title: Light-quality regulation of freezing tolerance in Arabidopsis thaliana.
abstract: To acquire freezing tolerance, higher plants require a period of low temperature (usually <4 degrees C) termed cold acclimation. Upon transfer of plants to low temperature, increased expression of the CRT/DRE binding factor (CBF) family of transcriptional activators leads to the upregulation of genes containing a C-repeat/drought-responsive (CRT/DRE) promoter element and metabolic changes that enhance tolerance to subzero temperatures. Here, we show that a low red to far-red ratio (R/FR) light signal increases CBF gene expression in Arabidopsis thaliana in a manner dependent on the circadian clock. This light quality-dependent increase in CBF expression is sufficient to confer freezing tolerance at temperatures higher than those required for cold acclimation. Furthermore, the use of light-quality signals to stimulate CBF expression has revealed ambient temperature-dependent coupling of CBF transcription factors to downstream COLD REGULATED (COR) genes, providing evidence for a second temperature-regulated step in this pathway.
authors.affiliation: Department of Biology, University of Leicester, Leicester LE1 7RH, UK. kaf5@le.ac.uk
authors.forename: Keara A
authors.initials: KA
authors.lastname: Franklin
authors.forename: Garry C
authors.initials: GC
authors.lastname: Whitelam
mesh_terms: D000222:Adaptation, Physiological; D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D003080:Cold Temperature; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D008027:Light; D051939:Phytochrome B / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C104387:CBF1 protein, Arabidopsis; C118228:CBF2 protein, Arabidopsis; C116166:COR15 protein, Arabidopsis; D004268:DNA-Binding Proteins; C114578:DREB1A protein, Arabidopsis; D018749:RNA, Plant; D015534:Trans-Activators; D014157:Transcription Factors; D051939:Phytochrome B