Riboflavin spraying impairs the antioxidant defense system but induces waterlogging tolerance in tobacco
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ORIGINAL PAPER
Riboflavin spraying impairs the antioxidant defense system but induces waterlogging tolerance in tobacco Benliang Deng • Xuehui Jin
Received: 13 January 2013 / Revised: 19 April 2013 / Accepted: 13 May 2013 / Published online: 22 May 2013 Ó Franciszek Go´rski Institute of Plant Physiology, Polish Academy of Sciences, Krako´w 2013
Abstract Riboflavin, which causes plants to produce reactive oxygen species (ROS) when exposed to light, is an excellent photosensitizer for biocidal reactions. This study explores the possible protective role of riboflavin against waterlogging stress in tobacco plants. Tobacco seedlings (4 weeks old) were divided into four groups and pretreated with 0, 0.2, 0.5 or 1.0 mM riboflavin for 1 week, after which all groups were exposed to waterlogging stress for 7 days. We observed delayed leaf senescence and extended survival time, suggesting that riboflavin can confer increased waterlogging tolerance to plants as compared with the control (0 mM riboflavin). Enhanced stomatal closure was observed in the riboflavin-pretreated tobacco. We evaluated the levels of oxidative damage (H2O2 and lipid peroxidation), antioxidant enzyme (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) activity and antioxidant metabolites (including ascorbate and glutathione) in tobacco leaves that were pretreated with riboflavin. However, the results show that riboflavin pretreatment caused a decrease in chlorophyll content, antioxidant enzyme activity and redox values (AsA/DHA and GSH/GSSG), while causing a significant increase in lipid peroxidation, H2O2 accumulation and total ascorbate or glutathione content. In addition, the survival time and stomatal aperture of riboflavin-treated plants were significantly modified by exogenous application of GSH, well-known ROS scavenger. To explain the stomatal
Communicated by J. Zwiazek. B. Deng (&) X. Jin Plant Pathology Laboratory, Department of Agronomy, Heilongjiang Bayi Agricultural University, Daqing 163319, Heilongjiang, China e-mail: [email protected]
closure observed in tobacco plants, we propose a ‘‘damage avoidance’’ hypothesis based on riboflavin-mediated ROS toxicity. The protective function of the photosensitizer riboflavin may be highly significant for farming in frequently waterlogged areas. Keywords Nicotiana benthamiana Riboflavin Oxidative damage Stomatal closure Waterlogging tolerance Abbreviations ROS Reactive oxygen species H2O2 Hydrogen peroxide SOD Superoxide dismutase CAT Catalase APX Ascorbate peroxidase GR Glutathione reductase TBARS Thiobarbituric acid reactive substance GSH Reduced glutathione GSSG Oxidized glutathione AsA Reduced ascorbate DHA Oxidized ascorbate
Introduction Waterlogging, which can result in low oxygen availability, represents the most severe abiotic stress and constrains agricultural production worldwide. One of the most wellcharacterized plant adaptations to hypoxia/anoxia is the switch from aerobic respiration to anaerobic fermentation (Ismond et al. 2003). While both dro
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