Studies Of Nitric Oxide And Trehalose On The Effects Of Antioxidative Responses Under Heat Stress In Pleurotus Eryngii Var. Tuoliensis

Pleurotus eryngii var. tuoliensis is a favored mushroom of rich nutrition and medicinal value. Now it keeps growing in demand and cultivation scale. However, the spawning of the mushroom cultivated in agricultural facilities are usually in naturally high temperature period, which always lead to “burnt mycelium” and declined production. Therefore, to explore the mechanism of mycelial heat stress response would establish a theoretical basis for a new species breeding and have both scientific and industrial significances.In organisms, nitric oxide and trehalose, as a signal molecular and protective metabolite respectively, have important roles in response to abiotic stresses. The research with respect to the functions of NO and trehalose in response to heat stress attracted more and more attentions.In this thesis, the responses of antioxidative enzyme activities to heat stress was investigated for Pleurotus eryngii var. tuoliensis. The effects of NO and trehalose on the responses of antioxidative enzyme activities under heat stress were also studied. We get several conclusions as follow:Heat stress caused oxidative stress and induced lipid peroxidation in mycelium of Pleurotus eryngii var. tuoliensis. When under heat stress for 48 h, the content of TBARS reached the maximum with 4.48 fold of those in control(0 h). The antioxidant enzymes in mycelium of Pleurotus eryngii var. tuoliensis changed significantly, while each responded differently under heat stress. The activity of SOD had no significant change in 48 h, but increased significantly after that with 1.55 fold of that in control(0 h); the activity of CAT increased significantly after 24 h and reached the maximum with 5.02 fold of that in control(0 h); the activity of POD expressed significant increase after 12 h and reached the maximum with 2.82 fold of that in control(0 h). Unlikely, GR activity increased first and then decreased, reached the maximum at 24 h. All of these showed that CAT was the most sensitive enzyme when Pleurotus eryngii var. tuoliensis responded to the heat stress.The application of exogenous NO decreased the content of TBARS in mycelium and relieved oxidative damage. Exogenous NO had different effects on the activities of antioxidant enzymes. The application of exogenous NO increased the activities of SOD,CAT and GR, but inhibited POD activity. Consequently, exogenous NO enhanced heat-resistance of Pleurotus eryngii var. tuoliensis mycelium by improving SOD,CAT,GR activities. Especially, the activity of CAT was measured by m M·min-1·mg-1 of protein, and it played the most important role in eliminating the reactive oxygen species and mitigating the oxidative damage.Heat stress enhanced the lipid peroxidation in mycelium, while the application of exogenous trehalose lowered the content of TBARS markedly. Exogenous trehalose had different effects on the antioxidant enzymes. The application of exogenous trehalose increased the activities of SOD,CAT and POD, but inhibited GR activity. Exogenous trehalose relieved oxidant damage, enhanced heat-resistance of Pleurotus eryngii var. tuoliensis by improving the activities of SOD,CAT and POD.The common pathway of exogenous NO and trehalose mitigating the oxidative damage is that they increase the activities of SOD and CAT. And the different way is that the exogenous NO increased GR activity while trehalose increased POD activity.