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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Bioproducts Research » Research » Publications at this Location » Publication #392511

Research Project: Domestic Production of Natural Rubber and Resins

Location: Bioproducts Research

Title: Downregulation of squalene synthase broadly impacts isoprenoid biosynthesis in guayule

item PLACIDO, DANTE - Former ARS Employee
item Dong, Niu
item AMER, BASHAR - Joint Bioenergy Institute (JBEI)
item Dong, Chen
item Ponciano, Grisel
item Kahlon, Talwinder
item WHALEN, MAUREEN - Retired ARS Employee
item BAIDOO, EDWARD - Joint Bioenergy Institute (JBEI)
item McMahan, Colleen

Submitted to: Metabolites
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2022
Publication Date: 3/29/2022
Citation: Placido, D., Dong, N., Amer, B., Dong, C., Ponciano, G.P., Kahlon, T.S., Whalen, M., Baidoo, E., McMahan, C.M. 2022. Downregulation of squalene synthase broadly impacts isoprenoid biosynthesis in guayule. Metabolites. 12(4). Article 303.

Interpretive Summary: Supply of natural rubber, a U.S. Critical Agricultural Material (Public Law 95-592), can be secured by production of domestic natural rubber by guayule, an arid adapted native U.S. crop. Guayule is under development as a drought-resistant crop in the western U.S. but requires higher yield of natural rubber for economic security. In this study, bioengineering of guayule resulted in modest gains of NR production. However, it introduces metabolomics technology that has the potential to transform crop improvement technologies.

Technical Abstract: Production of natural rubber by Parthenium argentatum (guayule) requires increased yield for economic sustainability. An RNAi gene silencing strategy was used to engineer isoprenoid biosynthesis by downregulation of squalene synthase (SQS), such that the pool of farnesyl diphosphate (FPP) substrate might instead be available to initiate natural rubber synthesis. Downregulation of SQS resulted in significantly reduced squalene and slightly increased rubber, but not in the same tissues nor to the same extent. This may be due to an apparent negative feedback regulatory mechanism that downregulated mevalonate pathway isoprenoid production, presumably associated with excess GPP levels. A detailed metabolomics analysis of isoprenoid production in guayule revealed significant differences in metabolism in different tissues, including in active MVA and MEP pathways in stem tissue, where rubber and squalene accumulate. New insights and strategies for engineering isoprenoid production in guayule were identified.