关键词: 跳枝碧桃, SSR标记, 基因组重测序, 系统发育树, 全基因组关联分析

Abstract:

Purnus persica f.versicolor has high ornamental value with its two-color and variegated flowers in one single plant. Here,57 P. persica f. versicolor trees from three main distribution areas of ornamental peach were genotyped using Simple Sequence Repeat（SSR）markers. Seventeen polymorphic bands were amplified using six polymorphic primer pairs;the average of effective allele numbers was 2.83. Based on genotyping results by SSR markers,the samples were grouped into three genotypes,of which two to three genotypes were obtained from each collection area. The genotypes of different branches from one peach tree were identical. Further,one representative tree of each genotype was used for the genomic resequencing and variant calling. And phylogenetic analysis was then performed in combination with public genomic resequencing dataset. The results showed that individuals of the three peach genotypes were clustered into one clade,although B20 and T3 were closely related to‘Sahongtao’,whereas W5 was relatively independent,indicating the three genotypes ofP. persica f.versicolorwere cultivated from closely related clones with limited genetic variations. Genome-wide association study（GWAS）was further carried out by integrating single nucleotide polymorphism（SNP）information and flower color phenotypes. Five SNPs significantly associated with flower color trait（P < 10 ^-100）were identified and all of them were located on chromosome 7 of peach genome. Three Dicer-like 2（DCL2）genes were identified in genome segments adjacent to correlated SNP loci,suggesting that DCL2-dependent epigenetic modification may play an important role in the formation of variegated flowers in peach.

Key words: Purnus persica f.versicolor, SSR marker, genomic resequencing, phylogenetic tree, GWAS