Abstract:Relationship of brossinolide promoted epicotyl elongation to protein, RNA, DNA and mRNA synthesis in mung bean cuttings were studied using radioactive precursors and inhibitors (cycloheximide, actinomycine D and 5-fluorouracil) of protein and nucleic acid synthesis. It was proved that epicotyl elongation of mung bean cutting depended on protein and nucleic acid synthesis, especially mRNA synthesis. This indicates that BR promoted epicotyl elongation was regulated at the level of gene transcription.