Identification of gibberellin A20, abscisic acid, and phaseic acid from flowering Bryophyllum daigremontianum by combined gas chromatography-mass spectrometry.

The presence of abscisic and phaseic acid in a purified acidic extract from flowering plants of the long-short-day plant Bryophyllum daigremontianum [(R. Hamet and Perr.) Berg.] was conclusively established by combined gas chromatography-mass spectrometry (GC-MS) of their methyl esters. Gibberellin A20 (GA20) was identified by GC-MS of the methyl ester and the trimethylsilyl ether of the methyl ester. The following levels of the 3 compounds per kg fresh weight were estimated: Abscisic acid, 5.5 μg; phaseic acid, 9.4μg; gibberellin A20, 0.8 μg. When GA20 and four other GAs were applied to Bryophyllum under shortday conditions, the order of effectiveness for induction of flower formation was: GA2>GA1>GA5=GA7>GA20. The low biological activity of the native GA20 is discussed.