorka apple varieties. Furthermore, it is important to note that in vitro tests showed that P. indigoferae seems to be more virulent than P. irregulare.
No preview · Article · Dec 2010 · Journal of Phytopathology
[Show abstract][Hide abstract] ABSTRACT: Phallusides 1,2,3 (1), Fasciculatin (2), Acanthelline (3), Axisonitrile (4), Oroïdin (5) and the Novel bromopyrolimidazolic compound Axinellizine (6) were evaluated for their antifungal effects against several phytopatogenic fungi and were found to possess considerable activities. Insecticidal effect of only Acanthellin (3) against the major pest of stored products Tribolium confusum Duv has been carried out using direct contact application method showing a significant inhibitory effect of the test material on the T. confusum Duv larvae growth. Forty-five percent mortality of the adults was achieved 8 days after treatment.
Full-text · Article · Nov 2010 · Comptes Rendus Chimie
[Show abstract][Hide abstract] ABSTRACT: Chalkbrood is a highly contagious disease of the honey bee Apis mellifera caused by the heterothallic fungus known as Ascosphaera apis. The disease appears to be most prevalent in the spring when the brood area is increasing. Certain essential oils are known for their antibacterial and antifungal properties. In this study, a number of essential oils have been shown to be particularly effective in controlling the in vitro growth of A. apis. We tested nine essential oils using two in vitro methods, a direct contact method and a confrontation method. The essential oils used were: Lavandula angustifolia; Rosmarinus officinalis; Thymus vulgaris; Salvia officinalis; Mentha x piperita; Pelargonium graveolens; Prunus dulcis; Citrus aurantium; and Olea europaea. Thyme oil produced the best results, followed by the Pelargonium oil. The remaining essential oils were shown to have limited efficacy against A. apis in this in vitro test system, but may contribute to the enhancement of biological or integrated pest management strategies in apiculture.
[Show abstract][Hide abstract] ABSTRACT: Pepper wilting and root rot disease have been observed in Tunisia for many years. This disease causes severe losses for pepper production both in fields and greenhouses in the main crop cultivated areas of pepper production. The causative agent of the syndrome belongs to the genus Phytophthora and has been identified as Phytophthora nicotianae. Being a soil-borne pathogen, effective disease control methods are limited apart from soil disinfestations by fumigation with methyl bromide and disinfection of internal space of greenhouses with a formaldehyde solution. With the general banning of methylbromide from Europe and countries exporting legumes to the European market, alternative measures for disease management are urgently required. In this study the efficacy of grafting commercial pepper cultivars (Starter and Torero) onto a new rootstock (Brutus) was examined in growth chamber and greenhouse experiments. Hole insertion grafting is shown in this study to be the grafting technique of choice for pepper and validates the general trend that grafting could be used as an alternative control method of soil-borne pathogens such as Phytophthora nicotianae.
Full-text · Article · Jan 2010 · Journal of Food Agriculture and Environment
[Show abstract][Hide abstract] ABSTRACT: Evaluation of the Resistance of some Varieties of Biological Potato to the Mildew Phytophthora infestans. To control the mildew, in particular in biological productions, the varietal resistance of potato could be an advantage to associate with other cultural measurements. For this purpose, sixteen varieties potentially interesting in conventional and biological production were tested with regard to the mildew. Eleven varieties were subscribed in the list A (Alaska, Arinda, Baraka, Fabula, Liseta, Mondial, Platina, Safrane, Santana, Spunta and Timate) and five are in the process of evaluation (Carréra, Cicéro, Derby, Vivaldi, and Voyager). It seemed that the mildew affected all the tested varieties. However, some of them appeared more tolerant than others. Indeed, the Derby and Voyager varieties revealed to be able to delay the starting of the disease of one month. Cicéro, Vivaldi and Timate could delay the development of mildew disease of twelve days, relatively to its appearance on susceptible varieties. Furthermore, the foliar level of destruction remained very limited compared to that on susceptible varieties and not exceed 10% for Timate. The varieties Fabula, Liséta, Carréra, Mondial, Spunta, Platina, Safrane, Arinda, Santana and Baraka showed an early and fast starting of the epidemy. In addition, the tolerance or varietal resistance could not resolve the problem when tubers are affected, since a relatively weak rate of leaves contamination is enough to cause a very important economic loss on the tubers.
[Show abstract][Hide abstract] ABSTRACT: Bioactivity guided fractionation of Echiochilon fruticosum Desf. (Boraginaceae) butanolic extract biautography assay against fungi led to the isolation of a new bioactive alkaloid, named saoussanabiloïde (1). Its structure was established on the basis of spectroscopic measurements, IR, MS and 2D NMR using COSY, HMQC and HMBC experiments. The strongest inhibitory effect of the butanolic extract, from fractions derived from the crude extract and saoussanabiloïde (1), were observed against Fusarium oxysporum f. sp. niveum.
Full-text · Article · Nov 2009 · Natural product research
[Show abstract][Hide abstract] ABSTRACT: Tomato, Lycospersicon esculentum, is an important vegetable crop in Tunisia and many other Mediterranean countries. Fusarium crown and root rot of tomato are new diseases in the area, first reported during 2000-2001 crop season, threatening tomato production. Being a soil-borne pathogen, effective disease control methods of Fusarium crown and root rot are limited thus requiring the alternative measures for disease management. In this study the efficacy of grafting commercial Tomato cultivars Bochra and Amal, used as scions, onto a new rootstock Beaufort and Kemerit RZ was examined in controlled and natural conditions. Grafting was found, in this study, to be an effective method to attenuate the impact of Fusarium wilt, Fusarium crown and root rot. Moreover, grafting increased tomato growth parameters, yield and improved fruit quality.
No preview · Article · Jul 2009 · Journal of Applied Horticulture
[Show abstract][Hide abstract] ABSTRACT: Surveys of 11 watermelon fields throughout production areas of this crop in southern and central regions in Tunisia were conducted in 2007 to determine the aetiology and distribution of watermelon vine decline. Monosporascus cannonballus was isolated from diseased roots in all surveyed fields. All the isolates were identified according to morphological features and confirmed by amplification of a fragment of the ITS region with specific primers. Ascospores of M. cannonballus were recovered from soil in all watermelon fields surveyed and the average population densities ranged from 3.65 to 10.14 ascospores per g of soil. Multiple linear regression analysis revealed that only four of the crop and soil factors evaluated had a significant correlation with ascospore density at the end of the growing season: vertisol vs. other soils, disease incidence, percentage of clay and pH. The pH of the soil showed a strong significant negative linear relationship with ascospore density, while the other three factors correlated positively.
No preview · Article · Jun 2009 · Journal of Phytopathology
[Show abstract][Hide abstract] ABSTRACT: Nine plants belonging to Chenopodiaceae family were collected around salt marshes near Monastir, located in the east Mediterranean coast of Tunisia. They were tested for their antifungal activities against six plant pathogenic fungi: Botrytis cinerea, Fusarium oxysporum f. sp. niveum, F. solani f. sp. cucurbitae, Phytophthora cactorum, Rhizoctonia solani and Nattrassia mangiferae. Data of this study showed that the highest inhibition of Botrytis cinerea growth was observed with the petroleum ether extract of Atriplex inflata fruits (F) (24.5 mm). The in vitro growth of F. oxysporum f. sp. niveum was reduced only with A. inflata whole plant (WP) petroleum ether extract (32.3 mm). The most important inhibition zones were obtained against F. solani f. sp. cucurbitae with Atriplex semibaccata methanol and acetone extracts (34.7 and 31.0 mm, respectively). This work revealed that fungitoxic compounds were probably present in the petroleum ether extract obtained from A. portulacoides (WP), since it has suppressed the growth of F. s. cucurbitae. Our investigation proved that many Chenopodiaceae species adapted to saline soils may contain phytochemical compounds with fungicidal properties.
No preview · Article · Jun 2009 · Natural product research
[Show abstract][Hide abstract] ABSTRACT: The tolerance of different Cucurbita spp. rootstocks to Fusarium spp. affecting watermelon crop was evaluated under greenhouse conditions. Grafted plants on TZ148, Ferro, GV 100 and Just rootstocks were inoculated with two isolates of Fusarium oxysporum f. sp. niveum and one isolate of F. solani f. sp. cucurbitae. The survey was undertaken at three stage of plant development: vegetative growth, flowering and fructification. Grafted plants revealed to be more resistant to tested Fusarium isolates compared to non-grafted ones. However, it is important to mention that the tolerance of plants depends on the development stages of plants. At young stage of plant development, no significant difference between all tested rootstocks was noted. At later stages (flowering and fructification), the level of resistance depends on isolates and vary between very to moderately resistant. For example, GV 100 and Just remained at high level of resistance. These rootstocks could be used in watermelon grafting to control the disease caused by two Fusarium species affecting watermelon.
Full-text · Article · Jan 2008 · Asian Journal of Plant Pathology
[Show abstract][Hide abstract] ABSTRACT: The chemical composition of the volatiles isolated by steam distillation from leaves, flowers and fruits of Opuntia lindheimeri var. linguiformis L. Benson, leaves and flowers of Opuntia macrorhiza Engelm and leaves of Opuntia microdasys (Lehmann) gathered in the sea cliff of Monastir town (Tunisia), has been studied by GC and GC-MS. Remarkable differences were noted between the composition and the constituent percentage of the different studied organs. The most important compounds found in leaves, flowers and fruits of Opuntia lindheimeri var. linguiformis were tetradecanoic acid (3.15-13.57%), hexadecanoic acid (8.5-17.33%), butyl tetradecanoate (8.05-21.47%) and (E)-3-Butyldiene phthalide (6.92-15.77%). In the flowers volatile extract of Opuntia macrorhiza, the main compound found was Butyl tetradecanoate (21.14%). The volatile extract from Opuntia microdasys leaves was mainly rich in hexadecanoic acid (13.13%), (E)-3-Butyldiene phthalide (21.4%) and butyl tetradecanoate (5.91%). Volatile components extracts were tested against the fungi Alternaria solani, Botrytis cinerea, Fusarium solani f. sp cucurbitae, Fusarium oxysporum f. sp niveum, Pythium ultimum and Rhizoctonia solani. The strongest inhibitory effect of the all volatile extracts was observed against
No preview · Article · Sep 2007 · Pakistan Journal of Biological Sciences
[Show abstract][Hide abstract] ABSTRACT: From 3 watermelon cultivars Sentinel, Charleston Gray and Sugar Pack tested against some Tunisian isolates of Fusarium solani f. sp. cucurbitae and Fusarium oxysporum f. sp. niveum, Sugar Pack revealed to be the most susceptible cultivar and was used for grafting to evaluate the resistance of 9 cucurbit rootstocks. Strong toza, TZ148, Emphasis, Polifemo and Ercole were resistant to highly resistant to five Fusarium isolates tested. Rootstocks of Ferro RZ, Macis and S.Camel showed a partial resistance to some isolates of Fsc and Fon. Achille revealed to be highly resistant to Fsc, but susceptible to some isolates of Fon. Seedlings grafted Strong toza x Sugar Pack, TZ 148 x Sugar Pack, Emphasis x Sugar Pack, Achille x Sugar Pack and Ercole x Sugar Pack were resistant to Fsc and Fon isolates. These rootstocks could be used in grafting of watermelon to resolve the problem of two Fusarium species affecting watermelon.