MORPHOGENESIS IN SCLEROTIUM‐FORMING FUNGI

SUMMARY Twenty‐six out of thirty‐six monoascospore isolates of Sclerotinia sclerotiorum (Lib.) de Bary, when grown in continuous darkness, produced regular zones of sclerotia. Patterns of zonation were independent of linear growth rate and, although rhythmic behaviour was endogenously determined, rhythms could be altered in detail by varying either glucose concentration or temperatue but not light regime. In some isolates, sclerotium production was accompanied by both generalized and localized changes in the growth rate of the colony margin. The implications of these observations are discussed in the context of nutrient availability and sclerotium morphogenesis.