PSII photochemistry is the primary target of oxidative stress imposed by ozone in Tilia americana |
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| Authors: | E. Pellegrini |
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| Affiliation: | 1. University of Novi Sad, Faculty of Agriculture, Trg D. Obradovica 8, 21000 Novi Sad, Serbia;2. University of Belgrade, Faculty of Forestry, Kneza Viseslava 1, 11000 Belgrade, Serbia;1. National University of Rwanda, Faculty of Science, University Avenue, Box 117, Huye, Rwanda;2. Department of Environmental Studies, Antioch University New England, 40 Avon St., Keene, NH 0343l, USA;3. School of Landscape Architecture, Beijing Forestry University, Beijing 100083, PR China;4. DFGFI-Karisoke Research Center, P.O. Box 1005, Musanze, Rwanda;1. Institute of Biometeorology, National Research Council, Firenze, Italy;2. Department of Bioscience and Territory, University of Molise, Pesche, Italy;3. Department of Agro-biotechnologies, University of Florence, Firenze, Italy;4. Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK;1. Department of Work Science, Business Economics and Environmental Psychology, Swedish University of Agricultural Sciences (SLU), Alnarp, Sweden;2. Department of Landscape Architecture, Planning and Management, Swedish University of Agricultural Sciences (SLU), Alnarp, Sweden;3. Environmental Psychology, Department of Architecture and Built Environment, Lund University, Lund, Sweden;4. School of Sport Sciences, Linnaeus University, Kalmar, Sweden;5. Department of Food and Nutrition, and Sport Science, Gothenburg University, Sweden;6. Department of Public Health Sciences, Karolinska institutet, Stockholm, Sweden;1. University of Eastern Finland, Department of Biology, POB 111, 80101 Joensuu, Finland;2. Plant Ecology and Environmental Science, National Botanical Research Institute (CSIR-NBRI), Lucknow, India;3. Radio and Atmospheric Sciences Division, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012, India |
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| Abstract: | Trees are essential in the urban environment not only because of their aesthetic and social values, but also for their effects on air quality. Data of the present experiment show some of the integrated mechanisms that may confer sensitivity/tolerance in Tilia americana saplings exposed to ozone treatment (120 ppb, 5 h day?1 for 45 consecutive days) in order to improve the management of green spaces responding to oxidative stress. At the end of exposure, plants do not exhibit any foliar symptoms. Profiles related to membrane injury, photosynthetic gas exchange, chlorophyll a fluorescence, pigment content and enzymes/metabolites linked to the synthesis of phenylpropanoids show a vulnerability in terms of: (i) change in the ionic and solute reactions of the membrane cells (maximum value of +34%, 28 days after the beginning of fumigation, compared to controls); (ii) inhibition of the carbon assimilation (?41%), mostly as a consequence of non-stomatal limitation of assimilation rate; (iii) progressive inhibition of the Calvin cycle, as demonstrated by decreases in Rubisco carboxylation efficiency and regeneration capacity (?35 and ?21%, respectively, at the end of exposure), quantum yield of electron transfer at PSII and in the fraction of energy passively dissipated as heat and fluorescence (?34% and ?31%); (iv) senescence process (decline in demand for reducing power and energy at the end of treatment); (v) damage to the chlorophyll pigment system. However, the activation of xanthophylls cycle and phenylpropanoid metabolism, that can be considered a strategy in plants in order to regulate light absorbed energy and to scavenge reactive oxygen species does not preserve PSII photochemistry from impairment at the end of exposure. |
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| Keywords: | Air pollution Carboxylation efficiency No-photochemical quenching Oxidative stress PSII photochemistry Xanthophyll cycle |
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