Establishing Of Hydropnic System Of Sweet Potato For Identification Of Resistance To Fusarium Wilt And Cloning Related Gene From The Pathogen

Sweet potato is an important crop used as food,feed and industrial raw material.China is the world's largest producer of sweet potato.The planting area is about 65%of the world and the accounts of output is about 84%.it's the production of sweet potato rank 4th in the food crops in China,just less then rice,wheat and corn.Thegrowing of sweet potato is affected by many kinds of diseases and insect pests,so sweet potato often have a loss in yield and quality.Fusarium wilt of sweet potato is the most important problems in the sweet potato production areas of the south of China,and its pathogen is fusarium oxysporum f.sp batatas.Breeding resistant varieties is the most effective way to prevent the fusarium wilt of sweet potato.So establishing a rapid,accurate,effective system of identifying resistance and understanding clearly the mechanism of pathogenic bacterias is important base to enhance the efficiency in breeding of sweet potatowith resistance.In this study,we have isolated Fusarium wilt pathogen from sweet potato in the field in the south China and identify their pathogenicability,established a protocol for identifying resistant to Fusarium wilt of sweet potato using hydroponic system,and studied on the mechanism of of pathopoiesis of Fusarium oxysporum f.sp batatas on sweet potato,then cloned the related genes from the pathogen and analyzed the sequence of the gene.The main results are as follows:1.Nine strains of Fusarium wilt pathogen,Fusarium oxysporum f.sp batataswere isolated from sweet potato in the field in south China.By morphological observation,analyzing sequence of ITS(Internal Transcribed Spacers)and result of RAPD(Random Amplified Polymorphic).four virulent pathogens(Fob-03,Fob-07,Fob-08,Fob-09),a weak pathogens(Fob-02),two nonpathogenic pathogens(Fob-01,Fob-04)were obtained.2.An appraisal system resistance to Fusarium wiltof sweet potato by hydroponic was established,under 30?,use fresh sweet potato seedlings as materials,the concentration of pathogen spore in the solutionis 4 x 103/mL,use water or nutrient solution to culture the sweet potato,the resistance to fusarium wilt disease of sweet potato can be identified effectively.3.Pretreatment of nonpathogenic pathogen(Fob-04)has an protective role for sweet potato seedlings resistance to fusarium wilt.The crude toxin and secreted protein were extracted from pahogentic pathogen to treat,sweet potato seedlings,it was found that the toxins could make tobacco leaf turning yellowand wilt,and the secreted proteins could induce progress cell death of the leaf of tobacco and sweet potato,tToxins and secreted proteins inhibited the root growing of sweet potato seedling.4.Two genes of NIP(Necrosis inducing protein,NIP),NIP 1 and NIP3,were cloned from fusarium oxysporum f.sp btatas.The sequence showed that high identity with the NEP-Like of fusarium oxysporum f.sp orobanche and the NIP3 of fusarium oxysporum f.sp.lycopersici.However,both of the two genes have a insertion with dozens of base pairs..