Inactivation of Rhizoctonia solani toxin by a putative a-glucosidase from coconut leaves for control of sheath blight disease in rice
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Date
2001
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Abstract
Inactivation of a host-specific toxin, RS-toxin, induced by Rhizoctonia solani, the cause of rice sheath blight disease was investigated. A putative a-glucosidase identified based on enzyme assay and Western blot analysis was purified from coconut (Cocos nucifera; the only known non-host of R. solani) leaves and tested for its efficacy in degrading RS-toxin. SDS-PAGE analysis showed the appearance of a 97 kDa protein, which appeared in proteins extracted from coconut leaf bits during 48 and 96 h after 7?5-toxin-treatment and the protein eventually disappeared. A comparison of the u.v. spectra read at 150-300 nm revealed conspicuous disturbances in the absorbance at 24 h of incubation of RS-toxin with the coconut leaf protein extracts as compared to that at 12 h, indicating the possible degradation of RS-toxin by coconut leaf a-glucosidase during incubation. Incubation of rice leaf sheath bits with coconut leaf protein extracts significantly reduced electrolyte leakage due to RS-toxin 30 min after the toxin treatment. Simultaneously, there was a significant reduction in sheath blight symptoms when the incubation of rice leaf sheaths with the coconut leaf protein extracts was extended up to 96 or 120 h. This appears to be the first report of purification and characterization of a putative plant a-glucosidase.
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Keywords
Coconut leaves, a-glucosidase, Rhizoctonia solani, RS-toxin, sheath blight
Citation
World Journal of Microbiology and Biotechnology 17 pp 545-552 2001