GbSBP13-GbFLS/GbF3'H module in regulating flavonoid biosynthesis during truncation-induced rejuvenation in Ginkgo biloba

Ginkgo biloba is an important medicinal tree species whose leaves are rich in flavonoids and other bioactive compounds. Leaf rejuvenation markedly enhances flavonoid biosynthesis; however, its underlying mechanism remains unclear. We performed truncation at three heights (H90, H20, H0) and analyzed bud origin, leaf morphology, and physiological traits. High cutting induced axillary buds, medium cutting stimulated epicormic buds, and low cutting depended on adventitious buds. Leaves derived from epicormic and adventitious buds exhibited pronounced juvenile traits, including increased lobation, shorter petioles, and greater thickness, together with higher photosynthetic and transpiration capacities, whereas axillary-bud shoots mainly restored canopy coverage rapidly and showed weaker rejuvenation features. Transcriptomic analysis identified an SBP family transcription factor, GbSBP13 , that was highly expressed in rejuvenated leaves under H0 and H20 treatments. Overexpression and virus-induced gene silencing (VIGS) experiments demonstrated that GbSBP13 acts as a critical promoter of flavonoid biosynthesis. In GbSBP13 -overexpressing tissues, transcriptome sequencing revealed significant up-regulation of auxin-related genes ( GH3 , SAUR ) and key flavonoid pathway genes ( GbFLS , GbF3′H ). Yeast one-hybrid, yeast two-hybrid, and dual-luciferase assays confirmed that GbSBP13 directly binds to the promoters of GbFLS and GbF3′H to regulate flavonoid biosynthesis. Taken together, this study reveals for the first time the molecular mechanism by which GbSBP13 controls flavonoid biosynthesis during rejuvenation, providing a mechanistic explanation for how rejuvenation in woody plants governs secondary metabolite production at the molecular level.