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An efficient protocol has been developed for the in vitro propagation of Bambusa tulda through shoot proliferation. Shoots from 3-week-old aseptically grown seedlings were used to initiate cultures. Multiple shoots were obtained on liquid Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine (8×10(-6)M) and kinetin (4×10(-6)M). Continuous shoot proliferation at a rate of 4-5 fold every three weeks was achieved through forced axillary branching. More than 90% of the shoots could be rooted on a modified MS medium containing indoleacetic acid (1×10(-5)M) and coumarin (6.8×10(-5)M). Following simple hardening procedures, the in vitro raised plants were transferred to the soil with more than 80% success.

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Asparagus racemosus Willd. is an important medicinal plant of tropical and subtropical India. Its medicinal usage has been reported in the Indian and British Pharmacopoeias and in traditional systems of medicine such as Ayurveda, Unani, and Siddha. The multiple uses of this species have increased its commercial demand, resulting in over-exploitation. Because of destructive harvesting, the natural population of A. racemosus is rapidly disappearing, and it is recognized as 'vulnerable' (Warner et al., Some important medicinal plants of the Western Ghats, India: a profile. International Development Research Centre, Artstock, New Delhi, India, 15 pp, 2001). The development of an efficient micropropagation protocol will play a significant role in meeting the requirements for commercial cultivation, thereby conserving the species in its natural habitat. In the present study, in vitro shoot proliferation was obtained by culturing single node segments in Murashige and Skoog's (MS) medium supplemented with 3.69 µM 2-isopentyl adenine and 3% sucrose with a multiplication rate of 3.5. For proper root formation, the in vitro-formed shoot clusters were cultured on half strength (major salts reduced to half) MS medium with 1.61 µM 1-naphthalene acetic acid, 0.46 µM kinetin, 98.91 µM adenine sulfate, 500 mg/l malt extract, 198.25 µM phloroglucinol, and 3% sucrose. On this medium, 85% rooting was observed within 20 d. Following a simple hardening procedure involving sequential transfer of plants to a greenhouse, polyhouse, and shade net, the tissue-cultured plants were transferred to the field where the survival rate was 100%.

Enhanced production of steviol glycosides (SGs) was observed in callus and suspension culture of Stevia rebaudiana treated with proline and polyethylene glycol (PEG). To study their effect, yellow-green and compact calli obtained from in vitro raised Stevia leaves were sub-cultured on MS medium supplemented with 2.0 mg l(-1) NAA and different concentrations of proline (2.5-10 mM) and PEG (2.5-10 %) for 2 weeks, and incubated at 24 ± 1 °C and 22.4 μmol m(-2) s(-1) light intensity provided by white fluorescent tubes for 16 h. Callus and suspension culture biomass (i.e. both fresh and dry weight content) was increased with 5 mM proline and 5 % PEG, while at further higher concentrations, they got reduced. Further, quantification of SGs content in callus (collected at 15th day) and suspension culture (collected at 10th and 15th day) treated with and without elicitors was analysed by HPLC. It was observed that chemical stress enhanced the production of SGs significantly. In callus, the content of SGs increased from 0.27 (control) to 1.09 and 1.83 % with 7.5 mM proline and 5 % PEG, respectively, which was about 4.0 and 7.0 times higher than control. However, in the case of suspension culture, the same concentrations of proline and polyethylene glycol enhanced the SG content from 1.36 (control) to 5.03 and 6.38 %, respectively, on 10th day which were 3.7 times and 4.7 times higher than control.

This communication describes for the first time an efficient and reproducible protocol for large-scale multiplication of Bambusa nutans. Nodal segments collected from field-grown clumps and cultured on Murashige and Skoog (MS) medium supplemented with 4.4 lM benzylaminopurine (BA) and 2.32 lM kinetin (Kin) gelled with 0.2% gelrite yielded 80% aseptic cultures with 100% budbreak. The in vitro-formed shoots obtained after bud-break were successfully multiplied in MS liquid medium supplemented with 13.2 lM BA, 2.32 lM Kin, and 0.98 lM indole-3-butyric acid (IBA). Sub-culturing of shoots every 3 weeks on fresh multiplication medium yielded a consistent proliferation rate of 3.5-fold. Shoot clusters containing three to five shoots were successfully rooted with 100% success on half-strength MS liquid medium supplemented with 9.8 lM IBA, 2.85 lM indole-3-acetic acid (IAA), 2.68 lM naphthaleneacetic acid (NAA), and 3% sucrose. Plantlets grown in vitro were acclimatized and subsequently transferred to the field. Inter-simple sequence repeat analysis has confirmed the genetic uniformity of the tissue-cultured plants up to 27 passages.

Bambusa balcooa is one of the most commercially important bamboo species. Regeneration of this species by sexual means is impossible because no seeds are set after flowering. Vegetative propagation is hindered due to bulky propagules, low rooting ability of the culm and branch cuttings, and seasonal specificity. This makes in vitro-based methods of regeneration important. This paper describes an efficient micropropagation protocol for multiplication of B. balcooa from nodal explants. Nodal segments were surface sterilized with 0.1% mercuric chloride for 10 min, and cultured on Murashige and Skoog (MS) medium supplemented with 4.4 μM 6-benzylaminopurine (BAP), 2.32 μM kinetin (Kn), and gelled with 0.2% w/v gelrite. Eighty-five percent of explants could be established in vitro with 90% of these achieving bud break. In vitro-formed shoots were successfully multiplied in MS liquid medium supplemented with 6.6 μM BAP, 2.32 μM Kn, 2.5% v/v coconut water, and 100 mg l −1 myo-inositol. Subculturing shoots every 3 wk yielded a consistent proliferation rate of 4.11-fold without decline in vigor. Shoot clusters, containing 5 to 8 shoots, were rooted with 87.5% success in 1/2 MS supplemented with 5.71 μM indole-3-acetic acid (IAA), 4.9 μM indole-3-butyric acid (IBA), and 5.37 μM naphthaleneacetic acid (NAA) within 3 wk. Plants regenerated in this manner were acclimatized in the greenhouse and under a shade net with 88% success.