Chemical and real-time based analysis revealed active gene machinery of glycyrrhizin biosynthesis and its accumulation in the aerial tissues of in-vitro regenerated Glycyrrhiza glabra L

The study reports a protocol for the regeneration of Glycyrrhiza glabra plantlet from the leaf explant. Notably, the chemical analysis of various developmental stages revealed presence of glycyrrhizin in the underground (7.0–29.8 µg/g) & aerial (7.3–23.4 µg/g) tissues of the in vitro regenerated plants, which was otherwise not detected in the aerial tissues of the field plant. Glycyrrhizin accumulation was reduced or undetected in the regenerated plants transferred to the glasshouse and subsequently under field conditions. Further, spatio-temporal relative gene expression analysis of aerial tissues of in-vitro regenerated G. glabra showed expression of all the known genes committed to glycyrrhizin pathway. In the shoot system, maximum expression of squalene epoxidase (7.9 fold), β-amyrin synthase (21.8 folds), Licorice β-amyrin 11-oxidase (5.9 folds) and UDP-glucosyltransferase (1.7 folds) was observed in different months. However, no expression was detected in the aerial tissues of the field grown plant. Also, a correlation was found between the expression patterns of Licorice β-amyrin 11-oxidase with glycyrrhizin accumulation. This is the first study demonstrating the presence of glycyrrhizin in the aerial tissues of the in-vitro regenerated Glycyrrhiza plant. This study will help in understanding glycyrrhizin regulation, precursor accumulation and their transport. Also, it will unlock the possibilities of understanding and enhancing glycyrrhizin biosynthesis and accumulation in the plant, under in-vitro conditions.