Genetic association of sugar and acid main constituents of China landrace peach(Prunus persica L.)

【Objective】This study aims to map the QTL of sugar and acid main constituents of peach fruitand find the markers associated to the trait through association analysis which can be applied for marker-assisted breeding.【Methods】96 peach landrace accessions from 6 Chinese geographical regions were eval-uated about sugar and acid main constituents traits. 52 SSR(Simple Sequence Repeats) primers wereevenly selected from peaches Tx E reference map(519 c M) to ensure broad genome- wide coverage.STRUCTURE 2.3.3 software was applied to estimate sample population structure,using TASSEL2.0.1software to measure LD value between SSR loci,GLM(General Linear Model)[10]model,combining char-acters traits data of fructose,glucose,sucrose,sorbitol,titratable acidity and pulp p H were used tomake regression analysis.【Results】Correlation analysis showed that sorbitol were significantly positivelycorrelated with sucrose,glucose and positively correlated with p H. Sucrose were significantly positivelycorrelated with glucose,p H and positively correlated with fructose. Glucose were significantly positivelycorrelated with p H,fructose. p H showed highly significant negative correlation to titratable acidity. Popu-lation structure analysis showed that the tested 96 peach cultivars can be divided into 7 subgroups based on mathematical models;LD analysis showed that 1 326 pairwise combinations were consist of 52 SSR lo-ci,in which 198 pairwise sites had significant LD and supported by statistical probability at P ≤ 0.05 lev-el. Phenotypic variation of 39 SSR loci were higher than 10%,they were 5 Fructose QTLs,11 glucoseQTLs,5 sucrose QTLs,9 sorbitol QTLs,5 Titratable acid QTLs,4 p H QTLs,respectively. And many ofthem were located in same chromosomes which were obtained using linkage analysis previously. SomeQTLs controlled both sugar and acid trait. After the Bonferroni multiple test,only 4 had statistical signifi-cance.【Conclusion】A total of 57 sugar and acid constituents QTLs were found. There are 53 QTLs report-ed for the first time,phenotypic variation of 39 SSR loci were higher than 10%. After the Bonferroni multi-ple test,there are still remain sites BPPCT023.2011 and UDP96-013.2011 associated with p H,site CP-PCT030.2011 associated with sorbitoland,site CPPCT033.2012 associated with fructose;the main effectQTLs mapped in this study will be useful to the further marker-assisted breeding development.