2019 ASHS Annual Conference

Phenological traits of peaches [Prunus persica (L.) Batsch] are important for breeders to evaluate in various environments for determining cultivar adaptability, and for the grower to efficiently manage their commercial orchards. Pedigree-based analysis (PBA) using Visual FlexQTL software was conducted on 162 peach individuals (143 F₁ seedlings and 19 founders and parents) grown in four environments (CA 2011, CA 2012, TX 2012, and TX 2013). A 9K SNP Illumina array was used for the genotyping. The objectives of this study were to 1) identify QTL(s) of three phenological traits including bloom date (BD), ripe date (RD), and fruit development period (FDP); 2) estimate QTL genotypes for important breeding parents of seven full-sib families; and 3) identify the haplotype alleles that are linked to the predictive SNP marker(s) of desired QTL alleles. The QTL for RD and FDP was co-localized at the central part of LG4 (40 - 44 cM) and explained about 35 % of the phenotypic variance. Three QTLs were discovered for BD. These were found on LG1 (88 – 92 cM), LG4 (48 – 50 cM), and LG7 (40 – 44 cM), explaining between 17-94%, 11-55%, and 11-18% of the phenotypic variance respectively. Haplotype analyses for these QTLs revealed predictive SNP haplotypes of desired QTL alleles along with their original sources among the important breeding parents of seven full-sib families. Our results will help peach breeders in developing new predictive, DNA-based molecular marker tests that can be used routinely in marker-assisted breeding (MAB).