FIONA1-mediated methylation of the 3'UTR of FLC affects FLC transcript levels and flowering in Arabidopsis

PLoS Genet. 2022 Sep 27;18(9):e1010386. doi: 10.1371/journal.pgen.1010386. eCollection 2022 Sep.


Adenosine bases of RNA can be transiently modified by the deposition of a methyl-group to form N6-methyladenosine (m6A). This adenosine-methylation is an ancient process and the enzymes involved are evolutionary highly conserved. A genetic screen designed to identify suppressors of late flowering transgenic Arabidopsis plants overexpressing the miP1a microProtein yielded a new allele of the FIONA1 (FIO1) m6A-methyltransferase. To characterize the early flowering phenotype of fio1 mutant plants we employed an integrative approach of mRNA-seq, Nanopore direct RNA-sequencing and meRIP-seq to identify differentially expressed transcripts as well as differentially methylated RNAs. We provide evidence that FIO1 is the elusive methyltransferase responsible for the 3'-end methylation of the FLOWERING LOCUS C (FLC) transcript. Furthermore, our genetic and biochemical data suggest that 3'-methylation stabilizes FLC mRNAs and non-methylated FLC is a target for rapid degradation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3' Untranslated Regions / genetics
  • Adenosine / genetics
  • Adenosine / metabolism
  • Arabidopsis Proteins* / metabolism
  • Arabidopsis* / metabolism
  • Flowers / genetics
  • Flowers / metabolism
  • Gene Expression Regulation, Plant
  • Histones / genetics
  • MADS Domain Proteins / genetics
  • MADS Domain Proteins / metabolism
  • Methylation
  • Methyltransferases / genetics
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism


  • 3' Untranslated Regions
  • Arabidopsis Proteins
  • Histones
  • MADS Domain Proteins
  • RNA, Messenger
  • Methyltransferases
  • Adenosine

Grant support

We acknowledge funding through NovoCrops Centre (Novo Nordisk Foundation project number 2019OC53580 to S. W.), the Independent Research Fund Denmark (0136‐00015B and 0135‐00014B to S. W.), the Novo Nordisk Foundation (NNF18OC0034226 and NNF20OC0061440 to S. W.), and the funding of DataPLANT (NFDI 7/1 – 42077441) as part of the German National Research Data Infrastructure funded by the Deutsche Forschungsgemeinschaft (DFG – German Research Foundation). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.