Genome-wide identification of the maize MAPK gene family and its response to Fusarium verticillioides infection

Fusarium ear rot (FER), caused by <italic>Fusarium verticillioides</italic>, is one of the most destructive fungal diseases limiting maize (<italic>Zea mays</italic> L.) production. The mitogen-activated protein kinase (MAPK) cascade is a central regulator of plant growth, development, and stress responses. Previous studies have shown that ZmMAPKs can enhance resistance to fungal pathogens by upregulating defense-related genes and activating key enzymes; however, the roles of individual MAPK family members in pathways associated with FER resistance remain unclear. Here, we conducted a comprehensive analysis of the ZmMAPK gene family, including genome-wide identification and characterization, chromosomal localization, phylogenetic reconstruction, collinearity analysis, promoter <italic>cis</italic>-element prediction, tissue-specific expression profiling, and expression responses to <italic>F. verticillioides</italic> infection. In total, 24 <italic>MAPK</italic> genes were identified in the maize B73 reference genome (V5). Phylogenetic analysis grouped these genes into four subgroups, with highly conserved exon-intron structures within each subgroup. Groups A, B, and C contain the canonical Thr-Glu-Tyr (TEY) activation motif, whereas group D contains the Thr-Asp-Tyr (TDY) motif. Expression analyses showed pronounced tissue-specific differences, suggesting functional diversification within the family. RT-qPCR further indicated that, after <italic>F. verticillioides</italic> inoculation, <italic>ZmMAPK12</italic>, <italic>ZmMAPK22</italic>, <italic>ZmMAPK23</italic>, and <italic>ZmMAPK24</italic> were differentially expressed between the resistant inbred line Qi 319 and the susceptible inbred line B73. Sequence comparisons revealed that, in addition to SNPs, structural variants such as transposon insertions occurred in both promoter and coding regions of these genes. Together, these results suggest that these MAPKs may participate in regulatory pathways controlling maize responses to <italic>F. verticillioides</italic> infection. This study provides a foundation for elucidating how MAPK cascades contribute to FER resistance and offers candidate genes to support genetic improvement of disease-resistant maize varieties.