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Effects of copper on the photosynthesis of intact chloroplasts: interaction with manganese

2010-03Journal article Restricted access
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dc.contributor.authorPádua, Mário
dc.contributor.authorCavaco, Ana M.
dc.contributor.authorAubert, Serge
dc.contributor.authorBligny, Richard
dc.contributor.authorCasimiro, Adalcina
dc.date.accessioned2016-08-18T13:36:10Z
dc.date.available2016-08-18T13:36:10Z
dc.date.issued2010-03
dc.description.abstractHighly purified, intact chloroplasts were prepared from pea (Pisum sativum L.) and spinach (Spinacia oleracea L.) following an identical procedure, and were used to investigate the cupric cation inhibition on the photosynthetic activity. In both species, copper inhibition showed a similar inhibitor concentration that decreases the enzyme activity by 50% (IC(50) approximately 1.8 microM) and did not depend on the internal or external phosphate (Pi) concentration, indicating that copper did not interact with the Pi translocator. Fluorescence analysis suggested that the presence of copper did not facilitate photoinhibition, because there were no changes in maximal fluorescence (F(m)) nor in basal fluorescence (F(o)) of copper-treated samples. The electron transport through the photosystem II (PSII) was also not affected (operating efficiency of PSII-F'v/F'm similar in all conditions). Yet, under Cu(2+) stress, the proportion of open PSII reaction centers was dramatically decreased, and the first quinone acceptor (Q(A)) reoxidation was fully inhibited, as demonstrated by the constant photochemical quenching (q(P)) along experiment time. The quantum yield of PSII electron transport (Phi(PSII)) was also clearly affected by copper, and therefore reduced the photochemistry efficiency. Manganese, when added simultaneously with copper, delayed the inhibition, as measured by oxygen evolution and chlorophyll fluorescence, but neither reversed the copper effect when added to copper-inhibited plastids, nor prevented the inhibition of the Hill activity of isolated copper-treated thylakoids. Our results suggest that manganese competed with copper to penetrate the chloroplast envelope. This competition seems to be specific because other divalent cations e.g. magnesium and calcium, did not interfere with the copper action in intact chloroplasts. All results do suggest that, under these conditions, the stroma proteins, such as the Calvin-Benson cycle enzymes or others are the most probable first target for the Cu(2+) action, resulting in the total inhibition of chloroplast photosynthesis and in the consequent unbalanced rate of production and consumption of the reducing power.pt_PT
dc.identifier.citationPádua M, Cavaco AM, Aubert S, Bligny R, Casimiro A. Effects of copper on the photosynthesis of intact chloroplasts: interaction with manganese. Physiol Plant. 2010;138(3):301-11.pt_PT
dc.identifier.doi10.1111/j.1399-3054.2009.01335.xpt_PT
dc.identifier.urihttp://hdl.handle.net/10400.21/6373
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherWileypt_PT
dc.relation.publisherversionhttp://onlinelibrary.wiley.com/doi/10.1111/j.1399-3054.2009.01335.x/abstract;jsessionid=82D66E514A13936AD1D1E62ADE7658BE.f03t02pt_PT
dc.rights.urihttp://creativecommons.org/licenses/by-nc/4.0/pt_PT
dc.subjectCarbon Dioxidept_PT
dc.subjectChlorophyllpt_PT
dc.subjectChloroplastspt_PT
dc.subjectCopperpt_PT
dc.subjectFluorescencept_PT
dc.subjectManganesept_PT
dc.subjectOxygen Consumptionpt_PT
dc.subjectPeaspt_PT
dc.subjectPhotosynthesispt_PT
dc.subjectPhotosystem II Protein Complexpt_PT
dc.subjectSpinacia oleraceapt_PT
dc.titleEffects of copper on the photosynthesis of intact chloroplasts: interaction with manganesept_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage311pt_PT
oaire.citation.issue3pt_PT
oaire.citation.startPage301pt_PT
oaire.citation.titlePhysiologia Plantarumpt_PT
oaire.citation.volume138pt_PT
rcaap.rightsrestrictedAccesspt_PT
rcaap.typearticlept_PT

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