Rapid Molecular Detection And Genetic Diversity Of Fusarium Oxysporum And Identification Of Resistance To Soybean Fusarium Wilt

Glycine max is an important cash crop and occupies a significant position in agricultural production system of China. In recent years, soybean Fusarium wilt has become an increasing threat to soybean production around the world. Fusarium wilt of soybean is caused by the fungus Fusarium oxysporum, which commonly spreads from one field to another by infested soil and can survive more than some years in soil. Highly resistant cultivars are the most effective and economical measure to combat Fusarium wilt. The country’s advances in breeding of wilt-resistant varieties are much less than the soybean production demands as result of lack of basic research in molecular detection of F. oxysporum, genetic diversity and selection of resistant varieties, etc.besides old research methods.1.285samples of suspected soybean Fusarium wilt of soybean were collected from different soybean-producing areas,126isolates of fungal were isolated from the root and stem and97strains were obtained from these samples with testing by Koch’s Postulation. Based on the morphological characteristics and the sequence of ITS(internal transcribed spacer),61F. oxysporum strains were isolated.2. Based on differences in sterol14α-demethylase (CYP51C) sequences of Fusarium genus, two primer pairs, C1/C2and C3/C4were synthesized respectively to amplify DNA from F. oxysporum by PCR. C1/C2amplified only a unique699bp band from F. oxysporum. The detection sensitivity with C1/C2was100ng for genomic DNA of F. oxysporum and100-microconidia/g soil for the soil pathogens. In contrast, the nested PCR with two pairs of primers (C3/C4and C1/C2) increased detection sensitivity to1pg for genomic DNA of E oxysporum and1-microconidia/g soil for the soil pathogens. And F. oxysporum could be specifically detected by PCR assay with C1/C2from diseased plant samples. Real-time fluorescent quantitative PCR assays were also developed to detect and monitor the F. oxysporum from the diseased plant tissues.3. In order to study the genetic variation among F. oxysporum isolates, the genomic fingerprints of55isolates of F. oxysporum collected from different corn-growing areas are analyzed by using10RAPD primers. The results show that there are75bands amplified and among them,55bands are polymorphic (73.3%). By using UPGMA, the55isolates are clustered into9groups based on the threshold of the genetic distance which is0.68, indicat that F. oxysporum isolates are diverse.4. Using dipping the root of soybean with F. oxysporum suspension,5lines of high resistance were identified. The high resistance lines which account for3%of the total materials are Wandou28, Zhonghuangl3, Zhonghuang51, ZhongzuoX08076and5D034. Besides, Different soybean producing areas of the proportion of resistant germplasm is different.