SEASONAL-VARIATION IN PROTEIN, ERGOSTEROL AND CHITIN IN 5 MORPHOTYPESOF PINUS-SYLVESTRIS L ECTOMYCORRHIZAE IN A MATURE SWEDISH FOREST

Pine ectomycorrhizae were collected from bedrock and moraine sites in a mature Pinus sylvestris L. forest in the vicinity of Uppsala, Sweden , on four;occasions over the period of a year. Ectomycorrhizae were ex amined microscopically and five characteristic types (Piloderma, tuber culate, Lactarius-like, Russula-like and an unidentified pink) were de scribed and used for further biochemical assays. Total protein, ergost erol and chitin extractions were performed in sequence for each sample of distinct mycorrhizal morphotype. Differences between sites (bedroc k moss vs moraine) from which the morphotypes originated were small, e xcept for an increase in protein in Piloderma and tuberculate mycorrhi zae on moraine sites in July and January. However, there were signific ant variations in protein and chitin concentrations and in the ergoste rol-to-chitin ratio, both between seasons and mycorrhizal types. Prote in concentrations were significantly higher in the winter samples for Piloderma, tuberculate and pink mycorrhizae and were at a minimum in t he early summer. Chitin concentrations peaked in both early summer and winter for all morphotypes, significantly so for Piloderma and tuberc ulate mycorrhizae, but remained low during mid-summer and fall. Althou gh the seasonal differences in ergosterol concentrations were small, a significant correlation was found between chitin and ergosterol for P iloderma mycorrhizae. For all morphotypes, the ergosterol-to-chitin ra tio varied seasonally from low January values increasing to high value s in October, the end of the season of maximum fungal growth. The smal l seasonal variation in ergosterol and development of the ergosterol-t o-chitin ratio suggests that ergosterol remains a better indicator of vital fungal biomass than chitin or other available measures. (C) 1997 Elsevier Science Ltd.