Fig. 16

Simplified working model of the role of BpMYB21 and BpMYB61 in hormone-induced triterpenoid synthesis in Betula platyphylla. BpMYB21 and BpMYB61 are induced by SA/MeJA. BpMYB21 and BpMYB61 interact with bHLH to induce BpSE and BpX expression by binding the MBS elements of the BpSE and BpX promoter, which subsequently regulates triterpenoid synthesis