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Metabolism in orange fruits is driven by photooxidative stress in the leaves

Authors

  • Florine Poiroux-Gonord,

    1. INRA – UR 1103 Génétique et Ecophysiologie de la Qualité des Agrumes, San Giuliano, France
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  • Jérémie Santini,

    1. INRA – UR 1103 Génétique et Ecophysiologie de la Qualité des Agrumes, San Giuliano, France
    2. UMR CNRS 6134, Laboratoire Biochimie et Biologie Moléculaire du Végétal, Quartier Grossetti, BP52, Corte, France
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  • Anne-Laure Fanciullino,

    1. INRA – UR 1103 Génétique et Ecophysiologie de la Qualité des Agrumes, San Giuliano, France
    2. INRA – UR 1115 Plantes et Systèmes de culture Horticoles, Site Agroparc, Avignon Cedex 9, France
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  • Félicie Lopez-Lauri,

    1. Laboratoire de Physiologie des Fruits et Légumes, Université d'Avignon et des Pays du Vaucluse, Bât Agrosciences, 301 rue Baruch de Spinoza, BP 21239, Avignon Cedex 9, France
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  • Jean Giannettini,

    1. UMR CNRS 6134, Laboratoire Biochimie et Biologie Moléculaire du Végétal, Quartier Grossetti, BP52, Corte, France
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  • Huguette Sallanon,

    1. Laboratoire de Physiologie des Fruits et Légumes, Université d'Avignon et des Pays du Vaucluse, Bât Agrosciences, 301 rue Baruch de Spinoza, BP 21239, Avignon Cedex 9, France
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  • Liliane Berti,

    1. UMR CNRS 6134, Laboratoire Biochimie et Biologie Moléculaire du Végétal, Quartier Grossetti, BP52, Corte, France
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  • Laurent Urban

    Corresponding author
    1. Laboratoire de Physiologie des Fruits et Légumes, Université d'Avignon et des Pays du Vaucluse, Bât Agrosciences, 301 rue Baruch de Spinoza, BP 21239, Avignon Cedex 9, France
    • INRA – UR 1103 Génétique et Ecophysiologie de la Qualité des Agrumes, San Giuliano, France
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Correspondence

Corresponding author,

e-mail: laurent.urban@univ-avignon.fr

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.

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