Genome-Wide Association Study Identified ZmMYB42 as a Negative Regulator for Resistance to Maize Head Smut

Maize (Zea mays L.) head smut, caused by Sporisorium reilianum (S. reilianum), is a serious disease affecting production in northern and eastern China. This study assessed head smut resistance in 292 maize inbred lines via field inoculation over two years. Genome-wide association study identified three significant SNPs associated with resistance, revealing 12 candidate genes. Among these, ZmMYB42 (Zm00001d053220) exhibited markedly different expression between resistant and susceptible lines after inoculation. qRT-PCR confirmed its role in resistance regulation. Subcellular localization showed the ZmMYB42 protein resides in the nucleus. Artificial inoculations with S. reilianum indicated that ZmMYB42 overexpression in maize increases susceptibility and mesocotyl damage, suggesting it acts as a negative regulator of resistance. Additionally, SNP837 was significantly linked to resistance, explaining 18.11% of phenotypic variation, and was successfully converted into a dCAPS marker (DNdCAPS837) with 77.78% genotype-phenotype concordance. These findings offer valuable germplasm resources and candidate genes for breeding head smut-resistant maize.