Yingxin Sun

Soil, as the foundation for the survival of understory ginseng, directly impacts its growth and development. However, studies focusing on the role of soil in determining the quality of understory ginseng are limited. This study examines the relationship between quality and yield of 5-, 9-, and 17-year-old understory ginseng and their soil microbiota. The results indicate that with the increase in growth years, the overall biomass of understory ginseng generally shows an upward trend, while its quality slightly decreases at 9 years. Compared to the other two growth years, the soil from 9-year-old ginseng shows lower enzyme activity and pH and a higher abundance of pathogens. The 17 years soil has higher OM and AHN content, along with increased abundance of denitrifying and nitrogen-reducing bacteria. Correlation networks reveal that AK significantly influences ginsenoside content, while AP and AHN are more closely related to soil microorganisms. Compared with other types of ginsenosides, ginsenosides Rh2 and Rd are affected by a greater variety of soil microorganisms and chemical factors. As growth years increase, the changes in ginseng quality, soil nutrients, and soil microbiota do not follow a single linear trend; instead, there appears to be a bottleneck phase at certain intermediate stages.

Panax ginseng, a perennial medicinal plant, utilizes its dried roots and rhizomes for medicinal purposes. Currently, in China, ginseng cultivation employs two methods: under-forest and farmland planting. These methods create distinct habitats, significantly influencing the ginseng’s rhizome morphology and, consequently, its economic value. In this study, two-year-old ginsengs were transplanted into farmland (TCG), a larch forest (TLCG) and a Quercus mongolica forest (TQCG) to analyze the differences in rhizome phenotypes caused by habitat changes. The results showed that there were significant differences in light intensity and the soil’s available phosphorus and potassium contents between farmland and forest environments. The differences in habitats led to different adaptability of the ginseng’s rhizome morphology. Compared with TCG, the rhizomes of TLCG and TQCG were significantly elongated by 48.36% and 67.34%, respectively. After the rhizomes’ elongation in TLCG and TQCG, there was an increase in indole-3-acetic acid (IAA) contents and a decrease in lignin contents. By analyzing the expression of key genes, we found that, compared with TCG, the expression of key enzymes of lignin biosynthesis genes such as PgCOMT and PgCCR4 were down-regulated. The difference in ginseng’s rhizome length is related to the signal transduction pathway of auxin and gibberellin. In addition, we preliminarily screened out transcription factors PgWRKY75, PgDIV, and PgbHLH93.1, which can actively respond to habitat changes and play important roles in the elongation of ginseng rhizomes. In summary, this study elucidates the phenotypic plasticity strategy of ginseng rhizomes in response to habitat changes and delineates the regulatory mechanism behind phenotypic adaptation, offering novel insights into ginseng’s morphogenesis.

Panax ginseng taproot serves as a crucial storage organ and constitutes a significant component of Chinese herbal medicine. In China, ginseng is cultivated using two primary methods: under-forest planting and farmland planting. These methods create distinct habitats that notably influence the morphology of ginseng taproots. However, the precise regulatory mechanisms governing ginseng taproot expansion remain to be fully elucidated. This study aimed to delineate the patterns of ginseng taproot expansion by examining taproots transplanted into farmland (TCG) and forest environments (TLCG and TQCG). Our findings indicate that light intensity and soil available potassium levels in TCG plots significantly exceed those in TLCG and TQCG plots. Compared with TLCG and TQCG, the taproot diameter of TCG increased by 11.54% and 27.73%, respectively. At the same time, combined with the microstructure of the transverse section of the taproot, it showed that the expansion of the TCG taproot was closely related to cell expansion. During TCG taproot expansion, there was an increase in indole-3-acetic acid (IAA) content, significant starch accumulation, and a decrease in lignin content. By analyzing the expression of key genes, we found that compared with TLCG and TQCG, the expression of genes PgTPS1 and PgALDH1 was upregulated, and the expression of genes PgHCT1, PgPAL3, PgPER3, and PgPER51 were downregulated in TCG taproot. Additionally, the transcription factors PgARF18.1 and PgbHLH42 were identified as responsive to habitat changes, playing pivotal roles in taproot expansion. In conclusion, this study provides foundational insights into the regulatory mechanisms of ginseng taproot expansion, offering significant implications for enhancing the quality and value of ginseng.

Ginseng is regarded as the “king of herbs” in China, with its roots and rhizomes used as medicine, and it has a high medicinal value. In order to meet the market demand, the artificial cultivation of ginseng emerged, but different growth environments significantly affect the root morphology of garden ginseng. In this study, we used ginseng cultivated in deforested land (CF-CG) and ginseng cultivated in farmland (F-CG) as experimental materials. These two phenotypes were explored at the transcriptomic and metabolomic levels so as to understand the regulatory mechanism of taproot enlargement in garden ginseng. The results show that, compared with those of F-CG, the thickness of the main roots in CF-CG was increased by 70.5%, and the fresh weight of the taproots was increased by 305.4%. Sucrose, fructose and ginsenoside were significantly accumulated in CF-CG. During the enlargement of the taproots of CF-CG, genes related to starch and sucrose metabolism were significantly up-regulated, while genes related to lignin biosynthesis were significantly down-regulated. Auxin, gibberellin and abscisic acid synergistically regulated the enlargement of the taproots of the garden ginseng. In addition, as a sugar signaling molecule, T6P might act on the auxin synthesis gene ALDH2 to promote the synthesis of auxin and, thus, participate in the growth and development of garden ginseng roots. In summary, our study is conducive to clarifying the molecular regulation mechanism of taproot enlargement in garden ginseng, and it provides new insights for the further exploration of the morphogenesis of ginseng roots.