Several studies have shown that the degree of stenospermocarpic seedlessness is largely controlled by a majar effect locus known as seed development inhibitor (SDJ) closely linked to the VMC7j2 microsatellite marker on linkage group 18. This locus also displays high pleiotropic effects on other quality traits such as berry and cluster size or berry crispiness. In this work we have analyzed the genetic structure of berry size and shape and their genetic interactions with traits like seed number and weight. For this purpose we perforrned a QTL mapping of seven quantitative variables defining those traits in a 292 hybrids offspring derived from the cross between table grape cultivars Red Globe and Crirnson Seedless. The large population size allowed us to detect a higher number of small-effect QTL than in smaller populations. In addition, we were able to perform independent QTL mapping in the two subpopulations, seeded and seedless, that can be defined based on the genotype of the SDI locus. This analysis detected additional QTLs which effects could be masked in the whole population. Both berry size and berry shape showed a complex genetic structure. Many QTLs of small to medium effects contributed to all variables related to berry size such as berry weight, berry volume, berry length or berry diameter. In addition the SDJlocus hada very large effect on all ofthem (explaining between 30 and 69% of total variance depending on trait and year). Only a reduced set of those loci that did not include SDI contributed to explain the variation in berry shape. Moreover, other additional loci showed a specific effect on berry shape but apparently without affecting size.

Póster presentado en el IX International Symposium on Grapevine Physiology and Biotechnology, celebrado en La Serena (Chile) del 21 al 26 de abril de 2013.

Acknowledgments: Project: BI02008-03892 Fellowship: BES-2009-027462.

Peer Reviewed