Elicitor-mediated enhancement of biomass and bioactive compounds in endangered Licorice (Glycyrrhiza glabra L.): insights from adventitious root cultures

Licorice ( Glycyrrhiza glabra L.) is a perennial plant known for its roots and rhizomes, which are rich in health-promoting compounds such as polyphenols, flavonoids, polysaccharides, and particularly glycyrrhizin, a triterpenoid saponin. In this study, we explored the effects of various elicitors, including yeast extract (YE) (50, 100, and 200 mg/L), salicylic acid (SA) (50, 100, and 200 µM), and methyl jasmonate (MeJA) (50, 100, and 200 µM), on root growth parameters and the accumulation of specialized metabolites in adventitious root cultures of G. glabra . Our findings revealed that YE elicitation significantly increased root biomass compared to other elicitors. The highest fresh weight (56.17 ± 3.33 g/L) and dry weight (3.62 ± 0.23 g/L) were observed at a YE concentration of 200 mg/L. Additionally, the highest total phenol yield (30.79 ± 1.16 mg/L DW), total flavonoid yield (26.90 ± 4.05 mg/L DW), and antioxidant activity (54.70 ± 4.93%) were recorded in adventitious root extracts treated with the highest concentration of YE (200 mg/L). In contrast, lower concentrations of SA (50 and 100 µM) and the ethanol control showed the highest total saponin yield (1120.06 ± 211.07 mg/L DW, 1065.64 ± 143.53 mg/L DW, and 1270.44 ± 260.41 mg/L DW, respectively), with no statistically significant differences between them. Consistent with these results, SA concentrations of 100 µM (9.43 ± 2.38 mg/L DW) and 50 µM (9.26 ± 5.76 mg/L DW) revealed the highest glycyrrhizin yield. However, the elicitors did not significantly affect polysaccharide production. These findings could support the establishment of a pilot-scale cultivation process for adventitious roots of G. glabra , aimed at optimizing biomass and bioactive compound yields. This approach could help meet the growing demand for natural ingredients in the pharmaceutical, cosmetic, and food industries while promoting the conservation of the plant's natural habitat.