Transcriptional regulation network of cold-responsive genes in higher plants

CBF (DREB1) genes act as nodes of regulatory network in Arabidopsis response to cold stress, which are conserved in many plants. Combined use of genetic and molecular approaches, a series of regulatory genes involved in CBF cold response pathway have been isolated and analyzed. Among them, some gene products are thought to function directly in transcription. HOS1 is a negative regulator of CBFs, whereas FRY2 acts as a transcriptional repressor and LOS2 as a positive regulator in the pathway. ICE1, the regulator of the CBF3 may be regulated by HOS1. Arabidopsis transcriptome profiling studies suggest multiplicity and complexity of the cold-responsive pathways. It is underestimated that 1000 genes are cold-responsive in the entire Arabidosis genome, some of which are transient or up-regulated and others of which are long lived or down-regulated. In addition, the data indicate that multiple regulatory pathways are activated during cold acclimation in addition to the CBF cold-responsive pathway. Two transcription factors, RAV1 and ZAT12 probably operate in pathways that are parallel to those of the CBFs. By contrast, two AP2 domain proteins, RAP2.6 and RAP2.1 might be targets of the CBF activators. Moreover, the latest results show that the expression of CBFs in Arabidopsis is also regulated by ABA, light and the circadian clock. It is suggested that there exist extensive crosstalks between the CBF cold response pathway and the non-temperature signaling transduction pathways. (c) 2005 Elsevier Ireland Ltd. All rights reserved.