FIONA1‐mediated mRNA m6A methylation regulates the response of Arabidopsis to salt stress

Abstract N 6 ‐methyladenosine (m 6 A) is an mRNA modification widely found in eukaryotes and plays a crucial role in plant development and stress responses. FIONA1 (FIO1) is a recently identified m 6 A methyltransferase that regulates Arabidopsis ( Arabidopsis thaliana ) floral transition; however, its role in stress response remains unknown. In this study, we demonstrate that FIO1‐mediated m 6 A methylation plays a vital role in salt stress response in Arabidopsis. The loss‐of‐function fio1 mutant was sensitive to salt stress. Importantly, the complementation lines expressing the wild‐type FIO1 exhibited the wild‐type phenotype, whereas the complementation lines expressing the mutant FIO1 m , in which two critical amino acid residues essential for methyltransferase activity were mutated, did not recover the wild‐type phenotype under salt stress, indicating that the salt sensitivity is associated with FIO1 methyltransferase activity. Furthermore, FIO1‐mediated m 6 A methylation regulated ROS production and affected the transcript level of several salt stress‐responsive genes via modulating their mRNA stability in an m 6 A‐dependent manner in response to salt stress. Importantly, FIO1 is associated with salt stress response by specifically targeting and differentially modulating several salt stress‐responsive genes compared with other m 6 A writer. Collectively, our findings highlight the molecular mechanism of FIO1‐mediated m 6 A methylation in the salt stress adaptation.