Biological and immunochemical characterization of a low molecular weight phytotoxin isolated from a protein—lipopolysaccharide complex produced by a potato isolate of Verticillium dahliae Kleb

A low molecular weight (less than 3000) phytotoxic polypeptide fraction was partially purified from the protein-lipopolysaccharide (PLP) complexes produced in culture by a strain of Verticillium dahliae pathogenic on potato. The toxic fraction was host-specific and antigenically identical to the high molecular weight PLP. Immunodiffusion and immunofluorescence assays showed that a substance is present in stems and tubers of infected potato plants which was antigenically related to the low molecular weight toxin. When used as a tool for screening new potato varieties for tolerance to Verticillium wilt disease, the low molecular weight toxin was more reliable than the PLP because non-specific sensitivity to macromolecules was not observed.