title: How does iron deficiency disrupt the electron flow in photosystem I of lettuce leaves?
abstract: The changes observed photosystem I activity of lettuce plants exposed to iron deficiency were investigated. Photooxidation/reduction kinetics of P700 monitored as ΔA820 in the presence and absence of electron transport inhibitors and acceptors demonstrated that deprivation in iron decreased the population of active photo-oxidizable P700. In the complete absence of iron, the addition of plant inhibitors (DCMU and MV) could not recover the full PSI activity owing to the abolition of a part of P700 centers. In leaves with total iron deprivation (0μM Fe), only 15% of photo-oxidizable P700 remained. In addition, iron deficiency appeared to affect the pool size of NADP(+) as shown by the decline in the magnitude of the first phase of the photooxidation kinetics of P700 by FR-light. Concomitantly, chlorophyll content gradually declined with the iron concentration added to culture medium. In addition, pronounced changes were found in chlorophyll fluorescence spectra. Also, the global fluorescence intensity was affected. The above changes led to an increased rate of cyclic electron transport around PSI mainly supported by stromal reductants.
authors.affiliation: Groupe de Recherche en Biologie Végétale (GRBV), Université du Québec à Trois-Rivières, Trois-Rivières, Québec G9A 5H7, Canada; Unité de Physiologie et de Biochimie de la Tolérance au Sel chez les Plantes, Faculté des Sciences de Tunis, Campus Universitaire, 1060, Tunisia.
authors.forename: Najoua
authors.initials: N
authors.lastname: Msilini
authors.forename: Jemâa
authors.initials: J
authors.lastname: Essemine
authors.forename: Maha
authors.initials: M
authors.lastname: Zaghdoudi
authors.forename: Johanne
authors.initials: J
authors.lastname: Harnois
authors.forename: Mokhtar
authors.initials: M
authors.lastname: Lachaâl
authors.forename: Zeineb
authors.initials: Z
authors.lastname: Ouerghi
authors.forename: Robert
authors.initials: R
authors.lastname: Carpentier
mesh_terms: D002734:Chlorophyll / Q000378:metabolism*; D004237:Diuron / Q000378:metabolism; D004579:Electron Transport; D007501:Iron / Q000378:metabolism*; D007700:Kinetics; D018545:Lactuca / Q000378:metabolism*; D008027:Light; D010084:Oxidation-Reduction; D010269:Paraquat / Q000378:metabolism; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D013050:Spectrometry, Fluorescence
chemical_list: D045331:Photosystem I Protein Complex; D002734:Chlorophyll; C001785:chlorophyll P 700; D004237:Diuron; D007501:Iron; D010269:Paraquat
keywords: 3 (3,4-dichlorophenyl)-1,1-dimethylurea; Absorbance changes; Chl; Cyclic electron flow; Cyt; DCMU; EDTA; FNR; FQR; FR; Fe deficiency; Fluorescence measurements; LHCI and LHCII; MV; NAD(P)H dehydrogenase complex; Ndh; P700; P700 oxidation/re-reduction kinetics; PAM; PSI and PSII; RC; Rubisco; chlorophyll; cytochrome; ethylenediaminetetracetic acid; far-red; ferredoxin:NAD(P)H reductase; ferredoxin:plastoquinone reductase; light harvesting complexes I and II; methyl viologen; photosystems I and II; pulse amplitude modulation; reaction center; reaction center of photosystem I; ribulose-1,5-diphosphate carboxylase/oxygenase