Date of Award

6-18-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

School of Biological Sciences

First Advisor

John C Sedbrook

Abstract

Pennycress (Thlaspi arvense L.) is being domesticated as an oilseed cash cover crop to be grown in the offseason throughout temperate regions of the world. With its diploid genome and ease of molecular mutagenesis, pennycress seed oil composition can be rapidly tailored for a plethora of food, feed, oleochemical and fuel uses. The first part of my research has utilized Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 technology to produce knockout mutations throughout the lipid biosynthetic pathway, with an emphasis to increase oleic acid (C18:1) content specifically within the seed. Oleic acid (18:1) is valued for its oxidative stability that is superior to the polyunsaturated fatty acids (PUFAs) linoleic (18:2) and linolenic (18:3), and better cold flow properties than the very long chain fatty acid (VLCFA) erucic (22:1). MALDI-MS spatial imaging analyses of phosphatidylcholine (PC) and triacylglycerol (TAG) molecular species in wild-type pennycress embryo sections revealed that erucic acid is highly enriched in cotyledons which serve as storage organs, suggestive of a role in providing energy for the germinating seedling. The other portion of my talk will discuss the creation of loss-of-function mutations targeting the glucosinolate pathway to reduce seed glucosinolate content. Glucosinolates are secondary metabolites that, upon herbivory, are metabolized by the enzyme myrosinase which forms toxic compounds (e.g. isothiocyanate) that can cause health issues when consumed at high levels. Multiplex CRISPR/Cas9 molecular tools were used to stack mutations reducing glucosinolate, seed oil erucic acid content, and seed fiber content thereby creating a pennycress variety having seed oil and meal compositions comparable to canola.

Comments

Imported from Jarvis_ilstu_0092E_11974.pdf

DOI

https://doi.org/10.30707/ETD2021.20211012065803528757.999982

Page Count

212

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