【摘要】 甜瓜(Cucumis melo)果实外观性状是重要的农艺性状,发掘影响甜瓜果实性状变异的基因(位点)是对果实外观品质进行遗传改良的基础。为此,本研究利用在甜瓜染色体上均匀分布的104个SSR,对甜瓜核心种质进行基因型鉴定,并对2013~2015年连续3年间的5个果实性状进行全基因组关联分析(genome-wide association study,GWAS)。结果表明,在甜瓜核心种质中共检测到456个等位基因,标记的多态性信息含量(polymorphism information content,PIC)为0.12~0.89,平均PIC为0.51。核心种质的遗传多样性较丰富,5个果实性状的多样性指数(Shannon Wiener index,H′)均高于2.0。基于贝叶斯模型可将核心种质分为2个亚群,亚群的划分与甜瓜亚种分类一致。利用GWAS在3个环境下共检测到42个极显著关联位点(P<0.01),4个位点(HNM36、DM0035、HNM38和DM0767)在3年间重复出现,21个位点在2年间重复出现,一些稳定表达的位点与前人连锁分析结果的一致性较高。与果纵径(fruit length,FL)、果横径(fruit diameter,FD)、果形指数(fruit shape index,FS)、果肉厚度(flesh thickness,FT)和单果鲜重(fruit fresh weight,FW)相关位点数分别有10、5、9、8和10个,具有最大表型解释率的位点分别为HNM36、HNM16、CMCCA145、HNM31和HNM31。研究结果为甜瓜果实性状QTL精细定位、候选基因发掘和分子标记开发提供基础。更多还原

【Abstract】 The external characters of melon(Cucumis melo)fruit are the important agronomic characters which are closely related to the consumption habits.Discovery of the genes/loci affecting melon fruit character variation provides a basis for genetic improvement of exterior fruit quality.For this purpose,a total of 104 SSR markers distributed evenly across the melon chromosomes were used in the present study for identification the genotypes of a melon core collection,which was established using a stratified sampling method in our previous study.Five fruit characters of melon,fruit length(FL),fruit diameter(FD),fruit shape index(FS),flesh thickness(FT)and fruit fresh weight(FW)were determined during three years(from 2013 to 2015),and the genotype data of the core set was performed with genome-wide association study(GWAS).The results showed that a total of 456 alleles were detected in the melon core set,with polymorphism information index(PIC)of the markers ranged from 0.12~0.89(mean=0.51).The core set had a high level of genetic diversity,all the Shannon’s index of the five characters in the core set exceeded 2.0.Based on the Bayesian model,the melon core set could be separated into two subgroups,which were coincident with the subspecies classification of melon.This finding indicated that the melon core collection was suitable for association mapping.Totally,42 loci(P<0.01)associated with the five characters were detected by GWAS within three successive years,of which four loci appeared repeatedly under three environmental conditions and 21 loci appeared repeatedly under two environmental conditions.Most of the stably expressed loci were in agreement with the previous results from linkage analysis.There were 10,5,9,8 and 10 loci associated with FL,FD,FS,FT and FW,respectively,with the maximum explanation of phenotypic variation(R2)loci of HNM36,HNM16,CMCCA145,HNM31 and HNM31,respectively.Ten loci were found to associate with two or more characters,indicating the existence of trait correlation or pleiotropism.The results will lay a basis for fine mapping of melon fruit character QTL,candidate gene discovery and molecular marker development.更多还原