Genetic Analysis of Wine Grape High-Quality Ripening in the 'Monastrell' x 'Syrah' Progeny

The technological (sugar/acid balance) and the phenolic ripening (accumulation and extractability of grape anthocyanins and tannins) have great relevance to wine quality. In order to find genes involved in high-quality wine grape ripening, we are carrying out a genetic analysis in a F1 progeny segregating for these traits, consisting of 230 hybrids from a cross between the cultivars 'Monastrell' and 'Syrah'. 'Monastrell' is a variety widely grown and used in the Murcia Region (southeast of Spain), and is very well adapted to the dry conditions of the Mediterranean climate. 'Syrah' is used in the same region blended with 'Monastrell'. We genotyped the 230 offspring for 138 SNP markers and 104 SSR markers scattered over 19 linkage groups (LGs). The consensus map contained 229 markers covering 1,180.79 cM, with an average distance between loci of 5.16 cM. The female and male genetic maps covered a total length of 1,039.66 and 1,027.20 cM, respectively. Grape quality traits and phenological parameters were evaluated for two years. QTL analyses are being carried out using a Multiple-QTL Mapping (MQM) method focused on QTLs previously detected during the two seasons via simple interval mapping (SIM analysis). Both genome-wide and linkage-group-wide LOD thresholds corresponding to alpha=0.20 were used as minimum values for QTL detection. QTLs for sprouting time with LOD value higher than the genome-wide threshold (significant QTLs) were consistently detected on LGs 1 and 8, explaining between 14% and 18% of total variance. Other QTLs for veraison time, fertility and berry weight were also found.