Internode length in Zea mays L.

¹³C, ³H]Gibberellin A₂₀ (GA₂₀) has been fed to seedlings of normal (tall) and dwarf-5 and dwarf-1 mutants of maize (Zea mays L.). The metabolites from these feeds were identified by combined gas chromatography-mass spectrometry. ¹³C, ³H]Gibberellin A₂₀ was metabolized to ¹³C, ³H]GA₂₉-catabolite and ¹³C, ³H]GA₁ by the normal, and to ¹³C, ³H]GA₂₉ and ¹³C, ³H]GA₁ by the dwarf-5 mutant. In the dwarf-1 mutant, ¹³C, ³H]GA₂₀ was metabolized to ¹³C, ³H]GA₂₉ and ¹³C, ³H]GA₂₉-catabolite; no evidence was found for the metabolism of ¹³C, ³H]GA₂₀ to ¹³C, ³H]GA₁. ¹³C, ³H]Gibberellin A₈ was not found in any of the feeds. In all feeds no dilution of ¹³C in recovered ¹³C, ³H]GA₂₀ was observed. Also in the dwarf-5 mutant, the ¹³C]label in the metabolites was apparently undiluted by endogenous ¹³C]GAs. However, dilution of the ¹³C]label in metabolites from ¹³C, ³H]GA₂₀ was observed in normal and dwarf-1 seedlings. The results from the feeding studies provide evidence that the dwarf-1 mutation of maize blocks the conversion of GA₂₀ to GA₁.Abbreviations GA_n gibberellin A_n - GC-MS combined gas chromatography-mass spectrometry - HPLC high-performance liquid chromatography - RP reverse phase