Mitochondrial DNA of Cryphonectria parasitica: Lack of Migration Between Vegetatively Compatible Strains. E. Gobbi. Department of Biology and Molecular Biology and Biochemistry Program, Utah State University, Logan 84322-4500 U.S.A. Y. Wang, R. M. Martin, W. A. Powell, and N. K. Van Alfen. Department of Biology and Molecular Biology and Biochemistry Program, Utah State University, Logan 84322-4500 U.S.A. MPMI 3:66-71. Accepted 18 October 1989. Copyright 1990 The American Phytopathological Society.

The mitochondrial (mt)DNA of Cryphonectria parasitica is approximately 144 kb, but the size varies among strains because of length polymorphisms. One of the restriction fragment length polymorphisms, a 2.4-kb SacI fragment of the mtDNA of strain EP2001, hybridizes to only a 0.7-kb SacI fragment in strain EP113. Migration of mtDNA between vegetatively compatible strains was examined by hybridization using as a probe a plasmid containing a clone of the 2.4-kb fragment of EP2001. RFLP analysis of isolates from various parts of the colonies and in situ colony hybridization procedures showed that the mtDNA of EP2001 does not migrate into strain EP113 when hyphal anastomosis occurs. Migration of dsRNA between the two strains showed that hyphal anastomosis had occurred. A genetic marker indicated that heterokaryons did not form and that hyphae of EP2001 did not grow beyond the zone of colony interaction.