Temperature and water potential relations of tropical Trametes and other wood-decay fungi from the indigenous forests of Zimbabwe

Three isolates each, of nine different Trametes and five other wood inhabit ing basidiomycetes, were collected from the indigenous forests of Zimbabwe, and the impact of temperature (20-60 degrees C), osmotic and matric potent ial (-0.5 to - 8.0 MPa), and their interactions on in vitro growth compared . Generally, there was no significant difference between growth of isolates of the same species in relation to temperature. Temperature relationships of the species studied correlated well with their geographic distributions. Species occurring in hot, dry regions tolerated a wide temperature range, with some showing unusually high thermotolerance (55 degrees, T. socotrana, T. cingulata and T. cervina). There were significant intra-strain differen ces for individual species in relation to solute potential on glycerol-modi fied media. Generally, growth of ail species was better on glycerol- and KC l-modified osmotic media than on a metrically-modified medium (PEG 8000) at 25, 30 and 37 degrees. The limits for growth on the osmotic media were sig nificantly wider than matric medium, being - 4.5 to - 5.0 and - 2.5 to - 4. 5 MPa, respectively. An Irpex sp. grew at lower water potentials than all o ther species, with good growth at - 7.0 MPa. This study suggests that the c apacity of these fungi for effective growth over a range of temperatures, o smotic and matric potentials contributes to their rapid wood decay capaciti es in tropical climates.