The Identification And Genetic Polymorphism Analysison Different Formae Speciales Of Fusarium Oxysporum

Fusarium oxysporum Schl. is a fungus diseasespreaded bysoil, it has large host range and spreads all over the world.According to its host speciality, Fusarium oxysporum Schl. can be divided into different formae speciales.To date,there is no simple and effective way to identify the different formae speciales. This research has identified several formae speciales through the method of pathogenicity measurement. Based on these speciales: first, determine fatty acid ingredient and content of those strains which has been identified, andestablish discriminant modelof fatty acid biomarkers;then develop SSR primers of Fusarium oxysporum Schl. genome and determine the genotype of the identified strainsto judge differences among the genotypes of different formae speciales aiming to screen new biomarkers or molecular markers to identify formae speciales. Further, analyse the genetic relationship among different host stains, understandintraspecificgenetic diversity of F. oxysporum by using the developed SSR primer, providing theoretical basis for prevent Fusariumwilt.The main results are as follows:1. 150 blight strains from Baoding were collected from 8 kinds of plants including cowpea, tomato, cucumber, eggplant, melon, bitter melon, pepper andpumpkin. 130 strains were isolated from them. Our analysis usedthe specific primers FOF1/FOR1 of Fusarium oxysporumby morphological method to identify Fusariumand get 100 strains.2. Obtain 36 strains which separatelybelong to 7 kinds of formae speciales from 58 strains from 9 kinds of plants used to determine pathogenicity including: F. oxysporum f. sp. tracheiphilum(6 cases), F. oxysporum f. sp.vasinfectum(6 cases), F. oxysporum f. sp.lycopersici(5 strains), F. oxysporum f. sp.cucumerinum(4 cases), F. oxysporum f. sp. melongenae(4 cases), F. oxysporum f. sp.melonis(6 cases), F. oxysporum f. sp. tuberosi(5 strains).3. Determinethe fatty acids composition and content of 36 strains Fusarium oxysporum, and based on SPSS software we establish 4 kinds of fatty acids marker model: the discriminant modelof F. oxysporum f. sp.Lycopersici: Y1 = 157.750 + 2.809 X1 + 3.391 X2 + 2.809 X3; the discriminant model of F. oxysporum f. sp.vasinfectum: Y2 = 178.343 + 0.586 X1 + 0.586 X2-0.214 X3; the discriminant model of F. oxysporum f. sp.Cucumerinum: Y3 = 129.132 + 2.749 X1 + 4.163 X2 + 4.476 X3; the discriminant model of F. oxysporum f. sp. Melongenae: Y4 = 201.307 + 2.016 X1 + 201.307 X2 + 2.400 X3. The three factors in discriminant respectivelyindicate C18:1CIS9(W9)[X1], C18:2 CIS 9,12/18:0a [X2] and C18:00 [X3]. The four formae speciales model can be used for identification strains fromthe plants of tomato, cotton, cumber and eggplant. 4. Based on the genomeof F. oxysporum f. sp.lycopersici strain(4287) we developedand designed 26 SSR primers, then we obtained 11 polymorphic SSR primers by verifying strains from different formae speciales. 5. We analysed genetic polymorphisms of 60 strains Fusarium oxysporumfrom different host plants using 11 SSR primers, thenfound that there had been obvious genetic differentiationamong Fusarium oxysporumof different hosts.SSR genotypecorrelatedwith the pathogenicity of isolates.