Structure and functional analysis of wheat ICE (inducer of CBF expression) genes
Structure and functional analysis of wheat ICE (inducer of CBF expression) genes
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DOI：
10.1093/pcp/pcn100
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发表时间：
2008-08-01
影响因子：
4.9
通讯作者：
Houde, Mario
中科院分区：
文献类型：
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作者：
Badawi, Mohamed;Reddy, Yedulla Venkat;Houde, Mario
两个不同的诱导CBF的表达（ICE 1-like基因），TaICE 41和TaICE 87，从冷处理的小麦气生组织制备的cDNA文库中分离。TaICE 41编码381个氨基酸的蛋白质，预测分子量为39.5 kDa，而TaICE 87编码443个氨基酸的蛋白质，预测分子量为46.5 kDa。TaICE 41和TaICE 87与拟南芥AtICE 1的同源性分别为46和50。表达分析表明，mRNA的积累并没有改变冷处理表明这两个基因的组成型表达。凝胶迁移率变动分析表明TaICE 41和TaICE 87与小麦TaCBFIVd-B 9启动子中不同的MYC元件结合。在本氏烟草中的瞬时表达试验表明，两种TaICE蛋白都可以激活TaCBFIVd-B 9的转录。TaICE 41和TaICE 87对MYC变体的不同亲和力表明，ICE结合特异性可能参与小麦CBF基因的差异表达。此外，MYC元件的分析表明，一个特定的变体是存在于小麦CBF组IV，这是与抗冻性。无论是TaICE 41或TaICE 87基因在拟南芥中的过表达增强抗冻性，只有在冷驯化表明，低温诱导的其他因素所需的活动。转基因拟南芥中增加的耐冻性与冷响应激活子AtCBF 2、AtCBF 3和几个冷调节基因的更高表达相关。
Two different inducers of CBF expression (ICE1-like genes), TaICE41 and TaICE87, were isolated from a cDNA library prepared from cold-treated wheat aerial tissues. TaICE41 encodes a protein of 381 aa with a predicted MW of 39.5 kDa while TaICE87 encodes a protein of 443 aa with a predicted MW of 46.5 kDa. TaICE41 and TaICE87 share 46 identity while they share 50 and 47 identity with Arabidopsis AtICE1 respectively. Expression analysis revealed that mRNA accumulation was not altered by cold treatment suggesting that both genes are expressed constitutively. Gel mobility shift analysis showed that TaICE41 and TaICE87 bind to different MYC elements in the wheat TaCBFIVd-B9 promoter. Transient expression assays in Nicotiana benthamiana, showed that both TaICE proteins can activate TaCBFIVd-B9 transcription. The different affinities of TaICE41 and TaICE87 for MYC variants suggest that ICE binding specificity may be involved in the differential expression of wheat CBF genes. Furthermore, analysis of MYC elements demonstrates that a specific variant is present in the wheat CBF group IV that is associated with freezing tolerance. Overexpression of either TaICE41 or TaICE87 genes in Arabidopsis enhanced freezing tolerance only upon cold acclimation suggesting that other factors induced by low temperature are required for their activity. The increased freezing tolerance in transgenic Arabidopsis is associated with a higher expression of the cold responsive activators AtCBF2, AtCBF3, and of several cold-regulated genes.