Actinomycin D Inhibits the GA_3-Induced Elongation of Azuki Bean Epicotyls and the Reorientation of Cortical Microtubules

概要

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Actinomycin D inhibited the elongation of epicotyl segments from azuki bean seedlings that was induced by simultaneous treatment with IAA and GA_3. The drug also inhibited the elongation of the segments that was caused by IAA alone when it was applied together with IAA. When the segments were pretreated with GA_3 and then incubated with IAA, GA_3 promoted the elongation caused by IAA and brought about a predominance of transverse cortical microtubules (MTs) in the epidermal cells of the segments. The change in the arrangement of MTs caused by pretreatment with GA_3 Was evident I h after the start of subsequent incubation with IAA when the effect of pretreatment with GA_3 On the elongation had not yet become apparent. Pretreatment with GA_3 did not cause any change in the arrangement of MTs when GA_3-pretreated segments were not incubated subsequently with IAA. Although actinomycin D applied before treatment with IAA did not inhibit the IAA-induced elongation, the drug diminished the promotion of the elongation caused by pretreatment with GA_3 and prevented GA_3 from bringing about a predominance of transverse MTs when the drug was applied during the pretreatment with GA_3-GA_3-induced synthesis of mRNA seems to be involved in the promotion by GA_3 of IAA-induced elongation and in the GA_3-induced rearrangement of cortical MTs.
日本植物生理学会の論文