N1-methyladenosine mRNA methylation in Arabidopsis

Abstract

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. This study profiles the global landscape of N1-methyladenosine (m1A) mRNA methylation and uncovers the physiological and molecular functions of m1A through the identification and functional characterization of novel m1A writers and readers in Arabidopsis.