PURIFICATION AND IMMUNOLOGICAL CHARACTERIZATION OF TOXIC COMPONENTS FROM CULTURES OF PYRENOPHORA-TRITICI-REPENTIS

To facilitate the genetic analysis of pathogenicity in the wheat-Pyren ophora tritici-repentis interaction, a host-selective toxic protein, d esignated ToxA, was purified from culture filtrates of this fungus, To xA was shown to be a 13.2-kDa heat-stable protein which induced visibl e necrosis in sensitive wheat cultivars at an average minimum concentr ation of 60 nM, Polyclonal antibodies raised against ToxA were shown b y Western analysis and indirect immunoprecipitation to be specific for this protein, Bioassays of immunoprecipitated protein and ToxA protei n eluted from polyacrylamide gels indicated that ToxA protein is the t oxic agent. Other less abundant necrosis-inducing components that are chromatographically and immunologically distinct from ToxA were also d etected in culture filtrates of P. tritici-repentis. These components were found in cationic and anionic protein fractions and, like ToxA, i nduced cultivar-specific necrosis.