Overexpression of the Arabidopsis CBF3Transcriptional Activator Mimics Multiple Biochemical Changes Associated with Cold Acclimation (original) (raw)
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Plant Physiology, 2000
We further investigated the role of the Arabidopsis CBF regulatory genes in cold acclimation, the process whereby certain plants increase in freezing tolerance upon exposure to low temperature. The CBF genes, which are rapidly induced in response to low temperature, encode transcriptional activators that control the expression of genes containing the C-repeat/ dehydration responsive element DNA regulatory element in their promoters. Constitutive expression of either CBF1 or CBF3 (also known as DREB1b and DREB1a, respectively) in transgenic Arabidopsis plants has been shown to induce the expression of target COR (cold-regulated) genes and to enhance freezing tolerance in nonacclimated plants. Here we demonstrate that overexpression of CBF3 in Arabidopsis also increases the freezing tolerance of cold-acclimated plants. Moreover, we show that it results in multiple biochemical changes associated with cold acclimation: CBF3-expressing plants had elevated levels of proline (Pro) and total soluble sugars, including sucrose, raffinose, glucose, and fructose. Plants overexpressing CBF3 also had elevated P5CS transcript levels suggesting that the increase in Pro levels resulted, at least in part, from increased expression of the key Pro biosynthetic enzyme ⌬ 1 -pyrroline-5-carboxylate synthase. These results lead us to propose that CBF3 integrates the activation of multiple components of the cold acclimation response.
Role of the Arabidopsis CBF transcriptional activators in cold acclimation
Physiologia Plantarum, 2001
Many plants increase in freezing tolerance upon exposure to COR genes and increases freezing tolerance without a low low nonfreezing temperatures, a phenomenon known as cold temperature stimulus. We have, therefore, proposed that the CBF genes are 'master switches' that activate a regulon of acclimation. A fundamental goal of cold acclimation research genes involved in cold acclimation. Significantly, the CBF is to identify genes with key roles in this response. Here we review results from our laboratory regarding the discovery of genes themselves are responsive to low temperature; the levels a family of transcriptional activators in Arabidopsis (Ara-ofCBF transcripts begin increasing within 15 min of transferbidopsis thaliana) that regulates the expression of freezing ring plants to low temperature followed by accumulation of tolerance genes. Specifically, we have identified 3 genes that COR gene transcripts at 2-4 h. The CBF genes do not appear to be subject to autoregulation as the promoter regions have encode nearly identical transcriptional activators that bind to no evident CRT/DRE elements and overexpression of CBF1 the CRT (C-repeat)/DRE (dehydration responsive element) does not induce expression of CBF3. Thus, we have suggested DNA regulatory element present in the promoters of many that COR gene induction involves a two-step cascade of cold-and drought-inducible genes, including those designated transcriptional activators: the first step, CBF induction, in-COR (cold-regulated). These regulatory genes, CBF1, CBF2 and CBF3 (C 6 RT/DRE b6 inding f6 actor), are located in tandem volving an unknown activator present at normal growth temarray on chromosome 4. Overexpression of the CBF genes in perature and the second step, COR gene induction, involving Arabidopsis induces expression of the entire battery of known the action of the CBF activators.
ICE1: a regulator of cold-induced transcriptome and freezing tolerance in Arabidopsis
Genes & …, 2003
Cold temperatures trigger the expression of the CBF family of transcription factors, which in turn activate many downstream genes that confer chilling and freezing tolerance to plants. We report here the identification of ICE1 (inducer of CBF expression 1), an upstream transcription factor that regulates the transcription of CBF genes in the cold. An Arabidopsis ice1 mutant was isolated in a screen for mutations that impair cold-induced transcription of a CBF3 promoter-luciferase reporter gene. The ice1 mutation blocks the expression of CBF3 and decreases the expression of many genes downstream of CBFs, which leads to a significant reduction in plant chilling and freezing tolerance. ICE1 encodes a MYC-like bHLH transcriptional activator. ICE1 binds specifically to the MYC recognition sequences in the CBF3 promoter. ICE1 is expressed constitutively, and its overexpression in wild-type plants enhances the expression of the CBF regulon in the cold and improves freezing tolerance of the transgenic plants.
Arabidopsis CBF1 Overexpression Induces COR Genes and Enhances Freezing Tolerance
Science, 1998
Many plants, including Arabidopsis , show increased resistance to freezing after they have been exposed to low nonfreezing temperatures. This response, termed cold acclimation, is associated with the induction of COR (cold-regulated) genes mediated by the C-repeat/drought-responsive element (CRT/DRE) DNA regulatory element. Increased expression of Arabidopsis CBF1, a transcriptional activator that binds to the CRT/DRE sequence, induced COR gene expression and increased the freezing tolerance of nonacclimated Arabidopsis plants. We conclude that CBF1 is a likely regulator of the cold acclimation response, controlling the level of COR gene expression, which in turn promotes tolerance to freezing.
Proceedings of The National Academy of Sciences, 2007
The C-repeat-binding factor (CBF)/dehydration-responsive element-binding factor (DREB1) proteins constitute a small family of Arabidopsis transcriptional activators (CBF1/DREB1B, CBF2/ DREB1C, and CBF3/DREB1A) that play a prominent role in cold acclimation. A fundamental question about these factors that remains to be answered is whether they are functionally equivalent. Recently, we reported that CBF2 negatively regulates CBF1 and CBF3 expression, and that CBFs are subjected to different temporal regulation during cold acclimation, which suggested this might not be the case. In this study, we have analyzed the expression of CBF genes in different tissues of Arabidopsis, during development and in response to low temperature, and characterized RNA interference (RNAi) and antisense lines that fail to accumulate CBF1 or/and CBF3 mRNAs under cold conditions. We found that CBF1 and CBF3 are regulated in a different way than CBF2. Moreover, in contrast to CBF2, CBF1 and CBF3 are not involved in regulating other CBF genes and positively regulate cold acclimation by activating the same subset of CBF-target genes. All these results demonstrate that CBF1 and CBF3 have different functions than CBF2. We also found that the CBF regulon is composed of at least two different kind of genes, one of them requiring the simultaneous expression of both CBF1 and CBF3 to be properly induced. This indicates that CBF1 and CBF3 have a concerted additive effect to induce the whole CBF regulon and the complete development of cold acclimation. freezing tolerance ͉ low temperature ͉ DREB1 ͉ abiotic stress ͉ cold signaling Author contributions: F.N. and J.S. designed research; F.N. and J.M. performed research;
PLOS ONE, 2018
Arabidopsis thaliana (Arabidopsis) increases in freezing tolerance in response to low nonfreezing temperatures, a phenomenon known as cold acclimation. The CBF regulatory pathway, which contributes to cold acclimation, includes three genes-CBF1, CBF2 and CBF3-encoding closely-related transcription factors that regulate the expression of more than 100 genes-the CBF regulon-that impart freezing tolerance. Here we compare the CBF pathways of two Arabidopsis ecotypes collected from sites in Sweden (SW) and Italy (IT). Previous studies showed that the SW ecotype was more freezing tolerant than the IT ecotype and that the IT ecotype had a nonfunctional CBF2 gene. Here we present results establishing that the difference in CBF2 alleles contributes to the difference in freezing tolerance between the two ecotypes. However, other differences in the CBF pathway as well as CBF-independent pathways contribute the large majority of the difference in freezing tolerance between the two ecotypes. The results also provided evidence that most cold-induced CBF regulon genes in both the SW and IT ecotypes are coregulated by CBF-independent pathways. Additional analysis comparing our results with those published by others examining the Col-0 accession resulted in the identification of 44 CBF regulon genes that were conserved among the three accessions suggesting that they likely have important functions in life at low temperature. The comparison further supported the conclusion that the CBF pathway can account for a large portion of the increase in freezing tolerance that occurs with cold acclimation in a given accession, but that CBF-independent pathways can also make a major contribution.
Cold stress regulation of gene expression in plants
Trends in plant science, 2007
Cold stress adversely affects plant growth and development. Most temperate plants acquire freezing tolerance by a process called cold acclimation. Here, we focus on recent progress in transcriptional, post-transcriptional and post-translational regulation of gene expression that is critical for cold acclimation. Transcriptional regulation is mediated by the inducer of C-repeat binding factor (CBF) expression 1 (ICE1), the CBF transcriptional cascade and CBF-independent regulons during cold acclimation. ICE1 is negatively regulated by ubiquitination-mediated proteolysis and positively regulated by SUMO (small ubiquitin-related modifier) E3 ligase-catalyzed sumoylation. Post-transcriptional regulatory mechanisms, such as pre-mRNA splicing, mRNA export and small RNA-directed mRNA degradation, also play important roles in cold stress responses.
Environmental science and pollution research international, 2017
Plants integrate and monitor low temperature signals to cope with the continual variations in their environment. Arabidopsis thaliana cold responsive-element binding factor 3 (AtCBF3) plays its role in various cellular activities by modulating multiple genes induced under chilling stress. In this work, AtCBF3 transcription was remarkably induced following chilling stress. AtCBF3-overexpressors namely AtCBF3-Rio Grande, AtCBF3-Moneymaker, and AtCBF3-Roma showed defensible response to various levels of chilling stress, while their isogenic wild type plants indicated hypersensitive response to chilling stress. Detailed photosynthetic studies revealed that AtCBF3 gene has harmonious influences on the expression of a large set of genes by virtue of improved stomatal conductance, transpiration rate, intercellular CO2 concentration, and photosynthetic rate compared to wild type plants. The AtCBF3 lines limited the water status-mediated hypersensitive response by lowering leaf osmotic poten...
The molecular biology of plant acclimation to low temperature
Journal of Experimental Botany, 1996
In many temperate plant species, a period of exposure to a low positive temperature will acclimate the plants to withstand a subsequent freezing stress. A number of plant genes, which are up-regulated at steady-state mRNA levels by an acclimation treatment, have been isolated from both monocotyledon and dicotyledon species. Most of these genes are also responsive to a drought treatment and/or abscisic acid. The acclimation of plants to freezing stress is a complex process and although genetic studies in some species have identified genes with a major effect, in general, the inheritance of frost tolerance is multigenic. In view of this, it is not surprising that a range of different genes have been cloned. The precise function of the proteins encoded by these genes is unknown. However, analysis of predicted protein products and studies of recombinant proteins, together with detailed expression studies, are beginning to provide information about some of the genes. Both transcriptional and post-transcriptional controls have been shown to be involved in the expression of these genes. Although studies of RNA stabilizing systems are still in their early stages, a number of low temperature responsive promoters have been studied using reporter gene constructs. Other approaches to the molecular analysis of cold acclimation include the isolation of non-acclimating mutants and the production of transgenic plants.