Elucidating the regulatory network of valerenic acid biosynthesis in Valeriana officinalis hairy roots under different light qualities: A coexpression perspective

Valerenic acid, a potent antistress sesquiterpene, is commercially valuable. This study employed integrated transcriptomic and metabolomic analysis to identify critical genes and transcription factors (TFs) that regulate valerenic acid biosynthesis in hairy roots of Valeriana officinalis under different LED light qualities. Blue light induced a significant up-regulation of the TFs R2R3 MYB and WRKY1 on day 2 (up to 4.99 and 5.89 times, respectively), while red light specifically affected MYB, TPS3 (day 1) and MYCS (day 4). Interestingly, BHLH emerged as a central TF that interacts directly with most pathway genes, suggesting a complex light-mediated regulation. Our results reveal a potential role for light in modulating the mevalonate (HMGR) and membrane epitope (MEP) pathways, potentially increasing metabolic flux toward terpene biosynthesis. Furthermore, we identified the terpene synthases VoTPS2 and VoTPS5 as critical for valerenic acid production, with TF MYCA acting as a critical activator. In addition, the TFs R2R3 MYB and WRKY1 may play an important role in the regulation of terpene biosynthesis. Remarkably, blue and red-light treatments induced valerenic acid accumulation in hairy roots (0.93 and 0.75 mg/g DW, respectively) within only two days. This discovery not only opens doors for targeted metabolic engineering based on the revealed co-expression network but also holds immense economic potential for valerenic acid-dependent industries. • Blue light up-regulates R2R3 MYB and WRKY1; red light influences MYB and TPS3. • Valerenic acid increased to 0.93 mg/g DW (blue LED) and 0.75 mg/g DW (red LED) in two days. • MYCA strongly activates terpene synthases, highlighting its importance in valerenic acid biosynthesis.