INFORM October 2025

BIOENGINEERING

inform October 2025, Vol. 36 (9) • 17

Euonymus alatus

sn-1

sn-1

O

O

O

sn-2

O

sn-2

sn-3

sn-3

O

O O

O

O

O

O

O

Euonymus fortunei

Celastrus scandens

duction of acetyl-triacylglycerol (acetyl-TAG), a unique TAG structure, in oilseed cover crops at levels comparable to those in native species. ACETYL-TAGS: WHY THEY MATTER Acetyl-TAGs differ from conventional TAGs in that the sn-3 position on the glycerol backbone contains an acetate group rather than a third long-chain fatty acid. As a result, ace tyl-TAGs have lower viscosity and melting points, making them suitable for use in lubricants, plasticizers, and drop-in biofuels. Certain native species, such as members of the Euonymus or Celastrus genera, predominantly produce acetyl-TAG in seeds, although trace amounts have been observed in the fruit and arils. The abundance of acetyl-TAG in seeds varies among native species, with some levels reaching 98 percent. Although promising, these species suffer from agronomic challenges such as a long growth cycle, non-uniform maturation of seeds, and the need for manual harvesting due to incompatibility with harvesting machinery. To engineer high levels of acetyl-TAGs, we needed crop species that could combine agronomic value, transformation ease, and scalability. COVER CROPS AS BIOTECHNOLOGY PLATFORMS Our lab focuses on two oilseeds, camelina ( Camelina sativa ) and pennycress ( Thlaspi arvense ). Both belong to the mus tard family (Brassicaceae), similar to rapeseed, canola, and the model plant Arabidopsis. Their close evolutionary relation ship to Arabidopsis allows us to draw on the extensive knowl

TAG edge of lipid metabolism and oil biosynthesis available for this well-studied model species. Because the genomes of both camelina and pennycress are sequenced and publicly available, we can directly apply insights from Arabidopsis to identify and manipulate key genes involved in oil production. In addition, both plants are prime candidates for biotechnology because Acetyl-TAG

Acetyl-CoA pool

Acetyl-TAG

1

EfDAcT

FAE1 18:1-CoA FAE1 20:1-CoA 22:1-CoA FA elongation 3

DAG

Acyl-CoA pool

DGAT1

2

RNAi

TAG

WT Simplified pathway of the last step of TAG and acetyl-TAG biosynthesis. Numbers represent the metabolic engineering strategies used in this study to optimize acetyl-TAG production: (1) Expression of high-activity EfDAcT enzyme; (2) suppression of endogenous DGAT1 to reduce competing TAG synthesis; (3) elimination of fatty acid elongation to increase acetyl-CoA supply. Source: Durrett Lab EfDAcT 1 EfDAcT DGAT1-RNAi 2 EfDAcT DGAT1-RNAi fae1 background 3

Pennycress

0%

68%

85%

98%