Kurzbeschreibung
(Französisch)
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Etude de la variation des stilbènes du bois de vigne de différents cépages cultivés en Suisse afin d'établir une corrélation entre les proportions des phytoalexines, les cépages et les conditions écologiques du terrain.
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Partner und Internationale Organisationen
(Englisch)
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AT, BG, CH, CY, CZ, DE, ES, FR, GR, HU, IL, IT, LU, PL, PT, RS, SE, SI
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Abstract
(Englisch)
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In parallel to this a project, initially directed by Dr. Eliane Abou-Mansour, was set up with the aim to increase the knowledge of the metabolites intervening in the mechanism of defense of grapevine. The objectives were the identification of constitutive stilbenes in grapevine wood and their quantification. A lot of studies have been carried out on stilbenes in grapes leaves and vine but very few studies was carried on wood. The originality of the project was based on the fact that no studies have been done to date on systemic comparison of stilbenes content in grapevine wood despite it is considered by some authors as a potential source for their storage. The realisation of the research on a great number of varieties allowed us to know if their production was related to a genetic intrinsic factor. This criteria could be then compared with the degree of resistance or tolerance with each cultivar against diseases (grey mould, downy mildew, grapevine wood diseases). At the end we compared the production of the different phytoalexins with the parental relationship among grape varieties (partly performed in an other COST project). Phytoalexins have been shown to possess biological activity against a wide range of pathogens and can be considered as markers for plant resistance. Phytoalexins form the Vitaceae is constituted of a restricted group of molecules belonging to the stilbenes family, the skeleton of which is based on trans-resveratrol structure. Several simple stilbenes such as trans-pterostilbene (dimethylated resveratrol), trans and cis piceid a 3-O-b-D-glucoside of resveratrol, and oligomers of resveratrol as viniferins have also been found in grapevine as a result of infection or stress. The major compound appears to be epsilon-viniferin, a cyclic dehydromer of resveratrol, delta-viniferin synthesized by V. vinifera under stress. Grapevine wood diseases such as eutypa dieback, esca, and black dead arm, are destructive diseases affecting vineyards all over the world, caused by one or several fungal xylotrophs respectively. The main research findings concern pathogen identification, reproduction of symptoms through inoculation with various fungi, as well, the influence of the environment on the incidence of the disease was studied. There is no emphasis on the influence of the wood constituent such as phytoalexins on fungal growth or diseases development within the bark. The aim of this study was to screen the wood of V. vinifera cultivars for the presence of phytoalexins in order to establish a correlation between the abundance of phytoalexins and the resistance of the cultivar to grape wood pathogens. Twenty swiss red and twenty eight white cultivars were selected for this study. Phytoalexins were extracted from milled basal stems of healthy plants. Samples were analysed by reverse chromatography with diode array detection. Quantification of phytoalexins was performed by adding an internal standard, 4-hydroxystilbene and the Identification by comparison with the standards. Standards were preliminary isolated and identified by MS and RMN from grape stem. We report, the quantification of trans and cis piceid, trans and cis resveratrol, trans and cis epsilon-vinifeine, trans and cis vitisine A and trans pterostilbene. Delta- viniferine was not detected in the stem. These results indicate a similar composition in phytoalexins but a high variation in concentration between cultivars. A statistical comparison between the acquired knowledge on grape resistance to wood pathogen with phytoalexin concentrations confirmed the correlation between phytoalexin and total phenols composition and wood resistance. More, comparison with the genetic parentage of the grape varieties based on 25 microsatellite markers established that there is no correlation between the amount of phytoalexins produced in a grape variety and the parentage. On the other hand there is a clear link between the color of the berries and production of phytoalexins as well as a gradient between the contents of resveratrol, viniferin and vitisin.
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