A genetic link between cold responses and flowering time through FVE in Arabidopsis thaliana

Cold induces expression of a number of genes that encode proteins that enhance tolerance to freezing temperatures in plants(1,2). A cis-acting element responsive to cold and drought, the C-repeat/dehydration-responsive element (C/DRE), was identified in the Arabidopsis thaliana stress-inducible genes RD29A(3) and COR15a(4) and found in other cold-inducible genes in various plants(1,5). C/DRE-binding factor/DRE-binding protein (CBF/DREB) is an essential component of the cold-acclimation response(1,2), but the signaling pathways and networks are mostly unknown. Here we used targeted genetic approach to isolate A. thaliana mutants with altered cold-responsive gene expression (acg) and identify ACG1 as a negative regulator of the CBF/DREB pathway. acg1 flowered late and had elevated expression of FLOWERING LOCUS C (FLC)(6), a repressor of flowering encoding a MADS-box protein. We showed that acg1 is a null allele of the autonomous pathway gene FVE. FVE encodes a homolog of the mammalian retinoblastoma-associated protein, a component of a histone deacetylase (HDAC) complex involved in transcriptional repression(7,8). We also showed that plants sense intermittent cold stress through FVE and delay flowering with increasing expression of FLC. Dual roles of FVE in regulating the flowering time and the cold response may have an evolutionary advantage for plants by increasing their survival rates.