| On the base of the studies on the production conditions of the toxin from C. sojina Hara,the toxin from C. sojina Hara was extracted and the pathogenic activity of the toxin was determined by bioassay methods. In paralle,the resistance of different soybean varieties was identified by using the toxin. And then,identified the components of the crude toxin of ten races of C. sojina Hara and analyzed the relationship among the components. The pathogenicity of 10 races in field condition was also stated,which indicated that the toxin from C. sojinaEara is one of important pathogenic factors. Then,the changes of biochemical substance that closely relating to resistance in soybeans leaves induced by the spores and the crude toxin of C. sojinaEara,and chemical factors were studied,for exploring biochemical pathogenic mechanism and induced resistant mechanism of C. sojinaEara and the crude toxin. The following are the main results and conclusions of this study:1 Extraction of the toxin produced by C. soj'inaEara and determination of pathogenic activityThe optimum conditions of producing toxin from C. sojina Hara were Czapek liquid medium that pH=6.0,three pieces(O=6mm) mycelia,25-28'C,static incubation,25-27days in dark and 3% sucrose as carbon resource respectively. The big molecule compounds which make leaves of soybean produce typical disease spot and wilting toxicity were extracted by the precipitation methods of the polar solvents (including methyl alcohol,ethyl alcohol and acetone) and ammonium sulfate,this crude extractive substances caused the typical symptom of Frog-eye leaf spot,which according with the concept of toxin,so the crude extractive substances should be defined as the toxin produced by C. sojina Hara. After inoculated by the toxin,the susceptible varieties of soybean showed typical spots,while the resistant varieties showed obvious resistance,these results further confirmed that the crude toxin produced by C. sojina Hara was supposed to be a kind of pathogenic factors. The optimum method of extracting the toxin from liquid medium is using methyl alcohol at double volume.The wilting method of excised leave was adopted as a bioassay method whichquantitatively determin pathogenic activity of the toxin produced by C. sojina Hara. In addition,the pathogenicity and the toxigenicity of the crude toxin to different resistant varieties by stabbing method and seedling method accorded with the results in field test. Moreover,the rate of coincidence between the pathogenicity of the crude toxins from No. 1 race to No. 10 race and the field resistibility by wilting method of excised leave was 91%. The research also revealed that the crude toxin produced by C. sojina Hara had pathogenic activity to different crops by stabbing method of excised leave. This result preliminary showed that the crude toxin belongs to the Non-Host-Specific Toxin(NHST).2 Studies on the components and characteristics of the toxin Produced by ?sojina HaraThe difference of protein content and polysaccharide content of the crude toxins produced by different races of C. sojina Hara can basically indicated the difference of the toxins produced by 10 races. The crude toxin was slightly sensitive to hot. The contributions of the protein components to pathogenic activity are more important then polysaccharide components of the crude toxins produced by different races. Pathogenic activity of the crude toxin all loosed after being treated with 6N Hcl,because of loss of protein activity components and thorough hydrolysis of polysaccharide components. Eletrophoresis bands of SDS-PAGE can showed that most proteins of the crude toxin produced by C. sojina Hara were glycoprotein. In addition,the clustering result of pathogenicity of 10 races in field according with the clustering results of protein components of the crude toxins of 8 races of C. sojina Hara,indicated that the crude toxin produced by C. sojina Hara is one of important pathogenic factors.3 Induction of the crude toxin and conidiospore of C sojina Hara on seve...
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