The novel roles of RNA m6A modification in regulating the development, infection, and oxidative DNA damage repair of Phytophthora sojae

N 6 -methyladenosine (m 6 A), a vital post-transcriptional regulator, is among the most prevalent RNA modifications in eukaryotes. Nevertheless, the biological functions of m 6 A in oomycetes remain poorly understood. Here, we showed that the PsMTA1 and PsMTA2 genes are orthologs of human METTL4, while the PsMET16 gene is an ortholog of human METTL16. These genes are implicated in m 6 A modification and play a critical role in the production of sporangia and oospores, the release of zoospores, and the virulence of Phytophthora sojae . In P . sojae , m 6 A modifications are predominantly enriched in the coding sequence and the 3’ untranslated region. Notably, the PsMTA1 knockout mutant exhibited reduced virulence, attributed to impaired tolerance to host defense-generated ROS stress. Mechanistically, PsMTA1-mediated m 6 A modification positively regulates the mRNA lifespan of DNA damage response (DDR) genes in reaction to plant ROS stress during infection. Consequently, the mRNA abundance of the DDR gene PsRCC1 was reduced in the single m 6 A site mutant ΔRCC1/RCC1 A2961C , resulting in compromised DNA damage repair and reduced ROS adaptation-associated virulence in P . sojae . Overall, these results indicate that m 6 A-mediated RNA metabolism is associated with the development and pathogenicity of P . sojae , underscoring the roles of epigenetic markers in the adaptive flexibility of Phytophthora during infection.