Effect of calcium on growth of submerged Terfezia boudieri mycelium

The effect of Ca2+ on mycelial growth in Terfezia boudieri was studied. Terfezia boudieri Chatin (Ascomycotinae) occurs in mycorrhizal association with Helianthemum shrubs in deserts with calcareous soils. External Ca2+ stimulated mycelial growth in both liquid media and solidified substrates. The response to Ca2+ was very faint in well-aerated culture but pronounced in mycelia immersed in the medium, indicating dependence on mycelial aeration. 2,4-Dinitrophenol (DNP), an inhibitor of oxidative phosphorylation, and succinate, a potential cytoplasm acidifier, inhibited mycelial growth but enhanced the stimulatory effect of Ca2+. This effect was reduced by the Ca2+ channel blocker verapamil.