Abstract

N 1 -methyladenosine (m 1 A) 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 m 1 A methylomes across diverse Arabidopsis tissues and show that m 1 A 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 m 1 A methyltransferase complex and interact with ATH3 to regulate m 1 A levels. Notably, we identify previously unknown m 1 A readers, including CP33B and ECT2. Functional analyses reveal that m 1 A is intricately involved in abscisic acid (ABA) signalling and that knockout or knockdown of key genes in m 1 A RNA methylation causes ABA hypersensitivity. Collectively, our findings establish m 1 A as a dynamic epitranscriptomic mark, highlighting its critical role in regulating the ABA signalling pathway.