Exploring the Genetic Determinants of Grapevine Phenology and QTL Identification in Vitis vinifera through Interval Mapping

Long-term studies on grapevine phenology have clearly demonstrated the anticipated phenological events due to gradual global warming, affecting the grape yield and wine quality. Adaptation of local grape varieties to changing climatic conditions is thus a major breeding target, which includes the selection of late ripening varieties/clones, whose bunches may escape the warmer summer condition by postponing the ripening period. However, assessment of the genetic basis of phenology and quality related traits is a prerequisite to develop effective breeding programs for grapevine varieties adapted for the cultivation in specific viticultural areas and to identify the candidate genes for the new breeding approaches. Grapevine phenological traits show complex quantitative inheritance. The potential genes with additive effects are mapped through QTL mapping approaches, to dissect the genomic regions harboring such QTLs to further explain the genetic basis of quantitative variation. For this purpose, we have evaluated a population from the cross between the locally (Verona province, Italy) grown grapevine variety “Corvina” and another variety viz. “Solaris”, highly divergent for their phenology and fruit ripening traits. Seedlings were developed, propagated and grown in field conditions to be evaluated for mapping of genetic traits. High throughput SNP genotyping of the cross population was applied through hybridization to an Illumina Vitis18KSNP chip. The phenotypic data, collected over three seasons included the determination of the main phenological stages (budbreak, flowering, veraison) together with the assessment of some morphological and quality traits at harvest on all progenies with the final purpose of QTL mapping. The results from QTL analysis revealed genetic determinants putatively involved in controlling grapevine phenology. Derived markers, in future, will not only help grapevine breeders to further understand the genetic control of phenology and quality related traits but also guide to regulate /incorporate desired traits in future selections.