The Differential Responses And Physiological Mechanisms Of Three Transgenic Sweet Potato In Response To Drought/Salt Stress

Sweet potato is the most important food,feed,industrial materials and bio-energy crops wordwide.Drought and salt stress severely restrict the growth and yield of sweet potato,which bring great economic losses to agricultural production.Therefore,comprehensive understanding the physiological mechanism of sweet potato to drought and saline stress,improving the resistance of sweet potato through genetic engineering and selecting transgenic sweet potato which has strong resistance to stress.It has great theoretical and practical significance to increase grain yield,improving sweet potato production potential in arid and saline area and alleviating energy crisis.In this study,three transgenic sweet potato(expression of Cu/ZnSOD-APX in YM?IbMYB1 in SHM and IbOr gene in SZM,respectively)and each control(YM?SHM and SZM)were used as experimental materials,through drought treatment(15% polyethylene glycol PEG-6000 to simulate drought)and salt treatment(100mM NaCl)respectively,the of net photosynthetic rate(Pn),chlorophyll content,carotenoids content,malondialdehyde(MDA)content antioxidants enzyme activity and nonenzymatic antioxidant capacity of three transgenic sweet potato after stress were analyzed.In this study,we comprehensively analyzed the drought and salt tolerrance of three transgenic sweet potatoes,and revealled the different physiological mechanism among of these three transgenic sweet potato plants.The main results are as follows:1 The three transgenic sweet potatoes all could enhance the resistance to drought and salt stress than control.Cu/ZnSOD-APX transgenic sweet potato can enhance tolerance to oxidative stress by enhancing antioxidant enzyme activity than control.IbMYB1 transgenic sweet potato can improve stress resistance after stressl by enhance the antioxidant enzyme activity and increasee the accumulation of anthocyanins,protect chloroplasts and slow down leaf senescence.IbOr transgenic sweet potato has a higher carotenoid content,increasing the antioxidant capacity thus enhanced the resistance to stress.2 After PEG stress treatment,the net photosynthetic rate and chlorophyll content of Cu/ZnSOD-APX and IbMYB1 genes transgenic sweet popato decreased slightly,the content of malondialdehyde was lower,thus the drought resistance was stronger,and the drought stress of of IbOr transgenic sweet potato was weak.The Cu/ZnSOD-APX transgenic sweet potato can effectively remove the reactive oxygen species after the stress through stronger antioxidant enzyme activity,reduce the membrane lipid damage,and maintain a high chlorophyll content,thus maintain a high net photosynthetic rate.The IbMYB1 transgenic sweet potato has a high nonenzymatic antioxidants content after stress,which can protect the chloroplast from damage,thereby maintaining high photosynthetic ability.3.After salt stress,the salt tolerlance of Cu/ZnSOD-APX transgenic sweet potato was strong,followed by IbMYB1 transgenic sweet potato,and the salt tolerance of IbOr transgenic sweet potato was weaker.The Cu/ZnSOD-APX transgenic sweet potato can effectively remove the reactive oxygen species after the salt stress through the stronger antioxidant enzyme activity,reduce the membrane lipid damage,and to maintain a high chlorophyll content,and thus maintain a high net photosynthetic rate.