Two-dimensional mapping of mycelial polypeptides of Ophiostoma ulmi and Ophiostoma novo-ulmi, causal agents of Dutch elm disease

Abstract

Two-dimensional mycelial polypeptide maps were used to compare interspecific and intraspecific relationships among six isolates of Ophiostoma ulmi and four Eurasian and four North American race isolates of Ophiostoma novo-ulmi. The basic polypeptide pattern of O. ulmi differs markedly from that of O. novo-ulmi. A number of polypeptides were identified that could differentiate the two species and one was detected that may discriminate Eurasian from North American races. Overall, a high degree of correlation between species, race, and polypeptides was evident. However, two O. ulmi isolates (MAB and M273) and one O. novo-ulmi isolate (83) exhibited the same unique polypeptides. These isolates otherwise exhibit typical O. ulmi or O. novo-ulmi nuclear DNA polymorphisms. This suggests that they may share a common developmental pathway absent in other isolates examined. In view of this phenomenon, the greatest value of two-dimensional polypeptide gels may lie in the elucidation of proteins involved in species or race specificity, in pathogenesis, or in development rather than in routine species identification. Key words: Ophiostoma ulmi, Ophiostoma novo-ulmi, two-dimensional polypeptide mapping, introgression.