| In this study,we have researched the effects of sulfur dioxide(SO2)on pakchoi and tobacco,and the mitigation of S02 fumigation on drought physiology of tobacco.The drought effects of wild-type mutant(eds5,nprl)associated with salicylic acid(SA)pathway were studied,and the mitigation effects of treatment with SO2 on drought stress were also studied.The results showed that hydrogen peroxide content in leaves of pakchoi increased significantly during 6 h-48 h of SO2 exposure at 30 mg/m.During 6 h-36 h exposure,the glutathione content in leaves increased,and the activities of glutathione peroxidase(GPX)and glutathione s-transferase(GST)increased.The activity of GST and gpx decreased and MDA content increased significantly in leaves exposed to SO2 for 48 h.The results showed that SO2 exposure conditions could induce oxidative stress on pakchoi seedlings,increase the level of sulfur-containing antioxidants in pakchoi leaves and enhance the cell reduction ability.When SO2 exposure time was prolonged,the accumulation of active oxygen in tissues decreased the activity of antioxidant enzymes,and the level of membrane lipid peroxidation products increased,resulting in oxidative damage.10 mg/m3 SO2 fumigation had different degree of oxidative stress on leaf at different seedling stage and different leaf tissues of tobacco.The content of MDA in the second,fourth and sixth leaves of tobacco grown for 25 days was detected.the results showed that the oxidative damage of S02 to the old leaves was greater than that of the new leaves.The changes of H2O2,MDA and SOD in the fourth leaf of tobacco grown for 20 and 25 days after S02 fumigation were detected,it was found that the severity of SO2 stress in tobacco grown for 20 days at seedling stage was greater than that in tobacco grown for 25 days at seedling stage.The relative water content,proline,fresh weight of aboveground parts and plant height of tobacco leaves were measured after SO2 fumigation and drought.It was found that SO2 fumigation at 10 mg/m3 for 18 h could enhance the adaptability of tobacco to drought.In the drought study of Arabidopsis thaliana,the relative water content,MDA and proline content,superoxide anion production rate were measured.Compared with wild Arabidopsis thaliana,the drought tolerance of eds5 mutant was weaker and nprl mutant was stronger.The results showed that increasing the content of SA in plants had positive significance in improving drought resistance of plants.Previous studies in the laboratory found that 30 mg/m3 SO2 fumigation for 30 h could improve drought resistance of wild-type Arabidopsis thaliana.On this basis,exogenous salicylic acid treatment,SO2 fumigation treatment and drought treatment were carried out on the two Arabidopsis mutants of wild-type Arabidopsis thaliana and SA pathway.The relative water content,MDA content and SOD activity of the wild-type Arabidopsis thaliana and mutant nprl were detected,S02 could significantly alleviate drought stress and reduce oxidative damage.However,the drought stress of mutant eds5 was less relieved,SO2 could significantly improve its drought resistance only when SA was applied.The eds5 and nprl genes belong to SA pathway related genes.It is suggested that the drought resistance induced by SO2 stimulation may be related to the activation of SA-related pathway,and eds5 gene is the key gene of SA-related pathway in plants. |
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