Studies in terpenoid biosynthesis. Part XIII. The biosynthetic relationship of the gibberellins in Gibberella fujikuroi

Abstract

A comparison of the results of feeding ent-7-hydroxygibberell-16-en-19-oic acid, ent-7-oxogibberell-16-en-19-oic acid, and ent-gibberell-16-ene-7,19-dioic acid (gibberellin A₁₂), in terms of the distribution of mevalonate, to Gibberella fujikuroi, reveals that there is a divergence between the pathways leading to the 3-hydroxylated and the non-3-hydroxylated gibberellins at the C-7 aldehyde stage. The distribution of label between the C₁₉ and C₂₀ gibberellins after 6 and 24 h incubations suggests that the free C₂₀ gibberellins (A₁₄, A₃₇, A₃₆, and A₁₃ or A₁₅, A₂₄, and A₂₅) may not lie on the direct pathway to the C₁₉ gibberellins. Gibberellins A₄ and A₇ are transformed into gibberellic acid. Incubation of gibberellin A₁₂ with G. fujikuroi may be used to prepare gibberellins A₂₄ and A₂₅.