Molecular tools enabling pennycress (Thlaspi arvense) as a model plant and oilseed cash cover crop

Abstract

Thlapsi arvense L. (pennycress) is being developed as a profitable oilseed cover crop for the winter fallow period throughout the temperate regions of the world, controlling soil erosion and nutrients run-off on otherwise barren farmland. We demonstrate that pennycress can serve as a user-friendly model system akin to Arabidopsis that is well-suited for both laboratory and field experimentation. We sequenced the diploid genome of the spring-type Spring 32-10 inbred line (1C DNA content of 539 Mb; 2n = 14), identifying variation that may explain phenotypic differences with winter-type pennycress, as well as predominantly a one-to-one correspondence with Arabidopsis genes, which makes translational research straightforward. We developed an Agrobacterium-mediated floral dip transformation method (0.5% transformation efficiency) and introduced CRISPR-Cas9 constructs to produce indel mutations in the putative FATTY ACID ELONGATION1 (FAE1) gene, thereby abolishing erucic acid production and creating an edible seed oil comparable to that of canola. We also stably transformed pennycress with the Euonymus alatus diacylglycerol acetyltransferase (EaDAcT) gene, producing low-viscosity acetyl-triacylglycerol-containing seed oil suitable as a diesel-engine drop-in fuel. Adoption of pennycress as a model system will accelerate oilseed-crop translational research and facilitate pennycress' rapid domestication to meet the growing sustainable food and fuel demands.

Progress toward the identification and stacking of crucial domestication traits in pennycress

“…In theory, it would have been faster to use gene-editing approaches to create the domestication traits described in this report. In fact, we have created an alternative zero erucic acid pennycress line using CRISPR-Cas9 mediated gene editing (McGinn et al 2018). However, successful utilization of gene editing requires precise knowledge about the genes one wishes to target.…”

GARNet gene editing workshop

“…Such edits were detectable in sequence traces from T 1 GE plants, and trace analysis was therefore recommended. Michaela had used CRISPR‐Cas9 to reduce the levels of an undesired fatty acid from 40% in WT Pennycress seed to < 1% in GE mutants (McGinn et al ., ).…”

Management of pennycress as a winter annual cash cover crop. A review

“…A recent evaluation of genetic diversity showed that the genetic variation present in North American pennycress accessions was limited (Frels et al 2017). Therefore, alternative tools such as chemical mutagenesis and gene editing have been used to create genetic variation for key domestication traits (Chopra et al , 2019aMcGinn et al 2018).…”

“…The reduction in erucic acid and sinigrin content has largely followed the steps laid out by researchers who developed canola from rapeseed (Bell 1982;Claver et al 2017). Recently, pennycress lines with reduced erucic acid content and increased oleic, linoleic, and linolenic acid content were identified through the use of both chemical mutagenesis and CRISPR-Cas9 gene editing (McGinn et al 2018;Chopra et al 2019b). In addition, pennycress lines with reduced sinigrin and silicle shatter were identified (Chopra et al 2019b).…”