Comparative mapping of quantitative traits in grape.

The development of DNA sequences and the increasing number of mapping projects are exploiting the potential of co-dominant molecular markers to generate a common reference genetic map for grape. A set of microsatellite markers enables the identification of all 19 homologous linkage groups (2n = 38 for Euvitis) and the direct comparison of information derived from different crosses. Several experiments are being conducted to assess QTL stability across different genetic backgrounds and environments. The comparative analysis and utility of molecular maps of grape based on both intra-vinifera crossings and F1 Vitis hybrid progenies are discussed. The preliminary evaluation of QTLs and candidate genes for the traits ‘Muscat flavor’ and ‘resistance to downy mildew’ is reported. These QTLs were produced from mapping experiments designed to investigate the genetic control of these important traits for wine and table grape production.