Regulatory network of gene expression during the development of frost tolerance in plants

Identification of the genetic background of cold acclimation and overwintering is necessary for improving low-temperature (LT) tolerance in plants. Winter hardiness consists of three major traits: LT tolerance, vernalization (VRN) response and photoperiod (PPD) sensitivity. Transcript pro?ling experiments have unveiled that the several regulatory pathways are activated during cold acclimation, but the best understood pathway involves the CBF/DREB1 regulon. CBF transcription factors can regulate the COR genes (COld Regulated genes) which are induced by LT and the continuation of this state provides freezing tolerance (FT). Furthermore posttranslational mechanisms may regulate the function of transcription factors involved in cold acclimation through influencing their sub-cellular localization, stability, activity or ability to interact with other proteins. Analysis of genes expression in response to cold acclimation have been showed that photosynthetic genes down-regulated as medium to long term cold-responsive genes. However the genes involved in the synthesis of osmoprotectants - organic compounds, enzymatic antioxidant, anti-pathogenic polypeptides, cytoskeletal proteins (alpha-tubulin) , dehydrins (LEA II family) and others significantly up-regulate during overwintering. Vernalization genes ( VRN1, VRN3 and VRN2 ) can control FT by regulating the duration of LT-induced genes expression. Induction of VRN1 and transition to the reproductive stage is critical in the expression of LT tolerance genes. Therefore, stage of phenological development strictly controls level and duration of FT expression.