NaCl-induced responses in giant duckweed (Spirodela polyrhiza)

Salt accumulation leads to a decline in species richness in aquatic ecosystems. The effects of salt (NaCl) stress on plant growth and antioxidaiive responses in giant duckweed were investigated. NaCl significantly reduced photosynthetic pigment accumulation and inhibited plant growth. This inhibition in plant growth, may also provoke oxidative stress, enhancing malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents in plant tissues. The antioxidative enzymatic analysis showed a significant increase in superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), and peroxidase (POD) activity, whereas glutathione reductase (GR) activities were marginally enhanced. POD is the most active enzyme in giant duckweed exposed to NaCl stress. These results suggest that an adapted reactive oxygen species (ROS) scavenging system could provide some protection against oxidative damage in giant duckweed plants under salt-stressed conditions.