Abstract: To investigate the regulatory effects of methyl jasmonate (MeJA) and brassinosteroid (BR) co-treatment on leaf color in Aeonium arboreum 'Halloween' and to identify key differentially expressed genes involved in anthocyanin biosynthesis, this study preliminarily explored the molecular mechanism underlying exogenous hormone-induced leaf color change in Aeonium succulent plants. One-year-old stem cuttings of 'Halloween' were sprayed with a mixture of 40 mg/L MeJA and 0.04 mg/L BR for 42 consecutive days. Leaf color parameters, anthocyanin content, and expression levels of anthocyanin synthesis-related genes were measured in functional leaves. After 14 ～ 42 days of treatment, leaves of the experimental group (EG) turned from green to purplish-red. From 28 to 42 days, the leaf color parameters L* (brightness), a* (red/green axis), and c* (saturation) were increased significantly (P < 0.05). Anthocyanin content in EG was significantly increased (P < 0.05) between 14 to 28. qRT-PCR analysis revealed that most structural genes (AaCHS2, AaCHI1, AaF3'H, AaUFGT4) in the anthocyanin pathway were up-regulated after 42 days. Notably, the expression levels of transcription factors AaMYB113 and AaMYB114 were significantly induced, reaching 2.20-fold (P < 0.05) and 47.96-fold (P < 0.001) of CK levels, respectively. These findings suggest that the synergistic effect of MeJA and BR was demonstrated to effectively induce purplish-red leaf coloration in 'Halloween'. This mechanism may involve activation of anthocyanin synthesis-related structural genes and transcription factors AaMYB113 and AaMYB114.¹