基于极端个体GBS测序初步定位西瓜果形基因

Mapping Gene for Fruit Shape in Watermelon Based on Extreme Individuals Genotyping-by-Sequencing(GBS)

西瓜果形是西瓜重要的外观性状,本研究利用以椭圆形品系K2和圆形品系L1为亲本的F2群体(351个个体),进行了西瓜果实宽、长及果形指数遗传和相关分析。结果表明果实宽度和果实长度呈典型正态分布,而果形指数分布上则出现双峰且圆果型∶椭圆果型接近于3∶1,说明在果形指数存在主效基因调控。果实宽度与果实长度、果实长度与果形指数呈极显著正相关,相关系数分别为0.427、0.669;果实宽度与果形指数呈极显著负相关,相关系数为-0.377。通过GBS(Genotyping-by-sequencing)分型技术对群体中果形指数大于1.4的10株个体和果形指数小于1.1的10株个体进行了基因分型,结合表型进行关联分析,将西瓜果形基因定位到了3号染色体的26.80~27.33 Mb区段内,并预测了14个候选基因。本研究结果为进一步精细定位果形基因打下基础。

The fruit shape is an important quality trait of watermelon.In this study,the 351 F2 populations derived from a cross between two inbred lines K2(Oval fruit)and L1(Spherical fruit)were used to genetic analysis and correlation analysis of watermelon fruit width,fruit length and fruit shape index,combined with the frequency distribution histogram of F2 population.The results showed that the fruit width and fruit length were closely to continuous distribution,the fruit shape index was non-conformance continuous distribution,and spherical fruit∶oval fruit was close to 3∶1,which proves that traits were the quantitative traits controlled by a major gene.Fruit length had significant positive correlation with fruit width and fruit shape index,coefficient correlation were 0.427 and 0.669,respectively;fruit width had significant negative correlation with fruit shape index,and the correlation coefficient was-0.377.The GBS genotyping technique was used to genotype the 10 individuals with the fruit shape index greater than 1.4 and the 10 individuals with the fruit shape index less than 1.1 in the population,and the association analysis was carried out combining with the phenotype to determine the candidate section of the fruit shape gene on chromosome 326.80~27.33 Mb,and 14 candidate genes were predicted.The results lay a foundation for further fine mapping of fruiting genes.