Jatropha curcas L. is one potential source of non-edible biofuel-producing energy crop. Its importance also lies in its medicinal properties. The species is primarily propagated through heterozygous seeds, and thus the seed oil content varies from 4 to 40%. Moreover, due to its perennial nature, seed setting requires 2 to 3 years time. The seed viability and rate of germination are low, and quality seed screening is another laborious task; thus, seed propagation alone cannot provide quality planting material for sustainable use. Somatic embryogenesis, a powerful tool of plant biotechnology for faster and quality plant production has been successfully applied to regenerate plants in Jatropha curcas for the first time. Embryogenic calli were obtained from leaf explants on MS basal medium supplemented with only 9.3 lM Kn. Induction of globular somatic embryos from 58% of the cultures was achieved on MS medium with different concentrations of 2.3-4.6 lM Kn and 0.5-4.9 lM IBA; 2.3 lM Kn and 1.0 lM IBA proved to be the most effective combination for somatic embryo induction in Jatropha curcas. Addition of 13.6 lM adenine sulphate stimulated the process of development of somatic embryos. Mature somatic embryos were converted to plantlets on half strength MS basal medium with 90% survival rate in the field condition. The whole process required 12-16 weeks of culture for completion of all steps of plant regeneration. This protocol of somatic embryogenesis in Jatropha curcas may be an ideal system for future transgenic research.

Swertia chirata is an endangered Gentian species used as herbal medicine for various health ailments including liver disorders, malaria, and diabetes. The depletion of S. chirata from the wild for such applications is a concern. Slow rates of propagation because of poor seed germination and low seed viability are presently limiting factors for its large-scale commercial cultivation. For commercial plantation and conservation of existing germplasm, in vitro multiplication is an attractive solution. The present investigation has achieved production of genetically uniform plants from the nodal explants. Shoot regeneration was obtained in shoot-inducing medium containing half-strength Murashige and Skoog's basal medium supplemented with 0.44 μM 6-benzylaminopurine and 4.65 μM 6-furfurylaminopurine. The highest number of shoots, at 18 per explant, regenerated when media was further fortified with 10 mM KNO 3 and 75 mg l −1 of casein hydrolysate. Tissue culture regenerated plantlets were successfully transferred to the field and produced viable seeds. Studies of chromosome number and a comparative analysis of the DNA fingerprinting profiles indicate genetic stability of the regenerated plants.

Plant tissue culture and molecular biology techniques are powerful tools of biotechnology that can complement conventional breeding, expedite crop improvement and meet the demand for availability of uniform clones in large numbers. Jatropha curcas Linn., a non-edible, eco-friendly, non-toxic, biodegradable fuelproducing plant has attracted worldwide attention as an alternate sustainable energy source for the future. This review presents a consolidated account of biotechnological interventions made in J. curcas over the decades and focuses on contemporary information and trends of future research.

Aloe vera L.

Cell culture of Taxus wallichiana Zucc (= T. baccata ssp wallichiana Zucc. Pilg.) (Himalayan yew) has been established and taxol-producing cell lines selected by cell line cloning. Cell line NC110 derived from needle leaf of a 40-year-old tree growing in Darjeeling Himalayas produced 0.018% taxol in B5 basal medium supplemented with 2,4-D (2 mg/l), kinetin (0.5 mg/l), and casein hydrolysate (0.5%). This cell line has been maintained for over 2 years. Significant enhancement in the level of taxol (0.05%) was obtained in this cell line by supplementation of the basal medium with 5 mg/l of IAA-phenylalanine instead of 2,4-D without adversely affecting cell growth. IAA-glycine also enhanced taxol level (0.03%) while IAA alone (1-10 mg/l) was ineffective in inducing taxol accumulation. Using three different cell lines with different taxol-producing capacities, it has been demonstrated that 2,4-D and IAA-phenylalanine when present alone favour growth and taxol production but when combined enhance biomass to a maximum (six-fold in NC110) without enhancing taxol accumulation, suggesting that a two-stage culture may be beneficial for optimising taxol accumulation in cell culture of T. wallichiana.

Extraction and analysis of paclitaxel and other taxanes in bark, needle leaves and stem segments of male and female plants of Taxus wallichiana, representing several populations, indicate that significant variation in taxane content exists within the population. Bark accumulated maximum amount of paclitaxel in almost all plants. Populations located at higher altitude tended to accumulate more paclitaxel than lower altitude plants. Seasons in which samples were collected and plant age have also been shown to affect paclitaxel accumulation. No effects of plant sex on paclitaxel content of the plants analyzed were observed. Significant differences in baccatin-III and 10-deacetylbaccatin III content were found to exist in the trees analyzed in this study.

The genus Drimia (syn. Urginea), commonly called squill, represents a species complex, infrageneric delimitation being ill-defined due to morphological variability, population variation within species and polyploidy. In the present study, fluorescent chromosome banding and measurements of nuclear DNA content by flow cytometry were performed in five Indian species of Drimia: Drimia indica, Drimia polyantha, Drimia razii, Drimia wightii and Drimia coromandeliana to elucidate taxonomic relationship and obtain possible insights into the evolutionary processes within this group. All taxa analyzed exhibited similar karyomorphology with subtle differences accounted by nucleolar chromosomes. Nuclear DNA content ranged from 20.41 pg/2C in D. polyantha to 40.80 pg/2C in D. coromandeliana and was positively correlated with chromosome number (r = 0.67, P = 0.02) and total diploid chromatin length (r = 0.59, P = 0.06). Fluorescent chromosome banding revealed the presence of CMA(+ve)/DAPI(-ve) signals associated with nucleolar chromosomes presumably coincident with NOR in all species and unique CMA(+ve) signals in diploid populations of D. indica. Satellite polymorphism between homologous NOR-bearing chromosomes was observed which supports hybrid origin of the taxon. UPGMA dendrogram and scatter diagrams based on karyological parameters indicated a close relationship of D. indica, D. razii and D. polyantha while D. wightii and D. coromandeliana appeared distant. D. wightii appeared more close to D. indica than to all other species based on genome size and karyomorphology. As a whole, D. indica showed high intra-specific variability with populations exhibiting intergrading characters with other species. In conclusion, it is likely that hybridization followed by reproductive isolation of polymorphic forms arising by adaptation to different ecological niches resulted in species diversification of Drimia in India, probably from a common ancestor similar to D. indica.

Crop improvement, conservation and utilization of plant genetic resources has benefited from chromosomal studies of germplasms. In the Indian sub continent, lentil (Lens culinaris Medik.) is a major rabi pulse crop with 2n = 2x = 14 chromosomes. Chromosomal studies were carried out on Indian lentils during the period of 1952 to 1991 employing orcein squash techniques by different authors but there was no unanimity on chromosome morphology and chromatin length. This is the first study conducted on two wild and 12 cultivated cultivars of Lens for detailed and comparative chromosomal analysis using enzymatic maceration and air drying (EMA) based Giemsa staining methods. Chromosomal analysis revealed chromosomal stability, uniform karyotype formula (3m + 1m (sat) + 2sm + 1st), one pair of interstitial sat in either chromosome number 3 or 4 and interesting variations in total chromatin length (53.6-121.2 μm) in all the studied cultivars. More studies on other species and cultivars along with the application of flurochrome dyes for characterizing apparently similar chromosomes at the cultivar level may be very useful for future crop improvements.