Transcriptional regulation of carotenoid biosynthesis in Goji Berry ( Lycium barbarum L.): Implications for fruit development and abiotic stress adaptation–A review

Goji berry ( Lycium barbarum L.), a nutritionally important fruit-bearing shrub in the Solanaceae family, possesses a distinctive carotenoid profile dominated by zeaxanthin esters, which contributes to its health benefits and stress resilience. However, the transcriptional networks governing carotenoid metabolism in Lycium remain incompletely understood across developmental stages and stress conditions. This review synthesizes recent multi-omics studies to propose a Lycium -centric regulatory framework for carotenoid biosynthesis and accumulation. We describe a ripening-associated transcriptional reprogramming that appears to activate core biosynthetic genes (PSY1, ZDS16) while modulating the expression of catabolic genes (CCD4, ZEP), although the precise regulatory mechanisms underlying this switch remain to be fully elucidated. We emphasize the potential role of transcription factor families — including R2R3-MYB, BBX, WRKY, NAC, ERF as candidate integrators of development and abiotic stress signals, with functional evidence available for key modules such as LbNAM2-LbZDS (drought response) and LbERF5.1-LbCCD4.1 (degradation control). A Solanaceae-wide comparison suggests conserved regulatory architecture alongside putative goji-specific adaptations, although comprehensive cross-species validation remains incomplete. We identify major knowledge gaps — including functional validation of candidate TFs, integration of multi-stress signaling, and characterization of epigenetic and post-transcriptional regulation — and propose key directions for future research. Overall, this synthesis provides a mechanistic framework for understanding carotenoid regulation in goji berry and may inform strategies for breeding nutritionally enhanced and climate-resilient Lycium cultivars, pending further experimental validation.