engleski

Phenotyping and polyphenolic discrimination of Croatian native grapevine varieties inoculated with Plasmopara viticola

Grapevine-downy mildew interaction is one the most challenging biotic stresses. In order to avoid undesirable features of non-vinifera species, usually used for resistance breeding, the resistance of cultivated (V. vinifera) varieties to the main diseases is in the spotlight again. Aiming to find differences among Croatian native grapevine varieties in susceptibility to downy mildew, whose causal agent is Plasmopara viticola, an experiment has been conducted. Young leaves of 14 Croatian native grapevine varieties, together with Chardonnay (susceptible control variety), Solaris (partially resistant variety) and Vitis riparia (resistant genotype) were sampled and used in this research. A leaf disc bioassay was applied according to the OIV descriptor 452-1 whereby the genotypes were ascribed to corresponding OIV classes 1, 3, 5, 7, and 9 from the most susceptible to the totally resistant ones. Polyphenolic compounds were quantified by high-performance liquid chromatography (HPLC). The results were analysed using one way ANOVA and the differences between the means were evaluated by Duncan’s multiple range test at a confidence level of 95 % (p < 0.05). Principal component analysis was performed to show the differences in the polyphenolic composition of grapevine leaves between non-inoculated and inoculated varieties belonging to OIV classes 1, 3 and 5 in different terms (24, 48 and 96 hpi) upon inoculation. Majority of evaluated native varieties (≈80 %) are highly susceptible or susceptible to P. viticola belonging to OIV classes 1 or 3, respectively. However, scarce sporulation (21-40 %) developed on leaf discs of the following varieties Malvazija istarska, Ranfol and Teran placed them to the OIV class 5. PCA clearly distinguished diverse classes of susceptibility among evaluated V. vinifera varieties based on their polyphenolic composition. Nonetheless, their polyphenolic composition in terms upon inoculation was not significantly different. Methods applied in this research proved to be reliable and complement one to another. Early changes in polyphenolic profiles upon inoculation were not found, although they served as a decisive feature for distinguishing classes of susceptibility which were previously obtained by artificial inoculation. Less susceptible grapevine varieties that belong to the class 5 could be of interest to use in breeding programs.

Vitis vinifera ; Downy mildew ; Susceptibility ; Leaf discs ; HPLC analysis

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