Detection of Verticillium lecanii in Pustules of Bean Rust (Uromyces phaseoli) by Immunofluorescence

Verticillium lecanii has been found growing in pustu'les of the uredial stage of a number of rust fungi (GAMS 1971, SCHROEDER and HAssEBRAuK 1957, CASPER and MENDGEN 1979, SPENCER 1'980), and in some insects (HALL 1980). SCHROEDER and HASSEBRi\UK (1957) observed that this fungus is able to penetrate the urediospores of Puccinia striiformis. It remains to be shown, however, whether Verticillium is restricted to the spores of a pustule or whether it also penetrates into the fungal mycelium or into the leaf tissue. To answer this question, an antiserum against V. lecanii was prepared to label Verticillium hyphae by immunofluorescence. This would allow differention between Verticillium, rust-hyphae and plant tissue since such an antiserum does not react with the rust or the plant tissue (CASPER and MENDGEN 1979).