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

Maize (<i>Zea mays</i> L.) head smut, caused by <i>Sporisorium reilianum</i> (<i>S. reilianum</i>), 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, <i>ZmMYB42</i> (<i>Zm00001d053220</i>) 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 <i>S. reilianum</i> indicated that <i>ZmMYB42</i> 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.