In vitro Microrhizome Induction and Essential Oil Production from Aromatic Ginger Kaempferia galanga : An Economically Important Medicinal Herb

Kaempferia galanga L. or ‘aromatic ginger’ is a stem-less herb in Zingiberaceae having different pharmacological properties like antioxidant, antimicrobial, nemeticidal, vasorelaxant and wound healing activity. The plant is generally a vegetatively propagated annual herb; its conservation using conventional methods takes more time to get sufficient amount of planting materials for commercial cultivation. Micropropagation by in vitro methods helps to overcome the present demand for this high sought medicinal and aromatic species. At present the concern on in vitro propagation is directed to rhizome or storage organ induction for productive acclimatization and to reduce the injury during transportation. Microrhizomes are the small rhizomes developed in in vitro conditions and its induction is an effective biotechnological tool for the production of quality planting materials as they are genetically stable and disease free. The present study is discussing the role of silver nitrate (AgNO3) along with sucrose in in vitro microrhizome induction in K. galanga for the first time. MS medium fortified with 2.0 mgl-1 AgNO3 along with 6% (w/v) sucrose produced maximum amount of microrhizomes i.e., 4.52±0.11 g after 3 months that increased to 5.70±0.20 g in six months of harvesting. Here we also reports the comparative analysis of chemical constituents in the essential oil of in vivo rhizomes and in vitro microrhizome through GC-MS analysis that further reveals the superior characteristics of the microrhizomes in terms of the bioactive components ethyl p-methoxy cinnamate and ethyl cinnamate, the esters that contribute the nematicidal, antituberculosis, anti-inflammatory, antifungal and larvicidal properties to the oil. This protocol for in vitro microrhizome induction can be used for the commercial production of rhizomes and essential oil in K. galanga and the outcome of this study can be further used for mass production of pathogen-free microrhizomes and conservation for its sustainable utilization of the species.