Plant Material Seeds of A. precatorius were collected from the medicinal plant garden of Department of Pharmaceutical Sciences, Dr. HS Gour University, Sagar, MP, India. The seeds were sterilized and germinated following the protocol described in our previous publication.[15]Starting cell cultures of A. precatoriusSeveral explants from aseptically germinated seeds, viz. leaves, epicotyl, and petiole were tested for crop initiation by variation of plant growth regulators (PGRs) and Agrobacterium-mediated transformation. Untransformed callus cultures were initiated by placing explants on solidified MS medium separately enriched with hormones: 1 mg/l naphthalene acetic acid (NAA); 1 mg/l Kinetin (Kn); 0.5 – 2.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) and related combinations (data not shown). For transformation experiments, leaves were removed from 30-day-old in vitro germinated A. precatorius seedlings. A. tumefaciens strains (MTCC 431, MTCC 609, MTCC 2250, and MTCC 2251) were used to establish transformed callus cultures. These strains were purchased from the Microbial Type Culture Collection (MTCC), Institute of Microbial Technology (IMTECH), Chandigarh, India. A minimum of 30 explants were used for each experiment. All explants were cultured on Petristerized plates comprising MS medium solidified with 1.0% agar and supplemented with 30 g/l sucrose. The pH was adjusted to 5.7 ± 0.2. The medium was autoclaved under 15 psig pressure at 121ºC for 20 minutes. Explants were co-cultured with Agrobacterium strains for infection to induce transformed callus. For this purpose, Agrobacterial colonies were grown for 48 hours on solid nutrient agar medium at 28 ± 2°C. Ten loop bacteria were therefore… middle of paper… in a maximal synergistic promotion of glycyrrhizin accumulation, i.e. 4.9 times higher than the transformed control culture. The present study indicates the potential of these biotechnology-based methodologies for large-scale production of glycyrrhizin. Furthermore, in order to develop a process for the commercial production of glycyrrhizin from plant cell cultures, some additional yield improvement strategies could be developed, such as optimization of medium composition, environmental conditions and addition of precursors. Acknowledgments The authors are grateful to Dr. Ashish Baldi, Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology, Hauz Khas, New Delhi, India for his valuable and timely assistance. Author VSK would like to acknowledge All India Council for Technical Education, New Delhi for providing junior research scholarships.