Phenotypic and molecular characterization of 18 Bulgarian newly bred grapevine varieties in relation to their resistance to downy mildew

Abstract

Eighteen Bulgarian newly bred grapevine varieties obtained by interspecific crossing were analysed through microsatellite markers in order to determine their genetic identity as well as the presence of resistance-related alleles linked to Rpv3, Rpv10 and Rpv12 loci. The levels of resistance of the investigated cultivars to downy mildew were assessed by leaf disk assay and were scored according to OIV descriptor 452. Seven isolates of Plasmopara viticola collected in different regions of Bulgaria were characterized and discriminated with seven microsatellite markers and were used in the assays. Analysis of variance showed significant differences in resistance to downy mildew among the analysed varieties. A clear correlation between the presence of particular Rpvs and the level of resistance was determined. Five cultivars, ‘Droujba’, ‘Garant’ and ‘Plevenska rosa’ harbouring Rpv3 and Rpv12, ‘Kajlashki rubin’ harbouring Rpv12 and ‘Slava’, Rpv10 and Rpv3, showed high level of resistance with mean OIV452 values ranging from 6.5 to 8.25 over all seven P. viticola isolates. The level of resistance of the remaining 14 cultivars, which carry only Rpv3 inherited from cultivar Villard Blanc, was found to vary significantly among the isolates with mean OIV452 values between 1.75 and 4.8 over all used P. viticola isolates. The results obtained in this study favoured five genotypes remarkable for their high resistance to downy mildew and very good quality of grape and wine. These varieties represent a valuable material for pyramiding of resistance through marker-assisted selection.

Keywords

• Plasmopara viticola
• downy mildew resistance
• Rpv
• genotyping
• SSRs
• interspecific crossing