Hypholoma fasciculare is a wood-decaying basidiomycete with a worldwide distribution, including tropical, temperate and boreal forest ecosystems. In Trás-os-Montes region (Northeast of Portugal) this species is commonly present in soils of several habitats, including chestnut and oak tree forests. The ectomycorrhizal fungus Pisolithus tinctorius is another species with high occurrence in those ecosystems. The present work intends to study the in vitro interaction between H. fasciculare and P. tinctorius through evaluation of fungal growth, changes on hyphae morphology, the production of volatile compounds and Iytic enzymes. The results obtained showed that H. fasciculare inhibited significantly the growth of P. tinctorius in 49%, long before hyphal contact of their colonies. This inhibition could be result from the liberation from H. fasciculare of volatile compounds and/or diffusible inhibitory substances, such as extracellular enzymes. Alteration in the production of volatile compounds, distributed in several chemical classes (alcohols, ketones, aldehydes, terpenes, among others) was detected over the time course of interaction. In addition, amylase, cellulase, laccase and lipase were produced by H. fasciculare. The possible role of these compounds during interaction will be discussed.This work is supported by FCT I&D grant PTDC/ AGR-AAM/099556/200
