A REVISION OF PLANT-ASSOCIATED VERTICILLIUM SPECIES

Molecular approaches were used to re-evaluate the morphological criteria used to identify plant-associated Verticillium species. ITS-RFLPs divided the 31 studied strains of seven Verticillium species, (including the type species V. luteo-album) into four clusters. Cluster one comprised strains of the type species, V. luteo-album, cluster two V. albo-atrum, V. dahliae, V. nubilum and V. tricorpus; cluster three comprised strains of V. theobromae, and cluster four comprised strains of V. nigrescens. b-tubulin gene RFLPs offered a higher degree of resolution, distinguishing all seven species from each other. The highest degree of resolution was obtained from mitochondrial DNA-RFLPs that divided strains of V. theobromae and V. nigrescens into infraspecific groups. The b-tubulin gene digested by Hae III offers a reliable way to separate the two economically important and controversial species V. albo-atrum and V. dahliae.