基于杂交群体解析玉米籽粒大小相关性状及其配合力的分子遗传机制

Dissecting the genetic basis of kernel size related traits and their combining ability based on a hybrid population in maize

配合力是育种过程中评价自交系潜力、筛选优良杂交组合的重要指标。籽粒大小相关性状是产量的重要构成因子,解析籽粒大小相关性状及其配合力的遗传基础有助于高产玉米品种的培育。本研究以NCII遗传交配设计获得的246份玉米杂交组合为材料展开籽粒大小相关性状及其配合力的全基因组关联分析。研究表明,粒长、粒宽、粒厚3个性状的广义遗传力分别为76.20%、86.52%和81.14%,各性状与其配合力均呈显著正相关(0.58~0.82)。基于EMMAX(efficient mixed-model association expedited)算法检测到31、21、5个显著的SNP(single nucleotide polymorphism),它们分别与性状、GCA(general combining ability)和SCA(special combining ability)关联,其中10个SNP为性状与配合力共定位的。对共定位的SNP进行效应分析,发现3个为加性效应、4个为部分显性效应、1个为超显性效应。结合公共数据库中基因注释及籽粒发育相关转录组数据,在共定位、主效SNP位点附近共筛选到17个候选基因,包括被报道与玉米籽粒发育相关的shrunken1、emp6等。本研究结果有助于进一步解析玉米籽粒大小及其配合力的遗传机制,可为籽粒大小相关性状的遗传改良提供参考。

Combining ability is a crucial index for evaluating elite inbred lines and selecting superior hybrids during maize breeding processes.Kernel size related traits are important components of grain yield.Therefore,dissecting the genetic basis of kernel size related traits and their combining ability is beneficial for improving maize yield.In this study,we performed genome-wide association study(GWAS)of kernel size related traits and their combining ability using 246 hybrids breed by designed as NCII mating.The broad-sense heritability of kernel length(KL),kernel width(KW),and kernel thickness(KT)was 76.20%,86.52%,and 81.14%,respectively.The correlation coefficient between each trait and their combining ability was more than 0.58,indicating there was significant positive correlation.Based on the efficient mixed-model association expedited(EMMAX)algorithm,we identified 31,21,and 5 significant single nucleotide polymorphisms(SNPs)associated with the best linear unbiased estimation(BLUE),general combining ability(GCA),and special combining ability(SCA)of kernel size related traits,respectively.Among these significant SNPs,10 SNPs were co-located both kernel size related traits and their combining ability.The effect analysis of co-located significant SNPs showed that three SNPs were additive,four were partial dominance and one was overdominance.Further,17 candidate genes were predicted from candidate regions of co-located SNPs or SNPs with large effect,such as shrunken 1,emp6 and so on.The results further dissect the genetic architecture of maize kernel size related traits and their combining ability and provide useful information for improving grain yield in maize breeding.