Reevaluation of the effect of calcium ions on auxin-induced elongation

Journal Article · Sat Jan 01 00:00:00 EST 1977 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.60.5.709· OSTI ID:5883933

Cleland, R E ^[1]; Rayle, D L

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1. Univ. of Washington, Seattle

The mechanism by which calcium ions inhibit cell elongation has been reinvestigated. Growth-inhibiting levels of calcium, when applied to isolated walls (in vitro treatment) do not decrease cell wall extensibility as measured by the Instron technique. Thus, the hypothesis that calcium inhibits growth by forming wall-stiffening calcium bridges must be abandoned. Treatment of living auxin-treated sections with calcium (in vivo treatment) does cause a decrease in the subsequently measured wall extensibility, but this decline appears to be simply a consequence of the growth inhibition rather that its cause. Growth-inhibiting levels of calcium do not appreciably reduce the rate of auxin-enhanced H+ excretion. Pretreatment with calcium does not reduce the capacity of walls to undergo acid-activated wall loosening in the absence of calcium. High concentrations of CaC1/sub 2/ (0.02 M) cause an initial elastic shrinkage of Avena sections comparable to that caused by the same osmolarity of mannitol, but the subsequent growth inhibition is to great to be explained by an osmotic inhibition.Calcium ions do inhibit H+-induced extension of frozen-thawed sections under tension. The growth-inhibitory effects of calcium, then, may be ascribed to a direct inhibition exerted by calcium ions on the H+-induced wall-loosening process.

• OSTI ID: 5883933
• Journal Information: Plant Physiol.; (United States), Vol. 60
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
AUXINS
CALCIUM
BIOCHEMISTRY
PLANT CELLS
PLANT GROWTH
INHIBITION
ELASTICITY
ELONGATION
EXTENSOMETERS
HYDROGEN IONS
IN VITRO
OATS
RESPONSE MODIFYING FACTORS
ALKALINE EARTH METALS
CEREALS
CHARGED PARTICLES
CHEMISTRY
ELEMENTS
GRAMINEAE
GRASS
GROWTH
IONS
MECHANICAL PROPERTIES
METALS
PLANT GROWTH REGULATORS
PLANTS
TENSILE PROPERTIES
550300* - Cytology