A New Family of Plant Antifungal Proteins. Alison J. Vigers. Department of Cellular and Structural Biology, University of Colorado Health Sciences Center, Denver 80262 U.S.A. Walden K. Roberts(2), and Claude P. Selitrennikoff(1). (1)Department of Cellular and Structural Biology, and (2)Department of Microbiology and Immunology, University of Colorado Health Sciences Center, Denver 80262 U.S.A. MPMI 4:315-323. Accepted 4 March 1991. Copyright 1991 The American Phytopathological Society.

Plant seeds contain high concentrations of many antimicrobial proteins. These include chitinases, Β-1,3-glucanases, proteinase inhibitors, and ribosome-inactivating proteins. We recently reported the presence in corn seeds of zeamatin, a protein that has potent activity against a variety of fungi but has none of the above activities. Zeamatin is a 22-kDa protein that acts by causing membrane permeabilization. Using a novel bioautography technique, we found similar antifungal proteins in the seeds of 6 of 12 plants examined. A polyclonal antiserum was raised against zeamatin and was used in immunoblots to confirm the presence of zeamatinlike proteins in these seeds. N-terminal amino acid sequencing was carried out on the antifungal proteins from corn, oats, sorghum, and wheat, and these sequences revealed considerable homology with each other. Interestingly, these N-terminal sequences are also similar to those of thaumatin, a pathogenesis-related protein from tobacco, and two salt stress-induced proteins. These results indicate that zeamatin is not unique but is a member of a previously unrecognized family of plant defense proteins that may include some species of pathogenesis-related proteins.