Hydrolysis of [17,17-2H2]gibberellin A20-glucoside and [17,17-2H2]gibberellin A20-glucosyl ester by Azospirillum lipoferum cultured in a nitrogen-free biotin-based chemically-defined medium

PICCOLI P, LUCANGELI D, SCHNEIDER G, BOTTINI R

PLANT GROWTH REGULATION

SPRINGER

Lugar: Berlin; Año: 1997 vol. 23 p. 179 - 182

0167-6903

Azospirillum lipoferum strain USA 5b, a gibberellin producing bacterium, was cultured in a nitrogen-free biotinbased chemically-defined medium in the presence of the glucosyl ester or the 13-O-glucoside of [17,17-2H2]- gibberellin A20. The [17,17-2H2]-gibberellin A20 conjugates were added at both the stationary phase of the cultures and at the beginning of the growth curve. Metabolism of the conjugates was examined after 72 h of incubation using capillary gas chromatography-mass spectrometry, with identification by full scan mass spectra. Metabolites identified were [17,17-2H2]-gibberellin A20, [17,17-2H2]-gibberellin A1 and [17,17-2H2]-gibberellin A3. Also, in the Azospirillum cultures fed at the beginning of the growth curve, gibberellin A5 and gibberellin A20 were characterized as endogenous by mass spectrometry/full spectrum. These results support the concept that the growth promotion in plants that is induced by Azospirillum infection may occur by a combination of both gibberellin production and gibberellin-glucoside/glucosyl ester deconjugation by the bacterium