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Radioimmunosorbent Assay for Botrytis cinerea. S. D. Savage, Graduate fellow, Department of Plant Pathology, University of California, Davis 95616; M. A. Sall, professor, Department of Plant Pathology, University of California, Davis 95616. Phytopathology 71:411-415. Accepted for publication 12 September 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-411.

Radioimmunosorbent assay (RISA) for somatic antigens of the pathogen Botrytis cinerea can be used to detect the presence of Botrytis antigens in homogenized samples. As little as 100 ng of original fungal dry weight can be detected, and the sensitivity curve is log-log linear in response up to 10 mg. The assay is highly specific for B. cinerea although some reaction is obtained with other members of the Sclerotiniaceae. B. allii showed 48% reactivity relative to B. cinerea, and species of Sclerotinia and Monilinia showed 10–24% reactivity. All other fungi tested showed less than 0.1% reactivity. The usefulness of the assay for detection of the fungus within host tissue is demonstrated by the high correlation (r = .833) of the assay results with an estimation of rot weight from field-infected lots. Artificially produced infection levels representing 0.1% infected tissue mixed with sound tissue homogenates are easily distinguished from background by the assay. It was found that the use of microtiter plates made of polyvinyl chloride greatly increased the response of the assay so that its resolving power was improved.