title: Characterization of Blue-Green Fluorescence in the Mesophyll of Sugar Beet (Beta vulgaris L.) Leaves Affected by Iron Deficiency.
abstract: The mesophyll of sugar beet (Beta vulgaris L.) leaves emits red (chlorophyll a) fluorescence and blue-green fluorescence when excited with ultraviolet light. The intensity of blue-green fluorescence was increased in mesophylls affected by iron deficiency. This increase was large and progressive. It was concomitant with a decrease of photosynthetic pigments per unit of leaf area. Most of the increase in blue-green fluorescence can be explained by the decrease of the screening of ultraviolet light by chlorophylls and carotenoids. In addition, chlorophylls selectively reabsorb blue fluorescence, which leads to a change in the form of the fluorescence emission spectra. This effect induces an increase of the blue-to-green fluorescence ratio in control mesophylls that was concomitant with the decrease of chlorophyll per unit of leaf area. Iron deficiency induced a decrease of the blue-to-green fluorescence ratio that may be attributed to an accumulation of flavins fluorescing in the green. Time-resolved fluorescence measurements indicate that they are mostly riboflavin and/or flavin mononucleotide phosphate. Our data also indicate that the blue-green fluorescence emitted from the mesophyll contains fluorescence of nicotinamide nucleotides.
authors.affiliation: Laboratoire pour I'Utilisation du Rayonnement Electromagnetique, Universite de Paris XI, 91405 Orsay, France.
authors.forename: F.
authors.initials: F
authors.lastname: Morales
authors.forename: Z. G.
authors.initials: ZG
authors.lastname: Cerovic
authors.forename: I.
authors.initials: I
authors.lastname: Moya