桃单果重与6个物候期性状的遗传关联分析

【目的】关联分析作为传统连锁分析方法的有效补充，可以鉴定果树的数量性状位点（Quantitative Trait Loci, QTLs）。本研究通过关联分析定位桃单果重及6个物候期性状的QTLs，以研究性状间的遗传相关，为提高桃品质育种的效率奠定理论基础。【方法】以来源于中国6个生态群的104份桃地方品种为试材，利用分布于桃8条连锁群上的53对SSR（Simple Sequence Repeats）引物，用STRUCTURE 2.3.3和TASSEL 2.0.1软件分别对群体结构和全基因组SSR位点间的连锁不平衡（Linkage Disequilibrium, LD）状况进行分析。在结合单果重和6个物候期性状表型数据后进行关联分析，以定位各性状的QTLs。【结果】群体结构显示供试的104份桃地方品种基于数学模型可以分为5群；LD分析表明在53个SSR位点组成的1378个成对组合中，23个成对位点存在着显著LD且得到统计概率支持。虽然相关性分析表明单果重只与展叶期显著相关，但关联分析却显示单果重不仅与盛花期、展叶期、果实成熟期和落叶期均具有相同的关联位点；而且桃单果重的关联位点与不同连锁群上盛花期、果实发育期和落叶期的关联位点也存在显著的LD现象。对单果重具有最大增效表型效应的等位变异UDP96-013-206同时具有提前花期1.46 d、延迟果实成熟期13.77 d、延迟落叶期2.17 d的表型效应。【结论】本研究得到27个与桃单果重及6个物候期性状关联的QTLs，部分位点与前人定位的连锁群相同。关联分析表明单果重与盛花期、展叶期、果实成熟期、果实发育期和落叶期确实存在遗传相关，主要表现为这几个性状可能受到基因多效性调控或者受连锁群内及连锁群间存在连锁或关联关系的基因调控。

Genetic Association of Fruit Weight and Six Phenological Traits in Peach(Prunus persica L.)

【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.