Amplifying, Cloning And Sequence Analysis Of Wheat DREB Gene

Adverse environmental conditions, such as drought and low temperature, greatly affect plant growth, development, survival and geographical distribution. They have become the critical factors which limit crop quality and productivity. To improve crop tolerance to these abiotic stresses, breeding researches have been focused on the physiological and molecular mechanisms of plant responses to the stresses. Understanding the mechanisms that plants have evolved to survive freezing is of basic scientific interest and has the potential to offer new strategies to improve the freezing tolerance of agronomic plants. It has been suggested that plants have common mechanisms in their physiological resposes and tolerance to osmotic stresses. For example, abscisic acid (ABA) is produced under both drought and low-temperature stresses and plays important roles in allowing plants to tolerate both stresses. At present, many investigators have focused on studying the phenomenon of cold acclimation, that is, the process whereby certain plants increase in freezing tolerance in response to low nonfreezing temperatures.Usually the products of genes inducible by dehydration can be divided into two groups. One is the protective proteins directly taking part in resisting environmental stresses, such as enzymes needed for biosynthesis of diverse osmotic regulators, late-embryo genesis-abundant protein, anti-freeze protein, molecular chaperons and antioxidants. The other is proteins function as regulators of gene expression and signal transduction factors, including transcriptional factors, proteinase and enzymes involved in phosphoinositide metabolism.Many transcriptional factors exist in plants, but DREB(Dehydration Responsive Element Binding) element discovery is a breakthrough in research on plant resistance to adversity in recent years. It plays an important role in anti-cold, -drought and -salty reaction. After being induced by stress environment, DREB factor can activate another 12 stress responsive genes expressions, such as rd29A, cor15a, rd17, which depend on DRE cis-acting elements. Besides, it can also improve the concentrations of proline and expression level of soluble sugars, such as sucrose, raffinose, glucose and fructose. So...