Central Drug Research Institute

About: Central Drug Research Institute is a facility organization based out in Lucknow, Uttar Pradesh, India. It is known for research contribution in the topics: Leishmania donovani & Brugia malayi. The organization has 4357 authors who have published 7257 publications receiving 143871 citations. The organization is also known as: Central Drug Research Institute, Lucknow & CDRI.

Expression of 3-hydroxy-3-methylglutaryl-CoA reductase, p-hydroxybenzoate-m-geranyltransferase and genes of phenylpropanoid pathway exhibits positive correlation with shikonins content in arnebia [Arnebia euchroma (Royle) Johnston]

Abstract: Geranyl pyrophosphate (GPP) and p-hydroxybenzoate (PHB) are the basic precursors involved in shikonins biosynthesis. GPP is derived from mevalonate (MVA) and/or 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway(s), depending upon the metabolite and the plant system under consideration. PHB, however, is synthesized by only phenylpropanoid (PP) pathway. GPP and PHB are central moieties to yield shikonins through the synthesis of m-geranyl-p-hydroxybenzoate (GHB). Enzyme p-hydroxybenzoate-m-geranyltransferase (PGT) catalyses the coupling of GPP and PHB to yield GHB. The present research was carried out in shikonins yielding plant arnebia [Arnebia euchroma (Royle) Johnston], wherein no molecular work has been reported so far. The objective of the work was to identify the preferred GPP synthesizing pathway for shikonins biosynthesis, and to determine the regulatory genes involved in the biosynthesis of GPP, PHB and GHB. A cell suspension culture-based, low and high shikonins production systems were developed to facilitate pathway identification and finding the regulatory gene. Studies with mevinolin and fosmidomycin, inhibitors of MVA and MEP pathway, respectively suggested MVA as a preferred route of GPP supply for shikonins biosynthesis in arnebia. Accordingly, genes of MVA pathway (eight genes), PP pathway (three genes), and GHB biosynthesis were cloned. Expression studies showed down-regulation of all the genes in response to mevinolin treatment, whereas gene expression was not influenced by fosmidomycin. Expression of all the twelve genes vis-a-vis shikonins content in low and high shikonins production system, over a period of twelve days at frequent intervals, identified critical genes of shikonins biosynthesis in arnebia. A positive correlation between shikonins content and expression of 3-hydroxy-3-methylglutaryl-CoA reductase (AeHMGR) and AePGT suggested critical role played by these genes in shikonins biosynthesis. Higher expression of genes of PP pathway was a general feature for higher shikonins biosynthesis.