Integrated Transcriptomic and Metabolomic Analysis Reveals the Mechanism of Gibberellic acid Regulates the Growth and Flavonoid Synthesis in Phellodendron chinense Schneid Seedlings

The phytohormone gibberellic acids (GAs) play a crucial role in the processes of growth, organ development, and secondary metabolism. However, the mechanism of exogenous GA regulating the growth and flavonoid synthesis in Schneid ( Schneid) seedlings remains unclear. In this study, the physicochemical properties, gene expression level, and secondary metabolite of Schneid seedlings under GA treatment were investigated. The results showed that GA significantly improved the plant height, ground diameter, fresh weight, chlorophyll content, soluble substance content, superoxide dismutase, and peroxidase activities. This was accompanied by elevated relative expression levels of , , , , , , and unigenes. Conversely, a notable reduction was observed in the carotenoid content, catalase activity and the relative expression abundances of / and unigenes in leaves of Schneid seedlings ( < 0.05). Furthermore, GA evidently decreased the contents of pinocembrin, pinobanksin, isosakuranetin, naringin, naringenin, (-)-epicatechin, tricetin, luteolin, and vitexin belonged to flavonoid in stem bark of Schneid seedlings ( < 0.05). These results indicated that exogenous GA promoted growth through improving chlorophyll content and gene expression in photosynthesis and phytohormone signal pathway and inhibited flavonoid synthesis in Schneid seedlings.