Genome-Wide Association Analysis Dissects the Genetic Architecture of Maize Leaf Inclination Angle and Leaf Area Index

Leaf inclination angle (LIA) and leaf area index (LAI) are important components of crop population canopy structure, which affect population photosynthetic production via altering canopy light interception and transmittance, and gas diffusion. In this study, we used a genetically diverse maize population of 378 inbred lines as materials to detect significantly associated SNPs with LIA and LAI using the mixed linear model (MLM) of genome-wide association study (GWAS). A total of 21 SNPs associated with LIA explain 6.07–10.86% of the phenotypic variation, containing two major-effect SNPs over 10%; 38 SNPs associated with LAI explain 2.91–10.36% of the phenotypic variation, containing one major-effect SNP. One candidate gene, GLCT1, significantly associated with LIA was identified, which might involve cell-wall biosynthesis. In addition, a cascade of SNPs significantly associated with LAI was identified in a single environment, and a candidate gene encoding the bHLH144 transcription factor was found. The results provide a theoretical basis for the selection of maize inbred lines with ideal canopy architecture and further investigation of the genetic mechanism of LIA and LAI.