Single nucleotide polymorphism analysis of the endopolygalacturonase gene in peach and its potential use in crossbreeding programs.

Abstract

Single nucleotide polymorphisms (SNPs) are the most abundant sequence variations found in plant genomes and are widely used as molecular genetic markers in genetic diversity studies and crossbreeding programs. In this study, we examined 113 DNA sequences of the endopolygalacturonase (endo-PG) gene from 67 peach accessions and found a total of 56 SNPs and 6 insertion/deletions (indels), with a frequency of 3, 1, and 3% for the transitions, transversions, and indels, respectively. Meanwhile, the majority of the observed SNPs were found in the intron regions, while only 2 variable sites and a single indel were detected in the exon regions. A dendrogram was obtained using neighbor-joining cluster analysis and divided into 2 main groups, providing evidence that most of the accessions of the clingstone nonmelting flesh phenotypes generally clustered together and were comparatively nonrelated to the "stony hard" peach cultivars, which were in a different branch altogether. Furthermore, 4 major haplotypes were formed and 3 cleaved amplified polymorphic sequence primer sets were mined according to fruit texture and stone adhesion, displaying their potential as candidate molecular markers for discriminating genotypes. This research will assist peach genetic enhancement by introducing a novel crossbreeding strategy.