Identification and functional analysis of the genic male-sterile mutant Ky335ms in maize

Genic male sterility (GMS) is a critical resource for heterosis application in crop breeding. Therefore, it is crucial to identify GMS candidate genes and uncover their regulatory mechanisms. Here, we identified a maize male-sterile mutant, Ky335ms, exhibiting stunted tassel development, shriveled anthers, and the absence of mature pollen grains. Cytological observations revealed that tapetal degradation in Ky335ms was notably delayed at stage S8b, leading to defective anther development. Meanwhile, we map-based cloned the candidate gene ms335 and identified this gene as a novel allelic mutation of the known male-sterile gene ZmMs2, containing a 340-bp insertion in its fifth exon. RNA in situ hybridization indicates that ZmMs2 is highly expressed in the anther tapetum during stages S8 to S10. Lipid metabolomics analysis revealed that the contents of multiple fatty acids in Ky335ms anthers were significantly reduced compared to the wild type. These results indicate that ZmMs2 plays a role in transporting lipid molecules from the tapetum to form the anther cuticle and pollen exine. This study provides valuable insights for further investigation into the function of ZmMs2 in anther development.