Responses of Three Endophyte Fungi Species Isolated from Natural Grass to Abiotic Stresses

Biological and physiological characteristics of three Neotyphodium species, isolated from native grasses, were compared with the model endophyte Neotyphodium coenophialum, isolated from tall fescues, under different temperature, water and salt conditions. Three Neotyphodium species included Neotyphodium gansuense, Neotyphodium sibiricum and Neotyphodium sp., among which N. sp. was isolated from Leymus chinensis while the other two species were isolated from Achanatherum sibiricum. The results showed that the optimal temperature for the four endophytes was 25˚C. The model endophyte N. coenophialum was un- able to grow at 32˚C, but the other endophytes were able to grow at 10˚C - 32˚C. Four fungi could not grow when the PEG concentration was 15%. For N. sp., it tended to increase when PEG concentration was 10%, and this situation is similar to N. coenophialum. For N. gansuense and N. sibiricum, the growth was not in- fluenced till the PEG concentration was up to 10%. Under the treatment of NaCl, the biomass of N. sibiricum and N. coenophialum significantly increased, but the growth of N. gansuense and N. sp. were significantly re- strained at 0.3 mol/L NaCl. N. sibiricum was unable to grow at 1.5 mol/L NaCl, but N. coenophialum can still grow under 3 mol/L NaCl. As a result, three species of endophytes which were isolated from native grasses can tolerate high temperature than the model endophyte. For the ability of resistance to osmotic stress, only N. sp. is similar to the model endophyte and two endophytes from A. sibiricum was significantly lower than model endophyte. For different salt stress, the tolerance of three native species was significantly lower than the model species.