A nucleic acid sequence is provided which encodes a gibberelin 2-oxidase gene which catalyzes the 2.beta.-oxidation of a gibberelin molecule to introduce a hydroxyl group at C-2 and further catalyzes the oxidation of the hydroxyl group introduced at C-2 to yield the ketone derivative. Such sequences can find application in the preparation of transgenic plants with altered levels of gibberelin 2-oxidase.