Journal Article

Structure and Functional Analysis of Wheat <i>ICE</i> (Inducer of CBF Expression) Genes

Mohamed Badawi, Yedulla Venkat Reddy, Zahra Agharbaoui, Yoko Tominaga, Jean Danyluk, Fathey Sarhan and Mario Houde

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 49, issue 8, pages 1237-1249
Published in print August 2008 | ISSN: 0032-0781
Published online July 2008 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcn100
Structure and Functional Analysis of Wheat ICE (Inducer of CBF Expression) Genes

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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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.

Keywords: Arabidopsis; DNA binding; Freezing tolerance; Promoter; Transcription factor; Transactivation

Journal Article.  7162 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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