QTLs related to berry acidity identified in a wine grapevine population grown in warm weather

The optimal balance between sugar and acidity is an essential criterion to elaborate equilibrated and stable wines. The aim of this study was to locate quantitative trait loci (QTLs) for these traits using an F1 population derived from Monastrell and Syrah wine cultivars. Several parameters related to acidity were evaluated during six consecutive years by measuring total soluble solids, total acidity, malic acid, and tartaric acid. Three genetic maps were developed using 104 SSR (simple sequence repeat) and 146 SNP (single-nucleotide polymorphism) markers. The consensus map covered 1174 cM with 238 markers assembled in 19 linkage groups (LGs). Significant QTLs at the genome-wide level were detected, and, although they exhibited a large degree of instability from year to year, QTLs for the ratio of soluble solids to acidity (LG2) and malic acid (LG8) and the ratio of tartaric to malic acid (LG8) were stable in at least 2 years. Several annotated genes involved in sugar and acidity pathways co-located with the confidence intervals of these QTLs and are proposed as putative candidate genes for future studies of these trait

Molecular mapping of grapevine genes

In this chapter, we review the history of grapevine genetics and gene mapping. Genetic markers are introduced considering both sequence-based and sequence-independent approaches used for variant discovery. We provide a survey of genotyping tools, from low- to high-throughput platforms. We describe general principles of map building and implementation, highlighting specificities for outbred species such as the grapevine. Then, we review the different approaches applied for QTL identification according to the genetic material, from bi-parental progenies, pedigree-supported segregating populations, to germplasm collection. In particular, our emphasis is on the relevance of such studies for the dissection of a complex trait. We describe the difficult process of identifying genes responsible for QTLs and the few cases of QTL cloning. Many years have passed from the first grapevine marker isolation, the development of genetic and physical maps, until the deciphering of the genome sequence. With such a wealth of detailed information on wild and cultivated grapevines, we discuss how data sharing and multidisciplinary data integration are the current challenges that the scientific community faces to effectively translate knowledge into practic