Photosynthetic electron transport and carbon-reduction-cycle enzyme activities under long-term drought stress in Casuarina equisetifolia Forst. and Forst
The inhibition of photosynthetic electron transport and the activity of photosynthetic carbon reduction cycle (PCR) enzymes under long-term water stress after slow dehydration was studied in non-nodulated Casuarina equisetifolia Forst. and Forst. plants. Initially, drought increased the fraction of closed Photosystem II (PS II) reaction centres (lowered qP) and decreased the quantum yield of PS II electron transport (Φ(PS II)) with no enhancement of nonradiative dissipation of light energy (qN) because it increased the efficiency of electron capture by open PS II centres F'(v)/,F'(m). As drought progressed, F'(v),/F'(m) fell and the decrease in Φ(PS II) was associated with an increased qN. The kinetics of dark relaxation of fluorescence quenching pointed to an increase in a slowly-relaxing component under drought, in association with increased contents of zeaxanthin and antheraxanthin. Total NADP-dependent malate dehydrogenase activity increased and total stromal fructose-1,6-bisphosphatase activity decreased under drought, while the activation state of these enzymes remained unchanged. Water stress did not alter the activity anti the activation state of ribulose bisphosphate carboxylase oxygenase.
| Main Authors: | , , |
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| Other Authors: | |
| Format: | artículo biblioteca |
| Published: |
Springer
1997-06
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| Subjects: | Chlorophyll fluorescence, Fructose bisphosphatase, NADP-malate dehydrogenase, Photosystem II, Ribulose bisphosphate carboxylase, Water stress, |
| Online Access: | http://hdl.handle.net/10261/271236 http://dx.doi.org/10.13039/501100003339 http://dx.doi.org/10.13039/501100000780 |
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