Polymerase II-Associated Factor 1 Complex-Regulated FLOWERING LOCUS C -Clade Genes Repress Flowering in Response to Chilling

• Published in: Frontiers in plant science 2022-02, Vol.13, p.817356-817356
• Main Authors: Nasim, Zeeshan, Susila, Hendry, Jin, Suhyun, Youn, Geummin, Ahn, Ji Hoon
• Format: Article
• Language: English
• Subjects: Arabidopsis; epigenetics; FLC; flowering; MAFs; PAF1C; Plant Science
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2022.817356

RNA polymerase II-associated factor 1 complex (PAF1C) regulates the transition from the vegetative to the reproductive phase primarily by modulating the expression of ( ) and [ , also known as ( )] at standard growth temperatures. However, the role of PAF1C in the regulation of flowering time at chilling temperatures (i.e., cold temperatures that are above freezing) and whether PAF1C affects other -clade genes ( - ) remains unknown. Here, we showed that mutants of any of the six known genes that encode components of PAF1C [ , ( )/ ( ), , , , and ] showed temperature-insensitive early flowering across a broad temperature range (10°C-27°C). Flowering of PAF1C-deficient mutants at 10°C was even earlier than that in , , and mutants, suggesting that PAF1C regulates additional factors. Indeed, RNA sequencing (RNA-Seq) of PAF1C-deficient mutants revealed downregulation of in addition to and at both 10 and 23°C. Consistent with the reduced expression of and the -clade members and , chromatin immunoprecipitation (ChIP)-quantitative PCR assays showed reduced levels of the permissive epigenetic modification H3K4me3/H3K36me3 and increased levels of the repressive modification H3K27me3 at their chromatin. Knocking down using artificial microRNAs (amiRNAs) in the background ( ) resulted in significantly earlier flowering than mutants and even earlier than ( ) mutants at 10°C. Wild-type seedlings showed higher accumulation of and -clade gene transcripts at 10°C compared to 23°C. Our yeast two-hybrid assays and co-immunoprecipitation (Co-IP) analyses revealed that MAF2-MAF5 directly interact with the prominent floral repressor SVP. Late flowering caused by overexpression was almost completely suppressed by the and mutations, suggesting that SVP-mediated floral repression required a functional PAF1C. Taken together, our results showed that PAF1C regulates the transcription of and -clade genes to modulate temperature-responsive flowering at a broad range of temperatures and that the interaction between SVP and these FLC-clade proteins is important for floral repression.