Hydrogen peroxide acts as a signal molecule in CO<sub>2</sub> laser pretreatment-induced osmotic tolerance in wheat seedling

Abstract

The objective of this study was to test whether hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) is involved in laser pretreatment-induced water tolerance in wheat seedlings due to its nature as a second messenger in stress responses. The results showed that 3 min laser pretreatment could enhance water tolerance in wheat seedlings by decreasing the concentration of malondialdehyde (MDA), the production rate of superoxide radical (O<sub>2</sub><sup>–</sup>), and increasing the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) and the concentration of glutathione (GSH), and having a positive physiological effect on the growth of osmotic stress seedlings. But the promotive effect of laser pretreatment-induced water tolerance in wheat seedling was effectively reversed by addition of 2 mmol AsA (ascorbic acid) or 5 µmol DPI (diphenyle iodonium), but exogenous 100 U/mL CAT could not reversed laser pretreatment-induced protective effect on wheat seedlings under osmotic stress. The results suggest that H<sub>2</sub>O<sub>2</sub> metabolism was involved as signal in the processes of laser-induced water acclimation and laser-induced protective effect was shown to be likely related to NADPH oxidase-dependent H<sub>2</sub>O<sub>2</sub> production.