Converts the inactive gibberellin (GA) precursors GA9 and GA20 in the bioactives gibberellins GA4 and GA1. Has a small activity on GA29, producing GA8. Unable to convert GA20 to GA5, GA5 to GA3 or GA12 to GA14. Involved in the production of bioactive GA for vegetative growth and development, but not for the 3-beta-hydroxylation of GA in developing seeds. 2-oxoglutarate + gibberellin A20 + O2 = CO2 + gibberellin A1 + succinate Binds 1 Fe(2+) ion per subunit. Plant hormone biosynthesis; gibberellin biosynthesis. Expressed in radicles, roots, internodes, cotyledons, leaves and shoots. Barely detected in developing seeds. Not detected in flowers or young fruits. Highly expressed in germinating seedlings. Dwarf phenotype. The Le gene controls the stem length trait studied by Gregor Mendel in 1866 (PubMed:9286112 and PubMed:9238076). Belongs to the iron/ascorbate-dependent oxidoreductase family. GA3OX subfamily. On the garden pea - Issue 159 of April 2014