干旱胁迫下转基因甘薯块根膨大期水分利用效率和生理代谢特征

以转Cu/Zn-SOD和APX基因及其非转基因甘薯进行盆栽试验,在甘薯块根膨大期进行正常供水(田间最大持水量的80%)、中度缺水(田间最大持水量的60%)和重度缺水(田间最大持水量的40%)3种水分处理,分别测定转基因植株和对照植株在薯块膨大期的第20天和第70天的抗氧化酶系统、可溶性糖含量、光合系统之间的差异,以及在不同水分胁迫处理下产量和水分利用效率之间的差异。以此研究外源基因的超表达是否可以提高甘薯的产量及水分利用效率。结果显示:(1)转基因甘薯(TS)的SOD、APX活性以及可溶性糖含量均高于非转基因对照株(NT),但POD活性低于NT;TS和NT植株的APX活性、可溶性糖含量、净光合速率以及蒸腾速率均随干旱胁迫加重呈递减趋势。(2)干旱胁迫70d时,TS和NT植株光合参数均较胁迫20d时降低,且TS和NT间的净光合速率没有明显差异。(3)TS和NT两株系的块根产量在中度胁迫下最高而在重度胁迫下最低,而TS具有较高的块根产量且在重度胁迫下产量降低幅度较小。(4)TS的气孔导度和蒸腾速率显著低于NT,且TS的水分利用效率较NT更高。研究表明,Cu/Zn-SOD和APX基因可以显著增加干旱胁迫下甘薯块根膨大期的SOD、APX活性和可溶性糖含量,提高其水分利用效率,从而减轻干旱胁迫对产量的影响。

Water Use Efficiency and Physiological Metabolism of Vegetatively Propagated Transgenic Sweet Potato under Drought Stress

A transgenic cultivar of sweet potato (TS) bearing Cu/Zn-SOD and APX genes and non-transgenic control cultivar (NT) were grown in pots under three different water treatments,including control treatment (80% of soil moisture),moderate drought stress (60% of soil moisture) and serious drought stress (40% of soil moisture).At 20 and 70 day of the stress treatments,the antioxidant enzymes,the content of soluble sugar,the photosynthetic system of TS and NT were assayed respectively,in addition with the final yield formation and the long-term water use efficiency.We studied the differences between TS and NT,in order to find out whether the over-expression of exogenous genes could enhance the yield formation and water use efficiency of sweet potato.The results showed that:(1)The activities of SOD and APX,as well as the soluble sugar content were higher in TS than that in NT,while POD showed an opposite manner.The activity of APX,contents of soluble sugars and photosynthetic rates and transpiration rate are all declined in both sweet potato types with increasing drought stress.(2)Although the photosynthetic parameters decreased from 20 d to 70 d of stress in two plant types,photosynthetic rates have no significant difference between TS and NT.(3)The yield formation of the two plant types showed the highest under moderate stress and the lowest under serious stress,respectively.Transgenic sweet potato has a higher yield formation and a smaller decrease tendency of yield formation under serious stress compared with non-transgenic sweet potato.(4)The stomatal conductances and transpiration rates of TS under the three drought treatments were significantly lower than that of NT,which resulting in a higher WUE in TS.In conclusion,the genes of Cu/Zn-SOD and APX could enhance the activities of SOD and APX,the content of soluble sugar and the water use efficiency of transgenic potato during the formation of potato tuber under drought stress.Thereafter,the yield formation could be better protected from drought stress.