Is wall‐bound calcium redistributed during the gravireaction of stems and coleoptiles?

Bagshaw, S. L.; Cleland, Robert E.

doi:10.1111/j.1365-3040.1996.tb02065.x

Cited by 11 publications

(15 citation statements)

References 37 publications

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“…Firstly, it is thought that gravitropic signalling initiates a redistribution of wall-bound calcium (Roux and Serlin 1987 and references therein). Calcium accumulations have been detected on the slower-growing side of both shoots and roots (Roux and Slocum 1982;Lee et al 1983a), although this may not always be observed (Bagshaw and Cleland 1994). Since exogenously applied Ca 2+ has frequently been reported to inhibit growth, and chelators to promote growth, these observations provide a simple means of curvature control, a point elegantly demonstrated by Lee et al (1983b).…”

Section: Introductionmentioning

confidence: 94%

The role of calmodulin in the gravitropic response of the Arabidopsis thaliana agr-3 mutant

Sinclair

Oliver

Maher

et al. 1996

Planta

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Calmodulin, a primary plant calcium receptor, is known to be intimately involved with gravitropic sensing and transduction. Using the calmodulin-binding inhibitors trifluoperazine, W7 and calmidazolium, gravitropic curvature of Arabidopsis thaliana (L.) Heynh, ecotype Landsberg, roots was separable into two phases. Phase I was detected at very low concentrations (0.01 microM) of trifluoperazine and calmidazolium, did not involve growth changes, accounted for about half the total curvature of the root and may represent the specific contribution of the cap to gravity sensing. Phase II commenced around 1.0 microM and involved inhibition of both growth and curvature. The agr-3 mutant exhibited a reduced gravitropic response and was found to lack phase I curvature, suggesting that the mutation alters either use or expression of calmodulin. The sequences of wild-type and agr-3 calmodulin (CaM-1) cDNAs, which are root specific were completely determined and found to be identical. Upon gravitropic stimulation, wild-type Arabidopsis seedlings increased calmodulin mRNA levels by threefold in 0.5 h. On the other hand, gravitropic stimulation of agr-3 decreased calmodulin mRNA accumulation. The possible basis of the two phases of curvature is discussed and it is concluded that agr-3 has a lesion located in a general gravity transmission sequence, present in many root cells, which involves calmodulin mRNA accumulation.

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Section: Introductionmentioning

confidence: 94%

The role of calmodulin in the gravitropic response of the Arabidopsis thaliana agr-3 mutant

Sinclair

Oliver

Maher

et al. 1996

Planta

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“…Displacement of the EGTA with Ca 2+ solution was followed by gravitropism. The question of a possible redistribution of Ca 2+ in the cell walls of shoots during a gravitropic response was investigated by Bagshaw and Cleland (1993a) by measuring the Ca 2+ concentration in cell walls of epidermal and cortical cells of gravitystimulated Pisum epicotyls, Helianthus hypocotyls and Zea coleoptiles. The authors found no evidence for apoplasmic movement of Ca 2+ due to gravity.…”

Section: Epicotyls Hypocotyls and Coleoptilesmentioning

confidence: 99%

BioelectriCity, gravity and plants

Weisenseel

Meyer

1997

Planta

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This brief review summarizes gravity-induced changes in bioelectric parameters and evaluates their contribution to our understanding of the sensing of gravity, and the transduction and transmission of the gravity stimulus in plants. During the last few decades, information has accumulated demonstrating gravity-induced changes in surface potentials, membrane voltages, endogenous electric currents and ion fluxes. These changes point to the plasma membrane as the site of perception and transduction of the gravity signal. To date, it is reasonable to assume that gravity affects the state of ion channels (in particular, Ca2+ channels) and the activity of ion pumps (in particular, the electrogenic H(+)-ATPase) in the plasma membrane leading to intracellular and apoplasmic changes in ion activities and in membrane voltages. The flow of H+ and Ca2+ currents is probably the means by which information about gravity is amplified and transmitted from sensing to responding cells. No data are available so far about the effect of microgravity on bioelectric parameters. However, it would be interesting to learn if plants become hypersensitive to gravity during a prolonged stay in microgravity. If so, such plants might fire action potentials after return to earth, because more Ca2+ channels than usual may be activated by 1 g in microgravity-adapted plants.

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“…These data were then used to quantify the spatiotemporal behavior of the gravitropic response. In some studies of gravitropism, changes in axis shape have been quantified by the change in stem tip angle (Bagshaw and Cleland, 1993;Perbal and DrissEcole, 1994). As stated by Firn and Digby (1980), this can lead to artifacts in the interpretation of axis shape changes because the tip angle is dependent on an integrated value, i.e.…”

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confidence: 99%

The Gravitropic Response of Poplar Trunks: Key Roles of Prestressed Wood Regulation and the Relative Kinetics of Cambial Growth versus Wood Maturation

2007

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In tree trunks, the motor of gravitropism involves radial growth and differentiation of reaction wood (Archer, 1986). The first aim of this study was to quantify the kinematics of gravitropic response in young poplar (Populus nigra x Populus deltoides, 'I4551') by measuring the kinematics of curvature fields along trunks. Three phases were identified, including latency, upward curving, and an anticipative autotropic decurving, which has been overlooked in research on trees. The biological and mechanical bases of these processes were investigated by assessing the biomechanical model of Fournier et al. (1994). Its application at two different time spans of integration made it possible to test hypotheses on maturation, separating the effects of radial growth and cross section size from those of wood prestressing. A significant correlation between trunk curvature and Fournier's model integrated over the growing season was found, but only explained 32% of the total variance. Moreover, over a week's time period, the model failed due to a clear out phasing of the kinetics of radial growth and curvature that the model does not take into account. This demonstrates a key role of the relative kinetics of radial growth and the maturation process during gravitropism. Moreover, the degree of maturation strains appears to differ in the tension woods produced during the upward curving and decurving phases. Cell wall maturation seems to be regulated to achieve control over the degree of prestressing of tension wood, providing effective control of trunk shape.

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Is wall‐bound calcium redistributed during the gravireaction of stems and coleoptiles?

Cited by 11 publications

References 37 publications

The role of calmodulin in the gravitropic response of the Arabidopsis thaliana agr-3 mutant

The role of calmodulin in the gravitropic response of the Arabidopsis thaliana agr-3 mutant

BioelectriCity, gravity and plants

The Gravitropic Response of Poplar Trunks: Key Roles of Prestressed Wood Regulation and the Relative Kinetics of Cambial Growth versus Wood Maturation

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