ZmMs25 Is Critical for Anther and Pollen Development in Maize.

Abstract

Fatty acyl reductases (FARs) catalyze the reduction of fatty acyl-coenzyme A (CoA) or -acyl carrier protein (ACP) substrates to primary fatty alcohols, which play essential roles in lipid metabolism in plants. However, the mechanism of FARs involved in male reproduction is poorly defined. Here, we found that two maize allelic mutants, ms25-6065 and ms25-6057, displayed defective anther cuticle, abnormal Ubisch body formation, impaired pollen exine formation and complete male sterility. Based on map-based cloning and CRISPR/Cas9 mutagenesis, Zm00001d048337 was identified as ZmMs25 gene, encoding a plastid-localized FAR with catalytic activities to multiple acyl-CoA substrates in vitro, and four conserved residues (G101, G104, Y327 and K331) of ZmMs25 were critical for its activity. ZmMs25 was predominantly expressed in anther at stage 9, and was directly regulated by transcriptional factor ZmMYB84. Lipidomics analysis revealed that ms25 mutation had significant effects on reducing most of cutin monomers and internal lipids, and altering composition of cuticular wax in anthers. Moreover, loss of ZmMs25 function significantly affected the expression of its four paralogous genes and five cloned lipid metabolic male-sterility genes in maize. These data suggest that ZmMs25 is required for anther development and male fertility, implying its application potential in maize and other crops.