Gravity induces fast electrical field change in soybean hypocotyls

Tanada, T.; Vinten-Johansen, C.

doi:10.1111/j.1365-3040.1980.tb00105.x

Cited by 5 publications

(7 citation statements)

References 10 publications

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Section: Introductionmentioning

confidence: 99%

“…Electric currents and fields have also been observed around entire organs, such as roots, hypocotyls, and coleoptiles (10-12, 17, 20). Suggested roles for these currents in roots are in ion uptake (13) segments tilted to the horizontal position were reported to undergo a change in surface potential within as short a time as 2 to 3 mi (17).We shall attempt to show that a vertical, freely growing root has a steady pattern of current and that the pattern changes when the root is placed horizontally. Such a change suggests that the current could be involved in the transduction of gravitropic stirnulus.…”

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confidence: 99%

“…However, since this transverse polarization has a latent period of 10 to 15 min, it is surely not related to the graviperception because the presentation time for gravistimulated plants lies between 12 and 30 s (18). It segments tilted to the horizontal position were reported to undergo a change in surface potential within as short a time as 2 to 3 mi (17).…”

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confidence: 99%

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Rapid Changes in the Pattern of Electric Current around the Root Tip of Lepidium sativum L. following Gravistimulation

Behrens¹,

Weisenseel²,

Sievers³

1982

Plant Physiol.

134

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Using a highly sensitive vibrating electrode, the pattern of naturally occurring electric currents around I-day-old primary roots of Lepidium sativum L. growing vertically downward and the current pattern following gravistimulation of the root has been examined. A more or less symmetrical pattern of current was found around vertically oriented, downward growing roots. Current entered the root at the root cap, the meristem, and the beginning of the elongation zone and left the root along most of the elongation zone and in the root hair zone. After the root was tilted to a horizontal position, we observed current flowing acropetally at the upper side of the root cap and basipetally at the lower side within about 30 seconds in most cases. After a delay of several minutes, acropetally oriented current was also found flowing along the upper side of the meristematic zone. The apparent density of the acropetal current in the root cap region increased and then decreased with time. Gravitropic curvature was first visible approximately 10 minutes after tilting of the root to the horizontal position. Since the change in the pattern of current in the root cap region precedes bending of the root and is different for the upper and lower side, a close connection is suggested between the current and the transduction of information from the root cap to the elongation zone following graviperception in the cap.Measurements with an extracellular vibrating electrode have revealed characteristic patterns of self-generated electric current traversing individual plant and animal cells (5,6,19,21). Growing pollen tubes and root hairs, for example, produce an electric current which enters at the growing tip and leaves at the basal, nongrowing region of the cell (19,22). Electric currents and fields have also been observed around entire organs, such as roots, hypocotyls, and coleoptiles (10-12, 17, 20). Suggested roles for these currents in roots are in ion uptake (13) segments tilted to the horizontal position were reported to undergo a change in surface potential within as short a time as 2 to 3 mi (17).We shall attempt to show that a vertical, freely growing root has a steady pattern of current and that the pattern changes when the root is placed horizontally. Such a change suggests that the current could be involved in the transduction of gravitropic stirnulus. MATERIALS AND METHODSGrowth Conditions and Holding Apparatus for Seedlings. Seeds of Lepidium sativum L. were soaked 30 min in tap water and then placed on vertical moist filter paper in a closed container. The seeds were oriented with their micropyles down so that the roots would not curve during germination. After 20 h at a temperature of 23 + 2°C, the primary roots were 6.0 ± 1.2 mm long. Single seeds were then transferred and fastened with a drop ofwarm agar medium to a small L-shaped Plexiglas holder which, after a further 3.5 h, was clamped in a micromanipulator, avoiding as much as possible any shaking of the seed. Using the micromanipulator, the root was placed...

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Rapid Changes in the Pattern of Electric Current around the Root Tip of Lepidium sativum L. following Gravistimulation

Behrens¹,

Weisenseel²,

Sievers³

1982

Plant Physiol.

134

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“…The sequence of events in the response of plant seedlings to an environmental stimuli, such as gravity, is ; 1) membrane depolarization that occurs in 8 s following the gravity (Behrents et al, 1985;Schrank, 1947;Tanada and Vinten-Johansen, 1980) ; 2) an asymmetric distribution of IAA occurring within 3 min (Bandurski et al, 1986a ;Bandurski et aI., 1986b); 3) an asymmetric distribution of endogenous calcium in 5 to 10 min (Goswami and Audus, 1976) ; followed, 4) within I h or less an asymmetric distribution of 42K, 32p (Goswami and Audus, 1976) and [14C] glucose (Momonoki, 1988). The negatively charged IAA, the uncharged esters of IAA, and the positively charged calcium, all become asymmetrically distributed in the cortical cells surrounding the stele during these short time periods.…”

Section: Discussionmentioning

confidence: 99%

Acetylcholine as a Signaling System to Environmental Stimuli in Plants: III. Asymmetric solute distribution controlled by ACh in gravistimulated maize seedlings

Momonoki

Hineno

Noguchi

1998

Plant Production Science

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“…Woodcock and Wilkins (15,16) and Wilkins (5) considered that asymmetric IAA distribution produced the electrical field across the gravitropically responding shoot during upward curvature. However, Tanada and Vinten-Johansen ( 11) observed the development of a positive electrical potential on the lower side approximately 1 min after horizontal placement. This time is less than the presumed gravitropic presentation time of the shoots.…”

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Electrical Potentials during Gravitropism in Bean Epicotyls

Imagawa

Toko²,

Ezaki

et al. 1991

Plant Physiol.

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An apparatus for measuring simultaneously the surface electrical potentials along epicotyl was developed to study the largely bending situation by gravity. Potentials increased on the upper side and decreased on the lower side after the horizontal placement. The time course of electrical changes consisted of two components which correspond to growth movements observed during gravitropism.The Cholodny-Went model of gravitropism in plants suggests that the asymmetric distribution of auxin results in a gravitropic response in shoots (14). The process leading to such an unequal auxin distribution is not known. Some investigators have suggested that auxin accumulation results from an electrical asymmetry between the upper side and the lower side in the horizontal position (1 1).In roots, electrical currents around a primary root after gravistimulation have been studied (1, 3), and also membrane potentials have been measured in lateral statocytes of vertically and nonvertically growing roots (2). The currents flow acropetally on the upper side of the root cap and basipetally on the lower side. Statocytes on the lower side of the root depolarize, and statocytes on the upper side hyperpolarize. This electrical asymmetry is the earliest event in graviperception.In shoots, early workers observed a transverse electrical potential in the horizontally oriented shoots (4,5,16). Grahm and Herz measured the potential between the upper and lower sides for 1 h and observed the potential increase after 15 min (4). Woodcock and Wilkins (15,16) and Wilkins (5) considered that asymmetric IAA distribution produced the electrical field across the gravitropically responding shoot during upward curvature. However, Tanada and Vinten-Johansen ( 11) observed the development of a positive electrical potential on the lower side approximately 1 min after horizontal placement. This time is less than the presumed gravitropic presentation time of the shoots. They suggested that Grahm and Hertz and others might have been unable to detect a fast positive gravielectrical effect. However, this experiment seems to need a reexamination because the electrical potentials on the lower side drift to negative in the vertical position (9).The explanation for the electrical potentials during gravitropism in epicotyls requires long-term, sensitive measurements of the potentials not only on the lower side but also on the upper side throughout the entire time course of gravitropism. We have measured the surface electrical potentials on the lower and upper surfaces of shoots by developing new measuring equipment that was not effected by the amount of gravicurvature. MATERIALS AND METHODS Plant MaterialEtiolated epicotyls of adzuki bean (Phaseolus angularis) seedlings were used. Seeds were soaked in distilled water (40 ± 1°C) for 4 h and were placed in trays on filter papers wetted with 0.1 mm KCI and 0.05 mM CaCl2 solution. The trays were kept in darkness at 30 ± 1°C. After 5 d, the seedlings were moved to plastic cases filled with 0.1 mm KCI, 0.05 mm CaC...

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Gravity induces fast electrical field change in soybean hypocotyls

Cited by 5 publications

References 10 publications

Rapid Changes in the Pattern of Electric Current around the Root Tip of Lepidium sativum L. following Gravistimulation

Rapid Changes in the Pattern of Electric Current around the Root Tip of Lepidium sativum L. following Gravistimulation

Acetylcholine as a Signaling System to Environmental Stimuli in Plants: III. Asymmetric solute distribution controlled by ACh in gravistimulated maize seedlings

Electrical Potentials during Gravitropism in Bean Epicotyls

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