title: Chloroplast-located flavonoids can scavenge singlet oxygen.
abstract: * The hypothesis was tested that flavonoids may scavenge singlet oxygen ((1)O(2)) in mesophyll cells of Phillyrea latifolia exposed to excess-light stress. * In cross-sections taken from leaves developed at 10% (shade) or 100% (sun) solar irradiance, we evaluated the excess photosynthetically active radiation (PAR)-induced accumulation of (1)O(2) in mesophyll cells by imaging the fluorescence quenching of the specific (1)O(2) probe N-[2-(diethylamino)ethyl]-N-[(2,5-dihydro-2,2,5,5-tetramethyl-1H-pyrrol-3-yl)methyl]-5-(dimethylamino)-1-naphthalenesulfonamide (DanePy). The intracellular location of flavonoids was also analyzed using three-dimensional deconvolution microscopy. * Photo-induced quenching of DanePy fluorescence was markedly greater in the mesophyll of shade leaves than in that of sun leaves, the former showing a negligible accumulation of mesophyll flavonoids. The photo-induced generation of (1)O(2) was inversely related to the content of flavonoids in the mesophyll cells of sun leaves. Flavonoids were located in the chloroplasts, and were likely associated with the chloroplast envelope. * Here we provide relevant evidence for the potential scavenger activity of chloroplast-located flavonoids against (1)O(2) and new insights into the photo-protective role of flavonoids in higher plants.
authors.affiliation: Istituto di Fisica Applicata 'Nello Carrara', IFAC, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, I-50019, Sesto F.no, Firenze, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Agati
authors.affiliation: Istituto di Fisica Applicata 'Nello Carrara', IFAC, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, I-50019, Sesto F.no, Firenze, Italy.|Dipartimento di Chimica Organica 'Ugo Schiff', Università di Firenze, Via della Lastruccia 13, I-50019 Sesto F.no, Firenze, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Matteini
authors.affiliation: Dipartimento di Chimica Organica 'Ugo Schiff', Università di Firenze, Via della Lastruccia 13, I-50019 Sesto F.no, Firenze, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Goti
authors.affiliation: Istituto per la Valorizzazione del Legno e delle Specie Arboree, IVALSA, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, I-50019, Sesto F.no, Firenze, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Tattini
mesh_terms: D002736:Chloroplasts / Q000378:metabolism*; D003619:Dansyl Compounds / Q000378:metabolism; D005419:Flavonoids / Q000032:analysis*; D005453:Fluorescence; D008027:Light; D029592:Oleaceae / Q000378:metabolism; D028223:Pinus / Q000378:metabolism; D010880:Piperidines / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D026082:Singlet Oxygen / Q000378:metabolism*
chemical_list: C112332:DanePy; D003619:Dansyl Compounds; D005419:Flavonoids; D010880:Piperidines; D026082:Singlet Oxygen