Summary Tabernaemontana coronaria of Apocynaceae is an economically important medicinal plant, distributed throughout the tropics of the world. The different alkaloids produced by this species are effective against various disorders like abdominal tumors, asthma, diarrhoea, epilepsy, eye infections and fever. Morphological characters including internode length, petiole length, leaf area and leaf index varied between these varieties. Cytological analysis revealed three diploid varieties with 2n=22 chromosomes (Wild type T. coronaria, T. coronaria var. Variegata, T. coronaria var. Dwarf) and a triploid variety with 3n=33 chromosomes (T. coronaria var. Florepleno). A variation was recorded in total chromosome length and volume among the diploid varieties of T. coronaria. Most of the centromeric chromosomes were either median or median region. The present study indicated that cryptic structural changes of chromosomes might be responsible in the evolution of different varieties of T. coronaria except the Flore-pleno variety. Moreover, differential condensation of chromosomes attributing to variable chromosome length and volume has been suggested.
SummaryThe present article describes an efficient technique for micropropagation and microtuberization of two species of Gloriosa, G. orangea and G. rothschildiana of Colchicaceae, the colchicine yielding plants. The plants were propagated in culture through apical shoot bud multiplication using modified Murashige and Skoog's nutrient medium (MS) supplemented with 6-benzylaminopurine (BAP) and a-naphthaleneacetic acid (NAA) in presence of two different concentrations of sucrose (3 and 6%). The process of microtuberization was found to be quite efficient in MS containing 3% sucrose, producing about 180-240 tubers per culture vessel within 6 months or less. On the other hand, the medium with 6% sucrose level induced microtuberization 2 weeks earlier with reduced rate of regeneration. The microtubers from 3% media showed 97% germination rate. The best result was obtained in a medium containing BAP (17.76 mM) and NAA (2.15 mM) with about 18-24 shoots and 14-21 microtubers/shoot. A 1.7 fold increase in colchicine accumulation in G. rothschildiana and a 2.0 fold increase in G. orangea estimated through High Pressure Liquid Chromatography (HPLC) were observed as compared to in vivo tubers. The extracted colchicine showed better efficacy than standard colchicine from Sigma Chemical Co. in treated root tip cells of Allium sativum L. and Mucuna pruriens L. In both these test plant systems, the extracted colchicine induced both polyploidy and diplochromatid formation at variable rates and the values were little higher in G. orangea than in G. rothschildiana. Moreover, G. orangea responded better than G. rothschildiana against the same concentrations of plant growth regulators and showed better colchicine accumulation as well. Key wordsThe species of Gloriosa of Colchicaceae (formerly under Liliaceae), distributed throughout tropical and sub-tropical regions of Asia and Africa, are medicinally important for treatment of chronic ulcers, hemorrhoids, leprosy and for inducing labor pains (Chopra et al. 1969). These plants contain the valuable alkaloids, the colchicine and colchicosides like another genus, Iphigenia under this family (Mukhopadhyay and Mukhopadhyay 2008a, b). The plants of Gloriosa are being overexploited for long time by the rural people for their medicinal purpose and that has caused its distribution very limited and so designated as threatened. Moreover, Gloriosa shows a very poor rate of vegetative propagation and one plant produces only one bi-forked tuber with one growing bud on top of each fork. The seed-grown plants, on the other hand, also take three to four years to flower and therefore, it is also not usually favored by the growers. In order to maintain different germplasms of these species of Gloriosa, suitable measures for rapid mass propagation and conservation are of much importance. Several
Reports on increment in L-DOPA content in micropropagated plants, regenerated through a simple technique following shoot bud multiplication in four strains of two different varieties of Mucuna pruriens are made. Nodal segments from in vitro grown seedlings were cultured on modified MS with various concentrations and combinations of BAP, 2iP, Kn either alone or with NAA. Highest shoot regeneration from the callus was achieved in modified MS fortified with BAP at 1.33 μM level. The regenerated shoots were rooted in vitro in half-strength of liquid MS supplemented with various levels of NAA (0.54 -10.7 µM) or IBA (0.49 -9.85 µM). However, roots of superior quality were obtained at 5.4 µM NAA level after two weeks in culture. The regenerants were acclimatized for 2 -3 weeks and about 85% survival rate was observed after transferring to the field. Both chromosome number stability as well as stability in nuclear DNA contents of the regenerants of all these strains was recorded with complete absence of aneuploidy. The different strains have revealed two to threefolds increase in L-DOPA contents in the cultured plants. The L-DOPA concentration in leaves of the regenerated plants varied from11.85 -15.42 mg/g dry weight in all these accessions. However, the highest amount was observed in the wild strain of M. pruriens. This is the first report on enhancement of L-DOPA content in differentiated tissue of cultured plants of both the varieties of M. pruriens.
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