RNA m6A methylation fine-tunes the jasmonic acid biosynthesis pathway to modulate plant aging

Abstract N 6-methyladenosine (m6A) is a context-dependent mRNA modification, yet how its dynamics integrate with endogenous signaling to shape plant development remains unclear. Here, we provide further evidence for HIZ2 as an essential component of the m6A writer complex in Arabidopsis, which methylates and destabilizes mRNAs decoding multiple enzymes acting in sequential steps of jasmonic acid (JA) biosynthesis, thereby ensuring JA homeostasis required for timely leaf senescence. HIZ2 interacts with and is indispensable for maintaining the abundance of key m6A writer complex components, including MTA. HIZ2 is required for transcriptome-wide m6A deposition, notably on transcripts of multiple JA biosynthesis genes, which are subsequently recognized and destabilized by the m6A readers ECT2/3/4. During aging, reduced m6A deposition on these transcripts permits their accumulation, thus elevating JA levels that drive the progression of leaf senescence. Our findings indicate that coordinated m6A-dependent regulation of multiple JA biosynthesis transcripts fine-tunes JA homeostasis and contributes to the timely progression of leaf senescence.