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. & 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 (PSII) with no enhancement of non-radiative dissipation of light energy (qN) because it increased the efficiency of electron capture by open PS II centres (Fv/Fm). As drought progressed, Fv/Fm fell and the decrease in PSII 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 and the activation state of ribulose bisphosphate carboxylase oxygenase.
DOI:
https://doi.org/10.1023/A:1005878307607Altmetric score:
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Publication year
1997
Authors
Sanchez-Rodriguez J; Martinez-Carrasco R; Perez P
Language
English
Keywords
water stress, photosynthesis, enzyme activity, enzymes, multipurpose trees, drought, casuarina equisetifolia
