Flammulina velutipes (Curt. ex Fr.) Sing. was grown on potatoglucose solution freed of most starch. Glucose uptake and dry weight changes in the colony indicated that the large fruitbodies derived their substrates partly from glucose remaining in the medium and partly from cellular constituents stored in the mycelium and small fruitbodies. Changes in the amounts of low molecular weight carbohydrates, glycogen, and four cell wall polysacchande fractions were followed in the mycelium and fruitbodies. Trehalose, arabitol, and smaller amounts of mannitol were the main stored low molecular weight carbohydrates. A large net loss of these compounds occurred in the mycelium and small fruitbodies after their growth ceased. The carbohydrates accumulated in the large fruitbodies, but were also partly metabolized in the colony.Reducing sugars were minor components, and induded about 30 to 50% glucose and a small undetermined quantity of fructose. Glycogen was the main storage carbohydrate in the mycelium, and was also stored in the small fruitbodies. It was broken down in both structures during growth of the large fruitbodies which accumulated only small amounts. During the same period, almost 45% of the maximum amount of cell wall polysaccharides were degraded in the small fruitbodies, but not in the mycelium.By feeding 14C-glucose in replacement medium, incorporation of radioactivity into carbohydrates was foRowed in the colony during fruitbody development. Total incorporation was highest in trehalose, next highest in glycogen, and the rest was found in polyols and cell wall polysaccharides except for a few per cent which remained in endogenous glucose. In the large fruitbodies, specific radioactivity in glucose was much lower than in trehalose and mannitol. The labeling patterns in the mycelium and large fruitbodies suggested that trehalose, mannitol, and possibly arabitol were translocated into the stipes and pilei.Stipe elongation in the fruitbodies of Flammulina velutipes (Agaricales) requires a supply of water and nutrients from the vegetative mycelium during most of the growth period (9, 10). The identity of the translocated nutrients was not determined, but the elongation of isolated whole fruitbodies is promoted by glucose and other low mol wt carbohydrates (10). Stipe elongation also depends on the lamellae in the pileus (7), and excised lamellae release a diffusate into agar which promotes stipe growth. Production of this diffusate is stimulated by glucose (8). These results indicated that a knowledge of the nature and distribution of cellular carbohydrates would contribute to a better understanding of the relationship between fruitbody growth and the mycelium. Few reports have been published on the quantitative distribution of cellular carbohydrates during the development of the vegetative mycelium and fruitbodies of Hymenomycetes. Most of the available information has been obtained for Schizophyllum commune (Aphyllophorales) where changes in total alcoholsoluble carbohydrates and especially in several...
Dry weights of stipes and pilei of Flammulina velutipes grown on nutrient-supplemented sawdust increased throughout the growth period. The pilei weighed only slightly less than the stipes. Amounts of total organic nitrogen, α-amino nitrogen, and alkali-soluble protein increased in the whole pileus and stipe as the fruitbodies elongated, but the concentrations on a dry weight basis decreased although they were always highest in the pileus. The concentration of alkali-insoluble nitrogen increased in both structures and was highest in the stipe. Concentrations of total nitrogen and protein in surface mycelium did not change significantly when fruitbodies formed but increased markedly when their growth ceased. An average of 8.3 mg dry weight of spores containing about 0.6 mg of nitrogen was released during the life of the fruitbody. Changes in 18 free and 17 protein amino acids were followed quantitatively in the pileus and stipe. Glutamic and aspartic acids and alanine were always among the four predominant free amino acids. Lysine and arginine concentrations remained low in the stipes but increased considerably in the expanding pilei. Ornithine levels increased strongly in the stipe during the early part of rapid elongation but remained almost constant and low in the pilei. Free proline was detected only in traces. Valine became the most abundant protein amino acid during elongation, especially in the stipe. There was very little bound methionine and cystine. In surface mycelium levels of free amino acids were low before fruiting and close to the end of fruitbody growth. Protein amino acids increased during that interval but their proportions remained virtually unchanged and valine was not predominant. The concentration of urea remained very low in both pilei and stipes during their growth.
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