Physiological and biochemical response to photooxidative stress of the fundamental citrus species

Jérémie Santini (1) , Jean Giannettini (1) , Stéphane Herbette (2) , Olivier Pailly (3) , Patrick Ollitrault (4) , Luro François (3) , Liliane Berti (1)

1 SPE - Sciences pour l'environnement
2 PIAF - Laboratoire de Physique et Physiologie Intégratives de l'Arbre Fruitier et Forestier
3 GEQA - Génétique et Ecophysiologie de la qualité des agrumes
4 UMR AGAP - Amélioration génétique et adaptation des plantes méditerranéennes et tropicales

Despite the economic importance of citrus, insights on the genetic response to stress are scarce. The aim of the present study was to compare fundamental citrus species for their response to photooxidative stress. The experiment was conducted under orchard conditions on three fundamental citrus species C. medica L., C. reticulata Blanco and C. maxima (Burm.) Merr., and on Fortunella japonica (Thunb.) Swing. We examined their respective net photosynthesis (Pnet), stomatal conductance (Gs) and chlorophyll fluorescence (Fv/Fm) on sun-acclimated leaves and shade-acclimated leaves returned under natural sunlight irradiance. To compare the respective response mechanism, we analyzed changes in oxidative status (hydrogen peroxide (H2O2) and malondialdehyde (MDA)), reactive oxygen species (ROS)-scavenging enzymes (superoxide dismutase (SOD), catalase, ascorbate peroxidase), recycling enzymes (monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase) and antioxidant metabolites (ascorbate and glutathione). Kumquat and pummelo exposed lower down-regulation and full recovery of photosynthetic parameters, lower accumulation of oxidized compounds associated with greater production of reduced glutathione (Gsh) and enhanced activity of the three ROS scavenging enzymes, especially SOD. Citron and mandarin showed a marked decrease and incomplete recovery in photosynthetic performance, mainly in Pnet and Fv/Fm, larger accumulation of oxidative parameters, slighter induction of antioxidant enzymes and down-regulation of reduced ascorbate (Asa) and Gsh synthesis. These results suggest that kumquat and pummelo have a greater tolerance to photooxidative stress than citron and mandarin.

Mots clés: Antioxidant system/Fortunella japonica/Citrus maxima/Citrus medica/Citrus reticulata/Light stress

Domaines: Biochimie, Biologie Moléculaire

Jérémie Santini, Jean Giannettini, Stéphane Herbette, Olivier Pailly, Patrick Ollitrault, et al.. Physiological and biochemical response to photooxidative stress of the fundamental citrus species. Scientia Horticulturae, 2012, 147, pp.126-135. ⟨10.1016/j.scienta.2012.09.014⟩. ⟨hal-00771130⟩