The OsMYB103-OsGLOX5 module regulates tapetum degradation and male fertility in rice

Anther tapetum degradation is essential for normal pollen formation in rice, yet the underlying regulatory network remains poorly understood. We isolated a novel male sterility rice mutant, osglox5, and confirmed that the target gene LOC_Os11g06870 encodes a glyoxal/galactose oxidase protein with both glyoxal oxidase (GLOX) and galactose oxidase (GAO) activities and is required for hydrogen peroxide (H2O2) production in anthers. Insufficient H2O2 content in osglox5 anthers causes delayed tapetum degradation and defective pollen wall formation, resulting in pollen abortion. OsGLOX5 is highly expressed during stage 9 of anther development, specifically in microspores and tapetum, and localizes to the endoplasmic reticulum. The tapetum-specific transcription factor OsMYB103 directly binds the OsGLOX5 promoter and activates its expression. This study provides the first evidence that a protein with both glyoxal oxidase and galactose oxidase activities plays an essential role in rice tapetum degradation, and identifies a novel MYBs-GLOXs regulatory axis, advancing our understanding of the tapetum degradation network.