Regulation of nitrogen and phosphorus content and terpenoid metabolite accumulation in P. ginseng by exogenous strigolactone

Abstract

Panax ginseng C.A. Meyer (P. ginseng) possesses extensive pharmacological uses, yet its cultivation demands specific soil conditions. Nutrient deficiencies frequently impede the growth of ginseng and its accumulation of pharmacologically active compounds, diminishing its medicinal value. One strategy to counteract nutrient shortages and boost the synthesis of active compounds involves applying exogenous plant hormones. This study investigated the effect of GR24, an exogenous strigolactone analog, on P. ginseng's resilience to low nitrogen and low phosphorus (LNLP) stress, using concentrations of 0, 3, 6, and 9 μM. Under LNLP conditions, GR24 mitigated the decrease in terpene metabolite accumulation, enhancing the levels of most terpenoid compounds. Furthermore, both LNLP and GR24 treatments significantly impacted IAA and CTK concentrations. LNLP stress and GR24 application influenced the expression of genes associated with the strigolactone biosynthesis pathway, such as PgD27–3 and PgSLs, although these genes operated independently of each other. Transient overexpression of PgD27–3 in Nicotiana benthamiana demonstrated that PgD27–3 reduced peroxide levels and antioxidant enzyme activity while upregulating genes related to nitrogen, phosphorus, phytohormone, and terpene metabolism. Therefore, PgD27–3 overexpression may alleviate LNLP stress by lowering peroxide content and antioxidant enzyme activity while enhancing gene expression, which in turn promotes terpene metabolite accumulation under LNLP stress. GR24 thus emerges as a viable strategy to mitigate N and P stress, potentially improving the yield and quality of P. ginseng through agronomic practices.