Simultaneous, bidirectional translocation of 32P and 33P between wood blocks connected by mycelial cords of Hypholoma fasciculare

Summary Translocation of nutrients through fungal mycelia has mainly been viewed in terms of unidirectional movement from sources to sinks. This paper describes an experiment designed to test the possibility of bidirectional phosphorus transport in mycelial cords of the white rot fungus Hypholoma fasciculare growing in soil microcosms. A novel technique is described that uses the different energy spectra of the radioactive phosphorus isotopes 32 P and 33 P, in combination with nondestructive electronic autoradiography, to monitor the distribution of the two isotopes within single mycelial cord systems. The tracer isotopes were applied to pairs of wood blocks connected by mycelial cords, and isotope translocations were monitored during a 29‐d period. Significant amounts of phosphorus were transported in both directions simultaneously between the two colonized wood blocks. Simultaneous, bidirectional translocation of phosphorus occurs in mycelial cords of H. fasciculare . Such circulation of nutrients in fungal mycelia should equalize differences in nutrient concentrations in different parts of the mycelia, enabling net translocation of nutrients from areas of high nutrient availability to those of high nutrient demand.