Identification of genetic loci conferring partial resistance to southern corn rust through a genome-wide association study

Southern corn rust (SCR), a fungal disease caused by Puccinia polysora Underw., can result in severe yield loss in maize (Zea mays L.). Identification of resistant germplasms and understanding the genetic basis of resistance would aid maize disease-resistant breeding. In this study, 253 maize inbred lines were used to evaluate the resistance to SCR at two locations in China from 2015 to 2016. A genome-wide association study (GWAS) was conducted using the Maize SNP3K Beadchip. Based on mixed linear model, seven single nucleotide polymorphisms (SNPs) associated with partial resistance to SCR were identified at P < 1.77 x 10(-5), including three SNPs aligned with previously reported genomic regions. A significant correlation (R-2 = 0.76) between partial resistance to SCR and the number of resistant alleles was observed. Several highly resistant germplasms harboring resistant alleles were identified, such as, '43.7', 'DH02', 'Zheng39', 'T2' and 'JH3372'. This research will increase our understanding of the genetic basis of partial resistance to SCR and provide important guidance for SCR resistance breeding.