Biosynthesis of gibberellins in <i>Gibberella fujikuroi</i>. Gibberellin A₄₇

Abstract

Two minor radioactive products in cultures of G. fujikuroi strain ACC 917 supplemented with labeled gibberellin A 4 have been identified as the 2α-hydroxy derivative, gibberellin A 47 , and the hydrate, gibberellin A 2 . In addition, evidence was obtained by combined gas chromatography – mass spectrometry for the formation of 3-O-acetylgibberellin A 1 3-O-acetylgibberellin A 3 , and gibberellin A 20 by the culture. The time course of gibberellin synthesis in defined and complex media, as well as changes in the relative amounts of radioactive gibberellins formed when [ 14 C]gibberellin A 4 was added to cultures at different ages, suggest that the composition of the gibberellin mixture produced is determined by the balance between synthesis and decay of key enzymes in the branching pathway.