Induction of sclerotialike mycelium in axenic cultures of Claviceps purpurea producing clavine alkaloids.

Aggregates of sclerotialike (SL) cells, present normally among filamentous sphacelial hyphae of submerged cultures of Claviceps purpurea strain 129 synthesizing clavine alkaloids, may represent an adaptation to unfavorable environmental conditions. Their formation can be induced by dyes (acriflavine, toluidine blue, fluorescein, basic fuchsin, ethidium bromide, and methylene blue). A treatment of the original strain with ethyl methanesulphonate yielded five mutants with stable SL phenotypes. Electron microscopy was used to illustrate the morphogenetic processes in mutant strains and the fragmentation of SL clusters to arthrospores.