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Heterokaryosis and Vegetative Compatibility in Leptographium wageneri. P. J. Zambino, Former graduate student, Department of Plant Biology, Nesmith Hall, University of New Hampshire, Durham 03824, Present address: USDA Cereal Rust Laboratory, 1551 Lindig St., University of Minnesota, St. Paul 55108; T. C. Harrington, Associate professor, Department of Plant Biology, Nesmith Hall, University of New Hampshire, Durham 03824. Phytopathology 80:1460-1469. Accepted for publication 12 July 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-1460.

Vegetative compatibility was tested among 76 isolates of Leptographium wageneri representing three taxonomic varieties and 14 electrophoretic phenotypes (i.e., unique combinations of isozyme patterns of 21 enzymes). Nitrate non-utilizing mutants selected on media containing the nitrate analogue chlorate were paired on nitrate media containing 200 ppm Triton X-100. The development of dense hyphal growth in the zone of confrontation between complementing phenotypes indicated compatibility. Heterokaryons were recovered from hyphal tips and conidiophores of complementing pairings but not from single conidia. Fourteen groups of vegetatively compatible isolates (VC groups) were detected among the three varieties. Each VC group contained isolates of similar electrophoretic phenotype, and most VC groups had unique geographic ranges. No complementation occurred between varieties. The relatively low number of VC groups and the correlations of VC groups with electrophoretic phenotype and geographic distributions indicate low diversity in L. wageneri, perhaps due to clonal selection, founder effects, and a lack of recombination.

Additional keywords: nit mutants, Ophiostoma wageneri.