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Potential Applications of Random DNA Probes and Restriction Fragment Length Polymorphisms in the Taxonomy of the Fusaria. B. Q. Manicom, Graduate research student, Citrus and Subtropical Fruit Research Institute, Private Bag X11208, Nelspruit 1200, Republic of South Africa; M. Bar-Joseph(2), A. Rosner(3), H. Vigodsky-Haas(4), and J. M. Kotze(5). (2)(3)(4)Institute of Plant Protection, Volcani Centre, Bet Dagan, Israel; (5)Professor, Microbiology and Plant Pathology, University of Pretoria, Pretoria 0001, Republic of South Africa. Phytopathology 77:669-672. Accepted for publication 2 October 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-669.

A range of Fusarium species was screened for DNA restriction fragment length polymorphisms in ethidium-stained agarose gels and by hybridization to random probes generated from total DNA of an isolate of Fusarium oxysporum f. sp. dianthi. DNA was digested with Hind III and ligated into the Hind III site of pBR322, and the recombinant plasmids were used to transform Escherichia coli MM294. Plasmid DNA from four clones harboring inserts ranging in size from 760 to 3,400 base pairs were 32P-labeled and hybridized to Southern blots of total DNA from two isolates of F. o. f. sp. dianthi and isolates of F. o. f. spp. lycopersici and gladioli. Three plasmids gave hybridization patterns that indicated that their inserts were present in one or a few copies per genome. A fourth plasmid hybridized to multiple fragment lengths in Hind III and Eco R 1 digests of the Fusarium DNA. The restriction fragment length polymorphism patterns differed among the three forma speciales tested, but there were constant bands within F. o. f. sp. dianthi and patterns were conserved over time despite phenotypic variation. The fourth plasmid hybridized only to a subset of the species oxysporum and not to isolates of seven other Fusarium spp. Combinations of probes and restriction enzymes enabled differentiation at species, forma speciales, and isolate levels. The technique holds promise for addressing problems in the taxonomy and identification of Fusarium.