Effect of Abscisic Acid on Uptake and Metabolism of [H]Gibberellin A(1) and [H]Pseudogibberellin A(1) by Barley Half-seeds

Uptake and metabolism of 1,2-³H]gibberellin A₁ (³H]GA₁, I) and its 3-hydroxy epimer (³H]pseudoGA₁, II) by barley (Hordeum vulgare L.) half-seeds were measured after 24 hours of incubation, in the presence or absence of abscisic acid in the media. Uptake of both compounds was enhanced by abscisic acid, and abscisic acid enhanced the extent of metabolism of ³H]GA₁. However, ³H]pseudoGA₁ was not metabolized, even in the presence of abscisic acid. The significance of the stereo-chemistry of the 3-hydroxyl position is discussed.