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Genetic Variation in Fusarium oxysporum from Cyclamen. L. P. Woudt, Department of Technology, S & G Seeds B.V., Postbus 26, 1600 AA Enkhuizen, the Netherlands; A. Neuvel(2), A. Sikkema(3), M. Q. J. M. van Grinsven(4), W. A. J. de Milliano(5), C. L. Campbell(6), and J. F. Leslie(7). (2)(3)(4)(5)Department of Technology, S & G Seeds B.V., Postbus 26, 1600 AA Enkhuizen, the Netherlands; (3)Current address: Agrico Research, Postbus 40, 8300 AA Emmeloord, the Netherlands; (6)(7)Department of Plant Pathology, Throckmorton Hall, Kansas State University, Manhattan 66506-5502; (6)Current address: Frito-Lay, Inc., 4295 Tenderfoot Road, Rhinelander, WI 54501. Phytopathology 85:1348-1355. Accepted for publication 12 August 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/Phyto-85-1348.

Fusarium isolates were recovered from cyclamen plant material and from public culture collections. Isolates were identified to species, and the majority (79/90) were F. oxysporum, although isolates of F. moniliforme, F. equiseti, and F. graminearum also were recovered. The F. oxysporum isolates were subdivided further based on pathogenicity to young cyclamen plants in greenhouse tests, vegetative compatibility tests, hybridization with a repetitive DNA (fingerprint) probe, and organization of the ribosomal intergenic spacer (IGS) sequences. Fifty-three pathogenic and twenty-six nonpathogenic isolates were identified. The pathogenic isolates could be subdivided into three clonal lineages, each containing a single vegetative compatibility group (VCG), whose members had similar IGS organization and DNA fingerprints. The nonpathogenic isolates could be distinguished clearly from the pathogenic isolates, and usually one another, using either the VCG or the fingerprint criteria, but not necessarily the IGS criterion.

Additional keywords: Fusarium oxysporum var. aurantiacum.