Effects of the heavy metal cadmium on photosynthetic activity and the xanthophyll cycle in Phaeodactylum tricornutum  

作　　者：JI Yan XIE Xiujun WANG Guangce 季琰;解修俊;王广策

机构地区：[1]School of Biological and Chemical Engineering,Qingdao Technical College [2]Key Laboratory of Experimental Marine Biology,Institute of Oceanology,Chinese Academy of Sciences [3]Laboratory for Marine Biology and Biotechnology,Qingdao National Laboratory for Marine Science and Technology

出　　处：《Journal of Oceanology and Limnology》2018年第6期2194-2201,共8页海洋湖沼学报（英文）

基　　金：Supported by the National Natural Science Foundation of China(No.41506172);the International S&T Cooperation Program of China(No.2015DFG32160)

摘　　要：A bstract Cadmium(Cd) is one of the most common and widespread heavy metals in the environment. Cd has adverse effects on photosynthesis that are countered by photosystem I(PSI) and photosystem II(PSII); however, the protective responses of these photosystems to heavy metal stress remain unclear. Using the model diatom P haeodactylum tricornutum, a biological indicator that is widely used to assess the impact of environmental toxins, we simultaneously measured the effects of Cd on PSI and PSII and examined the levels of pigments in response to high light treatments before and after Cd exposure. Cd significantly reduced the quantum yield and electron transport rates of PSI and PSII. The quantum yield of non-photochemical energy dissipation in PSI due to donor side limitation increased faster than the quantum yield due to acceptor side limitation. The Cd treatment activated the P. tricornutum xanthophyll cycle under artificial light conditions, as indicated by an increased diatoxanthin content. Xanthophyll is important for photoprotection; therefore, the accumulation of diatoxanthin may down-regulate PSII activities to reduce oxidative damage. Together, our results suggest that the rapid reduction in PSII activities following Cd exposure is an adaptive response to heavy metal stress that reflects the variable exposure to external stressors in the native P. tricornutum environment.A bstract Cadmium(Cd) is one of the most common and widespread heavy metals in the environment. Cd has adverse effects on photosynthesis that are countered by photosystem I(PSI) and photosystem II(PSII); however, the protective responses of these photosystems to heavy metal stress remain unclear. Using the model diatom P haeodactylum tricornutum, a biological indicator that is widely used to assess the impact of environmental toxins, we simultaneously measured the effects of Cd on PSI and PSII and examined the levels of pigments in response to high light treatments before and after Cd exposure. Cd significantly reduced the quantum yield and electron transport rates of PSI and PSII. The quantum yield of non-photochemical energy dissipation in PSI due to donor side limitation increased faster than the quantum yield due to acceptor side limitation. The Cd treatment activated the P. tricornutum xanthophyll cycle under artificial light conditions, as indicated by an increased diatoxanthin content. Xanthophyll is important for photoprotection; therefore, the accumulation of diatoxanthin may down-regulate PSII activities to reduce oxidative damage. Together, our results suggest that the rapid reduction in PSII activities following Cd exposure is an adaptive response to heavy metal stress that reflects the variable exposure to external stressors in the native P. tricornutum environment.

关 键 词：HEAVY metal CADMIUM photosystemⅠ photosystemⅡ PHAEODACTYLUM TRICORNUTUM 

分 类 号：P[天文地球]