Xanthophyll cycle activity in detached barley leaves senescing under dark and light |
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Authors: | M. Špundová K. Strzałka J. Nauš |
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Affiliation: | (1) Department of Experimental Physics, Palacký University, T. Svobody 26, 771 46 Olomouc, Czech Republic;(2) Department of Plant Physiology and Biochemistry, Faculty of Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland |
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Abstract: | Senescence-induced changes in the xanthophyll cycle activity and chlorophyll (Chl) fluorescence parameters were compared in detached barley (Hordeum vulgare L.) leaf segments kept for 6 d in darkness or under continuous white light (90 mol m–2 s–1). Before detachment of the leaf segments, the plants were grown at periodic regime [12 h light (90 mol m–2 s–1)/12 h dark]. The de-epoxidation state of the xanthophyll cycle pigments (DEPS) in the leaf samples was determined immediately (the actual DEPS), after 1 h of dark-adaptation (the residual DEPS), and during 14 min of a high-irradiance (HI) exposure (500 mol m–2 s–1) (HI-induced DEPS). In the light-senescing segments, senescence was delayed pronouncedly compared to dark-senescing ones as the Chl content, the photosystem 2 photochemistry, and electron transport processes were highly maintained. Further, the actual DEPS increased, probably due to the increased mean photon dose. The HI-induced increase in the DEPS was stimulated in the light-senescing segments, whereas it was slowed down in the dark-senescing ones. However, after the 14 min HI-exposure of the dark-senescing segments the HI-induced DEPS was not markedly lower than in the mature leaves, which indicated the maintenance of the xanthophyll cycle operation. |
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Keywords: | ageing carotenoids chlorophyll fluorescence induction de-epoxidation state Hordeum vulgare photosystem 2 |
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