2018 ASHS Annual Conference

Phenological traits of peaches (Prunus persica L. Batsch)are important for breeders to evaluate the adaptability in various environments and for the grower to efficiently manage their commercial orchards. Pedigree-based analysis (PBA) using Visual FlexQTL software was conducted on a total 162 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 objective of this study was to identify and compare quantitative trait loci (QTL) for three phenological traits including days to bloom (DTB), ripe date (RD), and fruit development period (FDP). The results showed that twenty-one QTLs were mapped for the three traits with strong [2ln(BF)>5] to decisive [2ln(BF)>10] evidence across the four environments of phenotypic evaluations. Four QTLs were located on linkage group (LG) 1, and two QTLs were on each LG4, and LG7 for DTB. Six QTLs were identified on LG4 for RD. Lastly, six QTLs were found on LG4 and one on LG6 for FDP. QTLs on LG4 for FDP in TX 2012 and CA 2012 were co-localized, and both overlapped with RD in TX 2013 and CA 2012. The proportion of phenotypic variance explained (PVE) by a QTL for the three traits ranged from 18.5 to 95.4%. These results of identifying QTLs for these traits have validated QTLs that were previously reported in other breeding programs. This study would help peach breeders to develop DNA marker test and enable implementing marker-assisted breeding for developing new peach cultivars.