Identification of genomic regions associated with harvesting date and mealiness susceptibility in peach using QTL analysis.

Chile is the first peach exporter in the South Hemisphere and the fifth producer in the world. Chilean initiatives of peach breeding have been carried out, where the fruit quality and postharvest performance are the main goals for the new peach varieties. Breeding is a time consuming and costly process. For this reason, the development of genomic tools to support the early selection of genotypes is quite relevant to improve the efficiency of breeding programs. Thus, the aim of this work was to identify genome regions associated with fruit quality traits in peach using a QTL analysis. Harvesting date, soluble solids content (SSC), color, weight, firmness, titratable acidity and mealiness were evaluated. The ‘Venus’ x ‘Venus’ segregating population was genotyped with microsatellite markers and SNPs using 9K SNP array for peach. A linkage map was built with 1,820 markers, which were mapped in 8 linkage groups. The resulting map spanned a total distance of 382.9 cM with an average of 0.21 cM between adjacent markers. A QTL for titratable acidity was associated to chromosome 1, another QTL linked to cover skin color was associated to chromosome 3, and QTLs detected in chromosome 4 were related with weight, harvesting date, soluble solids contents and firmness. Finally, six QTLs were detected for mealiness, four of them located in chromosome 4 and two in chromosome 2. These results provide insights into the genetic determinants of quality traits in peach, but further work is required to identify and to validate candidate genes and polymorphisms. (This work was supported by Fondecyt 11121396, FONDAP CRG 15070009; Genoma G13I0005, Conicyt fellowship D-21120635 to ACE and Basal PFB-16).