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Physiology and Biochemistry

Induction of Bean PR-4d-Type Protein in Divergent Plant Species After Infection with Tobacco Ringspot Virus and Its Relationship with Tobacco PR-5. O. P. Sehgal, Department of Plant Pathology, University of Missouri, Columbia 65211; Rose Rieger(2), and F. Mohamed(3). (2)(3)Department of Plant Pathology, University of Missouri, Columbia 65211. Phytopathology 81:215-219. Accepted for publication 11 October 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-215.

A pathogenesis-related (PR) protein, immunologically related to the 21-kDa Pinto bean PR-4d protein, was induced in 20 plant species from six dicotyledonous families after infection with tobacco ringspot virus. This protein was also induced in lima bean plants upon treatment with mercuric chloride, 2-chloroethylphosphonic acid, and benzoic acid. PR-4d protein was present in most plant species that developed necrotic symptoms, but there was no correlation between its induction and the types of symptoms produced. The Pinto bean PR-4d and Samsun NN tobacco PR-5 proteins were reciprocally immunoreactive. Gel diffusion tests showed that Pinto PR-4d and tobacco PR-5 proteins are related but not identical. The bean PR-4d and tobacco PR-5 proteins are examples of structurally homologous but functionally diverse proteins that are induced in plants in response to physiological and parasitic stresses.

Additional keywords: thaumatin-like protein, tissue necrosis, Western blotting