Intertidal macroalgae can cope with the dual effects of UV-B irradiation and allelopathy.To study the impacts of the two stressors,we co-cultured Corallina pilulifera with Sargassum thunbergii in 1:1 and l:10 ratios under different doses of UV-B radiation.The response of the antioxidant defense system,focusing on activities of superoxide dismutase(SOD),ascorbate peroxidase(APX),peroxidase(POX)and glutathione reductase(GR),was monitored.In addition,isoenzyme patterns were analyzed using non-denaturing polyacrylamide gel electrophoresis.The results show that the activities of SOD,APX,and GR were all significantly affected by both UV-B radiation and allelopathy,and the effect of their interaction was significant.However,POX activity was only influenced by UV-B radiation.The enzymatic assay revealed four distinct bands of SOD.The SODIII band weakened significantly when the co-cultures were exposed to extremely high dosage of UV-B irradiation under both co-culturing ratios of 1∶1 and 1∶10.When the co-culturing ratio was l:10,both POXII and APXII enzyme activities increased with different UV-B doses.GR activity was at its greatest when the co-culture ratio was 1∶10 and exposure was to the higher UV-B doses.The activities of GRIII and GRIV were elevated under all UV treatments whereas the activities of GRI and GRII were reduced under the lower UV-B treatments but were elevated under the higher UV-B treatments.However,lipid peroxidation,as indicated by the thiobarbituric acid-reacting substance(TBARS)assay,increased significantly under the dual stressors.Our data suggest that allelopathy and UV-B radiation stress can each affect the antioxidant enzyme activities of C.pilulifera.Critically,the adverse effects of UV-B on C.pilulifera were intensified by the compounding effects of allelopathy.

College of Life Sciences,Yantai University,Yantai 264005,China;Yantai Jien Biotechnology Co.,Ltd.,Yantai 264006,China

[1]Ming LIU;Jiqiang ZHAO;Yujuan PANG;Lipei ZHANG;Fuhua BIAN;Lixia LI-.UV-B irradiation and allelopathy by Sargassum thunbergii affects the activities of antioxidant enzymes and their isoenzymes in Corallina pilulifera)[J].海洋湖沼学报（英文版）,2022(05):1950-1962

allelopathy,Corallina,pilulifera,Intertidal,SODIII,POXII,APXII,GRIII,GRIV,GRII

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