Rice OsALKBH9 RNA-seq and merip-seq (PRJCA016394)

The N6 methyladenosine (m6A) mRNA modification plays vital roles in plant development and stress responses. In rice, the deficiency of OsFIP37, a core component of m6A methyltransferase complex, causing male sterility, indicating a significant role of m6A in male fertility. However, despite its importance, the rice mRNA m6A demethylase has yet to be described. In this work, we identified an mRNA m6A demethylase OsALKBH9. Knockout of OsALKBH9 caused male sterility, and its ability to regulate male fertility was dependent upon its m6A demethylase activity. Cytological analysis revealed that tapetal programmed cell death (PCD) was defective, and that there was excessive accumulation of microspores exine in Osalkbh9-1. Anthers transcriptome analysis showed that up-regulation of genes involved in tapetum development, sporopollenin synthesis and transport pathways in Osalkbh9-1. Furthermore, we demonstrated that OsALKBH9 removes the m6A modification in TDR and GAMYB transcripts, which affects the stability of these mRNAs, to affect the pollen development. Our findings highlight the precise control of mRNA m6A modification and reveal the important roles played by OsALKBH9-mediated m6A demethylation in tapetal PCD and pollen exine patterning in rice.