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Graduation Term

2018

Degree Name

Master of Science (MS)

Department

School of Biological Sciences

Committee Chair

John Sedbrook

Abstract

Pennycress (Thlaspi arvense) is an emerging oilseed cover crop that can be grown throughout temperate regions of the world. Pennycress produces copious amounts of seeds high in triacylglycerides (oil; ~34%), which can be used in foodstuffs, as lubricants and surfactants, as biodiesel, or hydrocracked to dodecane aviation fuel. The most abundant fatty acids in pennycress seed oil are erucic acid (C22:1), linoleic acid (C18:2), and oleic acid (C18:1). Oleic acid is converted to erucic acid by the enzyme FATTY ACID ELONGATION1 (FAE1). Erucic acid has value as a feedstock for the oleochemicals industry. Oleic acid is converted to linoleic acid by the enzyme FATTY ACID DESATURASE2 (FAD2). While linoleic acid is desirable in foodstuffs due to its Omega-3 fatty acid “heart-health” benefits, it is prone to oxidative instability and is therefore undesirable in biofuels and cooking oil. By using the emerging technology CRISPR-Cas9, we successfully created a pennycress loss of function mutation in FAD2, which resulted in substantial decreases in linoleic and linolenic acid thereby greatly improving the oxidative stability of the seed oil. Additionally, we successfully increased the erucic acid content of pennycress seed oil by ectopically expressing a “2 gene” DNA construct designed for seed-specific expression of the Brassica napus BnFAE1 gene and the Limnanthes douglasii lysophosphatidic acid acyltransferase (LdLPAAT) gene. Together, these genetic changes substantially improved the quality and value of pennycress seed oil for industrial uses.

Access Type

Thesis-ISU Access Only

DOI

http://doi.org/10.30707/ETD2018.Jarvis.B

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