title: Silencing of sterol glycosyltransferases modulates the withanolide biosynthesis and leads to compromised basal immunity of Withania somnifera.
abstract: Sterol glycosyltransferases (SGTs) catalyse transfer of glycon moiety to sterols and their related compounds to produce diverse glyco-conjugates or steryl glycosides with different biological and pharmacological activities. Functional studies of SGTs from Withania somnifera indicated their role in abiotic stresses but details about role under biotic stress are still unknown. Here, we have elucidated the function of SGTs by silencing SGTL1, SGTL2 and SGTL4 in Withania somnifera. Down-regulation of SGTs by artificial miRNAs led to the enhanced accumulation of withanolide A, withaferin A, sitosterol, stigmasterol and decreased content of withanoside V in Virus Induced Gene Silencing (VIGS) lines. This was further correlated with increased expression of WsHMGR, WsDXR, WsFPPS, WsCYP710A1, WsSTE1 and WsDWF5 genes, involved in withanolide biosynthesis. These variations of withanolide concentrations in silenced lines resulted in pathogen susceptibility as compared to control plants. The infection of Alternaria alternata causes increased salicylic acid, callose deposition, superoxide dismutase and H2O2 in aMIR-VIGS lines. The expression of biotic stress related genes, namely, WsPR1, WsDFS, WsSPI and WsPR10 were also enhanced in aMIR-VIGS lines in time dependent manner. Taken together, our observations revealed that a positive feedback regulation of withanolide biosynthesis occurred by silencing of SGTLs which resulted in reduced biotic tolerance.
authors.affiliation: Council of Scientific and Industrial Research-National Botanical Research Institute, Rana Pratap Marg, Lucknow-226001, Uttar Pradesh, India.|Banaras Hindu University, Varanasi, Uttar Pradesh, India.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Singh
authors.affiliation: Council of Scientific and Industrial Research-National Botanical Research Institute, Rana Pratap Marg, Lucknow-226001, Uttar Pradesh, India.
authors.forename: Manish
authors.initials: M
authors.lastname: Tiwari
authors.affiliation: Council of Scientific and Industrial Research-National Botanical Research Institute, Rana Pratap Marg, Lucknow-226001, Uttar Pradesh, India.
authors.forename: Surendra Pratap
authors.initials: SP
authors.lastname: Singh
authors.affiliation: Banaras Hindu University, Varanasi, Uttar Pradesh, India.
authors.forename: Surendra
authors.initials: S
authors.lastname: Singh
authors.affiliation: Council of Scientific and Industrial Research-National Botanical Research Institute, Rana Pratap Marg, Lucknow-226001, Uttar Pradesh, India.
authors.forename: Prabodh Kumar
authors.initials: PK
authors.lastname: Trivedi
authors.affiliation: Council of Scientific and Industrial Research-National Botanical Research Institute, Rana Pratap Marg, Lucknow-226001, Uttar Pradesh, India.
authors.forename: Pratibha
authors.initials: P
authors.lastname: Misra
mesh_terms: D000528:Alternaria / Q000502:physiology; D001483:Base Sequence; D053898:Biosynthetic Pathways / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D016695:Glycosyltransferases / Q000235:genetics* / Q000378:metabolism; D054884:Host-Pathogen Interactions; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D010840:Phytosterols / Q000378:metabolism; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D057865:Plant Immunity / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D012689:Sequence Homology, Nucleic Acid; D032341:Withania / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D054358:Withanolides / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D010840:Phytosterols; D010940:Plant Proteins; D054358:Withanolides; D016695:Glycosyltransferases