Document Type

Thesis

Degree

Master of Science

Major

Biology

Date of Defense

5-8-2018

Graduate Advisor

Bethany Zolman

Committee

Bethany Zolman

Wendy Olivas

Toni Kutchan

Elizabeth Kellogg

Abstract

The staple crop Sorghum bicolor shows potential as a source of secondary metabolite-based biofuels due to its diverse phenotype and chemical profile. S. bicolor produces a variety of high-energy metabolites, including terpenes which are a potential renewable source of fuel additives. Information on the biosynthetic and genetic pathways by which S. bicolor terpenes are produced is limited and these pathways must be better understood before they can be engineered for human applications. Recent work on plant biosynthetic pathways has shown that terpenes can be modified by the products of clustered genes. Identification of biosynthetic gene clusters may accelerate the elucidation of complete pathways, but few have been characterized in S. bicolor. The aims of this thesis were to identify a putative terpene biosynthetic gene cluster in S. bicolor, characterize the terpene synthase in the cluster, and express the terpene synthase alongside clustered enzymes to determine if they modify the terpene skeleton structure. The terpene synthase Sobic.001G339000 was found to produce a novel sesquiterpene product. Mass spectra analysis suggested that the novel product was similar to guaiol and β-eudesmol and possibly shared a mass (222.2 Da) and chemical formula (C15H26O) with these compounds. Transient expression of the putative gene cluster in N. benthamiana produced a metabolite of a significantly higher mass than anticipated based on the hypothesized mass of the unknown terpene. Elucidation of a structure by NMR spectroscopy will be required to characterize the unknown terpene product. Once the structure of the terpene is known, analysis of the metabolic profile of transfected N. benthamiana will be simplified and the effect of clustered enzymes on the terpene product can be better explored.

Included in

Plant Biology Commons

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