Effects of cadmium stress on growth and anti-oxidative systems in Achnatherum inebrians symbiotic with Neotyphodium gansuense

The effects of cadmium on biomass production and growth parameters of drunken horse grass (Achnatherum inebrians) over an 8-week period were determined in a controlled-environment experiment. Changes were determined for relative water content, anti-oxidative enzymes (i.e., catalase (CAT), Superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX)) and for H2O2 content, as well as levels of proline, malondialdehyde (MDA), and chlorophylls a and b present within leaves infected with Neotyphodium gansuense vs. non-infected controls. Observations began 4 weeks after addition of CdCl2 (0, 50, 100 and 200 mu M) to the nutrient solution. Under high concentrations (100 and 200 mu M) of CdCl2, endophyte-infected plants produced more biomass and had higher values for plant height and tiller number compared to non-infected controls, but there was no significant difference (P > 0.05) under 0 and 50 mu M CdCl2. Anti-oxidative enzyme activities, H2O2 concentration, and chlorophylls a and b levels increased, but proline and malondialdehyde content declined in the infected plants vs. non-infected plants under high (100 and 200 mu M) concentrations of CdCl2. There was no significant difference (P > 0.05) under 0 and 50 mu M CdCl2. Endophyte infection was concluded to be of benefit to the growth and anti-oxidative mechanisms within A. inebrians under high concentrations exposures to CdCl2. (C) 2009 Elsevier B.V. All rights reserved.