Biosynthesis of Gibberellins in Barley and Dwarf Rice Seedlings

Abstract

Incorporation studies with ¹⁴ CO₂ suggested that 11-day-old barley seedlings biosynthesized an A₁- like gibberellin de novo and that the biosynthesized gibberellin completely turned over within 12 h. Exogenous [¹⁴C]mevalonic acid, supplied in a variety of ways, was not incorporated into the gibberellins of barley seedlings.

Barley seedlings, which failed to elongate in response to exogenous ent-kaurenoic acid, metabolized exogenous [17-¹⁴C]ent-kaurenoic acid to a few compounds, but not to a biologically active gibberellin.

Dwarf rice seedlings (cv. Tan-ginbozu), which elongated in response to exogenous ent-kaurenoic acid, metabolized exogenous [17-¹⁴C]ent-kaurenoic acid to a number of radioactive compounds, one of which behaved like [¹⁴C]gibberellin A₁ in that it showed radioactivity and biological activity at the expected retention time during gas-liquid chromatography.