Analysis Of Genetic Diversity And QTL Mapping Of Anthocvanin In Peach Fruit

Red peach, as a kind of characteristic resource in peach plants, appeals to the consumerswith its unique charm of the sense. As the deeping study of anthocyanin, red peach became ahot spot in the breeding research at home and abroad. But problems that how to define the redpeach,how much anthocyanin content could be regarded as red peach,and which genes didplay a role in anthocyanin synthesis were not yet clearly reported.Peach originated in Chinawith abundant resources.It was necessary to analyze the genetic diversity in peach,give a redpeach criteria,explore the molecular markers related to anthocyanin synthesis and then targetthe candidate genes,which was better for red peach research.Linkage analysis and associationananlysis were the main method for molecular marker development to target traits.The studiesshowed that the combination of the two analyasis methods would greatly enhance theefficiency of locating genes and was particularly suitable for the analysis of quantitative traits.165natural groups and F2hybridization generation from Shuguang x Tianjinshuimi wereused in genetic diversity analysis using Vis-UV Spectrophomery and high performance liquidchromatography. By using SSR, SRAP molecular markers on rough genomic scanning and themethods of QTL mapping and association analysis, we tried to target the loci related toanthocyanin synthesis. The results were as followed:(1)Anthocyanin content in peach was measured by Vis-UV Spectrophomery and HPLCmethod,and then the data was used in relation analysis. The correlation coefficient was0.94between white flesh cultivars, while0.64between yellow flesh cultivars on a very significantlevel of0.01. The results showed that to simply compare anthocyanin content in white fleshvarirties, methods could be chosen one of them according to the actual situation; highperformance liquid chromatography should be chosen in yellow flesh varieties analysisbecause of carotenoids interference.(2)Based on the data anthocyanins content in peach fruit in the natural population byusing the method of high performance liquid chromatographic, peach was divided into fivegrades. The pulp evaluation were no red, reddish, compared red, red, and extremly red. Therelevant reference cultivars were shoubai、jizuibai、guangyibaihuatao、heibudai、tianjinshuimi.In classification, the critical point was fixed on20mg/100g, which was applied to most varieties, except low acid varieties with visual red-flesh. In the tested materials, we got ’Wanzhousuantao ’,’ Tianjinshuimi’,’ Zhengyin82-9’,’ Zhengzhou07-4-33’,’heibudai ’ as redpeach.(3)The content and type of anthocyanin were different in different varieties. Anthocyanincontent has a wide distribution range, which was0-56.35mg/100g in the165varietiesmeasured by UV with the average of4.30mg/100g. The content in most varieties wasdistributed in the interval of0-4mg/100g.74varieties were measured by high performanceliquid chromatographic method,the results were that, anthocyanin content was distribution in0~72.99mg/100g. The major anthocyanin in peach fruit was cyanidin3-glucoside that wasexisted in48varieties, while cyanidin3-rutinoside was identified in some varietiessimulataneously, such as ‘wuheijitoutao’，‘daguoheitao’. But cyanidin-3–rutinoside onlyin the variety was not found.(4)165peach varieties were used as natural population. Genomic DNA was amplifiedby forty-nine SSR primer pairs covered on the whole genome.231polymorphic bands wereproduced totally. Population structure was analyzed by the STRUCTURE software. Theresults indicated that the165varieties were divided into two subpopulations, respectivelynorthern ecological group which contained100species and southern ecological groupcontaining65species. The dividing results of28materials were different with theirgeographical classification.(5)Five SSR loci were found to be associated with anthocyanin by using TASSEL2.1software, and the phenotype variation explained by them ranged from0.0972to0.1443. Thehighest contribution locus was CPDCT045(14.43%,LG4), the secondly highest locus wasBPPCT030(14.23%,LG2).The contribution of other three loci were CPPCT018(13.64%,LG3), CPSCT018(13.57%,LG8), PCEGA34(9.72%,LG2). The distance between PCEGA34and CHI was0.4CM, while10.2CM between CPPCT019and MYB10which indicted thatCHI and MYB10took a part in anthocyanin synthesis.