Biotechnological Application of Meta-topolins as Highly Active Aromatic Cytokinins in Micropropagation of Medicinal Plants

Medicinal herbs and plants are the major reservoirs for new drug formulations. Owing to pharmaceutical demands and limited wild resources, it is vital to conserve genetic diversity, which is continuously under the risk of extinction due to its overexploitation which resulted in natural habitat abolition and unmonitored medicinal plant trade. To deal with this major havoc, plant biotechnological techniques and approaches such as plant tissue culture and micropropagation hold promise for conservation and rapid mass multiplication to obtain genetically elite (true to type) populations under in vitro conditions. The most critical factor that has an effect on in vitro plant propagation success is the choice and selection of plant growth regulators (i.e., auxins and cytokinins). Plant growth regulators are often supplemented in the nutrient medium to harness the totipotent potential such as development of shoots, roots and whole plants. Most commonly used cytokinin in plant tissue culture micropropagation protocols is N6-benzyladenine (BA), but nowadays meta-topolin as highly active aromatic cytokinin along with its derivatives have been largely investigated and proved as an effective alternative to BA in micropropagation protocols of medicinal plants. This chapter addresses the biotechnological application of meta-topolins such as their effect on in vitro plant regeneration, micropropagation and hardening, countering micropropagation troubles and its influences on secondary metabolite production.