MOLECULAR APPROACHES TO DIFFERENTIATE SUBPOPULATIONS OR FORMAE SPECIALES OF THE FUNGAL PHYTOPATHOGEN MICROBOTRYUM-VIOLACEUM

Microbotryum violaceum infects more than 200 species of Caryophyllacea e, although individual isolates of the fungus are Limited in host rang e to one or a feu species. The goal of the present study was to establ ish a molecular profile of individual haploid M. violaceum strains fro m different host species and to evaluate different methods for produci ng such profiles. Eighteen different sporidial strains from seven diff erent host species were examined for electrophoretic karyotype, for ra ndom amplification of polymorphic DNA (RAPD) profile, by phylogenetic analysis of intron sequences in the gamma-tubulin gene, and by parsimo ny analysis of melting curves of total genomic DNA (DNA thermal profil es). While no one method could resolve all isolates from closely relat ed host species, together the results obtained with these methods were able to group isolates based on their host species of origin. Taken t ogether, host range/host species of origin and the genetic differences indicated by die molecular methods in this study would appear to defi ne pathovars or formae speciales of this fungus.