Loss of Function of the RRMF Domain in OsROS1a Causes Sterility in Rice ( L.).

For crop seed production, the development of anthers and male fertility are the main agronomic traits and key biological processes for flowering plants. Active DNA demethylation regulates many plant developmental processes and is ensured by 5-meC DNA glycosylase enzymes. To find out the role of , gene editing mutants were generated using the CRISPR/Cas9 system. The mutants had shrink spikelets, smaller anthers and pollen grains, and were not stained by iodine staining showing a significant reduction in total soluble sugar and starch contents as compared to wildtype (WT), which caused complete male sterility. Similarly, the expression of genes involved in pollen and anther development was decreased in mutants as compared to WT. Furthermore, bisulfite sequencing showed that the CG and CHG methylation of the gene promoter was significantly increased in the mutant, which caused a reduced expression of in mutants. DNA methylation of the gene promoter was similar between WT and mutants, indicating that the DNA methylation effect by was gene specific. The expression of in the mutants was not changed, but it produced a frame-shift mutation to truncate the Pem-CXXC and RRMF domains. Combined with previous studies, our findings suggested that the RRMF domain in OsROS1a is the functional domain and loss of RRMF for causes sterility in rice.