Effects of Gibberellin on Auxin-Induced Hyperpolarization of Cell Membranes in Hypocotyls of Vigna unguiculate : GROWTH AND DEVELTOPMENT : MEMBRANES AND BIOENERGETICS

概要

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Auxin activates pumping of protons from the symplast to the apoplast and causes hyperpolarization of the symplast membrane in the elongation zone of Vigna stems prior to the acceleration of growth. This auxin-induced hyperpolarization has been studied in most cases in hypocotyl segments excised from the elongation zone. In the present study, mature-zone segments were per-fused with IAA by the xylem perfusion technique in an effort to determine whether or not IAA has any effects in the mature zone. Although no hyperpolarization of the symplast membrane was observed upon the perfusion with auxin alone, auxin-induced hyperpolarization was observed when mature-zone segments had been pretreated with GA_3, in the absence of an increase in the growth rate. These results suggest that cells in the mature zone have lost the ability to activate the proton-pumping machinery in response to auxin but that this ability can be restored by treatment with GA_3, This effect of GA_3 Suggests the possibility that the concentration of gibberellin in a tissue controls one of the cell's responses to auxin, namely, activation of the proton pump.
日本植物生理学会の論文