Novel stable QTLs identification for berry quality traits based on high-density genetic linkage map construction in table grape
Abstract Backgroud: Aroma, berry firmness and berry shape are three main quality traits in table grape production, and also the important target traits in grapevine breeding. However, limited information about their genetic determinants leads to low accuracy and efficiency of quality breeding in grapevine. Mapping and isolation of quantitative trait locus (QTLs) based on the construction of genetic linkage map is a powerful approach to decipher the genetic determinants of complex quantitative traits in grape.Results: In the present work, a final integrated map consisted of 6,436 SLAF markers on 19 linkage groups (LGs) spanning 3,365.41 cM in genome size with an average distance of 0.52 cM between adjacent markers was generated using the specific length amplified fragment sequencing (SLAF-seq) technique. Total 16 significant QTLs were identified on six linkage groups based on phenotypic data of Muscat flavor, berry firmness and berry shape among the hybrids analyzed over three consecutive years from 2016 to 2018. Notably, new QTLs for berry firmness and berry shape were found on LG 8 respectively for the first time, which had the strongest and most stable effects over 2-3 years. Based on biological function and expression profiles of candidate genes in the major QTL regions, 3 genes (VIT_08s0007g00440, VIT_08s0040g02740 and VIT_08s0040g02350) related to berry firmness and 3 genes (VIT_08s0032g01110, VIT_08s0032g01150 and VIT_08s0105g00200) linked to berry shape were highlighted. Overexpression of VIT_08s0032g01110 in transgenic Arabidopsis plants caused the change of pod shape.Conclusions: A new high-density genetic map with total 6634 markers was constructed with SLAF-seq technique, and thus enabled the detection of narrow interval QTLs for relevant traits in grapevine. VIT_08s0007g00440, VIT_08s0040g02740 and VIT_08s0040g02350 were found to be related to berry firmness, and VIT_08s0032g01110, VIT_08s0032g01150 and VIT_08s0105g00200 were linked to berry shape.