ABSTRACT
An elicitor has been isolated from Macrophomina phaseolina, the root rot and leaf blight pathogen of greengram. Suspension-cultured cells of greengram were established which responded to the fungal elicitor. When greengram leaves were inoculated with M. phaseolina two new peroxidases appeared. Similarly, two new peroxidases could be detected in suspension-cultured greengram cells when treated with the fungal elicitor. These peroxidases were purified by column chromatography and their molecular masses were 27 and 38 kDa. The new peroxidases detected in both leaves and cultured cells appear to be similar with the same molecular weights.
Subject(s)
Basidiomycota/pathogenicity , Fabaceae/microbiology , Peroxidases/biosynthesis , Plant Leaves/enzymology , Plant Leaves/microbiology , Cells, Cultured , Enzyme Activation , Fabaceae/cytology , Fabaceae/enzymology , Peroxidases/isolation & purification , Plant Diseases/microbiologyABSTRACT
The rice sheath blight pathogen, Rhizoctonia solani, produces a toxin designated as RS-toxin, a carbohydrate compound containing mainly alpha-glucose and mannose. Different microflora were tested for RS-toxin inactivation. Isolates of Trichoderma viride inactivated this toxin when it was provided as the sole food source, and these isolates reduced the severity of toxin-induced symptoms and electrolyte leakage from rice cells. The best-performing isolate, TvMNT7, produced two extracellular proteins of 110 and 17 kDa. The high molecular mass protein was shown to have alpha-glucosidase activity. The purified 110 kDa protein was able to reduce RS-toxin activity.
Subject(s)
Mycotoxins/metabolism , Oryza/microbiology , Rhizoctonia/metabolism , Blotting, Western , Electrophoresis, Polyacrylamide Gel , Fungal Proteins/chemistry , Fungal Proteins/isolation & purification , Fungal Proteins/metabolism , Molecular Weight , Mycotoxins/antagonists & inhibitors , Plant Diseases/microbiology , Rhizoctonia/pathogenicity , Trichoderma/isolation & purification , Trichoderma/metabolism , alpha-Glucosidases/chemistry , alpha-Glucosidases/metabolismABSTRACT
ABSTRACT Rhizoctonia solani, the rice sheath blight pathogen, produces a toxin that reproduces all symptoms of the disease. The toxin has been partially purified and it was found to be a carbohydrate containing glucose, mannose, N-acetylgalactosamine, and N-acetylglucosamine. The toxin was also detected in infected leaves. Highly virulent isolates produced more toxin than less virulent isolates. Several R. solani isolates from rice and one each from cotton and tomato produced a similar toxin. All rice cultivars tested were susceptible to the pathogen and sensitive to the toxin. Host specificity of the toxin has been demonstrated using hosts and nonhosts of the pathogen.