Floral regulators FLC and SOC1 directly regulate expression of the B3-type transcription factor TARGET OF FLC AND SVP 1 at the Arabidopsis shoot apex via antagonistic chromatin modifications

Abstract

Integration of environmental and endogenous cues at plant shoot meristems determines the timing of flowering and reproductive development. The MADS box transcription factor FLOWERING LOCUS C (FLC) of Arabidopsis thaliana is an important repressor of floral transition, which blocks flowering until plants are exposed to winter cold. However, the target genes of FLC have not been thoroughly described, and our understanding of the mechanisms by which FLC represses transcription of these targets and how this repression is overcome during floral transition is still fragmentary. Here, we identify and characterize TARGET OF FLC AND SVP1 (TFS1) , a novel target gene of FLC and its interacting protein SHORT VEGETATIVE PHASE (SVP). TFS1 encodes a B3-type transcription factor, and we show that tfs1 mutants are later flowering than wild-type, particularly under short days. FLC and SVP repress TFS1 transcription leading to deposition of trimethylation of Iysine 27 of histone 3 (H3K27me3) by the Polycomb Repressive Complex 2 at the TFS1 locus. During floral transition, after downregulation of FLC by cold, TFS1 transcription is promoted by SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), a MADS box protein encoded by another target of FLC/SVP. SOC1 opposes PRC function at TFS1 through recruitment of the histone demethylase RELATIVE OF EARLY FLOWERING 6 (REF6) and the SWI/SNF chromatin remodeler ATPase BRAHMA (BRM). This recruitment of BRM is also strictly required for SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 9 (SPL9) binding at TFS1 to coordinate RNAPII recruitment through the Mediator complex. Thus, we show that antagonistic chromatin modifications mediated by different MADS box transcription factor complexes play a crucial role in defining the temporal and spatial patterns of transcription of genes within a network of interactions downstream of FLC/SVP during floral transition.

Three-dimensional nuclear organization in Arabidopsis thaliana

“…FLC is not only regulated by a gene loop but also is involved in loop formation of its targets. Binding of FLC to the 3' regulatory region of TARGET OF FLC AND SVP1 (TFS1) was reported to enable the formation of a gene loop anchoring at this 3' region and the TFS1 gene body and promote TFS1 silencing (Richter et al 2019).…”

REM34 and REM35 Control Female and Male Gametophyte Development in Arabidopsis thaliana

“…In the context of finding new players involved in the control of this process, the REM gene transcription factor family promises to be a good candidate since two of the four REMs that were functionally chatacterized, VERDANDI ( VDD or REM20 ) and VALKYRIE ( VAL or REM11 ), have a function in gametophyte development (Matias-Hernandez et al, 2010; Mendes et al, 2016). The other two members, VERNALIZATION1 ( VRN1 or REM5 ) and TARGET OF FLC AND SVP1 ( TFS1 or REM17 ), were shown to be involved in the control of flowering time (Levy, 2002; Sung and Amasino, 2004; Richter et al, 2019).…”

Role of MADS-box Gene in the Development of Flower Organs in Pineapple of a Typical Collective Fruit

“…AcMADS31, a homologous gene of TT16, was speci cally expressed in the ovary of pineapple, manifested that AcMADS31 was involved in the development of ovary, and was essential for the formation of female gametophyte of pineapple. AcMADS33, which was homologous with FLC that is owering repressor in Arabidopsis [45], was also speci cally expressed in the ovary of pineapple. However, the involvement of this gene in pistil development is yet to be reported.…”