Methods and materials are disclosed for the inhibition and control of
gibberellic acid levels. In particular, nucleic acid sequences of copalyl
diphosphate synthase, 3-.beta. hydroxylase, and 2-oxidase and additional
nucleic acid sequences are disclosed. Gibberellic acid levels may be
inhibited or controlled by preparation of a chimeric expression construct
capable of expressing antisense RNA which suppresses the gibberellin
biosynthetic pathway sequence. The antisense sequence is the complement of
a copalyl diphosphate synthase sequence, a 3.beta.-hydroxylase sequence,
or a C20-oxidase sequence. Administration of a complementing agent,
preferably a gibberellin or gibberellin precursor or intermediate restores
bioactivity.
