Abstract
Fourteen gibberellins (GAs) have been identified in seeds of Helianthus annuus. They comprise the previously known GA 1, GA 4, GA 19, GA 20, and GA 45, and nine new 15β-hydroxyGAs. Of the new GAs, 15β-hydroxyGA 20 and 15β-hydroxyGA 1 have been previously synthesized chemically from GA 3 and are now assigned the numbers GA 67 and GA 72. The structures of 15β-hydroxyGA 15, 15β-hydroxyGA 24, and 15β-hydroxyGA 25 were established by their formation from the incubation of ent-15β-hydroxykaur-16-en-19-oic acid with cultures of Gibberella fujikuroi, mutant B1-41a; these new GAs have been respectively assigned the numbers, GA 64, GA 65 and GA 66. The remaining four GAs have been tentatively assigned the structures, 15β-hydroxyGA 17, 15β-hydroxyGA 19, 15β-hydroxyGA 44 and 15β-hydroxyGA 53 on the basis of the mass spectra of their MeTMSi derivatives. Abscisic acid, trans-abscisic acid, dihydrophaseic acid, dioxindole-3-acetic acid, ent-7α,16α,17-trihydroxy-16αH-kauranoic acid and ent-7α,16β,17-trihydroxy-and ent-6α,7α,16β,17-tetrahydroxy-16βH-kauranoic acids have also been detected in seeds of Helianthus annuus by capillary GC-MS. From the incubation of ent-15α-hydroxykaur-16-en-19-oic acid with Gibberella fujikuroi, mutant B1-41a, ent-7α,15α-dihydroxykaur-16-en-19-oic acid and 7β,15β-dihydroxykaurenolide have been isolated.
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