Roles Of AtCBF1 Gene In Tobacco Freezing And Drought Tolerance

Many plants increase in freezing tolerance upon exposure to low nonfreezing temperatures, a phenomenon known as cold acclimation. Recent advances in determining the nature and function of genes with roles in freezing tolerance and the mechanisms involved in low temperature gene regulation and signal transduction are achieved. A family of Arabidopsis transcription factors, the CBF/DREBlproteins, has been identified that control the expression of the basic mechanisms that plants have evolved to survives freezing temperatures. In this paper, the roles of CBF1 transcription factor were studied in tobacco under low temperature and dehydration condition, and their possible mechanisms in the development of freezing and drought tolerance were also discussed. Our experimental results were shown as follows:1. Kanamycin selection were used to detect AtCBFl transformed tobacco progeny, two pure T2 transgenic lines were obtained. PCR determination , Southern blot and Northern blot analysis were used to detect AtCBFl transformed tobacco progeny. It was demonstrated that foreign genes expressed and inherited in transgenic tobacco.2. Using the electrolyte leakage assay, freezing tolerance was measured in transgenic and the wild-type tobacco. It was find that at — 6.7 ℃, the survival rat of WT tobacco was 18.5±4.2% and transformed tobacco was 30.8±20.9%. At — 6.0℃, the survival rat of WT tobacco was 47.0+18.7% and transformed tobacco was 70.8±19.6%. The results represented that the expression of CBF1 enhanced the stabilization of the plasma membrane during freezing temperature.3. Using the content of chlorophyll assay, freezing tolerance was measured in transgenic and the wild-type tobacco. After — 8.5℃ treatment, the chlorophyll A, chlorophyll B and total chlorophyll in transformed tobacco were higher than WT tobacco. The results represented that the expression of CBF1 enhanced the stabilization of the chloroplast membrane during freezing temperature.4. Using the content of proline assay, proline content was measured in transgenic and the wild-type tobacco. The content of praline in transformed tobacco was 160μg/g FW higher than the content of WT tobacco,which only had 55μg/g FW. As a consequence, the transgenic plants were more tolerant to freezing stress.5. In comparison of different concentrations and treatment durations of PEG, it was...