A MYC2-like transcription factor regulates MeJA biosynthesis underlying flower fragrance in Cymbidium faberi

Cymbidium faberi is highly valued for its distinct floral scent, primarily consisting of methyl jasmonate (MeJA). This study aimed to elucidate the transcriptional regulation of MeJA biosynthesis in C. faberi , laying a theoretical foundation for enhancing fragrance in scentless Cymbidium varieties. We cloned four basic helix-loop-helix (bHLH) transcription factor genes ( CfbHLH5 , CfbHLH25 , CfbHLH31 , and CfMYC2-like ) that exhibit divergent roles in MeJA production. CfMYC2-like specifically represses CfJMT , a pivotal MeJA biosynthetic gene, by binding to the G-box element of its promoter, thereby inhibiting the positive regulatory function of CfbHLH5. Transient overexpression of CfMYC2-like in C. faberi protoplasts reduced MeJA-related gene expression, whereas CRISPR/Cas9-mediated mutation of CfMYC2-like markedly elevated MeJA levels in rhizomes. Furthermore, CfMYC2-like physically interacted with the AP2 transcription factor CfRAP2.4, limiting its ability to activate CfJMT . This mechanism underlies the low MeJA content observed in vegetative tissues and the robust MeJA emission during flowering. Collectively, our findings demonstrate that CfMYC2-like acts as a key regulator of MeJA biosynthesis in C. faberi and offer a promising avenue for improving floral scent in Cymbidium . Future research should further investigate the regulatory networks and environmental cues that modulate MeJA production, enhancing both the ornamental and commercial value of these orchids. • CfMYC2-like gene transiently reduced MeJA synthetic gene expression in C. faberi protoplasts. • Editing CfMYC2-like via CRISPR/Cas9 increased MeJA content in C. faberi rhizomes by 1.5-fold. • CfMYC2-like functions as a repressor of MeJA synthetic genes. • CfMYC2-like interacts with CfRAP2.4 to modulate MeJA biosynthesis in C. faberi .