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

Abstract

N6‐methyladenosine (m6A) 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 m6A methyltransferase that regulates Arabidopsis (Arabidopsis thaliana) floral transition; however, its role in stress response remains unknown. In this study, we demonstrate that FIO1‐mediated m6A 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 FIO1m, 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 m6A methylation regulated ROS production and affected the transcript level of several salt stress‐responsive genes via modulating their mRNA stability in an m6A‐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 m6A writer. Collectively, our findings highlight the molecular mechanism of FIO1‐mediated m6A methylation in the salt stress adaptation.

Regulatory Role of RNA N6‐Methyladenosine Modification in Plants

“…[33,36] Likewise, under salt stress, FIO1 adds m 6 A to regulatory factors associated with salt stimulation modulating their mRNA stability. [37] m 6 A demethylases ALKBH10B can affect the key flowering time regulators, FLOWERING LOCUS T (FT) and SQUAMOUSA PROMOTER BINDING PROTEIN-LIKE 3/9 (SPL3/9), mRNA stability, thereby affecting floral transition. [14] Moreover, ALKBH9B and ALKBH10B regulate the m 6 A level to modulate the stability of the transcripts of salt stress and ABA conditions related genes [38][39][40] (Figure 3).…”