Regulation of Bud Rest in Tubers of Potato, Solanum tuberosum L: VI. Biochemical Changes Induced in Excised Potato Buds by Gibberellic Acid

The rest period of the potato tuber was studied in relation to certain biochemical changes that are induced by gibberellic acid (GA₃). The concentration of reducing sugars in excised plugs with buds treated with 10⁻⁴m GA₃ decreased in the first 4 hours after treatment and then rapidly increased up to 70 hours. The pattern in control buds was similar, but the changes occurred more slowly. The response to GA₃ is temperature-dependent and is not limited to any particular tissue of the tuber. The concentration of reducing sugars in excised buds increased proportionally to the log of the concentration of GA₃ in a range from 10⁻⁸ to 10⁻⁴m. At 10⁻³m, GA₃ slightly inhibited production of reducing sugars. Malonate inhibits the initial decrease and the subsequent increase in reducing sugars in control buds, but not the increase induced by GA₃.