Investigation of Variation in Phenotype and DNA Content between Single-conidium Isolates of Single Penicillium Strains

1 CAB International Mycological Institute, Ferry Lane, Kew, Surrey TW9 3AF, UK 2 Department of Immunology, St George's Hospital Medical School, Cranmer Terrace, London SW17 ORE, UK 3 Ministry of Agriculture, Fisheries and Food, Slough Laboratory, London Road, Slough, Berkshire SL3 7HJ, UK ABSTRACT SUMMARY: Variation in phenotypic properties was examined in three strains of closely related fasciculate species of Penicillium using 114 morphological, physiological, and biochemical characters. Thirty-six of these characters showed variation within single-conidium isolates of the same strain. Conidial sizes and nuclear DNA contents were compared using flow microfluorimetry; these results suggested that significant differences in conidial DNA content are associated with phenotypic variation. The taxonomic significance of the results is discussed.