Physiological Studies of Growth and Development in the Three Basidiomycete species Lepista Nuda (Bull. ex Fr.) Cooke, Lepista Saeva (Fr.) Orton and Calocybe Gambosa (Fr.) Singer

Abstract

Studies were undertaken into the general physiology and fruiting of three wild Basidiomycetes, Lepista nuda (Bull. ex Fr.) Cooke (wood blewit), Lepista saeva (Fr.) Orton (pasture blewit), and Calocybe gambosa (Fr.) Singer (St George's mushroom). The three species were formally grouped together within the genus Tricholoma on overall fruit-body characteristics but have since been subdivided on the basis of detailed ultrastructure of the fruit-body and spores into the genera Lepista and Calocybe, both within the family Tricholomataceae. C. gambosa is a vernal species, and both Lepista species produce fruiting bodies in late autumn. L. nuda occupies a variety of habitats, in particular accumulations of partly decomposed leaf litter and rich soils, fruiting in troops under sheltered conditions. L. saeva and C. gambosa generally occupy more open positions in pastures, meadows, and fringing woods, often forming 'fairy-rings', and occasionally within woods. Results from screening a large number of isolates within each species for P-diphenol oxidase and cellulase activity indicate considerable diversity within species and between species. Response to a range of temperature and hydrogen ion concentrations for a smaller number of isolates indicates a more uniform response within the individual species range. Growth of a restricted number of isolates within each species was determined on a large number of individual carbon and nitrogen sources at a selected carbon : nitrogen ratio. Vitamin, trace metal, and fatty acid nutrition was examined for selected strains. Good growth and a wide nutritional diversity were shown by isolates of L. nuda and L. saeva on a wide range of mono-, di-, tri- and polysaccharides, sugar alcohols, hemi-cellulose, cellulose, and many nitrogen sources. C. gambosa generally showed restricted growth except where the basal medium was supplemented with natural extracts. The effect of a range of oxygen and carbon dioxide concentrations was assessed for individual species. A number of L. nuda and L. saeva isolates were selected for fruiting trials on solid substrates based on their performance in specially constructed tubes and in flasks. Three strains of L. nuda used throughout the survey fruited successfully under artificial conditions, one strain of which almost completed fruit-body maturation on a natural agar medium under simulated environmental conditions.