An efficient and cost effective micropropagation protocol using liquid medium was developed for Catharanthus roseus, a commercially important medicinal plant. Comparative analysis of shoot growth and proliferation in liquid Murashige and Skoog (MS) medium supplemented with different concentrations of cytokinins [6-Benzyladenine (BA), Kinetin (KN) and Thidiazuron (TDZ)] was conducted. Better response in terms of shoot proliferation, shoot diameter, number of leaves/shoot, number of branches/shoot, fresh weight and dry weight was observed in a liquid medium vis-à-vis solid medium. A sample of 20 ml of liquid medium supplemented with 5 lM of BA was optimized for propagation of C. roseus by a liquid culture system. Among various concentrations of auxins tried, 1-Naphthaleneacetic acid (NAA) 5 lM was found to be the best for root induction. Quantification of pharmaceutically important constituents (vincristine and vinblastine) and total alkaloid content of microshoots grown in solid and liquid medium as well as in vitro raised plants and mother plant was also conducted, hitherto unreported in this highvalue medicinal plant. This work further lays the foundations for the shifting of plant production from small to commercial scale.

Context Dunaliella salina Teodoresco (Dunaliellaceae) is one of the promising microalgae consumed as food and medicine for many years. Objective Dunaliella salina was grown under different stress conditions for enhancing carotene production. The carotene enriched extract was evaluated for antioxidant and cytotoxic activity. Materials and methods Carotene content was calculated under salinity, nitrogen and temperature stress conditions. Antioxidant activity was determined through DPPH assay by incubating the samples for 45 min with 250 lg/mL of extract and reducing power assay was performed with 50, 100, 150 and 200 lg/mL of extract. Cytotoxicity was determined by incubating $2 Â 10 4 MCF-7 (breast cancer) cells with 250 lg of extract in each well for 72 h by MTT assay. Result Carotene content was significantly increased to 9.8 (3.5 M NaCl), 13.9 (37 C), 8.2 (250 mM KNO 3 ) and 10.6 lg/mL (nitrogen-depleted medium) as compared with 3.2 lg/mL in normal conditions (1.7 M NaCl, 0.75 mM KNO 3 and 28 C). Free radical scavenging activity increased at 3.0 and 3.5 M NaCl (27.8 and 57.5%, respectively), 37 C (31.4%) and in nitrogen-depleted medium (41.9%) compared with normal (15%) conditions. Carotene content and scavenging activity were positively correlated under salinity (r ¼ 0.97), temperature (r ¼ 0.85) and nitrogen (r ¼ 0.7) stress conditions. Cytotoxicity against MCF-7 cell lines increased due to increase in carotene content suggesting that cytotoxicity may be associated with carotene accumulation. Discussion and conclusions Carotene content enhanced by D. salina under stress conditions increased the antioxidant and cytotoxic activity. ARTICLE HISTORY

Withania somnifera is one of the most valued plants and is extensively used in Indian, Unani, and African systems of traditional medicine. It possess a wide array of therapeutic properties including anti-arthritic, anti-aging, anti-cancer, anti-inflammatory, immunoregulatory, chemoprotective, cardioprotective, and recovery from neurodegenerative disorders. With the growing realization of benefits and associated challenges in the improvement of W. somnifera, studies on exploration of genetic and chemotypic variations, identification and characterization of important genes, and understanding the secondary metabolites production and their modulation has gained significant momentum. In recent years, several in vitro and in vivo preclinical studies have facilitated the validation of therapeutic potential of the phytochemicals derived from W. somnifera and have provided necessary impetus for gaining deeper insight into the mechanistic aspects involved in the mode of action of these important pharmaceutically active constituents. The present review highlights some of the current developments and future prospects of biotechnological intervention in this important medicinal plant.

Withania somnifera is a highly valued medicinal plant in traditional home medicine and is known for a wide range of bioactivities. Its commercial cultivation is adversely affected by poor seed viability and germination. Infestation by various pests and pathogens, survival under unfavourable environmental conditions, narrow genetic base, and meager information regarding biosynthesis of secondary metabolites are some of the other existing challenges in the crop. Biotechnological interventions through organ, tissue, and cell culture provide promising options for addressing some of these issues. In vitro propagation facilitates conservation and sustainable utilization of the existing germplasms and broadening the genetic base. It would also provide means for efficient and rapid mass propagation of elite chemotypes and generating uniform plant material round the year for experimentation and industrial applications. The potential of in vitro cell/organ cultures for the production of therapeutically valuable compounds and their large-scale production in bioreactors has received significant attention in recent years. In vitro culture system further provides distinct advantage for studying various cellular and molecular processes leading to secondary metabolite accumulation and their regulation. Engineering plants through genetic transformation and development of hairy root culture system are powerful strategies for modulation of secondary metabolites. The present review highlights the developments and sketches current scenario in this field.

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