In Vivo Gibberellin Biosynthesis in Endosperm of Sechium edule Sw. Seeds.

Biosynthesis of gibberellins (GAs) was studied in vivo in endosperms of Sechium edule Sw. Exogenous ent-[(14)C]kaurene was metabolized into four major products: GA(12), GA(4), GA(7) and 16, 17-dihydro-16-hydroxy-GA(15) alcohol glucoside. Other minor metabolites were also observed including ent-kaurenol and ent-kaurenal. Conversion of ent-[(14)C]kaurene to ent-kaurenol glucoside by endosperm cell-free preparations in the presence of UDPG was observed. However, the finding was not confirmed in in vivo studies and is probably artifactual. Overall evidence coming from the analysis of endogenous GAs and in vitro and in vivo biosynthetic studies are discussed in relation to the possible existence in the Sechium seeds of a different route, along with the known pathway, branching from ent-kaurene or ent-7-alpha-hydroxykaurenoic acid and this also leading to biologically active GAs.