The Expression Of W16in The Backcross Lines Of Transgenic Bread Wheat And Its Relation With Drought Tolerance

Drought is one of the abiotic stresses affecting wheat yield, and breeding newwater-saving or drought tolerant varieties with high and stable yield is the most economic andefficient way for solving the problem of drought. With plant genetic engineering techniquebecoming more mature, cultivating drought-resistant wheat varieties through genetictransformation of drought related genes, combined with conventional backcross breedingtechnology has become an effective method of improving drought resistance.The DREB transcription factors play important roles in improving plant tolerance ofabiotic stresses through regulating the expressions of the stress-related genes. The expressionpatterns of transcription factor W16were analyzed, and the physiological and biochemicalindexes related to drought tolerance were investigated in backcross lines of transgenic wheatunder different water stress treatments and irrigation treatments, which can provide areference for developing drought-resistant transgenic wheat varieties. The main results of thisresearch are as follows:1. W16exogenous gene was integrated into the receptor materials and steadily inheritedto BC3F2. The expression of W16under the control of Ubiquitin promoter was strong andstable in transgenic wheat during the whole water stresses. Besides, the expression of W16gene was up-regulated as drought stress enhanced and reached the peak, then its expressiondropped rapidly at serious water stress, which displayed a curve of "up-Max-down" in wildtype.2. In this study jointing stage is a relatively dry period throughout the wholedevelopment process of wheat and the soil moisture content exhibited significant differencefrom tillering to heading stages under different water stresses. The analysis on thephysiological and biochemical indexes related to drought tolerance indicated that the changesof cholorophyll content, relative water content(RWC), POD activity, photosynthetic rate andwater use efficiency of the transgenic lines decreased less along with the enhancement of thewater stress,and the content were significantly higher than that of wild type under differentwater stresses. Besides, soluble protein content was high before flowering under W1,increased in the later stage with the increasing extent and duration of drought stress, whereastransgenic lines constantly higher than that of wide type. Leaf relative electric conductivity and malondialdehyde content of transgenic lines, slightly increase under the droughtstress and was lower than that of wild type.3. Survey on agronomic characters showed that water stress in jointing stage was the keystage that caused the reduction of spike number and effective panicle number, transgenic lineswere significantly or very significantly higher than that of wild type under each treatment. Asto other Agronomic index, the number in transgenic lines was slightly higher or equal withthat of wild type. The yield of transgenic lines were higher than that of wild type, increased4.67%-6.62%,4.00%-6.22%and11.16%-23.47%respectively under the treatment of W2-W0,and the yield greatly increased under W0. The result of calculation on drought-resistant indexrevealed that the three transgenic lines were in the category of strong-very strongdrought-resistant materials. Comparison on root system demonstrated that root length, rootsurface area, root diameter, root fresh weight and dry weight of transgenic lines were allhigher than that in wild type. The root was thick and short under W2while it was thin andlong under W0. The above results stated that overexpression of W16can improve droughtresistance and increase the yield of the backcross lines of transgenic wheat.