Relation of growth process to spatial patterns of electric potential and enzyme activity in bean roots

Toko, Kiyoshi; Iiyama, Satoru; Tanaka, Chikako; Hayashi, Kenshi; Yamafuji, Kaoru

doi:10.1016/0301-4622(87)80045-5

Cited by 32 publications

(20 citation statements)

References 45 publications

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“…Plant roots make stable electrochemical patterns around themselves spontaneously (1,6,11,22,25,26). These patterns are closely related to growth, and hence the elongation of roots and shoots can be controlled by an electric field and voltage applied externally (7,9,15) and disturbance of such patterns causes suppression of elongation (24). Similar electrochemical patterns are observed in unicellular systems (2,4,5,25) and the electric asymmetry also appears in gravireception (20).…”

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confidence: 50%

Electric Current Precedes Emergence of a Lateral Root in Higher Plants

Hamada¹,

Ezaki²,

Hayashi³

et al. 1992

Plant Physiol.

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Stable electrochemical patterns appear spontaneously around roots of higher plants and are closely related to growth. An electric potential pattern accompanied by lateral root emergence was measured along the surface of the primary root of adzuki bean (Phaseolus angularis) over 21 h using a microelectrode manipulated by a newly developed apparatus. The electric potential became lower at the point where a lateral root emerged. This change preceded the emergence of the lateral root by about 10 h. A theory is presented for calculating two-dimensional patterns of electric potential and electric current density around the primary root (and a lateral root) using only data on the one-dimensional electric potential measured near the surface of the primary root. The development of the lateral root inside the primary root is associated with the influx of electric current of about 0.7 gA.cm-2 at the surface.

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supporting

confidence: 50%

Electric Current Precedes Emergence of a Lateral Root in Higher Plants

Hamada¹,

Ezaki²,

Hayashi³

et al. 1992

Plant Physiol.

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“…In this experiment, three electrodes were arranged near the root surface in the elongation region. Removing the root after the measurement, the offset potential caused by each electrode itself in the aqueous medium was input to the computer and extracellular surface potential was obtained by subtraction of offset potential (19,20). Elongation was evaluated from the change of the position of the root tip on the monitor.…”

Section: Measurementmentioning

confidence: 99%

“…Electric current patterns appear along the surfaces of roots (1,4,20,25). Oscillations of surface electric potential also occur (7,8,16,19,22).…”

Section: Introductionmentioning

confidence: 99%

“…It is noticeable that the oscillation appears consistent (or coherent) in the mature region over several centimeters, because the phase and also the period are the same at any position (16,19,22). Resonance of oscillation occurs in such a way that the phase of osmotic pressure variation sets the phase of electric oscillation when an oscillation of osmotic pressure is applied to a root (7,8).In a previous paper (22), the membrane potential within the root was measured with a microelectrode technique (2) while the surface electric potential was measured using a multielectrode measuring method (4,19,20). In the elongation region, the membrane potential of epidermal cells oscillated with the same period and the same phase as the surface potential.…”

mentioning

confidence: 99%

“…In a previous paper (22), the membrane potential within the root was measured with a microelectrode technique (2) while the surface electric potential was measured using a multielectrode measuring method (4,19,20). In the elongation region, the membrane potential of epidermal cells oscillated with the same period and the same phase as the surface potential.…”

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confidence: 99%

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Relationship between Growth and Electric Oscillations in Bean Roots

et al. 1990

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Extracellular and intracellular electric potentials in bean roots are known to show electric oscillations along the longitudinal axis with a period of several minutes. The relationship between growth and the electric oscillations was studied using roots of adzuki (Phaseolus chrysanthos). We measured surface electric potentials with a multielectrode apparatus while simultaneously measuring elongation using a CCD camera and monitor. Roots having an electric oscillation grew faster than roots with no oscillation. Furthermore, elongation rate was higher in roots with higher oscillation frequency. Oscillation frequency had a strong dependence on temperature; i.e. 010 was estimated at 1.7. These results suggest a correlation between electric oscillation and elongation.A periodic electrical pattern is formed near the surface of the internodal cell of Characean species (13). Electric current patterns appear along the surfaces of roots (1,4,20,25). Oscillations of surface electric potential also occur (7,8,16,19,22). Bean roots show spontaneously electric oscillations without a stimulus along the root surface with about 5 min period, which continues constant for over a few hours (16,19). The amplitude of the oscillation is maximal in the elongation region and the phase of the oscillation in that region differs by 1800 from that in the mature region. It is noticeable that the oscillation appears consistent (or coherent) in the mature region over several centimeters, because the phase and also the period are the same at any position (16,19,22). Resonance of oscillation occurs in such a way that the phase of osmotic pressure variation sets the phase of electric oscillation when an oscillation of osmotic pressure is applied to a root (7,8).In a previous paper (22), the membrane potential within the root was measured with a microelectrode technique (2) while the surface electric potential was measured using a multielectrode measuring method (4,19,20). In the elongation region, the membrane potential of epidermal cells oscillated with the same period and the same phase as the surface potential. In the mature region, on the other hand, the membrane potential did not oscillate, although the surface potential oscillated. It was concluded from a theoretical analysis using an equivalent electrical circuit that the source ofsurfacepotential oscillations existed in the membrane at the xylem/ parenchyma interface in the elongation region and the oscillation was propagated to the mature region inside the parenchyma. A mechanism for the oscillations has not, however, been elucidated especially from the viewpoint of a relation to growth.The purpose ofthe present paper is to study the relationship between growth and electric oscillation in roots. The surface electric potentials were measured together with a measurement of elongation. MATERIALS AND METHODS Plant MaterialExperiments were done using roots of adzuki bean (Phaseolus chrysanthos) seedlings which were 4 to 5 d old. Seeds were soaked in water at 40 ± 1°C for 3 h and were ...

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