Antioxidant defence in UV-irradiated tobacco leaves is centred on hydrogen-peroxide neutralization

• Published in: Plant physiology and biochemistry Vol. 82; pp. 239 - 243
• Main Authors: Majer, Petra, Czégény, Gyula, Sándor, Györgyi, Dix, Philip J., Hideg, Éva
• Format: Journal Article
• Language: English
• Published: Paris Elsevier Masson SAS 01.09.2014; Elsevier
• Subjects: Antioxidant; Antioxidants - metabolism; Ascorbate Peroxidases - metabolism; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Hydrogen peroxide; Hydrogen Peroxide - metabolism; Lipid Peroxidation - radiation effects; Nicotiana - metabolism; Nicotiana - radiation effects; Oxidative Stress - radiation effects; Peroxidase; Peroxidases - metabolism; Photosynthesis; Plant Leaves - metabolism; Plant Leaves - radiation effects; Plant physiology and development; Reactive oxygen species; Reactive Oxygen Species - metabolism; Tobacco; Ultraviolet Rays; UV treatment; PAR; UV; Reactive oxygen species; Hydrogen peroxide; PS; Y(II); POD; APX; SOD; Antioxidant; UV treatment; Tobacco; Fv/Fm; Peroxidase; FRAP; PPFD; Photosynthesis; ABTS; Enzyme; Plant leaf; Ultraviolet irradiation; Peroxidases; Plant physiology; Oxidoreductases
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2014.06.011

Greenhouse grown tobacco (Nicotiana tabacum L. cv. Petit Havana) plants were exposed to supplemental UV centred at 318 nm and corresponding to 13.6 kJ m−2 d−1 biologically effective UV-B (280–315 nm) radiation. After 6 days this treatment decreased photosynthesis by 30%. Leaves responded by a large increase in UV-absorbing pigment content and antioxidant capacities. UV-stimulated defence against ROS was strongest in chloroplasts, since activities of plastid enzymes FeSOD and APX had larger relative increases than other, non-plastid specific SODs or peroxidases. In addition, non-enzymatic defence against hydroxyl radicals was doubled in UV treated leaves as compared to controls. In UV treated leaves, the extent of activation of ROS neutralizing capacities followed a peroxidases > hydroxyl-radical neutralization > SOD order. These results suggest that highly effective hydrogen peroxide neutralization is the focal point of surviving UV-inducible oxidative stress and argue against a direct signalling role of hydrogen peroxide in maintaining adaptation to UV, at least in laboratory experiments. •Supplemental UV decreased photosynthesis by 30% and activated antioxidant defence.•Defence against ROS focussed on H2O2 (peroxidases, especially APX).•Chloroplast antioxidants APX and Fe-SOD were activated more than other pathways.•Under low PAR/UV conditions acclimation to UV may not rely on H2O2 signals.