He-Ne laser pretreatment protects wheat seedlings against cadmium-induced oxidative stress.

The aim of the investigation is to determine the effect of He-Ne laser pretreatment of wheat seeds on the resistance of seedlings to cadmium stress. Changes in physiological, biochemical and molecular characters were measured. Our results showed that 150 μM Cd treatment significantly reduced plant height, root length, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, ascorbate acid (AsA) and glutathione (GSH) concentration, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and gene expression levels of SOD, APX, enhanced the concentration of malondialdehyde (MDA), hydrogen peroxide (H(2)O(2)) and the rate of superoxide radical (O(2)(•-)) generation in the wheat seedlings when compared with the control. However, seeds with He-Ne laser pretreatment 5 min conferred tolerance to cadmium stress in wheat seedlings by decreasing the concentration of MDA and H(2)O(2), the rate of O(2)(•-) generation and increasing the gene expression levels of SOD, POD, APX, the activities of SOD, POD, CAT, APX and AsA and GSH concentration. These results suggest that those changes in MDA, O(2)(•-), H(2)O(2), anti-oxidative enzymes, gene expression level and anti-oxidative compounds are responsible for the increase in cadmium stress resistance observed in the experiments. The results also showed that the laser had a positive physiological effect on the growth of cadmium stressed seedlings. This is the first investigation reporting the use of He-Ne laser pretreatment to enhance of wheat seedlings tolerance to cadmium stress.