title: Biophysical probing of Spartina maritima photo-system II changes during prolonged tidal submersion periods.
abstract: Submergence is one of the major constrains affecting wetland plants, with inevitable impacts on their physiology and productivity. Global warming as a driving force of sea level rise, tend to increase the submersion periods duration. Photosynthesis biophysical probing arise as an important tool to understand the energetics underlying plant feedback to these constrains. As in previous studies with Spartina maritima, there was no inhibition of photosynthetic activity in submerged individuals. Comparing both donor and acceptor sides of the PSII, the first was more severely affected during submersion, driven by the inactivation of the OEC with consequent impairment of the ETC. Although this apparent damage in the PSII donor side, the electron transport per active reaction centre was not substantially affected, indicating that this reduction in the electron flow is accompanied by a proportional increase in the number of active reaction centres. These conditions lead to the accumulation of excessive reducing power, source of damaging ROS, counteracted by efficient energy dissipation processes and anti-oxidant enzymatic defences. This way, S. maritima appears as a well-adapted species with an evident photochemical plasticity towards submersion, allowing it to maintain its photosynthetic activity even during prolonged submersion periods.
authors.affiliation: Centre of Oceanography, Faculty of Sciences, University of Lisbon (CO), Campo Grande, 1749-016 Lisbon, Portugal. Electronic address: baduarte@fc.ul.pt.
authors.forename: B
authors.initials: B
authors.lastname: Duarte
authors.affiliation: Centre of Oceanography, Faculty of Sciences, University of Lisbon (CO), Campo Grande, 1749-016 Lisbon, Portugal.
authors.forename: D
authors.initials: D
authors.lastname: Santos
authors.affiliation: Institute of Marine Research, Marine and Environment Research Centre (IMAR-CMA), c/o Department of Zoology, Faculty of Sciences and Technology, University of Coimbra, 3000 Coimbra, Portugal.
authors.forename: J C
authors.initials: JC
authors.lastname: Marques
authors.affiliation: Centre of Oceanography, Faculty of Sciences, University of Lisbon (CO), Campo Grande, 1749-016 Lisbon, Portugal.
authors.forename: I
authors.initials: I
authors.lastname: Caçador
mesh_terms: D000064:Acclimatization; D000975:Antioxidants / Q000378:metabolism; D004579:Electron Transport; D057232:Global Warming; D007101:Immersion; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000502:physiology; D006109:Poaceae / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D053833:Wetlands
chemical_list: D000975:Antioxidants; D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species
keywords: Biophysical probing of photosynthesis; OJIP transients; PSII photochemistry; Sea level rise; Underwater photosynthesis