Patterns and dynamics of 32P-phosphate and labelled 2-aminoisobutyric acid (14C-AIB) translocation in intact basidiomycete mycelia

Following uptake of 32P-orthophosphate and 14C-aminoisobutyric acid (14C-AIB) the patterns of distribution of the isotopes through intact basidiomycete mycelia were non-destructively mapped at regular intervals using a beta-scanner. Analysis of the results suggests that translocation of 32P and 14C-AIB through mycelia of Pleurotus ostreatus and Schizophyllum commune occurred along a restricted number of clearly defined, but macroscopically invisible, routes through the mycelium. In contrast to this, 32P added to mycelia of Coprinus cinereus remained immobilised at the addition point. Simultaneous acropetal and basipetal translocation of 32P and 14C-AIB was observed in different regions of colonies of P. ostreatus and S. commune. Translocation of label around the periphery of colonies strongly suggested the existence of anastomoses around the colony margin. Both 32P and 14C-AIB were initially immobilised at the addition point, from which each was subsequently translocated to other parts of the mycelium. The observed translocation of nutrients could not be explained by simple diffusion alone. The velocity of translocation and the complexity of the translocation pattern of 32P were greatest in mycelia of P. ostreatus, a hardwood decomposer, followed by S. commune, a wood and litter decomposer and parasite. Translocation through mycelia of C. cinereus, a coprophilus saprophyte, was very slow. This study provides the first detailed description of nutrient translocation through intact, entire fungal mycelia over time.