Effect Of Ectopically Expressing CBF Gene On Growth And Development Of Transgenic Tobacco Directed By Synthetic Promoters

Environmental stresses such as drought, high salt and low temperature affect plant growth and account for significant reductions in the yields of agriculturally important crops. Many plants increase in freezing tolerance in response to low nonfreezing temperatures, a phenomenon known as cold acclimation. A number of genes have been induced to expression during cold acclimation. Many of them have CRT/DRE cis-acting promoter element. Cold responsive transcriptional factor CBFs that encoded by a small number of family gene have been demonstrated to play a key role in cold acclimation. CBF specifically interacts with the CRT/DRE and induces expression of stress tolerance genes. Overexpression of CBF in transgenic plants activates the expression of many of these stress tolerance genes under normal growing conditions and results in improved tolerance to drought, salt loading, and freezing. However, use of the strong constitutive 35S promoter to drive expression of CBF also results in severe growth retardation under normal growing conditions. In contrast, stress induced expression of CBFs directed by the stress inducible rd29A promoter give rise to minimal effects on plant growth while providing an even greater tolerance to stress conditions than do expression of the gene from the 35S promoter. We suppose use of Chemical-inducible Promoter to control expression of CBF also do not retard growth of transgenic crop, and do not affect the level of stress resistance.So, we designed and synthesized two plant promoters. One of them has tissue special expression pattern and another response to salicylic acid and wounding. C2W and SAR by combining mini-35S promoter (-62 to+1) and several pathogen responsive cis-acting elements derived from defense genes in plant. In order to study expression pattern of these synthetic plant promoters, a coding sequence of GUS (β-glucuronidase) gene was fused to their downstream and transformed into arabidopsis plants. We also constructed six plant expression vectors with AtCBF1 or AtCBF3 drived by C2W or 35S promoter combining with or without arabis pumila COR15a gene. We analyzed the effect of ectopically expressing arabidopsis CBF1 on growth and development in transgenic tobacco plants using different promoter. The results are described as following:1. Synthetic promoter SAR conferred GUS express preferably in cotyledon, trichome,...