Gene

Cell biology

Methyltransferase

Untranslated region

Biology

Messenger RNA

Coding region

Genetics

Arabidopsis

Three prime untranslated region

Mutant

Methylation

Polyadenylation

Arabidopsis thaliana

Advanced Science

N 6 ‐methyladenosine (m 6 A) mRNA modification represents the most widespread form of internal modifications in eukaryotic mRNAs. In the model plant Arabidopsis thaliana , those known methyltransferases mainly deposit m 6 A at their target transcripts near the stop codon or in the 3′ untranslated region. Here, it is reported that FIONA1 (FIO1), a human METTL16 ortholog, acts as a hitherto unknown m 6 A methyltransferase that determines m 6 A modifications at over 2000 Arabidopsis transcripts predominantly in the coding region. Mutants of FIO1 show a decrease in global m 6 A mRNA methylation levels and an early‐flowering phenotype. Nanopore direct RNA sequencing reveals that FIO1 is required for establishing appropriate levels of m 6 A preferentially in the coding sequences of a subset of protein‐coding transcripts, which is associated with changes in transcript abundance and alternative polyadenylation. It is further demonstrated that FIO1‐mediated m 6 A methylation determines the mRNA abundance of a central flowering integrator SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 ( SOC1 ) and its upstream regulators, thus preventing premature flowering. The findings reveal that FIO1 acts as a unique m 6 A methyltransferase that mainly modifies the coding regions of transcripts, which underlies the key developmental transition from vegetative to reproductive growth in plants.

FIONA1‐Mediated m<sup>6</sup>A Modification Regulates the Floral Transition in <i>Arabidopsis</i>

FIONA1‐Mediated m6A Modification Regulates the Floral Transition in Arabidopsis

FIONA1‐Mediated m⁶A Modification Regulates the Floral Transition in Arabidopsis