Changes of fluorescence and xanthophyll pigments during dehydration in the resurrection plantSelaginella lepidophylla in low and medium light intensities |
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Authors: | Catharina Casper William G Eickmeier C Barry Osmond |
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Institution: | (1) Department of Botany, Duke University, 27706 Durham, NC, USA;(2) Department of Biology, Vanderbilt University, 37235 Nashville, TN, USA;(3) Research School of Biological Sciences, Australian National University, Box 475, 2601 Canberra, ACT, Australia |
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Abstract: | The changes in photosynthetic efficiency and photosynthetic pigments during dehydration of the resurrection plantSelaginella lepidophylla (from the Chiuhahuan desert, S.W. Texas, USA) were examined under different light conditions. Changes in the photosynthetic
efficiency were deduced from chlorophyll a fluorescence measurements (Fo, Fm, and Fv) and pigment changes were measured by HPLC analysis. A small decrease in Fv/Fm was seen in hydrated stems in high light (650 μmol photons·m−2·s−1) but not in low light (50 μmol photons·m−2·s−1). However, a pronounced decline in Fv/Fm was observed during dehydration in both light treatments, after one to two hours of dehydration. A rise in Fo was observed only after six to ten hours of dehydration. Concomitant with the decrease in photosynthetic efficiency during
dehydration a rise in the xanthophyll zeaxanthin was observed, even in low-light treatments. The increase in zeaxanthin can
be related to previously observed photoprotective non-photochemical quenching of fluorescence in dehydrating stems ofS. lepidophylla. We hypothesize that under dehydrating conditions even low light levels become excessive and zeaxanthin-related photoprotection
is engaged. We speculate that these processes, as well as stem curling and self shading (Eickmeier et al. 1992), serve to
minimize photoinhibitory damage toS. lepidophylla during the process of dehydration. |
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Keywords: | Fluorescence Photoinhibition Photoprotection Selaginella lepidophylla Xanthophyll cycle |
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