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.