A Major QTL is associated with berry grape texture characteristics

Berry texture and berry skin mechanical properties are traits with high agronomic relevance because they are related to quality parameters and marketing requirements of wine, table, and raisin grapes. Searching for QTLs linked to berry texture, an F1 population of 152 individuals and their parents were used in this study. These F1 plants were obtained crossing Raboso Veronese, a seeded black wine grape cultivar, and Sultanina, a seedless white grape variety, especially used for raisins. Density flotation was applied for berry sorting improving the management of many and highly variable genotypes, irrespective of the quantification of specific molecule classes. Berries were evaluated for technological ripeness parameters and mechanical properties. Texture parameters were taken as raw data and as data normalised on berry dimensions, i.e., berry diameter or surface or volume. SSR molecular markers were used to produce a genetic map and a major QTL for berry texture was found on chromosome 18 with traits related to berry firmness showing a phenotypical explained variance higher than 60 %, and traits related to berry resilience, springiness and cohesiveness showing a variance higher than 50 %. Surprisingly, this QTL showed to be associated with SSR markers linked to VviAGL11, the main gene linked to seedlessness. VviAGL11 expression and co-expression profiling during grape ripening was evaluated using available information; this data suggested a role for this gene on the texture of a ripe berry. List of Abbreviations: ABW, average berry weight BR, berry resilience BR_diam, berry resilience normalised on berry diameter BR_sur, berry resilience normalised on berry surface BR_vol, berry resilience normalised on berry volume BS_ratio, berry springiness BS_ratio_diam, berry springiness normalised on berry diameter BS_ratio_sur, berry springiness normalised on berry surface BS_ratio_vol, berry springiness normalised on berry volume BCo, berry cohesiveness BCo_diam, berry cohesiveness normalised on berry diameter BCo_sur, berry cohesiveness normalised on berry surface BCo_vol, berry cohesiveness normalised on berry volume BH, berry hardness BH_diam, berry hardness normalised on berry diameter BH_sur, berry hardness normalised on berry surface BH_vol, berry hardness normalised on berry volume BG, berry gumminess BG_diam, berry gumminess normalised on berry diameter BG_sur, berry gumminess normalised on berry surface BG_vol, berry gumminess normalised on berry volume BCh_ratio, berry chewiness BCh_ratio_diam, berry chewiness normalised on berry diameter BCh_ratio_sur, berry chewiness normalised on berry surface BCh_ratio_vol, berry chewiness normalised on berry volume Fsk, berry skin break force Wsk, berry skin break energy Esk, berry skin resistance to the axial deformation Spsk, berry skin thickness