PHYLOGENETIC INFERENCE BASED ON INFORMATION THEORY-BASED PCR AMPLIFICATION

As a method for the determination of the taxonomic affinities of plant pathogens and other organisms, a set of 'universal' polymerase chain reaction (PCR) primers which amplify a taxonomically diverse sequence domain of 28S ribosomal DNA (rDNA) were designed. The PCR primers chos en by information-theory analysis generated PCR products using DNA tem plates from a wide diversity of organisms. Sequences of PCR products w ere then obtained which allowed phylogenetic dendrograms to be constru cted. Based on the above analysis, the Oomycete pathogen Phytophthora infestans clustered with the protist Prorocentrum micans rather than w ith representatives of the true fungi, consistent with its designation as a 'pseudofungus'. Magnaporthe grisea, another important plant path ogen, clustered with the true fungi as expected. The approach describe d can be used with other plant pathogens to clarify phylogeny of new o r ambiguously designated species.