title: Metabolism in orange fruits is driven by photooxidative stress in the leaves.
abstract: In plants, stress signals propagate to trigger distant responses and thus stress acclimation in non-exposed organs. We tested here the hypothesis that leaves submitted to photooxidative stress may influence the metabolism of nearby fruits and thus quality criteria. Leaves of orange trees (Citrus sinensis (L.) Osbeck cv. 'Navelate') were acclimated to shade for 1 week and then submitted to full (FL) and medium light (ML) conditions. As expected, photoinhibition was detected in leaves of both FL and ML treatments as revealed by stress indicators (Fv /Fm , Performance Index) for at least 99 h after treatments. In the fruits near the stressed leaves, we then determined the activities of enzymes related to oxidative stress, superoxide dismutase, catalase and the enzymes of the ascorbate (AA)/glutathione cycle, as well as the contents in sugars, organic acids and carotenoids. Ascorbate peroxidase and monodehydroascorbate reductase activities in the pulp of fruits were dramatically higher in both treatments when compared to the control. AA and total sugars were not affected by the photooxidative stress. However, the FL treatment resulted in a 16% increase in total organic acids, with succinic acid being the major contributor, a shift towards less glucose + fructose and more sucrose, and a 15% increase in total carotenoids, with cis-violaxanthin being the major contributor. Our observations strongly suggest the existence of a signal generated in leaves in consequence of photooxidative stress, transmitted to nearby fruits. Exploiting such a signal by agronomic means promises exciting perspectives in managing quality criteria in fruits accumulating carotenoids.
authors: INRA - UR 1103 Génétique et Ecophysiologie de la Qualité des Agrumes, F-20230, San Giuliano, France.
authors: Florine
authors: F
authors: Poiroux-Gonord
authors: Jérémie
authors: J
authors: Santini
authors: Anne-Laure
authors: AL
authors: Fanciullino
authors: Félicie
authors: F
authors: Lopez-Lauri
authors: Jean
authors: J
authors: Giannettini
authors: Huguette
authors: H
authors: Sallanon
authors: Liliane
authors: L
authors: Berti
authors: Laurent
authors: L
authors: Urban
mesh_terms: D060387:Ascorbate Peroxidases / Q000378:metabolism; D001205:Ascorbic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D002264:Carboxylic Acids / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D032084:Citrus sinensis / Q000378:metabolism* / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005632:Fructose / Q000378:metabolism; D005638:Fruit / Q000378:metabolism* / Q000528:radiation effects; D005947:Glucose / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D008027:Light; D018384:Oxidative Stress / Q000502:physiology* / Q000528:radiation effects; D018515:Plant Leaves / Q000378:metabolism* / Q000528:radiation effects; D010940:Plant Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000528:radiation effects; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D002264:Carboxylic Acids; D010940:Plant Proteins; D002734:Chlorophyll; D005632:Fructose; D002338:Carotenoids; C036225:ascorbyl monostearate; D006861:Hydrogen Peroxide; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase; D005978:Glutathione; D005947:Glucose; D001205:Ascorbic Acid