Inhibition of Cell Division and DNA Synthesis by Gibberellin in Isolated Zinnia Mesophyll Cells

概要

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A culture system of isolated mesophyll cells of Zinnia elegans was used to examine the action of gibberellic acid (GA) on cell division. Isolated Zinnia mesophyll cells cultured in a medium containing auxin and cytokinin reinitiated cell division in a partly synchronized manner. When mesophyll cells isolated from 21-day-old seedlings were used, GA added to the culture medium at concentrations of 1 × 10^<-6> M or higher suppressed the initial rise in the number of divided cells. Tracer experiments with [3^H]-dThd revealed that GA treatment inhibited the incorporation of [3^H]-dThd into DNA in the nucleus without inhibiting the uptake of [3^H]-dThd into the cells, indicating that GA inhibited DNA synthesis. GA applied at 48 h inhibited the incorporation of [3^H]-dThd into DNA during the following 24 h, but GA applied at 72 h did not inhibit the incorporation during the subsequent 24 h. This suggests that GA affects the process of reinitiation of DNA synthesis, but does not affect DNA synthesis once cells have become proliferative.
日本植物生理学会の論文