MORPHOLOGY AND PHYSIOLOGY OF MORCHELLA-ESCULENTA DURING SCLEROTIAL FORMATION

Six major stages were identified in the growth of Morchella esculenta, using the split-plate method of cultivation, up to sclerotial maturat ion. One side of the plate contained Noble agar (NA), amended with 0.5 M glucose, on which the sclerotia formed. The other contained PDA, on which mycelium formed. Inoculum was placed on the NA side of the plat e and the hyphae grew towards the PDA side. When the hyphae reached th e end of the plate, the direction of the cytoplasm stream reversed, tr anslocating carbohydrates from the young part of the colony (mycelium) to the older part, at which stage initials formed. As the sclerotia d eveloped, the soluble carbohydrates changed quantitatively and qualita tively , mannitol, arabitol and trehalose appearing in addition to glu cose. Total carbohydrates decreased from 50 to 3.2% of the dry weight of the sclerotia. Meanwhile, the mycelial biomass decreased and the so luble carbohydrates virtually disappeared, probably moving to the scle rotia. The hyphal morphology on the NA side developed into pipes to su it the conduction of the cytoplasm stream from the mycelium to the scl erotium.