Identification of six endogenous gibberellins in spinach shoots

Analysis of highly purified extracts from spinach shoots by combined gas chromatography-mass spectrometry has demonstrated the presence of six 13-C-hydroxylated gibberellins (GAs): GA(53), GA(44), GA(19), GA(17), GA(20), and GA(29). The major GAs were GA(17), GA(19), and GA(20), whereas the other three GAs occurred in trace amounts. Structural considerations suggest that the six GAs identified in spinach are related in the following metabolic sequence: GA(53) --> GA(44) --> GA(19) --> GA(17) --> GA(20) --> GA(29).