Hypoxia induces membrane depolarization and potassium loss from wheat roots but does not increase their permeability to sorbitol

F. Buwalda, C. J. Thomson, W. Steigner, E. G. Barrett-lennard, J. Gibbs, H. Greenway

Research output: Contribution to journalArticle

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Abstract

This paper deals with the responses of roots of wheat {Triticum aestivum L.) to hypoxia with special emphasis on the effects of severe O2 deficiency on membrane integrity, loss of K+ from the root and root membrane potentials.Seminal and crown roots of 26-d-old plants exposed to severe hypoxia (0.003 mol O2 m-3) for 3 h or 10 d prior to excision and subsequently exposed to hypoxic solutions, had slightly lower rates of sorbitol influx and a slightly smaller apparent free space than roots in aerated solutions. These results indicate that neither a few hours nor a 10-d exposure to hypoxia had adverse effects on the membrane integrity of the bulk of the cells in the roots. However, both 6-d-old seedlings and 26-d-old plants lost K+ from the roots following their transfer from aerated to hypoxic nutrient solutions. In the 26-d-old plants, which were of high nutritional status, there was a net K+ efflux from the roots to the external solution. In contrast, with the 6-d-old seedlings, which were of low nutritional status, the decrease in the K+ content of the roots was smaller than the net K+ uptake to the shoots.Exposure of excised roots to 0.008 mol O2 m-3caused a rapid and reversible membrane depolarization from -120 to --80 mV. These data and the magnitude of the net effluxes strongly suggest that K+ losses during the early stages of hypoxia are due to membrane depolarization rather than to increases in the permeability of membranes to K +.

Original languageEnglish
Pages (from-to)1169-1183
Number of pages15
JournalJournal of Experimental Botany
Volume39
Issue number9
DOIs
Publication statusPublished - 1 Sep 1988
Externally publishedYes

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Sorbitol
sorbitol
Triticum
hypoxia
Permeability
Potassium
permeability
potassium
wheat
Membranes
Nutritional Status
Seedlings
Crowns
Membrane Potentials
nutritional status
Hypoxia
seedlings
membrane permeability
membrane potential
tree crown

Cite this

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title = "Hypoxia induces membrane depolarization and potassium loss from wheat roots but does not increase their permeability to sorbitol",
abstract = "This paper deals with the responses of roots of wheat {Triticum aestivum L.) to hypoxia with special emphasis on the effects of severe O2 deficiency on membrane integrity, loss of K+ from the root and root membrane potentials.Seminal and crown roots of 26-d-old plants exposed to severe hypoxia (0.003 mol O2 m-3) for 3 h or 10 d prior to excision and subsequently exposed to hypoxic solutions, had slightly lower rates of sorbitol influx and a slightly smaller apparent free space than roots in aerated solutions. These results indicate that neither a few hours nor a 10-d exposure to hypoxia had adverse effects on the membrane integrity of the bulk of the cells in the roots. However, both 6-d-old seedlings and 26-d-old plants lost K+ from the roots following their transfer from aerated to hypoxic nutrient solutions. In the 26-d-old plants, which were of high nutritional status, there was a net K+ efflux from the roots to the external solution. In contrast, with the 6-d-old seedlings, which were of low nutritional status, the decrease in the K+ content of the roots was smaller than the net K+ uptake to the shoots.Exposure of excised roots to 0.008 mol O2 m-3caused a rapid and reversible membrane depolarization from -120 to --80 mV. These data and the magnitude of the net effluxes strongly suggest that K+ losses during the early stages of hypoxia are due to membrane depolarization rather than to increases in the permeability of membranes to K +.",
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Hypoxia induces membrane depolarization and potassium loss from wheat roots but does not increase their permeability to sorbitol. / Buwalda, F.; Thomson, C. J.; Steigner, W.; Barrett-lennard, E. G.; Gibbs, J.; Greenway, H.

In: Journal of Experimental Botany, Vol. 39, No. 9, 01.09.1988, p. 1169-1183.

Research output: Contribution to journalArticle

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T1 - Hypoxia induces membrane depolarization and potassium loss from wheat roots but does not increase their permeability to sorbitol

AU - Buwalda, F.

AU - Thomson, C. J.

AU - Steigner, W.

AU - Barrett-lennard, E. G.

AU - Gibbs, J.

AU - Greenway, H.

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Y1 - 1988/9/1

N2 - This paper deals with the responses of roots of wheat {Triticum aestivum L.) to hypoxia with special emphasis on the effects of severe O2 deficiency on membrane integrity, loss of K+ from the root and root membrane potentials.Seminal and crown roots of 26-d-old plants exposed to severe hypoxia (0.003 mol O2 m-3) for 3 h or 10 d prior to excision and subsequently exposed to hypoxic solutions, had slightly lower rates of sorbitol influx and a slightly smaller apparent free space than roots in aerated solutions. These results indicate that neither a few hours nor a 10-d exposure to hypoxia had adverse effects on the membrane integrity of the bulk of the cells in the roots. However, both 6-d-old seedlings and 26-d-old plants lost K+ from the roots following their transfer from aerated to hypoxic nutrient solutions. In the 26-d-old plants, which were of high nutritional status, there was a net K+ efflux from the roots to the external solution. In contrast, with the 6-d-old seedlings, which were of low nutritional status, the decrease in the K+ content of the roots was smaller than the net K+ uptake to the shoots.Exposure of excised roots to 0.008 mol O2 m-3caused a rapid and reversible membrane depolarization from -120 to --80 mV. These data and the magnitude of the net effluxes strongly suggest that K+ losses during the early stages of hypoxia are due to membrane depolarization rather than to increases in the permeability of membranes to K +.

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