Relationships among species of Verticillium: protein composition of spores and mycelium

Buffer-soluble proteins extracted from six morphologically different isolates of Verticillium were separated by polyacrylamide gel-electrophoresis. Protein patterns from the six isolates were different from one another whether extracts were prepared from conidia, from young colonies composed of mycelium and conidia, or from 6-day-old mycelium. However, the nature of the patterns, and therefore the degree of differences among species patterns, was influenced by the types of cells from which the extracts were prepared.Patterns of proteins from V. tricorpus, V. nigrescens, and an isolate of uncertain identity (isolate 2) which produced chlamydospores and dark mycelium were clearly different from one another whether extracts were prepared from conidia or mycelium. In contrast, conidia of V. albo-atrum, of V. dahliae, and of an isolate which did not produce pigmented structures produced very similar patterns which differed by only a few protein bands. This close similarity of patterns supports the view that V. albo-atrum and V. dahliae are genetically closely related.The protein composition of conidia differed from that of mycelium. In V. albo-atrum, spore extracts contained at least three proteins not detected in mycelium extracts. Differences between spores and mycelium were even greater in V. nigrescens and isolate 2. Analysis of V. dahliae showed differences between spores, 3-day-old mycelium, and 6-day-old mycelium.Our results support the view that gel-electrophoresis of proteins is useful as a taxonomic tool provided attention is given to the degree of morphological differentiation of the materials to be compared.