[Excellent appearance of Dao-di Ginseng Radix et Rhizoma and interaction mechanism between genetic and environmental factors: a review].

Dao-di medicinal materials produced in a specific environment always present excellent appearance and high quality. Because of the unique appearance, Ginseng Radix et Rhizoma is regarded as a paradigm in the research on excellent appearance. This paper systematically summarized the research progress in the genetic and environmental factors influencing the formation of the excellent appearance of Ginseng Radix et Rhizoma, aiming to provide reference for the quality improvement of Ginseng Radix et Rhizoma and the scientific connotation of Dao-di Chinese medicinal materials. The Ginseng Radix et Rhizoma with high quality generally has a robust and long rhizome, a large angle between branch roots, and the simultaneous presence of a robust basal part of rhizome, adventitious roots, rhizome bark with circular wrinkles, and fibrous roots with pearl points. The cultivated and wild Ginseng Radix et Rhizoma have significant differences in the appearance and no significant difference in the population genetic diversity. The differences in the appearance are associated with cell wall modification, transcriptional regulation of genes involved in plant hormone transduction, DNA methylation, and miRNA regulation. The rhizosphere soil microorganisms including Fusarium and Alternaria, as well as the endophytes Trichoderma hamatum and Nectria haematococca, may be the key microorganisms affecting the growth and development of Panax ginseng. Cultivation mode, variety, and root exudates may be the main factors influencing the stability of rhizosphere microbial community. Ginsenosides may be involved in the formation of the excellent appearance. However, most of the available studies focus on the partial or single factors in the formation of Dao-di medicinal materials, ignoring the relationship within the complex ecosystems, which limits the research on the formation mechanism of Dao-di medicinal materials. In the future, the experimental models for the research involving genetic and environmental factors should be established and mutant materials should be developed to clarify the internal relationship between factors and provide scientific support for the research on Dao-di medicinal materials.