Responses of Antioxidant System of Indocalamus decorus to High Tem-perature and Drought Stress
This study aimed to explore the antioxidative responses of Indocalamus decorus to different intensities of high temperature and drought stress,which will potentially provide a theoretical basis for its stress-resistant cultivation.Two-years-old I.decorus plantlets were used and exposed to simulated drought and high temperature in the present study.Two contrasting atmosphere temperature(T1,normal temperature;T2,high temperature)were implemented in the experiment,with plantlets in each atmosphere temperature suffering different for drought conditions(CK,normal watering condition;LD,slight drought;MD,medium drought;and HD,severe drought).The species of reactive oxygen(ROS),content of malondialdehyde(MDA),activities of antioxidant defense enzymes,and the kinetics of substances related to the ascorbic acid-glutathione cycle(AsA-GSH Cycle)in I.decorus leaves were determined two days after all the drought conditions arrived the designed levels.The results showed that in normal atmosphere temperature,the accumulation of H2O2 and malondialdehyde(MDA)in I.decorus leaves increased with the intensification of drought,while the activities of superoxide dismutase(SOD)and catalase(CAT)increased significantly when the drought stress increased to the medium drought level,and the activity of Oxidase(POD)only increased under severe drought condition.The efficiency of the AsA-GSH Cycle approximately showed an curve linear relationship with the drought intensity,peaking at the slight drought intensity(LD),in which the reducing power of ascorbic acid(AsA/DHA)was more stable and the pool of glutathione(GSH/GSSG)was more sensitive to drought with high potential to get imbalance.However,in high atmosphere temperature,the activity of POD in leaves under the normal watering condition(CK)was significantly lower than that under other drought conditions,whereas the content of ascorbic acid(AsA)and dehydroascorbic acid(DHA)under CK were higher;Greater increase of ROS with the intensification of drought was observed compared with that in normal atmosphere temperature,and the increase in activity of CAT occurred forwards to the slight drought condition,and the activity of SOD and CAT under high temperature shows a more obvious superimposing effect than normal temperature,similar with that in normal atmosphere temperature,while the ascorbic acid cycle showed higher sensitivity under the combined conditions of high temperature and drought compared to that in normal atmosphere temperature,but performed more tolerant to the combined stressful conditions than the glutathione cycle.Thus,we concluded that I.decorus has potential resistance to drought and high temperature.A combination of high temperature and moderate drought dose not threaten plant survival of I.decorus,but severe drought would confer to an unbalanced reaction of the antioxidant system and a damage of cell membranes,which would be exacerbated by high atmosphere temperature.Therefore,I.decorus plantlets should not be exposed to long-term severe drought and additional high temperature in practices.
Indocalamus decorusAntioxidaseAsA-GSH CycleHigh temperature and drought stress
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