Generation of a Common Set of Mapping Markers to Assist Table Grape Breeding

Abstract

Classical grapevine breeding is based on the controlled hybridization of elite genotypes and the selection of F_l hybrids. It is a slow process, especially for fruit traits, which requires a high investment in growing surface and culture management. Understanding the genetic control of trait variation and using linked molecular markers could allow the rapid identification of seedlings with high probability to express the desired characters. The present work is a preliminary result of a cooperative effort aimed at acquiring a broad and robust knowledge of the genetic determinism of key quality traits in table grape and tools to facilitate and accelerate the generation of new cultivars. Its starting goal was the selection of a common set of mapping markers to support the development and comparison of saturated linkage maps and quantitative trait loci (QTLs) in different grapevine genetic backgrounds. Two hundred ninety-eight simple sequence repeats (SSRs) were tested for polymorphism in 13 table grape cultivars involved as progenitors in seven intraspecific (Vitis vinifera L.) crosses. Based on polymorphism rate, amplification quality, and available mapping information, a common set of 86 highly polymorphic and well-distributed SSRs were chosen to match the homologous linkage groups in the different parental lines. Given its high level of polymorphism, this marker set is expected to be useful for rapid genotyping of additional progenies and comparison with the progenies analyzed here. The analysis of such a high number of loci led to some considerations about heterozygosity in table grape cultivars.