A comparative study of cultural and electrophoretic characteristics of the Eurasian and North American races of Ophiostoma ulmi

Abstract

Cultural characteristics and isoenzyme and soluble protein patterns on polyacrylamide gradient gels were compared in field isolates of the aggressive subgroup of Ophiostoma ulmi. Fourteen isolates were tested, 7 of the Eurasian race and 7 of the North American race. Values of fresh weight, dry weight, acetone powder weight, and water content of the flask-grown mycelia of Eurasian isolates were significantly higher than corresponding values measured in the North American isolates. The intramycelial protein content was the same for both races. Toxin (cerato-ulmin) production in the culture filtrates, expressed on the basis of dry mycelial weight, was greater in the North American isolates. Isoenzymes of peroxidase, tetrazolium oxidase, and certain protein bands can be used as biochemical markers to distinguish the two races. Results strongly suggest that isolate 83 is a hybrid between the Eurasian and North American races.