title: Silver nanoparticles induced reactive oxygen species via photosynthetic energy transport imbalance in an aquatic plant.
abstract: The rapid growth in silver nanoparticles (AgNPs) commercialization has increased environmental exposure, including aquatic ecosystem. It has been reported that the AgNPs have damaging effects on photosynthesis and induce oxidative stress, but the toxic mechanism of AgNPs is still a matter of debate. In the present study, on the model aquatic higher plant Spirodela polyrhiza, we found that AgNPs affect photosynthesis and significantly inhibit Photosystem II (PSII) maximum quantum yield (Fv/Fm) and effective quantum yield (ΦPSII). The changes of non-photochemical fluorescence quenching (NPQ), light-induced non-photochemical fluorescence quenching [Y(NPQ)] and non-light-induced non-photochemical fluorescence quenching [Y(NO)] showed that AgNPs inhibit the photo-protective capacity of PSII. AgNPs induce reactive oxygen species (ROS) that are mainly produced in the chloroplast. The activity of ribulose-1, 5-bisphosphate carboxylase-oxygenase (Rubisco) was also very sensitive to AgNPs. The internalized Ag, regardless of whether the exposure was Ag+or AgNPs had the same capacity to generate ROS. Our results support the hypothesis that intra-cellular AgNP dissociate into high toxic Ag+. Rubisco inhibition leads to slowing down of CO2assimilation. Consequently, the solar energy consumption decreases and then the excess excitation energy promotes ROS generation in chloroplast.
authors.affiliation: a Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences , Wuhan , China.|b University of Chinese Academy of Sciences , Beijing , China.|c BIP UMR 7281, Aix Marseille Univ CNRS , 31 Chemin Joseph Aiguier, Marseille Cedex 20, Marseille, France.
authors.forename: Hong Sheng
authors.initials: HS
authors.lastname: Jiang
authors.affiliation: d Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, Hainan University , Haikou , China.
authors.forename: Li Yan
authors.initials: LY
authors.lastname: Yin
authors.affiliation: e College of Geosciences, China University of Petroleum , Beijing , China.
authors.forename: Na Na
authors.initials: NN
authors.lastname: Ren
authors.affiliation: a Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences , Wuhan , China.|b University of Chinese Academy of Sciences , Beijing , China.
authors.forename: Su Ting
authors.initials: ST
authors.lastname: Zhao
authors.affiliation: a Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences , Wuhan , China.|b University of Chinese Academy of Sciences , Beijing , China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Li
authors.affiliation: a Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences , Wuhan , China.
authors.forename: Yongwei
authors.initials: Y
authors.lastname: Zhi
authors.affiliation: a Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences , Wuhan , China.|b University of Chinese Academy of Sciences , Beijing , China.
authors.forename: Hui
authors.initials: H
authors.lastname: Shao
authors.affiliation: a Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences , Wuhan , China.|f Hubei Key Laboratory of Wetland Evolution & Ecological Restoration, Wuhan Botanical Garden, Chinese Academy of Sciences , Wuhan , China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: c BIP UMR 7281, Aix Marseille Univ CNRS , 31 Chemin Joseph Aiguier, Marseille Cedex 20, Marseille, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Gontero
mesh_terms: D029064:Araceae / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D002734:Chlorophyll / Q000378:metabolism; D004735:Energy Transfer; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects*; D010788:Photosynthesis / Q000187:drug effects*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012834:Silver / Q000737:chemistry / Q000633:toxicity*; D013472:Sunlight
chemical_list: D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D012834:Silver
keywords: AgNPs; ROS; Rubisco; Spirodela polyrhiza; photosynthesis