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Type: Journal article
Title: Polyamines as potential regulators of nutrient exchange across the peribacteroid membrane in soybean root nodules
Author: Whitehead, L.
Tyerman, S.
Day, D.
Citation: Functional Plant Biology, 2001; 28(7):677-683
Publisher: C S I R O Publishing
Issue Date: 2001
ISSN: 1445-4408
Statement of
Lynne F. Whitehead, Stephen D. Tyerman and David A. Day
Abstract: The effect of cytoplasmic polyamines on peribacteroid membrane transport processes in soybean (Glycine max L.) was investigated. The concentration of free polyamines in soybean nodule cytoplasm has been estimated by others to be in the micromolar range. The H+ -ATPase was inhibited by 37 and 54% by 200 µM spermidine and putrescine, respectively. Spermine applied to the cytoplasmic face of the peribacteroid membrane was found to inhibit both inward and outward currents through a non-selective cation channel permeable to ammonium (K d 2.1 µM at –100 mV). Malate transport into intact symbiosomes was reduced by 15–30% by 15 mM spermidine, cadaverine and putrescine. A non-specific stimulation of malate transport by polycations was found to occur at concentrations in the micromolar range. The results suggest that polyamines can affect all the peribacteroid membrane transport processes tested. In particular, we conclude that the combined inhibitory effects of polyamines on the ATPase and the ammonium channel have the potential to reduce nitrogen supply to the plant in vivo. The possibility of competing polyamine and ureide synthesis in the nodule is discussed.
Keywords: Cation channel; H + -ATPase; malate transport; membrane transport; nitrogen fixation; polyamines; soybean
RMID: 0020065127
DOI: 10.1071/PP01025
Appears in Collections:Wine Science publications

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