Osmotic Adjustment and the Role of Turgor in Mycelial Fungi

Abstract

Mycelial fungi crack pavements and destroy homes, burrow through soils and into plants and animals, harpoon rotifers, lasso nematodes, and ejaculate spores. Turgor pressure is responsible, at least in part, for all these phenomena. Like other eukaryotic microorganisms, fungal cells contain a higher concentration of solutes than their surroundings. In consequence, water flows into cells by osmosis during growth. To control cytoplasmic dilution, and the concomitant increase in volume, cells must either remove water with a contractile vacuole or resist swelling with a wall. Therefore, walled cells are pressurized by an influx of water which is driven by osmosis. Because growth must be accompanied by water uptake, mechanisms to control dilution and avoid dehydration are found in all fungi.