Micropropagation and in vitro elicitation of licorice (Glycyrrhiza spp.)

The Glycyrrhiza genus, in the Fabaceae family, includes numerous medicinal and edible herbs that contain a wide range of phytochemicals which are used pharmaceutically and commercially. Glycyrrhiza spp. are under the threat of overexploitation and depletion; therefore, there is an urgent need for conservation. It is advantageous to develop in vitro techniques not only for propagation, multiplication and preservation but also for elicitation of secondary metabolite production. This review provides information on the micropropagation of different Glycyrrhiza spp. related to the use of different explants, the combination of plant growth regulators with different sterilization strategies, the culture conditions and additional factors influencing in vitro propagation (such as light, temperature, humidity and pH). Enhanced production of bioactive secondary metabolites by different elicitors is discussed. Different strategies for conservation of germplasm from Glycyrrhiza spp., namely encapsulation, cryopreservation and slow-growth system, are deliberated. The storage and availability of germplasm for commercial cultivation over the long run along with their germplasm evaluation using random amplification of polymorphic DNA and inter-simple sequence repeat techniques have also been presented. Successful multiplication, elicitation and downstream processing will lead to the production of not only greater quantities of planting material with improved quality but also commercially desired metabolites. The production of clinically novel compounds through biotransformation by cultured Glycyrrhiza spp. cells which can be used in future studies on somaclonal variation, genetic transformation and drug discovery is also reviewed.