Establishment Of The Regeneration System Of Virus-free Potato And Preliminary Study On The Function Of StBAG3 Gene

BAG(Bcl-2 associated athanogene)proteins are a family of multifunctional proteins widely existing in biology,They can regulate various physiological processes,such as programmed cell death,tumorigenesis and neuronal differentiation.At the same time,the BAG proteins can also regulate stress resistance and disease resistance in plant.Based on the function of BAG proteins in regulating plant disease resistance,this study used potato as a material,try to establish the regeneration system of virus-free potato tuber,and study the function of potato BAG gene(StBAG3)involve in potato resistance against late blight.The specific results were as follows:1.Determining the optimal conditions for virus-free potato to inducing regeneration potato tuber.The best number of seeds in each tissue culture bottle was four,the concentration of 6-BA was 3mg/L.Under this condition,total number of regeneration potato tuber in Shepody and Kexin 1 was 8 and 8.25 per bottle,and total weight of regeneration potato tuber was 6.62g and 6.27g respectively.The average number of regeneration potato tubers produced by Shepody and Kexin 1 were 2 and 2.06,and the average regeneration potato tuber weight was 1.56g and 1.66g,respectively.2.Establishing the regeneration system for virus-free seed potato.Among them,the optimal medium of adventitious bud differentiation for Shepody and Favorite was MS+lmg/L IAA+lmg/L 6-BA+0.5mg/L GA3+2mg/L ZT;the optimal medium for Kexin 1 was MS+1mg/L IAA+1mg/L 6-BA+0.2mg/L GA3+2mg/L ZT.3.By comparing the adventitious bud differentiation rate between virus-free seed potato and filed seed potato,the result show that the adventitious bud differentiation rates of virus-free seed potato in Shepody,Favorite and Kexin 1 was 62.5%,84.12%and 66.67%respectively,while the differentiation rates of filed seed potato in the above varieties were 26.16%,24.1%and 37.5%,respectively.It indicating that the adventitious bud differentiation rate of virus-free seed potato was significantly higher than that of field seed potato.4.The function of StBAG3 gene in potato resistance to late blight was studied by Agrobacterium-mediated transient expression system.The results showed that the relative lesion area on potato leaf which transiently expressing StBAG3 gene was 3.90%after inoculation with Phytophthora infestans for 72h,while the relative lesion areain control leaf was 28.29%.This indicate StBAG3 positively regulated the resistance level of potato against late blight.5.The number of necrotic cells in the inoculated site was studied by Agrobacterium-mediated transient expression system.The results showed that the number of necrotic cells in the transiently expression site of StBAG3 gene was significantly less than that in the control leaves.6.Through qualitative and quantitative methods the accumulation of H2O2 in inoculation site was tested.The result shown that the amount of H2O2 accumulated in the StBAG3 gene transient expression site was significantly higher than that in the control leaves.The activity of ROS scavenging enzymes(CAT?POD and SOD)in the same site was significantly higher than that in control leaves also indicated H2O2 participated in the establishment of resistance of potato to late blight mediated by StBAG3 gene indirectly.