Low temperature regulation of the Arabidopsis CBF family of AP2 transcriptional activators as an early step in cold-induced COR gene expression
TL;DR: It is proposed that cold-induced expression of CRT/DRE-containing COR genes involves a low temperature-stimulated signalling cascade in which CBF gene induction is an early event and theCBF gene family is not subject to autoregulation.
Abstract: Cold-induced expression of the Arabidopsis COR (cold-regulated) genes is mediated by a DNA regulatory element termed the CRT (C-repeat)/DRE (dehydration-responsive element). Recently, we identified a transcriptional activator, CBF1, that binds to the CRT/DRE and demonstrated that its overexpression in transgenic Arabidopsis plants at non-acclimating temperatures induces COR gene expression and increases plant freezing tolerance. Here we report that CBF1 belongs to a small family of closely related proteins which includes CBF2 and CBF3. DNA sequencing of an 8.7 kb region of the Arabidopsis genome along with genetic mapping experiments indicated that the three CBF genes are organized in direct repeat on chromosome 4 at 72.8 cM, closely linked to molecular markers PG11 and m600. Like CBF1, both CBF2 and CBF3 activated expression of reporter genes in yeast that contained the CRT/DRE as an upstream activator sequence. The transcript levels for all three CBF genes increased within 15 min of transferring plants to low temperature, followed by accumulation of COR gene transcripts at about 2 h. CBF transcripts also accumulated rapidly in response to mechanical agitation. The promoter regions of the CBF genes do not contain the CRT sequence, CCGAC, and overexpression of CBF1 did not have a detectable effect on CBF3 transcript levels, suggesting that the CBF gene family is not subject to autoregulation. We propose that cold-induced expression of CRT/DRE-containing COR genes involves a low temperature-stimulated signalling cascade in which CBF gene induction is an early event.
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TL;DR: Salt and drought stress signal transduction consists of ionic and osmotic homeostasis signaling pathways, detoxification (i.e., damage control and repair) response pathways, and pathways for growth regulation.
Abstract: Salt and drought stress signal transduction consists of ionic and osmotic homeostasis signaling pathways, detoxification (i.e., damage control and repair) response pathways, and pathways for growth regulation. The ionic aspect of salt stress is signaled via the SOS pathway where a calcium-responsive SOS3-SOS2 protein kinase complex controls the expression and activity of ion transporters such as SOS1. Osmotic stress activates several protein kinases including mitogen-activated kinases, which may mediate osmotic homeostasis and/or detoxification responses. A number of phospholipid systems are activated by osmotic stress, generating a diverse array of messenger molecules, some of which may function upstream of the osmotic stress-activated protein kinases. Abscisic acid biosynthesis is regulated by osmotic stress at multiple steps. Both ABA-dependent and -independent osmotic stress signaling first modify constitutively expressed transcription factors, leading to the expression of early response transcriptional activators, which then activate downstream stress tolerance effector genes.
5,328 citations
TL;DR: The present review summarizes the recent advances in elucidating stress-response mechanisms and their biotechnological applications and examines the following aspects: regulatory controls, metabolite engineering, ion transport, antioxidants and detoxification, late embryogenesis abundant (LEA) and heat-shock proteins.
Abstract: Abiotic stresses, such as drought, salinity, extreme temperatures, chemical toxicity and oxidative stress are serious threats to agriculture and the natural status of the environment. Increased salinization of arable land is expected to have devastating global effects, resulting in 30% land loss within the next 25 years, and up to 50% by the year 2050. Therefore, breeding for drought and salinity stress tolerance in crop plants (for food supply) and in forest trees (a central component of the global ecosystem) should be given high research priority in plant biotechnology programs. Molecular control mechanisms for abiotic stress tolerance are based on the activation and regulation of specific stress-related genes. These genes are involved in the whole sequence of stress responses, such as signaling, transcriptional control, protection of membranes and proteins, and free-radical and toxic-compound scavenging. Recently, research into the molecular mechanisms of stress responses has started to bear fruit and, in parallel, genetic modification of stress tolerance has also shown promising results that may ultimately apply to agriculturally and ecologically important plants. The present review summarizes the recent advances in elucidating stress-response mechanisms and their biotechnological applications. Emphasis is placed on transgenic plants that have been engineered based on different stress-response mechanisms. The review examines the following aspects: regulatory controls, metabolite engineering, ion transport, antioxidants and detoxification, late embryogenesis abundant (LEA) and heat-shock proteins.
3,248 citations
Cites background from "Low temperature regulation of the A..."
...6, cor15a, erd10, kin1, kin2 and others in response to cold and water stress (Ingram and Bartels 1996; Stockinger et al. 1997; Gilmour et al. 1998; Liu et al. 1998; Seki et al. 2001; Thomashow et al. 2001)....
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01 Jun 1999
TL;DR: This review of recent advances in determining the nature and function of genes with roles in freezing tolerance and the mechanisms involved in low temperature gene regulation and signal transduction concludes that cold acclimation includes the expression of certain cold-induced genes that function to stabilize membranes against freeze-induced injury.
Abstract: ▪ Abstract Many plants increase in freezing tolerance upon exposure to low nonfreezing temperatures, a phenomenon known as cold acclimation. In this review, recent advances in determining the nature and function of genes with roles in freezing tolerance and the mechanisms involved in low temperature gene regulation and signal transduction are described. One of the important conclusions to emerge from these studies is that cold acclimation includes the expression of certain cold-induced genes that function to stabilize membranes against freeze-induced injury. In addition, a family of Arabidopsis transcription factors, the CBF/DREB1 proteins, have been identified that control the expression of a regulon of cold-induced genes that increase plant freezing tolerance. These results along with many of the others summarized here further our understanding of the basic mechanisms that plants have evolved to survive freezing temperatures. In addition, the findings have potential practical applications as freezing te...
2,938 citations
Cites background from "Low temperature regulation of the A..."
...The results of Stockinger et al (109) and Jaglo-Ottosen et al (49) have recently been extended by Gilmour et al (22), Liu et al (72), and Shinwari et al (102)....
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...6, COR15a, COR47, andCOR78, which are located on chromosomes 5, 2, 1, and 5, respectively (22)....
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...As noted by Gilmour et al (22), the fact that CBF transcripts begin accumulating within 15 min of plants being exposed to low temperature strongly suggests that the low-temperature “thermometer” and “signal transducer” are present at warm noninducing temperatures....
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...Figure 2 Model forCBF regulation ofCORgene expression (22)....
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...Thus, Gilmour et al (22) suggested that CORgene expression involves a low-temperature signaling cascade in which CBF gene expression is an early step....
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01 Jan 1999
TL;DR: A review of recent advances in determining the nature and function of genes with roles in freezing tolerance and the mechanisms involved in low temperature gene regulation and signal transduction are described in this article.
Abstract: ▪ Abstract Many plants increase in freezing tolerance upon exposure to low nonfreezing temperatures, a phenomenon known as cold acclimation. In this review, recent advances in determining the nature and function of genes with roles in freezing tolerance and the mechanisms involved in low temperature gene regulation and signal transduction are described. One of the important conclusions to emerge from these studies is that cold acclimation includes the expression of certain cold-induced genes that function to stabilize membranes against freeze-induced injury. In addition, a family of Arabidopsis transcription factors, the CBF/DREB1 proteins, have been identified that control the expression of a regulon of cold-induced genes that increase plant freezing tolerance. These results along with many of the others summarized here further our understanding of the basic mechanisms that plants have evolved to survive freezing temperatures. In addition, the findings have potential practical applications as freezing te...
2,665 citations
TL;DR: Various factors pertaining to cold acclimation, promoter elements, and role of transcription factors in stress signaling pathway have been described, and the role of calcium as an important signaling molecule in response to various stress signals has been covered.
2,626 citations
References
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TL;DR: A technique for conveniently radiolabeling DNA restriction endonuclease fragments to high specific activity is described, and these "oligolabeled" DNA fragments serve as efficient probes in filter hybridization experiments.
23,324 citations
01 Jan 1984
TL;DR: In this article, a technique for conveniently radiolabeling DNA restriction endonuclease fragments to high specific activity is described, where DNA fragments are purified from agarose gels directly by ethanol precipitation and are then denatured and labeled with the large fragment of DNA polymerase I, using random oligonucleotides as primers.
Abstract: A technique for conveniently radiolabeling DNA restriction endonuclease fragments to high specific activity is described. DNA fragments are purified from agarose gels directly by ethanol precipitation and are then denatured and labeled with the large fragment of DNA polymerase I, using random oligonucleotides as primers. Over 70% of the precursor triphosphate is routinely incorporated into complementary DNA, and specific activities of over 10(9) dpm/microgram of DNA can be obtained using relatively small amounts of precursor. These "oligolabeled" DNA fragments serve as efficient probes in filter hybridization experiments.
21,435 citations
TL;DR: A computer package, called MAPMAKER, designed specifically for the construction of linkage maps in a number of organisms, including the human and several plants, and it is outlined the mapping strategies that have been used.
6,745 citations
TL;DR: Overexpression of the DREB1A cDNA in transgenic Arabidopsis plants not only induced strong expression of the target genes under unstressed conditions but also caused dwarfed phenotypes in the transgenic plants, and revealed freezing and dehydration tolerance.
Abstract: Plant growth is greatly affected by drought and low temperature. Expression of a number of genes is induced by both drought and low temperature, although these stresses are quite different. Previous experiments have established that a cis-acting element named DRE (for dehydration-responsive element) plays an important role in both dehydration- and low-temperature-induced gene expression in Arabidopsis. Two cDNA clones that encode DRE binding proteins, DREB1A and DREB2A, were isolated by using the yeast one-hybrid screening technique. The two cDNA libraries were prepared from dehydrated and cold-treated rosette plants, respectively. The deduced amino acid sequences of DREB1A and DREB2A showed no significant sequence similarity, except in the conserved DNA binding domains found in the EREBP and APETALA2 proteins that function in ethylene-responsive expression and floral morphogenesis, respectively. Both the DREB1A and DREB2A proteins specifically bound to the DRE sequence in vitro and activated the transcription of the b-glucuronidase reporter gene driven by the DRE sequence in Arabidopsis leaf protoplasts. Expression of the DREB1A gene and its two homologs was induced by low-temperature stress, whereas expression of the DREB2A gene and its single homolog was induced by dehydration. Overexpression of the DREB1A cDNA in transgenic Arabidopsis plants not only induced strong expression of the target genes under unstressed conditions but also caused dwarfed phenotypes in the transgenic plants. These transgenic plants also revealed freezing and dehydration tolerance. In contrast, overexpression of the DREB2A cDNA induced weak expression of the target genes under unstressed conditions and caused growth retardation of the transgenic plants. These results indicate that two independent families of DREB proteins, DREB1 and DREB2, function as trans-acting factors in two separate signal transduction pathways under low-temperature and dehydration conditions, respectively.
2,886 citations
TL;DR: The rd29A promoter in both transgenic Arabidopsis and tobacco was analyzed and a novel cis-acting, dehydration-responsive element (DRE) containing 9 bp, TACCGACAT, was identified that is involved in the first rapid response of rd 29A to conditions of dehydration or high salt.
Abstract: Two genes, rd29A and rd29B, which are closely located on the Arabidopsis genome, are differentially induced under conditions of dehydration, low temperature, high salt, or treatment with exogenous abscisic acid (ABA). It appears that rd29A has at least two cis-acting elements, one involved in the ABA-associated response to dehydration and the other induced by changes in osmotic potential, and that rd29B contains at least one cis-acting element that is involved in ABA-responsive, slow induction. We analyzed the rd29A promoter in both transgenic Arabidopsis and tobacco and identified a novel cis-acting, dehydration-responsive element (DRE) containing 9 bp, TACCGACAT, that is involved in the first rapid response of rd29A to conditions of dehydration or high salt. DRE is also involved in the induction by low temperature but does not function in the ABA-responsive, slow expression of rd29A. Nuclear proteins that specifically bind to DRE were detected in Arabidopsis plants under either high-salt or normal conditions. Different cis-acting elements seem to function in the two-step induction of rd29A and in the slow induction of rd29B under conditions of dehydration, high salt, or low temperature.
2,032 citations