Although oscillations in membrane-transport activity are ubiquitous in plants, the ionic mechanisms of ultradian oscillations in plant cells remain largely unknown, despite much phenomenological data. The physiological role of such oscillations is also the subject of much speculation. Over the last decade, much experimental evidence showing oscillations in net ion fluxes across the plasma membrane of plant cells has been accumulated using the non-invasive MIFE technique. In this study, a recently proposed feedback-controlled oscillatory model was used. The model adequately describes the observed ion flux oscillations within the minute range of periods and predicts: (i) strong dependence of the period of oscillations on the rate constants for the H1 pump; (ii) a substantial phase shift between oscillations in net H1 and K1 fluxes; (iii) cessation of oscillations when H1 pump activity is suppressed; (iv) the existence of some ‘window’ of external temperatures and ionic concentrations, where nondamped oscillations are observed: outside this range, even small changes in external parameters lead to progressive damping and aperiodic behaviour; (v) frequency encoding of environmental information by oscillatory patterns; and (vi) strong dependence of oscillatory characteristics on cell size. All these predictions were successfully confirmed by direct experimental observations, when net ion fluxes were measured from root and leaf tissues of various plant species, or from single cells. Because oscillatory behaviour is inherent in feedback control systems having phase shifts, it is argued from this model that suitable conditions will allow oscillations in any cell or tissue. The possible physiological role of such oscillations is discussed in the context of plant adaptive responses to salinity, temperature,osmotic, hypoxia, andpHstresses.

Oscillations in plant membrane-transport activity: model predictions, experimental validation, and physiological implications / S. SHABALA; L. SHABALA; I. NEWMAN; D. GRADMANN; C. ZHONGHUA; S. MANCUSO;. - In: JOURNAL OF EXPERIMENTAL BOTANY. - ISSN 0022-0957. - STAMPA. - 57:(2006), pp. 171-184.

Oscillations in plant membrane-transport activity: model predictions, experimental validation, and physiological implications.

MANCUSO, STEFANO
2006

Abstract

Although oscillations in membrane-transport activity are ubiquitous in plants, the ionic mechanisms of ultradian oscillations in plant cells remain largely unknown, despite much phenomenological data. The physiological role of such oscillations is also the subject of much speculation. Over the last decade, much experimental evidence showing oscillations in net ion fluxes across the plasma membrane of plant cells has been accumulated using the non-invasive MIFE technique. In this study, a recently proposed feedback-controlled oscillatory model was used. The model adequately describes the observed ion flux oscillations within the minute range of periods and predicts: (i) strong dependence of the period of oscillations on the rate constants for the H1 pump; (ii) a substantial phase shift between oscillations in net H1 and K1 fluxes; (iii) cessation of oscillations when H1 pump activity is suppressed; (iv) the existence of some ‘window’ of external temperatures and ionic concentrations, where nondamped oscillations are observed: outside this range, even small changes in external parameters lead to progressive damping and aperiodic behaviour; (v) frequency encoding of environmental information by oscillatory patterns; and (vi) strong dependence of oscillatory characteristics on cell size. All these predictions were successfully confirmed by direct experimental observations, when net ion fluxes were measured from root and leaf tissues of various plant species, or from single cells. Because oscillatory behaviour is inherent in feedback control systems having phase shifts, it is argued from this model that suitable conditions will allow oscillations in any cell or tissue. The possible physiological role of such oscillations is discussed in the context of plant adaptive responses to salinity, temperature,osmotic, hypoxia, andpHstresses.
2006
57
171
184
S. SHABALA; L. SHABALA; I. NEWMAN; D. GRADMANN; C. ZHONGHUA; S. MANCUSO;
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/313043
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