REGULATION OF SCLEROTIUM PRODUCTION BY PRIMARY METABOLITES IN COPRINUS-CINEREUS (= COPRINUS-LAGOPUS-SENSU LEWIS)

Aerial sclerotia of C. cinereus (Schaeff. ex Fr.) S.F. Gray were produced most abundantly in conditions which strongly favored mycelial growth. With the N concentration maintained at 25 mM ammonium tartrate, the number of sclerotia formed increased as the initial maltose concentration of the medium was increased, reaching a maximum at 25 mM. The length of time required for sclerotium maturation was also minimal on media which initially contained 25 mM maltose. Changing the concentration of ammonium tartrate (in media containing 25 mM maltose) did not markedly affect the total number of sclerotium initials which were formed but had a profound influence on sclerotial maturation. With 5 mM ammonium tartrate maturation occurred most rapidly and most completely, with 63% of the final total sclerotial yield being matured within 7 days, and 91% within 14 days. Higher ammonium concentrations first delayed and then prevented maturation so that at 100 mM less than 0.3% of the initials had matured within 21 days. It is suggested that the ability of ammonium ions to regulate sclerotium maturation can be correlated with the ability of the sporophore to excrete ammonia into the medium so as to provide a mechanism for sequencing the 2 pathways. While sporophores are developing, the ammonium concentration will be maintained at a level which prevents sclerotial maturation, thus avoiding competition for metabolities between the 2 morphogenetic sequences.