In vitro manipulation and propagation of medicinal plants.

Well developed techniques are currently available to help growers meet the demand of the pharmaceutical industry in the next century. These protocols are designed to provide optimal levels of carbohydrates, organic compounds (vitamins), mineral nutrients, environmental factors (e.g. light, gaseous environment, temperature, and humidity) and growth regulators required to obtain high regeneration rates of many plant species in vitro and thereby facilitate commercially viable micropropagation. Well-defined cell culture methods have also been developed for the production of several important secondary products. An overview of the regeneration of medicinal plants by direct and indirect organogenesis and by somatic embryogenesis from various types of explants is presented, and the use of these techniques combined with other biotechnological approaches to improve medicinal plants through somaclonal variation and genetic transformation is reviewed.