Taxonomy of the Nematophagous Fungi Verticillium chlamydosporium and V. suchlasporium Based on Secreted Enzyme Activities and RFLP Analysis

Abstract

Eight isolates of Verticillium chlamydosporium Goddard, which have been recently reclassified into two species and two varieties of each species, were studied for biochemical and genetic evidence to support subdivision of the species aggregate. A commercial test system (LRA ZYM, bio-Mérieux UK Ltd) was used to assay for the presence of 87 enzyme activities (glycosidases, esterases, arylamidases, and one transferase) in culture media. Heterologous DNA probes, most derived from the plant pathogenic species V. dahliae and V. alboatrum, were used to examine RFLPs. Most of the RFLPs seen were probably associated with the ribosomal RNA gene cluster. Although cluster analysis of the LRA ZYM results indicated that some subspecific groupings of isolates may exist it did not support their division into two species. Similarly, RFLPs were found which distinguished between isolates but these were not correlated with the proposed species classilication.