The damage repair role of He-Ne laser on wheat exposed to osmotic stress

Abstract

In order to determine the damage repair role of helium-neon (He-Ne) laser on wheat (Triticum aestivum L.) exposed to osmotic stress, 12-d-old seedlings (with two fully expanded leaves) were treated with osmotic stress using 5% (wt/vol), 10% (wt/vol) and 15% (wt/vol) polyethylene glycol (PEG 6000) treatment for 9 d. After 9 d of osmotic stress, a He-Ne laser was employed to irradiate seedlings of spring wheat for 0 min, 1 min and 3 min. Changes in the concentration of malondialdehyde (MDA), hydrogen peroxide (H2O 2), glutathione (GSH), ascorbate (AsA), the production rate of superoxide radical (O-2), the activities of ascorbate peroxidase (APX), peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR) were measured to test the effects of laser radiation. The results showed that laser radiation for 3 min conferred tolerance to osmotic stress in wheat seedlings by decreasing the concentration of MDA and the production rate of O-2 , and increasing the activities of SOD and APX and GSH concentration. It was suggested that those changes in MDA, O-2, antioxidative enzymes and antioxidative compounds were responsible for the increase in osmotic stress tolerance observed in the experiments. Therefore, antioxidative enzymes and antioxidative compounds may participate in the repair effect of laser on seedlings under osmotic stress. This is the first investigation reporting the damage repair role of He-Ne laser on plants exposed to osmotic stress.