FIONA1 is an N6-methyladenosine methyltransferase that plays a vital role in floral transition via affecting the splicing of FLC and the stability of SPL3 and SEP3 in Arabidopsis.

N 6-methyladenosine (m 6A) RNA methylation has been shown to play a crucial role in plant development and floral transition. Two recent studies have identified FIONA1 as an m 6A methyltransferase that regulates the floral transition via influencing the stability of CONSTANS (CO), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1), and FLOWERING LOCUS C (FLC) in Arabidopsis. In this study, we confirmed that FIONA1 is an m 6A methyltransferase that installs m 6A marks in a small group of mRNAs. Furthermore, in addition to its role in influencing the stability of CO, SOC1, and FLC, we show that FIONA1-mediated m 6A methylation influences the splicing of FLC, a key floral repressor, and the stability of SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 3 (SPL3) and SEPALLATA3 (SEP3), floral activators, which plays a vital role in the floral transition in Arabidopsis. Our study confirms FIONA1 as an m 6A methyltransferase and suggests a close molecular link between FIONA1-mediated m 6A methylation and the splicing of FLC and the destabilization of SPL3 and SEP3 in flowering time control.