玉米叶向值的全基因组关联分析

Genome-wide association studies of leaf orientation value in maize

叶向值是反映叶片"直"和"立"两个特性的综合指标。叶向值高的品种,叶片直而不弯,叶夹角小,有利于群体通风透光,在群体密度较高时比平展型更容易获得高产。阐明叶向值的遗传基础,对玉米理想株型分子设计育种具有重要的意义。本研究以285份多样性玉米自交系为材料,利用Illumina的maizeSNP50芯片基因分型结合连续2年的叶向值表型鉴定,通过全基因组关联分析方法挖掘玉米叶向值显著关联的SNP位点。方差分析表明,不同自交系的叶向值差异达到极显著水平(P<0.01)。在最优模型选择时,发现Q+K模型最适合本研究的叶向值关联分析。在2个年份下,共检测到15个与叶向值显著关联的位点(P<4.05E-5),包括27个SNP,解释5.54%~8.73%的表型变异,并挖掘了15个候选基因。其中1.07 bin上的位点2是本研究发现的重要位点,其候选基因可能是编码细胞周期蛋白依赖性蛋白激酶的Zm00001d032050,有待进一步图位克隆工作验证。

Leaf orientation value is a comprehensive index reflecting the two characteristics of"straight"and"vertical"of leaves.The varieties with high leaf orientation value have straight and not curved leaves,and small angle,which are conducive to the wind ventilation and light transmission for maize population.When the planting density is high,it is easier to obtain high yield than the expanded plant-type.It is of great significance for molecular design breeding of ideal plant type to clarify the genetic basis of leaf orientation value.In this study,285 diverse lines genotyped by the MaizeSNP50 chip were evaluated for leaf orientation in 2017 and 2018.The genome-wide association analysis(GWAS)were used to identified the SNPs,which were significant association with leaf orientation values.The analysis of variance showed that the significant variations were observed for leaf orientation value of different inbred lines(P<0.01).In the selection of the optimal model,it was found that the Q+K model was the most suitable for the leaf orientation association analysis in this study.A total of 15 loci(P<4.05 E-5)were detected by GWAS,including 27 SNPs,explaining 5.54%–8.73%of phenotypic variation,and 15 candidate genes were mined in two years.Among them,site 2 in 1.07 bin was an important site found in this study,and its candidate gene might be Zm00001 d032050 encoding cyclin dependent protein kinase,which needed to be further confirmed by map-based cloning.