Abstract: 【Objective】 Association mapping is an effective approach for identifying quantitative trait loci (QTLs) and may be an alternative to QTL mapping based on crosses between different lines. The study aims to improve the speed and efficiency of fruit quality breeding by investigating the genetic correlation of fruit weight and six phenological traits in peach (Prunus persica) using association mapping approach. 【Method】 In the current study, 104 peach landrace accessions from 6 Chinese geographical regions were evaluated for fruit and phenological period traits. The accessions were genotyped with 53 genome-wide simple sequence repeats (SSR) markers. The population structure and linkage disequilibrium (LD) of peach were analyzed by using STRUCTURE 2.3.3 and TASSEL 2.0.1 software. The genetic correlation was studied based on the results of association mapping of fruit weight and six phenological traits. 【Result】 Based on population structure analysis, the 104 peaches were divided into 5 groups. Of the 1378 SSR pairs composed of 53 SSR primers, 27 were in LD (P＜0.01). Although correlation analysis showed that the fruit weight was only related to leaf expansion date trait positively, same QTLs were found associated with fruit weight and the date of full bloom, leaf expansion, harvest maturity, and defoliation based association mapping. Simultaneously, the obviously LD was observed among the interchromosomal loci association with fruit weight and the date of full bloom, defoliation and fruit development period. UDP96-013-206, an allele which possesses a significantly positive effect on fruit weight also acted on the phenological trait to advance the bloom date for 1.46 days, delay the fruit development period and defoliation date for 13.77 and 2.17 days, respectively. 【Conclusion】 Twenty-seven QTLs associated with fruit weight and six phenological traits were obtained using association mapping, and many of them were located in same chromosomes which obtained using linkage analysis previously. Although fruit weight was only related to leaf expansion date through correlation analysis, the real genetic correlation was found between fruit weight and the date of full bloom, leaf expansion, harvest maturity, defoliation, and fruit development period. Pleiotropy or close linkage are the two major reasons for genetic correlation in these correlated traits.

Key words: 桃, 单果重, 关联分析, 遗传相关