Gibberellin 3-oxidases in developing embryos of the southern wild cucumber, Marah macrocarpus.

摘要: Abstract Immature seeds of the southern wild cucumber, Marah macrocarpus , are a rich source gibberellins (GAs) and were used in some earliest experiments on GA biosynthesis. The main biologically active GAs developing embryos endosperm M. 4 7 which have been shown previously to be formed from 9 separate pathways, being directly by 3β-hydroxylation, while is produced two steps via 2,3-didehydroGA . In order identify enzymes responsible for these conversions, three cDNA clones encoding functionally different 3-oxidases, MmGA3ox1, -2 -3, obtained young immature embryos. Their biochemical functions determined expression cDNAs Escherichia coli incubation cell lysates with 14 C-labelled substrates. MmGA3ox1 MmGA3ox3 converted as sole product, MmGA3ox2 several products, including 2,3-epoxyGA 20 5 last products requiring 13-hydroxylation respectively. this substrate 2,3-epoxide, also epoxide, but 5. Thus, formation requires sequential activities not involved production. catalysed similar reactions when incubated 13-hydroxylated GAs, although reduced efficiencies. 13-hydroxylase activity may production 1 3 present at low levels seeds.