Relationship of Transplasmalemma Redox Activity to Proton and Solute Transport by Roots of Zea mays
| Autor: | Bernard Rubinstein, Arthur I. Stern |
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| Rok vydání: | 1986 |
| Předmět: | |
| Zdroj: | Plant Physiology. 80:805-811 |
| ISSN: | 1532-2548 0032-0889 |
| DOI: | 10.1104/pp.80.4.805 |
| Popis: | Transplasmalemma redox activity, monitored in the presence of exogenous ferricyanide stimulates net H+ excretion and inhibits the uptake of K+ and α-aminoisobutyric acid by freshly cut or washed, apical and subapical root segments of corn (Zea mays L. cv “Seneca Chief”). H+ excretion is seen only following a lag of about 5 minutes after ferricyanide addition, even though the reduction of ferricyanide occurs before 5 minutes and continues linearly. Once detected, the enhanced rate of H+ excretion is retarded by the ATPase inhibitors N,N′-dicyclohexylcarbodiimide, diethylstilbestrol, and vanadate. A model is presented in which plasmalemma redox activity in the presence of ferricyanide involves the transport only of electrons across the plasmalemma, resulting in a depolarization of the membrane potential and activation of an H+-ATPase. Such a model implies that this class of redox activity does not provide an additional and independent pathway for H+ transport, but that the activity may be an important regulator of H+ excretion. The 90% inhibition of K+ (86Rb+) uptake within 2 minutes after ferricyanide addition can be contrasted with the 5 to 15% inhibition of uptake of α-aminoisobutyric acid. The possibility exists that a portion of the K+ and most of the α-aminoisobutyric acid uptake inhibitions are related to the ferricyanide-induced depolarization of the membrane potential, but that the redox state of some component of the K+ uptake system may also regulate K+ fluxes. |
| Databáze: | OpenAIRE |
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