In vitro salt and thermal tolerance of fungal endophytes of Nicotiana spp. growing in arid regions of north-western Australia

摘要

Endophytic fungal strains isolated from indigenous Nicotiana plants naturally growing in dry and hot regions of northwestern Australia were characterised based on their tolerance to salinity and temperature. Sixty-eight fungal isolates were tested oneight levels (0.5 M, 1.0 M, 1.5 M, 2.0 M, 2.5 M, 3.0 M, 3.5 M and 4.0 M) of five different of salts solutions NaCl, KCl, MgCl_2, CaCl_2 and MgSO_4 and at various temperatures (25-50 °C). The salt adaptation test indicated that the fungal strains namelyAspergillus niger (E-202), A. ochraceous-A (E-134), Aurantiporus sp. (E-135), Cladosporium halotolerance (E-128), Pleurostomophora richardsiae (E-13) and Trichoderma sp. (E-185.1) were tolerant to higher concentrations of various salts. The most growth-limiting salt turned out to be MgCl_2 followed by the chaotrope CaCl_2. Responses to temperature tolerance revealed that most fungi tested could grow at 30 °C. About 50% all the fungi did not show any growth when the temperature was raised above 30 °C.When the temperature was raised up to 50 °C all the fungi failed to grow but the fungus Rasamsonia piperina (E-172). Endophyte strains identified could be promising candidates for future research in investigating the fungus-plant interactions and theirroles in plant adaptation to inhospitable environments.