Genome-wide association study discovers novel germplasm resources and genetic loci with resistance to Gibberella ear rot caused by Fusarium graminearum.

Abstract

Gibberella ear rot (GER) in maize caused by Fusarium graminearum is one of the most devastating maize diseases reducing grain yield and quality worldwide. The genetic bases of maize GER resistance remain largely unknown. Using artificial inoculation across multiple environments, GER severity of an association panel consisting of 316 diverse inbred lines was observed with wide phenotypic variation. In the association panel, a genome-wide association study (GWAS) using a general linear model (GLM) identified 69 single-nucleotide polymorphisms (SNPs) significantly associated with GER resistance at the threshold of 2.04 x 10-5, and the average phenotypic variation explained (PVE) of these SNPs was 5.09%. We also conducted a GWAS analysis using a mixed linear model (MLM) at a threshold of 1.0 x 10-4, and 16 significant association SNPs with an average PVE of 4.73% were detected. A combined GLM and MLM method obtained 10 co-localized significant association SNPs linked to GER resistance including the most significant SNP (PZE-105079915) with the greatest PVE value, 9.07%, at bin 5.05 following ten candidate genes. These findings are significant for the exploration of the complicated genetic variations in maize GER resistance. The regions and genes identified herein provide a list of candidate targets for further investigation, in addition to the elite germplasm resources that can be used for breeding GER resistance in maize.