| 摘要: |
| 紫外辐射增强常导致藻类体内活性氧成分的产生，从而损伤藻类光合器官，引起藻类光抑制。马尾藻（Sargassum）金潮近些年在世界多地频繁暴发，金潮暴发时，漂浮于海面的藻体接受更多的紫外辐射，但金潮藻应对这种紫外胁迫的生理学机制尚不明确。本研究以中国金潮种——铜藻（Sargassum horneri）为研究对象，在实验室条件下，以太阳模拟器提供光源，设置P （光合有效辐射，Photosynthetically active radiation，PAR，400~700 nm，200 W/m2）、PA （PAR+UVA （紫外线A，Ultraviolet A），320~700 nm）和PAB （PAR+UVA+UVB （紫外线B，Ultraviolet B），280~700 nm），探讨了紫外辐射下铜藻的光合活性变化和抗氧化应激响应。结果显示，3种光辐射处理下，藻体光合活性均受到抑制，最大光化学量子产量（Fv/Fm）都随辐射时间延长而逐渐降低，降低幅度为PAB＞PA＞P。后继的240 min低光P （PAR，2.0 W/m2）恢复过程中，藻体Fv/Fm均逐渐恢复。相应地，光辐射处理后，藻体内的活性氧成分O2–和H2O2及膜脂过氧化产物MDA含量均显著升高，且O2–和MDA在PAB处理中升高幅度更大。同时，这种高水平的O2–、H2O2和MDA含量一直延续至低光恢复过程。光辐射处理后，抗氧化酶超氧化物歧化酶（Superoxide dismutase，SOD）、过氧化氢酶（Catalase，CAT）、过氧化物酶（Peroxidase，POD）的活性和抗氧化物抗坏血酸（Ascorbic acid，AsA）的含量均显著增加，低光恢复后，抗氧化酶CAT和POD活性降低，而SOD和抗氧化物AsA始终保持较高水平，最终使得总抗氧化能力（Ttotal antioxidant capacity，T-AOC）在辐射处理和低光恢复阶段一直保持较高水平。在光辐射处理和低光恢复整个过程中，紫外辐射（UVA和UVB）的存在，显著提高了铜藻的抗氧化酶、抗氧化剂含量及总抗氧化能力，且PAB处理中具有更高的值。本研究首次对金潮藻在紫外胁迫下的抗氧化应激响应做了较系统全面的探究，为铜藻适应漂浮生活生理机制的揭示提供了重要的数据支持。 |
| 关键词: 铜藻(Sargassum horneri) 紫外辐射 光合活性 氧化应激响应 |
| DOI：10.11759/hykx20210713001 |
| 分类号:P735 |
| 基金项目:山东省自然科学基金项目（ZR2020MD092；ZR2019MC015；ZR2020QC025） |
|
| Anti-oxidative stress response of Sargassum horneri to UV radiation exposure |
|
LI Ling-xue1, YAN Fang1,2, WU Hong-yan1,2, ZANG Sha-sha1,2, JIANG Xiao-tong1, LI Bao-qi1, LV Zheng-zheng1, XU Zhi-guang1,2
|
|
1.School of Life Sciences, Ludong University, Yantai 264025, China;2.Key Laboratory of Marine Biotechnology in Universities of Shandong, Ludong University, Yantai 264025, China
|
| Abstract: |
| The enhancement of ultraviolet radiation (UVR) usually leads to the production of reactive oxygen species in algae,thus damaging the photosynthetic organs of algae and causing algae photoinhibition.Sargassum golden tide frequently broke out in many parts of the world in recently years.When the golden tide forms,the algae drifting on the sea surface would receive more UVR,but the physiological mechanism of the golden tide algae to cope with this UVR stress is still unclear.In this study,Sargassum horneri,the species responsible for the Golden tide in China,was selected as the research object and was introduced to three distinct radiation treatments of P (PAR,photosynthetic active radiation,400–700 nm,200 W/m2),PA (PAR+UVA,320–400 nm) and PAB (PAR+UVA+UVB,280–700 nm) implemented by the laboratory set solar simulator,to investigate the photosynthetic activity and the anti-oxidative stress response of this algae to the UVR exposure.The results demonstrated that the photosynthetic activity of algae was inhibited by all three radiation treatments,emulated by the decline in the maximum photochemical quantum yield (Fv/Fm) with radiation period,which included the decreasing degree of PAB>PA>P.During the following recovery of low light (PAR,2.0 W/m2),Fv/Fm of algae recovered gradually.Correspondingly,the contents of the O2–,H2O2(reactive oxygen species,ROS) and the MDA (product of membrane lipid peroxidation) in the algae exposed to UVR increased significantly under the PAB treatment demonstrating a higher proportion in comparison to the PA treatment.Additionally,such UVR-induced high levels of the O2–,H2O2,and the MDA was sustained till the low-light recovery process.The antioxidant enzymatic activities of the SOD,CAT,and the POD,along with the AsA capacity,also significantly rose from the initial respective radiation treatments.However,during the low light recovery process,the CAT and the POD activity declined,but no such decrease was measured in the SOD and the AsA activity,illustrating that the total antioxidant capacity (T-AOC) of the algae sustained a comparatively higher level throughout the culture.During both the respective radiation treatments and the low light recovery process,the UVR,including the UVA and the UVB,exhibited substantive elevation in the accumulation of the oxidases,antioxidants,and the T-AOC,with the highest values measured under the PAB treatment.The innovation of this study is that for the first time,the anti-oxidative stress responses of golden tide algae under UVR stress have been systematically and comprehensively explored,which would provide important data support for revealing the physiological mechanism of adaption to drifting in S.horneri. |
| Key words: Sargassum horneri UVR photosynthetic activity oxidative stress response |
