N¹-methyladenosine mRNA methylation in Arabidopsis

N¹-methyladenosine (m¹A) is a recently identified mRNA methylation mark that affects gene expression and translation. In the model plant Arabidopsis thaliana, its landscape and function remain uncharacterized. Here we present base-resolution m¹A methylomes across diverse Arabidopsis tissues and show that m¹A is enriched in the 5' untranslated region and preferentially localizes to highly expressed genes, negatively correlating with mRNA translation. We demonstrate that TRM6 and TRM61 form the m¹A methyltransferase complex and interact with ATH3 to regulate m¹A levels. Notably, we identify previously unknown m¹A readers, including CP33B and ECT2. Functional analyses reveal that m¹A is intricately involved in abscisic acid (ABA) signalling and that knockout or knockdown of key genes in m¹A RNA methylation causes ABA hypersensitivity. Collectively, our findings establish m¹A as a dynamic epitranscriptomic mark, highlighting its critical role in regulating the ABA signalling pathway.