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Immunofluorescence Microscopy for the Detection and Identification of Propagules of Phaeolus schweinitzii in Infested Soil. Frances M. Dewey, Visiting scientist, Department of Biochemistry, University of Oxford, Oxford, United Kingdom, Present address: Department of Botany, University of Durham, South Road, Durham DH1 3LE, U.K.; Don K. Barrett(2), Ian R. Vose(3), and Chris J. Lamb(4). (2)Staff scientist, Department of Agriculture and Forest Sciences, University of Oxford, Oxford, United Kingdom; (3)(4)Research student and staff scientist, Department of Biochemistry, respectively, University of Oxford, Oxford, United Kingdom, (4)Present address: Plant Biology Laboratory, The Salk Institute for Biological Studies, P.O. Box 85800, San Diego, CA 92138. Phytopathology 74:291-296. Accepted for publication 25 August 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-291.

In liquid culture, the fungus Phaeolus schweinitzii, which causes a root- and butt-rot of conifers, secretes a number of species-specific and strain-specific polypeptides which are detectable by dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focussing. Indirect immunofluorescence microscopy was used to detect the binding of species-specific antisera to these antigens to extracellular macromolecules secreted by the fungus, to the cell surface of basidiospores and chlamydospores, and to the cell surface and cross walls of mycelia. Common antigenic determinants were present in extracellular culture filtrate material and walls of mycelia, chlamydospores, and basidiospores. Indirect immunofluorescence, performed by using antisera to culture filtrate molecules has been used to demonstrate the presence of mycelium, and on occasions chlamydospores, in naturally and artificially infested soil samples. This makes possible identification of the kind of propagule most likely to be the source of field isolates of the organisms; this information, which cannot be obtained by using selective media, strongly suggests that the pathogen can survive saprophytically in the soil. In contrast, isolated mycelial cell wall preparations did not prove to be a suitable source of immunogenic material for these studies.

Additional keywords: extracellular glycoprotein, Polyporus schweinitzii.