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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]

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Title 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]
 
Creator Singh, R S
Gara, R K
Bhardwaj, P K
Kumar, R
Malik, S
Ahuja, Paramvir Singh
Sharma, Madhu
Kumar, Sanjay
 
Subject Nutraceuticals
 
Description Background: 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.
Results: 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-à-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.
Conclusion: 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.
 
Date 2010
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://ihbt.csircentral.net/351/1/574_2010_Expression.pdf
Singh, R S and Gara, R K and Bhardwaj, P K and Kumar, R and Malik, S and Ahuja, Paramvir Singh and Sharma, Madhu and Kumar, Sanjay (2010) 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]. BMC Molecular Biology, 32. pp. 292-296.
 
Relation http://ihbt.csircentral.net/351/