title: Tolerance to clomazone herbicide is linked to the state of LHC, PQ-pool and ROS detoxification in tobacco (Nicotiana tabacum L.).
abstract: In this study, plantlets of two tobacco (Nicotiana tabacum L.) varieties that are clomazone-tolerant (cv. Xanthi) and clomazone-sensitive (cv. Virginie vk51) were subjected to low concentration of clomazone herbicide. The oxygen-evolving rate of isolated chloroplasts, chlorophyll a fluorescence transients, JIP-test responses, hydrogen peroxide contents, antioxidant enzyme activities, cytohistological results and photosynthetic pigment contents were recorded. The results indicated that the carotenoid content was 2-fold higher in Virginie, which had greater clomazone sensitivity than Xanthi. Virginie exhibited noticeable decreases in the LHC content (Chl a/b ratio), the maximum photochemical quantum efficiency of PSII (Fv/Fm), the performance index on the absorption basis (PIabs), and the electron flux beyond the first PSII QA evaluated as (1-VJ) with VJ=(FJ-F0)/(Fm-F0) as well as increases in the rate of photon absorption (ABS/RC) and the energy dissipation as heat (DI0/RC). These results suggest that PSII photoinhibition occurred as a consequence of more reduced PQ-pool and accumulated QA(-). The oxygen evolution measurements indicate that PSI electron transport activity was not affected by clomazone. The more significant accumulation of H2O2 in Virginie compared to Xanthi was due to the absence of ROS-scavenging enzymes, and presumably induced programmed cell death (PCD). The symptoms of PCD were observed by cytohistological analysis, which also indicated that the leaf tissues of clomazone-treated Virginie exhibited significant starch accumulation compared to Xanthi. Taken together, these results indicate that the variable tolerance to clomazone observed between Virginie and Xanthi is independent of the carotenoid content and could be related to the state of the LHC, the redox state of the PQ-pool, and the activity of detoxification enzymes.
authors.affiliation: Laboratoire Physiologie des Fruits et Légumes (EA 4279), Université d'Avignon et des Pays de Vaucluse, Bât Agrosciences, 301 rue Baruch de Spinoza, BP 21239, F-84916 Avignon cedex 9, France. Electronic address: majd.darwish@alumni.univ-avignon.fr.
authors.forename: Majd
authors.initials: M
authors.lastname: Darwish
authors.affiliation: Laboratoire Physiologie des Fruits et Légumes (EA 4279), Université d'Avignon et des Pays de Vaucluse, Bât Agrosciences, 301 rue Baruch de Spinoza, BP 21239, F-84916 Avignon cedex 9, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Vidal
authors.affiliation: Laboratoire Physiologie des Fruits et Légumes (EA 4279), Université d'Avignon et des Pays de Vaucluse, Bât Agrosciences, 301 rue Baruch de Spinoza, BP 21239, F-84916 Avignon cedex 9, France.
authors.forename: Félicie
authors.initials: F
authors.lastname: Lopez-Lauri
authors.affiliation: Laboratoire Physiologie des Fruits et Légumes (EA 4279), Université d'Avignon et des Pays de Vaucluse, Bât Agrosciences, 301 rue Baruch de Spinoza, BP 21239, F-84916 Avignon cedex 9, France.
authors.forename: Osama
authors.initials: O
authors.lastname: Alnaser
authors.affiliation: Laboratoire Physiologie des Fruits et Légumes (EA 4279), Université d'Avignon et des Pays de Vaucluse, Bât Agrosciences, 301 rue Baruch de Spinoza, BP 21239, F-84916 Avignon cedex 9, France.
authors.forename: Sanders
authors.initials: S
authors.lastname: Junglee
authors.affiliation: Laboratoire Physiologie des Fruits et Légumes (EA 4279), Université d'Avignon et des Pays de Vaucluse, Bât Agrosciences, 301 rue Baruch de Spinoza, BP 21239, F-84916 Avignon cedex 9, France.
authors.forename: Mohamed
authors.initials: M
authors.lastname: El Maataoui
authors.affiliation: Laboratoire Physiologie des Fruits et Légumes (EA 4279), Université d'Avignon et des Pays de Vaucluse, Bât Agrosciences, 301 rue Baruch de Spinoza, BP 21239, F-84916 Avignon cedex 9, France.
authors.forename: Huguette
authors.initials: H
authors.lastname: Sallanon
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis; D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000378:metabolism; D004579:Electron Transport; D006540:Herbicides / Q000494:pharmacology*; D007555:Isoxazoles / Q000494:pharmacology*; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D023303:Oxazolidinones / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D010971:Plastoquinone / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D036226:Seedlings / Q000187:drug effects / Q000502:physiology; D014026:Nicotiana / Q000187:drug effects / Q000502:physiology*
chemical_list: D000975:Antioxidants; D006540:Herbicides; D007555:Isoxazoles; D045342:Light-Harvesting Protein Complexes; D023303:Oxazolidinones; D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D002338:Carotenoids; C095255:clomazone; D010971:Plastoquinone; D010100:Oxygen; D000077194:Chlorophyll A
keywords: Chlorophyll a fluorescence transients; Chloroplast oxygen evolution; Clomazone; Nicotiana tabacum; Tolerance