Black-pod disease of cocoa, 2: A study of host-parasite relations
Active pectolytic enzyme could not be recovered from cocoa-pod shell tissue parasitized by Phytophthora palmivora, but was recovered from autoclaved potato blocks invaded by this parasite. Browned extracts of cocoa bean and pod tissue inactivated pectolytic enzymes of P. palmivora obtained from invaded potato blocks. When allowed to brown before exposure to enzyme, discs of cocoa-pod tissue showed increased resistance to maceration by pectolytic enzymes of P. palmivora. Attack of cocoa pods by a weakly virulent isolate was promoted by low oxygen tension and low temperature. Attack by a virulent strain was accelerated at low oxygen tension and retarded at high oxygen tension. The results suggest that a balance exists during parasitism of cocoa pods by P. palmivora between the pectolytic enzyme system of the fungus and the polyphenol oxidase system of the host and that the activity of the polyphenol oxidase system acts as a host resistance mechanism.
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| Format: | biblioteca |
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1961
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| Subjects: | THEOBROMA CACAO, PHYTOPHTHORA PALMIVORA, ENFERMEDADES FUNGOSAS, HUESPEDES, PARASITOS, ACTIVIDAD ENZIMATICA, |
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