Effect of laser irradiation and ethylene on chilling tolerance of wheat seedlings

In order to determine the mechanism of laser-enhanced chilling tolerance in wheat (Triticum aestivum L.) seedlings, the seeds were exposed to different treatments, and some physiological and biochemical parameters were measured in 5-day-old seedlings. The results showed that in wheat seedlings subjected to 1-aminocyclopropane-1-carboxylic acid (ACC) followed by chilling stress (CS), the concentrations of H2O2, O2 .− and MDA were lower, while the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as the soluble protein content (SPC) and the seedling length (SL) were higher than those in chilling stress treatment. When wheat seedlings were subjected to aminooxyacetic acid (AOA) followed by chilling stress, the results were different from those in which the seedlings were subjected to ACC. Although ACC and AOA treatments followed by laser irradiation led to an increase in the aforementioned enzyme activities, SPC, and SL, with a simultaneous decrease in concentrations of H2O2, O2 .−, and MDA, the effect of ACC treatment followed by laser irradiation was more favorable than that of AOA treatment followed by laser light. Similarly, the oxidative damage induced by chilling stress was alleviated in treatment with ACC+LR and AOA+LR, but alleviation effects of ACC+LR+CS were more prominent than in the treatment AOA+LR+CS. These results suggest that the laser light and ethylene have a positive synergistic effect, thus enhancing chilling tolerance in wheat seedlings.