Browsing by Author "Singh, Digvijay"

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Alkaloid profiles of the Indian land races of the opium poppy Papaver somniferum L
(Kluwer Academic Publishers, 2002) Prajapati, Seema; Bajpai, Suphla; Singh, Digvijay; Luthra, Rajesh; Gupta, Madan M.; Kumar, Sushil
The capsule husks of a set of 115 Indian land races of opium poppy Papaver somniferum L. obtained over two cropping seasons were screened for the percent contents of papaverine, reticuline, narcotine, thebaine, codeinone, codeine, morphine and oripavine. Among the accessions screened 36, 7 and 1 did not accumulate papaverine, papaverine and narcotine and codeine and morphine, respectively. The alkaloid profiles and correlations between alkaloids in all the four classes of accessions showed that in the Indian genetic resources of P. somniferum (a) morphine is synthesized from codeine rather than oripavine, (b) net alkaloid contents are low under narcotine deficiency, and (c) accumulation of morphine and codeine was limited upstream of codeinone and morphinone. The accessions identified to be harboring genetic blocks in the phenenthrine and benzylisoquinoline biosynthetic pathways will be useful for understanding the genetic control of secondary metabolism in opium poppy.
Expression of terpenoid indole alkaloid biosynthetic pathway genes corresponds to accumulation of related alkaloids in Catharanthus roseus (L.) G. Don
(Springer, 2005) Dutta, Ajaswrata; Batra, Jyoti; Pandey-Rai, Sashi; Singh, Digvijay; Kumar, Sushil; Sen, Jayanti
Madagascar periwinkle, Catharanthus roseus (L.) G. Don, a medicinally important plant, produces anticancer dimeric alkaloids, vinblastine and vincristine, in the leaves and accumulates antihypertensive alkaloids, ajmalicine and serpentine, in the roots. This plant grows wild in distant tropical and sub-tropical geographical locations with different agro-climates and shows wide variations in morphological and alkaloid yield-related traits. In order to understand the correlation between the expression of terpenoid indole alkaloid (TIA) pathway genes and accumulation of related alkaloids, six different genetic resources of C. roseus, including the medicinal cultivars Nirmal, Prabal, Dhawal, the mutants gsr-3 and gsr-6, and one horticultural variety, Pacifica blush, were studied. The expression profiles of one early and two late TIA biosynthetic pathway genes, namely, strictosidine synthase, desacetoxyvindoline 4-hydroxylase and deacetyl vindoline 4-O-acetyl transferase were analyzed in these plants. A positive correlation between transcript abundance and accumulation of related alkaloids was observed in the different genetic resources. The potential of these TIA biosynthetic pathway genes for use in screening of high-yielding C. roseus germplasm has been discussed.
Growth and terpenoid indole alkaloid production in Catharanthus roseus hairy root clones in relation to left- and right-termini-linked Ri T-DNA gene integration
(Springer, 2004) Batra, Jyoti; Dutta, Ajaswrata; Singh, Digvijay; Kumar, Sushil; Sen, Jayanti
Hairy root cultures of Catharanthus roseus var. Prabal were established by infecting the leaves with Agrobacterium rhizogenes agropine-type A4 strain. Two hundred and fifty independent root clones were evaluated for growth, morphology, number of integration of Ri T-DNA genes and alkaloid contents. On the basis of growth pat- tern, type of branching and number of lateral roots we were able to separate the hairy root clones into four categories. However based on the integration of the Ri TL-DNA and TR-DNA genes, there were only three different categories of independent hairy root clones–C1 (rolA&B+/ags+), C2 (rolA&B-/ags+) and C3 (rolA&B+/ags ). Southern hybridization analysis revealed both single and multiple copies of T-DNA integration in the root clones. The accumulation of considerable amounts of the root-specific alkaloids ajmalicine and serpentine was observed in the presence of both the TL-DNA and TR-DNA genes (C1) and the TL-DNA gene (C3) alone. Two rolA&B but ags+ clones (C2) accumulated much less or only very negligible amounts of ajmalicine. The possible role of the TL-DNA and TR-DNA genes on growth and alkaloid accumulation in these root clones is discussed
High yields of artemisinin by multi-harvest of Artemisia annua crops
(Elsevier B.V., 2004) Kumar, Sushil; Gupta, S.K.; Singh, Poorinima; Bajpai, Pratima; Gupta, M.M.; Singh, Digvijay; Gupta, A.K.; Ram, Govind; Shasany, A.K.; Sharma, Srikant
Several field crop experiments were carried out on the annual determinate anti-malarial medicinal plant Artemisia annua over three annual cropping periods in the subtropical agroclimate of Indo-Gangatic plains. The experiments examined the effects of variation in the time of planting and harvest and of number of harvests on the yield of artemisinin and plant growth and development characters related to it. The observations showed that the artemisinin yield was positively correlated with leaf yield and number of harvests. High yields of artemisinin were realized when crop produced artemisinin-rich leaves accompanied by least possible growth of stem tissue, attained by multiple harvesting in early planted full time grown crops. The crops grown for ≥30 weeks and harvested three and four times gave average yields of 44.1 ± 14.2 and 74.2 ± 15.6, respectively, much higher than the maximum yield of 25 kg ha−1 reported for A. annua in earlier studies. It was concluded that for obtaining artemisinin in high yields the A. annua crop should be ratooned/multi-harvested four times.
Predominance of the serpentine route in monoterpenoid indole alkaloid pathway of Catharanthus roseus
(Indian National Science Academy, 2008) Singh, Digvijay; Rai, Sanjay Kumar; Pandey-Rai, Shashi; Srivastava, Suchi; Mishra, Raghvendra Kumar; Sharma, Srikant; Kumar, Sushil
Single runs of RP-HPLC procedure were used for simultaneous and organ-wise quantification of the terpenoid indole alkaloids (TIAs) serpentine, ajmalicine, vindoline, catharanthine, vincristine and vinblastine in whole adult plants of Catharanthus roseus, sampled from 81 accessions and F2 generation of a cross. The average total TIA content was 159 mg distributed among stem, root, leaf and inflorescence organs in 13:8:3:1 proportion. The root and stem barks, leaf-petiole and corolla petals were several fold TIA-richer than root and stem woods, leaf–lamina and rest of flower organs, respectively. TIAs were undetectable in seed but present in the seedling. Quantitatively, serpentine (+ ajmalicine), serpentine and catharanthine, vindoline, serpentine, catharanthine and vinblastine (+ vincristine) were the principal TIAs detected in stem, root, leaf and inflorescence organs, respectively. Significant amounts of vinblastine, vindoline and catharanthine were found present in the non-chlorophyllous corolla petals. Correlation studies showed that contents of catharanthine and serpentine in roots, catharanthine, vindoline and vinblastine in leaves, serpentine in roots and stems and stems and leaves were interdependent. Serpentine could be involved in suppressing the accumulation of other TIAs in leaves. The observed inter- and intra- organ contents of end-products from serpentine, catharanthine and vindoline TIA branch pathways and correlations between them showed predominance of the serpentine branch.
Regulation of unipinnate character in the distal tendrilled domain of compound leaf-blade by the gene MULTIFOLIATE PINNA (MFP) in pea Pisum sativum
(Elsevier B.V., 2004) Kumar, Sushil; Rai, Sanjay Kumar; Pandey-Rai, Shashi; Srivastava, Suchi; Singh, Digvijay
The wild type compound leaf-blade of Pisum sativum has one to three pairs of simple leaflet pinnae in its petiole proximal domain, one to four pairs of simple tendril pinnae in the distal domain and a simple tendril pinna in the apical domain. A novel ethyl methane sulfonate induced dominant mutant was isolated and characterized whose leaf-blades formed MULTIFOLIATE PINNA pairs in the distal domain. The distal multifoliate pinnae or compound pinna-blades had three tendrilled-leaflets as pinnules. The pinnules had a bifacial elliptic-lanceolate leaflet body and arc shaped apex that mimicked the ringlet shaped apex of tendrils. The TL/tl, mfp/mfp and tl/tl, mfp/mfp leaf-blades also produced multifoliate (compound) pinna-blades in distal positions; the pinnules of these genotypes had elliptic shape. The pinnae were branched tendrils in TL/TL, MFP/mfp plants. The leaf-blade rachis was more ramified in af mfp double mutants than in af mutant. In the af mfp double mutant, the multifoliate pinna-blades were present on tertiary and secondary branches of the rachis in the proximal domain and on secondary branches and the primary rachis in the distal domain. The leaf-blades of the af tl mfp triple mutant genotype were an order of magnitude more ramified than those of af tl and af mfp genotypes in proximal as well as distal domains. The leaf-blade phenotypes of various genotypes revealed in this study and those known from previous work have allowed the following conclusions about the nature of mfp mutation and mfp function(s). (a) The presence of mfp mutation or mfp function changes the identity of distal primordia, from tendrils in the wildtype (MFP/MFP) leaf-blades to multifoliate pinna-blades in mfp/mfp mutant. (b) A pathway for the lamination of pinnules of multifoliate blades formed in distal and terminal domains in the mfp mutant and all domains in af mfp double mutant is activated by the mfp mutation. (c) The leaflet-/pinnule-lamination pathway activated by the tl mutation interacts with the mfp-directed pathway. (d) The mfp mutation intensifies rachis ramification in proximal and distal domains activated by the af mutation. This process is distinct from analogous rachis ramification that occurs in the af tl double mutant.
Transcript profiling of terpenoid indole alkaloid pathway genes and regulators reveals strong expression of repressors in Catharanthus roseus cell cultures
(Springer, 2007) Dutta, Ajaswrata; Singh, Digvijay; Kumar, Sushil; Sen, Jayanti
The understanding of the complexities and molecular events regulating genes and the activators involved in terpenoid indole alkaloid (TIA) metabolism is known to a certain extent in cell cultures of an important TIA yielding plant, Catharanthus roseus, though it is not yet complete. Recently, the repressors of early TIA pathway genes have also been identified. However, their roles in the regulation of TIA pathway in C. roseus cell cultures remains yet unknown. We have made a comparative profiling of genes catalyzing the important steps of 2-C methyl-D-erythritol-4- phosphate (MEP), shikimate and TIA biosynthetic pathways, their activator and repressors using macro- array, semiquantitative RT-PCR and northern analyses in a rotation culture system of C. roseus comprising differentiated and proliferated cells. Our results demonstrate that TIA biosynthetic pathway genes and their activators show variable expression pattern, which was correlated with the changes in the cellular conditions in these systems. Under similar conditions, TIA pathway repressors show strong and consistent expression. The role of repressors in the complex regulation of the TIA pathway in C. roseus cell cultures is discussed. The results were supported by HPLC data, which demonstrated that the molecular program of cellular differentiation is intimately linked with TIA pathway gene expression and TIA production in C. roseus cell cultures.
Volatile compounds of leaves and flowers of periwinkle Catharanthus roseus (L.) G. Don from New Delhi
(Wiley-Blackwell, 2006) Pandey-Rai, Shashi; Mallavarapu, Gopal Rao; Naqvi, A. A.; Yadav, Anju; Rai, Sanjay Kumar; Srivastava, Suchi; Singh, Digvijay; Mishra, Raghvendra; Kumar, Sushil
The hydrodistilled waxy oils of the leaves and flowers of Catharanthus roseus (L.) G. Don cv. Nirmal plants grown at New Delhi were analysed by GC and GC–MS. A total of 52 compounds were identified, accounting for the 91.3% of the leaf oil.Among these the main constituents were as follows: (E,E )-2,4-hexadienal (7.7%), citronellol (7.9%), geraniol (7.9%), p-cresol (4.7%), (Z,E )-pentadecanal (6.6%), hexadecanoic acid (4.9%), palmitic acid (4.9%) and phytol (6.4%). A total of 41 compounds were identified, accounting for 99.4% of the flower oil, whose main constituents were heneicosane (20.8%), tricosane (37.9%), tetracosane (6.1%) and docosane (4.3%). A total of 24 compounds occurred in both the leaf and flower oils.