Identification of Rye-type and Wheat-type of Pseudocercosporella-herpotrichoides With DNA Probes

A partial genomic library of the plant-pathogenic fungus Pseudocercosporella herpotrichoides was prepared in a bacterial plasmid vector. Plasmids from 20 random recombinant clones were radioactively labelled and used as probes in Southern blot experiments with genomic DNA isolated from seven isolates belonging to the rye-type and four isolates of the wheat-type of P. herpotrichoides. Most of the probes tested revealed polymorphisms between the two types. In addition, some of them distinguished different isolates within each type. One probe that gave strong hybridization signals may correspond with repetitive DNA sequences. It was shown by dot-blot hybridization to be specific to all the wheat-type isolates tested.