Identification of endogenous gibberellins in immature seeds of loquat (Eriobotrya japonica Lindl.).

Abstract

Gibberellins (GAs) A9, A15, A19, A20, A29, A35, A44, A50 and A61 were identified by capillary gas chromatography/selected ion monitoring (GC/SIM) in immature seeds of loquat (Eriobotrya japonica Lindl). Furthermore, five unknown GA-like compounds with apparent parent ions of m/z 418, 504 or 506 (as methyl ester trimethylsilyl ether derivatives) were found by GC/mass spectrometry (GC/MS) in the biologically active fractions. The m/z 418 and 504 compounds may have been C-11β hydroxylated GA9 and dehydro-GA35, respectively. The bioassay and GC/MS results suggest that the major GAs were GA50 and the five unknown GA-like compounds. In the immature seeds, at least two GA metabolic pathways may thus exist, one being the non-hydroxylation pathway of GA15→GA24→GA9, and the other, the early C-13 hydroxylation pathway of GA44→GA19→GA20→GA29. A late C-11β hydroxylation pathway is also possible.