High Density Map Construction And Genome-wide Association With Texture And Acidity In Peach

Peach（Prunus persica [L.] Batsch） is originated from China,which is widely cultivated in the worlds and is one of the most prevalent stone fruits in the genus prunus, Rosaceae family. Texture and acidity are the important index of the fruit quality,because hard melting can prolong the shelf life of peach and acidity is one of the main factors that determines the fruit taste.But its genetic mechanism is still not clear based on different genetic populations. In order to solve this problem, we constructed a linkage mapbetween’Chula’ x ’02-25-106’, with a genome-wide association analysis for a simple traits and QTL mapping.The main results were as follows:1. Analysis of 593 hybrids identification based on 8 SSR markersAfter testing 16 SSR markers distributed evenly over 8 linkage groups （LG） in the peach of T×E linkage map on two parents’Chula’and’02-25-106’, we chose 8 SSR with characteristic bands from father..The results showed 386 hybrids were the real progeny, and the selected 220 progeny which had a phenotypic data were continued to do Illumina peach 9K SNP genotyping.2. SNP genetic map constructionThe two parents and 216 progeny were genotyped by Illumina peach 9K SNP chip,which produced 8,144 SNP loci.A total of 3,506 polymorphic SNP loci were obtained when deleted the non-polymorphic loci by using JoinMap4.0,the polymorphism rate was 43.1%.A SNP map was constructed comprising 1,021 markers distrubuted over eight linkage groups.The map spans 529.7cM with an average distance between markers of 0.53cM,covering 91% of the physical length of the peach genome,everyone centimorgan had a 1.92 SNP.3. Genome-wide association analysis and QTL mapping based on Illumina peach 9K SNP chipsIn this study,687 markers were used for QTL analysis by WinQTLcartographer 2.5.The results were classified three types:In the type of hkxhk,two QTLs were associated with acidity on LG5,accounting for 86.7% of the phenotypic variation and the associated SNP marker was SNP_IGA₅45261,whose genotype of AG and AA was associated with low acidity,the genotype of GG was associated with high acidity;Five QTLs were associated with texture,which located on LG3,LG4,LG7,LG8.The QTL which on LG7 was accounting for 52.5% of the phenotypic variation and the associated SNP marker was SNP_IGA₇87064,this marker includingthe genotype of TC was associated with the soft melting,but the genotype about hard melting was not obvious. In the type of lmxll,we only found one QTL association with acidity,which phenotypic variation was 30.0%.In the type of nnxnp,four QTLs were accociation with acidity,which located on LG5 and LG6 respectively,the highest explaining phenotypic variation was 26.7% among four QTLs,and one QTL was associated with texture on LG4, accounting for 6.3% of the phenotypic variation.