Badawi Mohamed, Reddy Yedulla Venkat, Agharbaoui Zahra, Tominaga Yoko, Danyluk Jean, Sarhan Fathey, Houde Mario
Département des Sciences Biologiques, Université du Québec à Montréal, Case Postale 8888, Succursale Centre-ville, Montréal, Québec, Canada H3C 3P8.
Plant Cell Physiol. 2008 Aug;49(8):1237-49. doi: 10.1093/pcp/pcn100. Epub 2008 Jul 16.
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.
从经冷处理的小麦地上组织制备的cDNA文库中分离出两种不同的CBF表达诱导因子（ICE1样基因），即TaICE41和TaICE87。TaICE41编码一个由381个氨基酸组成的蛋白质，预测分子量为39.5 kDa，而TaICE87编码一个由443个氨基酸组成的蛋白质，预测分子量为46.5 kDa。TaICE41和TaICE87的同源性为46%，而它们与拟南芥AtICE1的同源性分别为50%和47%。表达分析表明，冷处理并未改变mRNA积累，这表明这两个基因都是组成型表达的。凝胶迁移率变动分析表明，TaICE41和TaICE87与小麦TaCBFIVd - B9启动子中的不同MYC元件结合。在本氏烟草中的瞬时表达分析表明，这两种TaICE蛋白都能激活TaCBFIVd - B9的转录。TaICE41和TaICE87对MYC变体的不同亲和力表明，ICE结合特异性可能参与了小麦CBF基因的差异表达。此外，对MYC元件的分析表明，在小麦CBF第IV组中存在一个与抗冻性相关的特定变体。在拟南芥中过表达TaICE41或TaICE87基因，仅在冷驯化后增强了抗冻性，这表明它们的活性需要低温诱导的其他因子。转基因拟南芥中抗冻性的提高与冷响应激活因子AtCBF2、AtCBF3以及几个冷调节基因的更高表达相关。
