title: Exogenous feeding of immediate precursors reveals synergistic effect on picroside-I biosynthesis in shoot cultures of Picrorhiza kurroa Royle ex Benth.
abstract: In the current study, we asked how the supply of immediate biosynthetic precursors i.e. cinnamic acid (CA) and catalpol (CAT) influences the synthesis of picroside-I (P-I) in shoot cultures of P. kurroa. Our results revealed that only CA and CA+CAT stimulated P-I production with 1.6-fold and 4.2-fold, respectively at 2.5 mg/100 mL concentration treatment. Interestingly, feeding CA+CAT not only directed flux towards p-Coumaric acid (p-CA) production but also appeared to trigger the metabolic flux through both shikimate/phenylpropanoid and iridoid pathways by utilizing more of CA and CAT for P-I biosynthesis. However, a deficiency in the supply of either the iridoid or the phenylpropanoid precursor limits flux through the respective pathways as reflected by feedback inhibition effect on PAL and decreased transcripts expressions of rate limiting enzymes (DAHPS, CM, PAL, GS and G10H). It also appears that addition of CA alone directed flux towards both p-CA and P-I production. Based on precursor feeding and metabolic fluxes, a current hypothesis is that precursors from both the iridoid and shikimate/phenylpropanoid pathways are a flux limitation for P-I production in shoot cultures of P. kurroa plants. This work thus sets a stage for future endeavour to elevate production of P-I in cultured plant cells.
authors.affiliation: Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology, Waknaghat-173234, Solan (HP), India.
authors.forename: Varun
authors.initials: V
authors.lastname: Kumar
authors.affiliation: Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology, Waknaghat-173234, Solan (HP), India.
authors.forename: Neha
authors.initials: N
authors.lastname: Sharma
authors.affiliation: Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology, Waknaghat-173234, Solan (HP), India.
authors.forename: Hemant
authors.initials: H
authors.lastname: Sood
authors.affiliation: Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology, Waknaghat-173234, Solan (HP), India.
authors.forename: Rajinder Singh
authors.initials: RS
authors.lastname: Chauhan
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics; D002934:Cinnamates / Q000378:metabolism*; D025461:Feedback, Physiological; D018506:Gene Expression Regulation, Plant; D057888:Iridoid Glucosides / Q000378:metabolism*; D032261:Picrorhiza / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism*; D046509:Tissue Culture Techniques
chemical_list: D002934:Cinnamates; D057888:Iridoid Glucosides; D010940:Plant Proteins; C029010:cinnamic acid; C078040:catalpol; C109270:picroside I