Genome-Wide Identification, Evolutionary Analysis, and Expression Profiling of the NSUN Gene Family in Maize Reveal Candidate Genes for Stress Adaptation and Agronomic Improvement

The NSUN family is essential for RNA 5-methylcytosine modification (m5C) in eukar-yotes. However, no NSUN genes have been identified in maize, and the characteristics of ZmNSUN genes remain unexplored. Here, we performed a comprehensive in-vestigation of NSUN genes across seven Poaceae species. Our analysis identified a total of 63 Poaceae NSUN genes, including eight ZmNSUN genes in maize. Phylogenetic and feature analyses classified the Poaceae NSUNs into six subgroups (SGs), suggest-ing that the divergence of these SGs may have occurred prior to the divergence between plants and animals. Expression profiling indicated that ZmNSUN genes are generally repressed by heat stress. Co-expression network analysis suggested potential roles of ZmNSUN genes in maize development, and expression quantitative trait locus (eQTL) analysis results demonstrated that expression levels of multiple ZmNSUN genes are significantly associated with maize agronomic traits. Collectively, these findings provide novel insights into the evolutionary dynamics of the NSUN family and highlight specific ZmNSUN genes as promising candidates for molecular breeding to improve maize yield and stress adaptability.