转betA基因增强小麦的干热风抗性

Introduction of betA Gene Enhancing Tolerance to Hot-dry Windy Tolerance in Wheat

甜菜碱是细胞内重要的渗透调节物质,其积累能有效提高植物对非生物逆境的抗性。以转betA基因小麦和未转基因的野生型为材料,在灌浆期模拟干热风胁迫处理植株3d,研究干热风对植株生长和籽粒产量的影响。胁迫处理后,转基因植株保持较好长势,叶片青枯失水较少,旗叶持绿面积显著大于野生型。各株系植株的光合作用能力和蔗糖磷酸合成酶(SPS)及蔗糖合成酶(SS)活性在胁迫处理后均有所下降,转基因植株的净光合速率下降到2.3～3.7μmolCO2m-2s-1,而野生型下降到1.2μmolCO2m-2s-1;野生型植株的SPS和SS活性的下降幅度分别为处理前56.8%和53.9%,而转基因株系的下降幅度分别为62.3%～69.8%和56.5%～64.5%。干热风胁迫使得各株系植株的旗叶甜菜碱含量升高,但转基因株系的叶片甜菜碱含量比野生型的高18%～87%。在甜菜碱保护作用下,转基因植株在胁迫条件下能够维持较高的光合速率,合成较多的碳水化合物,使得百粒重和单株产量均高于野生型。因此,通过转betA基因可显著提高小麦在干热风处理条件下的甜菜碱含量从而增强其抗干热风能力。

Hot-dry windy climate is the weather phenomenon of low humidity, high temperature, and wind stress occurring simultaneously, which causes great reduction of wheat yield in northern China during grain filling stage. As a compatible solute in cells, glycinebetaine plays an important role in tolerance to environmental stresses of plants. In this study, we used three betA transgenic wheat lines and their wild type （WT） to disclose the effects of glycinebetaine accumulation on the growth and yield components of wheat plants suffering from hot-dry windy stress for three days. After the hot-dry windy treatment, the transgenic plants maintained more vigorous growth compared with the WT and showed slower dehydration rates of flag leaf with significantly larger green blade area than that of WT. Under the hot-dry windy stress, the photosynthetic ability and the activities of su-crose phosphate synthase （SPS） and sucrose synthase （SS） in flag leaf were reduced in both transgenic lines and the WT. However, the reductions were smaller in the transgenic lines than in the WT. After 3-day of stress, the net photosynthetic rates of the trans-genic lines fell to 2.3–3.7 μmol CO2 m-2 s-1, while that of the WT plant was 1.2 μmol CO2 m-2 s-1. After the 3-day stress, the ac-tivities of SPS and SS were decreased to 62.3–69.8% of the levels before stress treatment in the transgenic lines of those before stress, whereas those were decreased to 56.5–64.5% of the levels before treatment in the WT plant. The glycinebetaine contents in flag leaf were increased in all lines, especially in the transgenic lines （18–87% higher than that of WT）.Based on these results, we concluded that under the protection of glycinebetaine, the transgenic plants could maintain higher net photosynthetic rate than that of the WT plant, resulting in more accumulation of carbohydrate and higher grain yield per plant and 100-grain weight after the stress of hot-dry windy stress. Therefore, the betA transgenic wheat might be practical in improving tolerance to the hot-dry windy climate in winter wheat.