SEROLOGICAL EVIDENCE FOR THE OCCURRENCE OF RACES IN SCLEROSPORA-GRAMINICOLA AND IDENTIFICATION OF A RACE-SPECIFIC SURFACE PROTEIN INVOLVED IN HOST RECOGNITION

A protein specific to a virulent pathotype of the downy mildew pathoge n Sclerospora graminicola was identified on the Western transfers usin g the cross-adsorbed antibody. This protein was approximately 90 kDa a nd without subunits. Serological agglutination studies localized the p rotein on the cell wall surfaces. Enzyme linked immunosorbent assay an d dot blotting using the specific antibodies identified distinct races of the pathogen. Immunofluorescence studies and enzyme linked immunos orbent assay using suspension cultures of host cells showed that the p rotein bound to the cells of susceptible cultivar but not to those of resistant cultivar. These results suggested that this protein may be i nvolved in host recognition.