2017 ASHS Annual Conference

Strawberries with better consumer acceptance are currently in demand in the U.S. market. Thus, fruit quality traits are major breeding targets for the University of Florida (UF) strawberry breeding program. In recent decades, several quantitative trait loci (QTL) for quality traits have been detected in various germplasm sets using low-density genetic maps. Now that the IStraw90^® single nucleotide polymorphism (SNP) array has enabled high-throughput genotyping and high-density mapping, QTL analyses in large, complex breeding populations are now feasible. A dataset of 3,799 genetically mapped SNP markers spanning 28 linkage groups was obtained and genotyped for 1100 pedigree-connected and clonally-replicated individuals arising from circular diallel mating designs. Soluble solids content (SSC) was measured for two years and pedigree-based analysis conducted using FlexQTL™ software. A consistent moderate-effect QTL was identified for SSC on LG 6A over the two years. The QTL explained approximately 10% and 15% of the total phenotypic variance in 2013-14 and 2014-15 respectively, across all genetic backgrounds. Although previously published experiments have also detected a QTL for SSC on LG 6A, the genetic location of the SSC QTL detected in UF germplasm is different from previous studies. Haplotyping of this locus is underway to identify QTL alleles and individuals predicted to have high as well as low levels of SSC. Validation of QTL effects and identification of QTL alleles will be discussed in the context of future breeding considerations and possibilities for marker-assisted parent selection.