Continuous imaging of amino-acid translocation in intact mycelia of Phanerochaete velutina reveals rapid, pulsatile fluxes

Nitrogen translocation by woodland fungi is ecologically important, however, techniques to study long-distance amino-acid transport in mycelia currently have limited spatial and temporal resolution. We report a new continuous, noninvasive imaging technique for β-emitters that operates with submillimetre spatial resolution and a practical sampling interval of 10-60 min. • Transport of the nonmetabolized,14C-labelled amino-acid analogue, α-aminoisobutyric acid (AIB) was imaged using a photon-counting camera as it was transported in foraging mycelium of the cord-forming woodland fungus, Phanerochaete velutina, grown over an intensifying screen in microcosms. • The maximum acropetal transport velocity of14C-AIB to the colony margin was 50 mm h-1(average 23 mm h-1), with a mass transfer of 4.6-51.5 pmol14C-AIB h-1per cord. Transport in cords had a pulsatile component with a period of 11-12 h. • Transport was significantly faster than diffusion, consistent with rapid cycling of nutrients throughout the mycelium between loading and sink regions. The increased spatial and temporal resolution of this method also revealed the rhythmic nature of transport in this fungus for the first time. © New Phytologist (2002).