title: DNA fingerprinting of Peronospora parasitica, a biotrophic fungal pathogen of crucifers.
abstract: The fungus Peronospora parasitica (Pers. ex Fr.) Fr. is an obligate biotroph infecting a wide range of host species in the family Cruciferae. Isolates from different hosts are morphologically similar, and pathotypes are usually distinguished on the basis of host range. Random Amplified Polymorphic DNA (RAPD) fingerprints were generated from a range of P. parasitica isolates from different Brassica species. Reaction conditions, in particular DNA template, primer and Mg(2+) concentrations, were optimized to ensure that amplifications were reproducible. Possible artefacts arising through host plant DNA were assessed by including such DNA in control reactions. Confirmation that diagnostic RAPD bands were generated from fungal DNA was also obtained by Southern hybridization of a RAPD band to genomic fungal DNA. By screening 20 decamer primers, 2 were found to detect sufficient genetic variation to allow complete differentiation between pathotypes. These results illustrate the potential value of RAPDs for detecting polymorphisms between isolates of a non-culturable plant pathogenic fungus.
authors.affiliation: Department of Life Science, University of Nottingham, NG7 2RD, University Park, Nottingham, UK.
authors.forename: F Y
authors.initials: FY
authors.lastname: Tham
authors.forename: J A
authors.initials: JA
authors.lastname: Lucas
authors.forename: Z A
authors.initials: ZA
authors.lastname: Wilson