Gibberellic Acid and Ion Release from Barley Aleurone Tissue: Evidence for Hormone-dependent Ion Transport Capacity

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The release of potassium, magnesium, and phosphate ions from aleurone cells of barley (Hordeum vulgare L. cv. Himalaya) is a gibberellic acid-dependent process. The release of these ions is preceded by a lag period of 6 to 8 hours after gibberellic acid addition. The effect of gibberellic acid on the release of ions is not mediated through an effect on ion solubilization. Thus, gibberellic acid does not apreciably affect the sum of extracted and released ions relative to controls. Rather, the effect of the hormone is on the release process itself. Inhibitors of oxidative phosphorylation when added with gibberellic acid or at times up to 6 hours after gibberellic acid inhibition release. When these inhibitors are added after ion release has begun, however, rapid efflux of ions occurs. These results suggest a strong correlation between energy levels and ion transport capacity. Inhibitors of RNA and protein synthesis also inhibit gibberellic acid-stimulated ion release. Evidence suggests that RNA and protein synthesis are required to establish and maintain ion release capacity of aleurone cells.

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