title: Role of CBFs as integrators of chloroplast redox, phytochrome and plant hormone signaling during cold acclimation.
abstract: Cold acclimation of winter cereals and other winter hardy species is a prerequisite to increase subsequent freezing tolerance. Low temperatures upregulate the expression of C-repeat/dehydration-responsive element binding transcription factors (CBF/DREB1) which in turn induce the expression of COLD-REGULATED (COR) genes. We summarize evidence which indicates that the integration of these interactions is responsible for the dwarf phenotype and enhanced photosynthetic performance associated with cold-acclimated and CBF-overexpressing plants. Plants overexpressing CBFs but grown at warm temperatures mimic the cold-tolerant, dwarf, compact phenotype; increased photosynthetic performance; and biomass accumulation typically associated with cold-acclimated plants. In this review, we propose a model whereby the cold acclimation signal is perceived by plants through an integration of low temperature and changes in light intensity, as well as changes in light quality. Such integration leads to the activation of the CBF-regulon and subsequent upregulation of COR gene and GA 2-oxidase (GA2ox) expression which results in a dwarf phenotype coupled with increased freezing tolerance and enhanced photosynthetic performance. We conclude that, due to their photoautotrophic nature, plants do not rely on a single low temperature sensor, but integrate changes in light intensity, light quality, and membrane viscosity in order to establish the cold-acclimated state. CBFs appear to act as master regulators of these interconnecting sensing/signaling pathways.
authors.affiliation: Department of Biology and the Biotron Center for Experimental Climate Change Research, Western University, London, ON N6A 5B7, Canada. lkurepin@uwo.ca.
authors.forename: Leonid V
authors.initials: LV
authors.lastname: Kurepin
authors.forename: Keshav P
authors.initials: KP
authors.lastname: Dahal
authors.forename: Leonid V
authors.initials: LV
authors.lastname: Savitch
authors.forename: Jas
authors.initials: J
authors.lastname: Singh
authors.forename: Rainer
authors.initials: R
authors.lastname: Bode
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Ivanov
authors.forename: Vaughan
authors.initials: V
authors.lastname: Hurry
authors.forename: Norman P A
authors.initials: NP
authors.lastname: Hüner
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D002736:Chloroplasts / Q000378:metabolism*; D003080:Cold Temperature; D010084:Oxidation-Reduction; D010834:Phytochrome / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D010937:Plant Growth Regulators; D010940:Plant Proteins; D010834:Phytochrome