Genome-wide association study and candidate genes predication of yield related ear traits in maize

Abstract

Ear traits directly affect the final yield of maize, and the analysis of its genetic mechanisms can provide useful guidance for yield enhancement in maize. In this study, 733 maize inbred lines were planted in randomized block designs under two environments, and three yield-related traits, kernel row number (KRN), ear length (EL), and ear diameter (ED), were investigated. Genotyping was performed using MaizeSNP3072 chip and FarmCPU (fixed and random model circulating probability unification) model was used to conduct genome-wide association study (GWAS). 16, 13, and 24 single nucleotide polymorphism (SNP) loci significantly associated with the three traits were identified, and the values of phenotypic variation explained (PVE) for single locus were 0.01%–7.08%, 0.01%–5.34%, and 0.07%–4.34%, respectively. Further, six, two, and five high confidence (HC) SNPs that were repeatedly detected in multiple environments for KRN, EL, and ED were retrieved, among which two SNPs were simultaneously associated with KRN and ED traits, and one KRN HC-SNP and three ED HC-SNPs were firstly reported in this study. By searching 200 kb regions around the 11 HC-SNPs loci, 33 important candidate genes were identified, including a known gene PIN1a regulating ear development via auxin polar transport located in the confidence interval of chromosome 9 SNP marker PZE-109003046. Other candidate genes encoded transcription factors, hormone (such as auxin, gibberellin, and ethylene) pathway related proteins, DNA methylation, and protein phosphorylation related proteins, which might regulate ear traits by different mechanisms. The 11 HC-SNPs and 33 important candidate genes detected in this study can provide valuable information for further cloning of functional genes and reveal the molecular regulatory mechanisms and marker-assisted selection for ear trait in maize.