Low temperature regulation of the Arabidopsis CBF family of AP2 transcriptional activators as an early step in cold-induced COR gene expression
Low temperature regulation of the Arabidopsis CBF family of AP2 transcriptional activators as an early step in cold-induced COR gene expression
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DOI：
10.1046/j.1365-313x.1998.00310.x
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发表时间：
1998-11-01
期刊：
影响因子：
7.2
通讯作者：
Thomashow, MF
中科院分区：
文献类型：
--
作者：
Gilmour, SJ;Zarka, DG;Thomashow, MF
冷诱导拟南芥COR（冷调控）基因的表达是由一种称为CRT (C-repeat)/DRE（脱水响应元件）的DNA调控元件介导的。最近，我们发现了一个与CRT/DRE结合的转录激活因子CBF1，并证明其在非驯化温度下在转基因拟南芥植物中过表达诱导COR基因表达并提高植物的抗冻性。在这里，我们报告CBF1属于一个密切相关的蛋白小家族，包括CBF2和CBF3。对拟南芥基因组8.7 kb区域的DNA测序和遗传定位实验表明，三个CBF基因在72.8 cM处的4号染色体上直接重复，与分子标记PG11和m600密切相关。与CBF1一样，CBF2和CBF3都激活了酵母中包含CRT/DRE作为上游激活子序列的报告基因的表达。三种CBF基因的转录本水平均在低温处理后15分钟内升高，随后在2小时左右开始积累COR基因转录本。CBF转录本在机械搅拌下也迅速积累。CBF基因的启动子区域不包含CRT序列和CCGAC，并且CBF1的过表达对CBF3转录水平没有可检测到的影响，这表明CBF基因家族不受自我调节的影响。我们认为脐带诱导的含有CRT/ re的COR基因表达涉及低温刺激的信号级联，其中CBF基因诱导是一个早期事件。
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 revels, suggesting that the CBF gene family is not subject to autoregulation. We propose that cord-induced expression of CRT/DRE-containing COR genes involves a low temperature-stimulated signalling cascade in which CBF gene induction is an early event.