2019 ASHS Annual Conference

Fruit quality traits have a significant effect on consumer acceptance and subsequently on peach (Prunus persica L. Batsch) consumption. Pedigree-based analysis (PBA) using Visual FlexQTL software has been conducted on seven low to medium chill F₁ families along with the founders and parents. Phenotypic data were collected over two years at a high chill (Fowler, CA) and medium chill (College Station, TX) locations and genotyped using the 9K SNP Illumina array. The objectives of this study were to 1) identify QTL(s) associated with fruit quality traits; 2) estimate QTL genotypes for important breeding parents; 3) identify predictive single-nucleotide polymorphism (SNP) or haplotype alleles for desired QTL alleles; and 4) determine source of the alleles for three important fruit quality traits, namly blush (BL), soluble solids content (SSC), and titratable acidity (TA) through pedigree-based analysis (PBA) on Texas peach/nectarine germplasm. Our analysis detected one major QTL on the central part of LG4 for blush at interval 42 – 44 cM that explained about 20 % of the total phenotypic variance (PVE). A major QTL for TA co-localized with the major locus for low-acid fruit (D-locus) at the proximal end of LG5 at 0 - 0 cM. This QTL was consistent across all data sets, explaining about 60 % of the phenotypic variance. There was a QTL at the distal end of LG5 at 52 - 62 cM that was associated with both TA and SSC, which explained about 15 % of the phenotypic variance. In addition, haplotype analyses for these QTLs revealed unique SNP haplotypes that are associated with the predictive SNP marker(s) of desired QTL alleles along with their original sources. Our findings will help peach breeders develop new predictive DNA-based molecular marker tests that can be used routinely in marker-assisted breeding (MAB) for enhancing peach quality traits.