Chlorophyll fluorescence in the resurrection plantSelaginella lepidophylla(Hook. & Grev.) Spring during high-light and desiccation stress, and evidence for zeaxanthin-associated photoprotection
✍ Scribed by William G. Eickmeier; Catharina Casper; C. Barry Osmond
- Publisher
- Springer-Verlag
- Year
- 1993
- Tongue
- English
- Weight
- 970 KB
- Volume
- 189
- Category
- Article
- ISSN
- 0032-0935
No coin nor oath required. For personal study only.
✦ Synopsis
The function of photosystem (PS)II during desiccation and exposure to high photon flux density (PFD) was investigated via analysis of chlorophyll fluorescence in the desert resurrection plant Selaginella lepidophylla (Hook. and Grev.) Spring. Exposure of hydrated, physiologically competent stems to 2000 gmol. m-2. s-1 PFD caused significant reductions in both intrinsic fluorescence yield (Fo) and photochemical efficiency of PSII (Fv/FM) but recovery to pre-exposure values was rapid under low PFD. Desiccation under low PFD also affected fluorescence characteristics. Both Fv/FM and photochemical fluorescence quenching remained high until about 40% relative water content and both then decreased rapidly as plants approached 0% relative water content. In contrast, the maximum fluorescence yield (FM) decreased and non-photochemical fluorescence quenching increased early during desiccation. In plants dried at high PFD, the decrease in Fv/FM was accentuated and Fo was reduced, however, fluorescence characteristics returned to near pre-exposure values after 24-h of rehydration and recovery at low PFD. Pretreatment of stems with dithiothreitol, an inhibitor of zeaxanthin synthesis, accelerated the decline in Fv/FM and significantly increased Fo relative to controls at 925 pmol. m-2. s-1 PFD, and the differences persisted over a 3-h low-PFD recovery period.