Identification of QTL underlying soluble solids content and titratable acidity in sweet cherry (Prunus avium L.)

Sweetness and acidity are important fruit quality traits that drive consumer acceptability of sweet cherry. Developing new sweet cherry cultivars with superior taste attributes is a major breeding objective in fruit breeding programs. This study was designed to identify quantitative trait loci (QTL) associated with soluble solids content (SSC) and titratable acidity (TA) in sweet cherry to facilitate development of new cultivars with exceptional taste characteristics. A total of 601 pedigree-linked individuals were used in this study. Five largest fruits from each individual were selected at maturity for SSC measurement. Juice from a bulked sample of 25 fruit was used for TA measurement. One thousand and ninety one (1091) single nucleotide polymorphism (SNP) and four simple sequence repeat (SSR) markers were used to provide genome-wide markers for determining marker-locus-trait associations. QTL analyses were performed in FLexQTL™ for SSC and TA using phenotypic data collected in 2010, 2011 and 2012. Three QTL for SSC were mapped on the ‘Texas’ x ‘Earlygold’ Prunus reference map on linkage group (LG) 2 (in 2011 and 2012), on LG 4 (in 2012) and on LG 7 (a minor one in 2011). Three QTL were identified for TA; one mapped on LG 2 in 2010, the other on LG 4 in 2011 and 2012 and the third on LG 6 in 2012. The haplotypes for these QTL are discussed in relation to breeding for SSC and TA in sweet cherry.