CO_2加富对UV-B辐射胁迫下亚心形扁藻光合作用和膜脂过氧化以及抗氧化酶活性的影响(英文)

在CO2浓度分别为当今CO2浓度(360 mL/L)和加富浓度(5 000 mL/L)条件下,研究了UV-B胁迫对亚心形扁藻(Platymonas subcordiformis (Wille) Hazen)的光合作用、膜脂过氧化和抗氧化酶活性的影响。实验结果表明:(1) UV-B单独作用下,亚心形扁藻的干重、光合速率、叶绿素a (Chl a)和类胡萝卜素(Car.)含量显著降低,CO2加富单独作用下,亚心形扁藻的干重和光合速率显著升高,叶绿素a和类胡萝卜素含量与对照相比没有显著变化,而UV-B与CO2共同作用则使亚心形扁藻的干重和光合速率与对照相比没有显著变化,叶绿素a和类胡萝卜素含量显著降低。(2) UV-B单独作用和CO2加富单独作用都使可溶性蛋白含量显著降低,UV-B与CO2共同作用下的可溶性蛋白含量比UV-B单独作用的要高。高CO2对藻的可溶性蛋白含量的变化在很大程度上归因于Rubisco蛋白的降低。(3)UV-B单独作用下,O2-. 产生速率、H2O2 含量和MDA含量显著升高,而CO2加富单独作用下,O2-. 产生速率、H2O2 含量和MDA含量显著降低,与UV-B单独作用相比,UV-B与CO2共同作用使O2-. 产生速率、H2O2 含量和MDA含量显著降低。说明CO2加富可以减少活性氧对亚心形扁藻的氧化胁迫,同时减少UV-B对亚心形扁藻的膜脂过氧化伤害。(4) UV-B单独作用下,SOD、POD、CAT、GR和GPX活性显著升高,高CO2

Effects of CO_2 Enrichment on Photosynthesis, Lipid Peroxidation and Activities of Antioxidative Enzymes of Platymonas subcordiformisSubjected to UV-B Radiation Stress

When the CO2 concentration was kept at 360 mL/L (ambient) and 5 000 mL/L (elevated), theeffects of UV-B stress on photosynthesis, lipid peroxidation and antioxidative enzymes of marine microalgaePlatymonas subcordiformis (Wille) Hazen were examined. The experiment indicated that: (1) UV-B alonesignificantly decreased dry weight, photosynthetic rate, chlorophyll a (Chl a) and carotenoid (Car.) contents;CO2 enrichment alone enhanced dry weight and photosynthetic rate, but Chl a content and Car. contenthad no major difference compared with those of ambient UV-B and ambient CO2; the dry weight andphotosynthetic rate of P. subcordiformis grown under the combination of UV-B and CO2 had no majordifference compared with that under ambient UV-B and ambient CO2; while the Chl a content and Car.content significantly decreased compared to those of P. subcordiformis grown under ambient UV-B andambient CO2. (2) Both UV-B alone and CO2 enrichment alone significantly decreased soluble proteincontent, when UV-B and CO2 were in combination, the soluble protein content was higher than that of UV-B alone. Changes in soluble protein content of algae grown in high CO2 could be largely due to a decline inRubisco protein. (3) UV-B alone significantly increased the rate of O2-. production, H2O2 and malondialdehyde(MDA) content, CO2 enrichment alone significantly decreased the rate of O2-. production, H2O2 and MDAcontents, when UV-B and CO2 were in combination, the rate of O2-. production, H2O2 and MDA contentswere significantly lower than those of UV-B alone. The results suggested that CO2 enrichment couldreduce oxidative stress of reactive oxygen species to P. subcordiformis, and reduce the lipid peroxidationdamage of UV-B to P. subcordiformis. And (4) UV-B alone significantly increased SOD, POD, CAT, GR andGPX activities, CO2 enrichment alone significantly decreased the activities of SOD, POD and GR, while theCAT and GPX activities were decreased a little but not changed significantly compared to ambient UV-B andambient CO2. The SOD, POD, CAT, GR and GPX activities of P. subcordiformis grown under the combinationof UV-B and CO2 were much lower than those of P. subcordiformis grown under UV-B alone. The resultsindicated that CO2 enrichment showed a protective effect against the oxidative damage of UV-B-inducedstress. Therefore, elevated CO2 can be favor of enhancing the capacity of stress resistance.