Control of storage root development and secondary growth in Panax ginseng

Panax ginseng C.A. Mey. is a perennial medicinal plant whose economic value is predominantly determined by the size, biomass, and bioactive metabolite content of its storage roots.Storage root thickening in ginseng requires sustained vascular cambial activity and secondary radial growth; however, these processes proceed slowly and are highly sensitive to environmental factors.Recent advances in genomics, transcriptomics, and functional analyses have substantially improved our understanding of the molecular mechanisms underlying these developmental processes.This review summarizes recent advances in knowledge of the regulation of storage root thickening in P. ginseng, with emphasis on cambial dynamics and stage-specific developmental transitions during early root thickening.We highlight the pivotal roles of phytohormones-comprising auxin, cytokinin, gibberellins, jasmonic acid, and brassinosteroids -in controlling cambial stem cell maintenance, parenchyma cell proliferation, and cell expansion.We discuss the integration of nitrate signaling and environmental cues, such as high-temperature stress, into hormonal networks to modulate storage root growth and metabolic allocation.In addition, we outline emerging biotechnological strategies for improvement of ginseng productivity, including targeted manipulation of phytohormone signaling pathways, nutrient-responsive regulatory modules, and stress-adaptive mechanisms.This integrated overview provides a conceptual framework for understanding storage root development in ginseng, and presents molecular insights relevant to the breeding and biotechnological improvement of this valuable medicinal crop.