Changes in vacuolar and mitochondrial motility and tubularity in response to zinc in a Paxillus involutus isolate from a zinc-rich soil

Short-term effects of zinc on organelles were investigated in Paxillus involutus from a zinc-rich soil. Vacuoles were labelled with Oregon Green 488 carboxylic acid and mitochondria with DiOC6(3). Hyphae were treated with ZnSO4 in the range 1–100 mM and examined by fluorescence microscopy. ZnSO4 caused loss of tubularity and motility in both organelles depending on concentration and exposure time. Tubular vacuoles thickened after 15 min in 5 mM ZnSO4 and became spherical at higher concentrations. Mitochondria fragmented after 30 min in 25 mM ZnSO4. Vacuoles recovered their tubularity after transfer to reverse osmosis water depending on ZnSO4 concentration and exposure time during treatment. Mitochondria recovered their tubularity with time, both with and without removal of the ZnSO4 solution. K2SO4 (as control) had no effect on vacuoles but disrupted mitochondria, the effect also depending on concentration and duration of exposure.