Changes of fluorescence and xanthophyll pigments during dehydration in the resurrection plantSelaginella lepidophylla in low and medium light intensities.
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/Fmwas 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/Fmwas observed during dehydration in both light treatments, after one to two hours of dehydration. A rise in Fowas 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.
Department of Botany, Duke University, 27706, Durham, NC, USA.
Catharina
C
Casper
Department of Biology, Vanderbilt University, 37235, Nashville, TN, USA.
William G
WG
Eickmeier
Research School of Biological Sciences, Australian National University, Box 475, 2601, Canberra, ACT, Australia.
C Barry
CB
Osmond
Fluorescence; Photoinhibition; Photoprotection; Selaginella lepidophylla; Xanthophyll cycle