Redox system in the plasma membranes of two ecotypes of reed (Phragmites communis Trin.) leaves from different habitats

Two ecotypes of reed (Phragmites communis Trin.), named 'swamp reed' and 'heavy salt meadow reed' according to their habitats, growing in the desert regions of northwest China were investigated for plasma membrane (PM) redox activities in their leaves. The results showed that the PM redox system in both ecotypes of reed leaves can use NADH (reduced nicotinamide adenine dinucleotide) and NADPH (reduced nicotinamide adenine dinucleotide phosphate) as the electron donors and Fe(CN)(6)(3-) and EDTA-Fe3+ as the electron acceptors. Inhibitors of respiratory chain such as KCN and NaN3 had no inhibitory effects on the PM redox activities. The rates of NADH and NADPH oxidation and Fe(CN)(6)(3-) reduction in heavy salt meadow reed were higher compared to those in swamp reed. Reduction rates of EDTA-Fe3+ in both ecotypes of reed were relatively low. It is suggested that higher redox activities of PM in the heavy salt meadow reed may be responsible for its adaptation to the saline habitats, as proved by previous studies that the PM redox system was involved in intercellular [Na+] and [K+] regulation. (C) 2003 Elsevier B.V. All rights reserved.