The differentiation of Phytophthora species that are pathogenic on potatoes by an asymmetric PCR combined with single-strand conformation polymorphism analysis.

The goal of this study was to develop a polymerase chain reaction (PCR) capable of differentiating Phytophthora species that are pathogenic on potatoes using a single primer pair. To achieve this objective, primers were derived from conserved regions flanking variable sequences in the internal transcribed spacer 1 (ITS1) of Phytophthora species. One primer pair produced a 140 bp product from P. infestans, P. erythroseptica and P. nicotianae. The PCR products were purified and used in an asymmetric PCR (A-PCR) protocol to generate single-strand DNA (ssDNA). The ssDNA of the Phytophthora potato pathogens reproducibly migrated in non-denaturing polyacrylamide gels in a species-specific manner.