Expression of W16 in the Backcross Lines of Transgenic Bread Wheat(Tritium aestivum) under Different Water Stresses and Its Relation with Drought Tolerance
Abstract：The dehydration responsive element binding protein(DREB) transcription factors play important roles in improving plant tolerance of abiotic stresses through regulating the expressions of the stress-related genes. To study the characteristics of drought resistance of the transgenic plant，the expression patterns of transcription factor W16 were analyzed in wild type and backcross lines of transgenic wheat(Tritium aestivum) cultivated in pots under different water stress treatments from tillering to heading stages, and the physiological and biochemical indexes related to drought tolerance were investigated. Semi-quantative RT-PCR analysis revealed that the expression of W16 was weak under no water stress condition, and its expression was up-regulated along with the enhancement of the water stress and reached the peak(12 h), then its expression dropped rapidly at serious water stress, which displayed a curve of "up-max-down" in wild type. Whereas the expression of W16 under the control of Ubiquitin promoter was strongand stable in transgenic wheat during the whole water stresses. The analysis on the physiological and biochemical indexes related to drought tolerance indicated that the changes of cholorophyll content, proline content, soluble protein content and water use efficiency of the transgenic lines were significantly higher than that of wild type under different water stresses, having significantly more dissimilarities especially under severe drought stress(SD), exceeding maximally 8.48% in chlorophyll content, 124.72% in proline, 37.74% in soluble protein content and 32.75% in water use efficiency of the controls and being more sensitive to water in jointing stage. Soluble protein content increased under moderate drought stress (MD) and decreased under severe drought stress (SD). The yield of transgenic lines were higher than that of wild type under different water stress, increasing more significantly under drought stress. Respectively, the yields of the strains A29-15 and A31-8 increasd 4.00% and 6.22% under moderate drought stress (MD), and that of the strains A29-15 and A31-8 increasd 11.16% and 16.27% under serious water stress, and their drought tolerant index was in the category of strong drought tolerance. Our results showed that over expression of W16 improves physiological and biochemical characteristics related to drought, and improves drought resistance in the backcross lines of transgenic wheat, achieving the goal of increasing production.
