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The influence of light quality on growth and development of in vitro grown Doritaenopsis hort. (Orchidaceae) plants was investigated. Growth parameters like leaf and root fresh/dry mass and leaf area were highest with plants grown under red plus blue light emitting diodes (LEDs). Leaf length was greater with the plants grown under red LED. Carbohydrate (starch, sucrose, glucose and fructose) and leaf pigment (chlorophylls and carotenoids) biosynthesis of the plants was significantly increased in plants grown under red plus blue LEDs compared to red or blue LED and fluorescent light treatments. This study suggests that the production of quality Doritaenopsis plants is possible by culturing the plants in vitro under a mixture of blue plus red light sources.

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Adventitious roots of ginseng were treated with methyl jasmonate (MJ) up to 150 microM and cultured for 40 days. Up to 100 microM MJ inhibited the root growth but increase ginsenoside accumulation. In a two-stage bioreactor culture, total ginsenosides, after elicitation with 100 microM MJ peaked after 10 days at 48 mg g(-1) dry wt and then dropped sharply. Of the two groups of ginsenosides (Rb and Rg), higher amounts of Rb accumulated in the adventitious roots.

In this study, we investigated the influence of initial sucrose concentration on the accumulation of biomass, phenols, flavonoids, chlorogenic acid, and hypericin in adventitious root cultures of Hypericum perforatum L. Cultures were initiated in shake flasks by using halfstrength Murashige and Skoog (MS) medium, 1.0 mg l -1 indolebutyric acid (IBA), 0.1 m g l -1 kinetin, and different concentrations 0, 1, 3, 5, 7, or 9% in w/v) of sucrose and were maintained in darkness. The medium supplemented with 3% (w/v) sucrose resulted in the optimum biomass accumulation, but higher sucrose concentrations (5, 7, and 9%) inhibited biomass accumulation due to the relatively higher osmotic pressure. However, the amount of total phenols, flavonoids, chlorogenic acid, and total hypericin was increased with the roots grown in the medium supplemented with 5, 7, and 9% (w/v) sucrose. The antioxidant potential of methanolic extract [1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid; ABTS) radical scavenging activities] of H. perforatum adventitious roots was also assessed and correlated with the metabolite accumulation. Cultures maintained with higher initial sucrose concentration (5, 7, and 9% w/v) showed increased accumulation of phenols, flavonoids, chlorogenic acid, and total hypericin, and this might be due to the osmotic stress at elevated sucrose concentrations. To verify the effect of osmotic stress on lipid peroxidation, the levels of hydrogen peroxide (H 2 O 2 ), malondialdehyde (MDA), and proline were determined in the adventitious roots and the results revealed a marked increase in the concentrations of these compounds. These results suggest that optimal adventitious root biomass could be achieved in the MS medium with 3% (w/v) sucrose and increased sucrose concentration resulted in osmotic stress and, in turn, induces the accumulation of secondary metabolites.

Recently, plant secondary metabolites are considered as important sources of pharmaceuticals, food additives, flavours, cosmetics, and other industrial products. The accumulation of secondary metabolites in plant cell and organ cultures often occurs when cultures are subjected to varied kinds of stresses including elicitors or signal molecules. Application of exogenous jasmonic acid (JA) and methyl jasmonate (MJ) is responsible for the induction of reactive oxygen species (ROS) and subsequent defence mechanisms in cultured cells and organs. It is also responsible for the induction of signal transduction, the expression of many defence genes followed by the accumulation of secondary metabolites. In this review, the application of exogenous MJ elicitation strategies on the induction of defence mechanism and secondary metabolite accumulation in cell and organ cultures is introduced and discussed. The information presented here is useful for efficient large-scale production of plant secondary metabolites by the plant cell and organ cultures.

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Ginseng (Panax ginseng C. A. Meyer) is one of the most famous oriental medicinal plants used as crude drugs in Asian countries, and now it is being used worldwide for preventive and therapeutic purposes. Among diverse constituents of ginseng, saponins (ginsenosides) have been found to be major components responsible for their biological and pharmacological actions. On the other hand, difficulties in the supply of pure ginsenosides in quantity prevent the development of ginseng for clinical medicines. Cultivation of ginseng in fields takes a long time, generally 5-7 years, and needs extensive effort regarding quality control since growth is susceptible to many environmental factors including soil, shade, climate, pathogens and pests. To solve the problems, cell and tissue cultures have been widely explored for more rapid and efficient production of ginseng biomass and ginsenosides. Recently, cell and adventitious root cultures of P. ginseng have been established in large scale bioreactors with a view to commercial application. Various physiological and engineering parameters affecting the biomass production and ginsenoside accumulation have been investigated. Advances in adventitious root cultures including factors for process scale-up are reviewed in this chapter. In addition, biosafety analyses of ginseng adventitious roots are also discussed for real application.