Cloning And Functional Analysis Of DREB Type Transcription Fact-Or In Tobacco And Abiotic Stress Tolerance Of Transgenic Tobacco

Drought,high-salt and low temperature are adverse environment condition that affect the growth of plants and productivity of crops.It has been reported that DREB (dehydration responsive element-binding protein) plays an important role in resisting drought, high-salt and low temperature. DREB transcription factors differ from functional proteins that occur in physiological response to these stresses. Functional proteins in physiological response, such as the enzymes required for biosynthesis of various osmoprotectants, late-embryogenesis-abundant (LEA) proteins, antifreeze proteins, chaperones, and detoxification enzymes, may directly protect plants from damages of abiotic stresses by themselves. As a abiotic stress-inducible transcription factor, however, DREB can regulate expression of a number of genes and thus produce a series of proteins that widely participate in physiological and biochemical processes of stress tolerance and consequently improve comprehensive resistances of plant.Tobacco is an important economic crop in China. Both of cultivated area and yield in our country takes top position in the world. Tobacco industry is always the biggest tax resource in China and accounts for 7%~10% of national total tax income. The slower growth and development of tobacco plantlets after being transplanted is one of the key limited factors in tobacco production. Usually the root system of transplant's can't efficiently absorb water and nutrient from earth due to lower soil temperature or relative shortage of water supply. Moreover, sometimes plants present early flowering because of sustaining lower temperature and drought in south tobacco region of China during earlier development of tobacco, resulting in irreversible loss in tobacco quality.In this study DREB-like genes were isolated and cloned from different tobacco cultivars and their functions were analyzed. The gene of BnDREB1-5 transcription factor was transformed with different tobacco cultivars and tolerances of transgenic tobacco for abiotic stress were studies. The major results were as follows:Two DREB-like genes, NbDREB1 and NbDREB2, were cloned from Nicotiana Benthamiana. The deduced amino acid sequences of NbDREB1 and NbDREB2 comprise...