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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Commodity Utilization Research » Research » Publications at this Location » Publication #427047
Research Project: Development of Novel Cottonseed Products and Processes

Location: Commodity Utilization Research

Title: Complete replacement of Arabidopsis oil-producing enzymes with heterologous diacylglycerol acyltransferases

Author
item MCGUIRE, SEAN - Washington State University
item Shockey, Jay
item RICHARDS, ALEXANDRA - Washington State University
item SMERTENKO, ANDREI - Washington State University
item BATES, PHILIP - Washington State University

Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2025
Publication Date: 10/30/2025
Citation: Mcguire, S.T., Shockey, J.M., Richards, A., Smertenko, A., Bates, P.D. 2025. Complete replacement of Arabidopsis oil-producing enzymes with heterologous diacylglycerol acyltransferases. Plant Physiology. 199(3). Article kiaf552. https://doi.org/10.1093/plphys/kiaf552.
DOI: https://doi.org/10.1093/plphys/kiaf552

Interpretive Summary: Rational, predictable metabolic engineering outcomes are a long-standing, rarely achieved goal in biology. This is especially true for oilseed engineering. Expression of genes from exotic plants that produce valuable unusual fatty acids in their seed oils, in agronomic oilseed crops, rarely results in meaningful levels of the valuable fatty acid component. This may occur in part because of negative interactions between the transgene and the related genes that already exist in the host plant. In this study, and one that preceded it, we have identified the minimal necessary genetic elements that allow for complete replacement of the native genes, so that these negative interactions do not occur. The findings from three test case experiments are presented, which show both successes and additional levels of complexity that will be addressed in future work.

Technical Abstract: • Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) and phospholipid:diacylglycerol acyltransferase 1 (PDAT1) share responsibility for triacylglycerol (TAG) biosynthesis, and their selectivities control TAG fatty acid (FA) compositions. To control seed TAG compositions, it is desirable to replace endogenous TAG biosynthesis with exogenous enzymes containing different substrate FA selectivities; however, the dgat1-1/pdat1-2 double mutant is pollen lethal. • We transformed a dgat1-1 parent with foreign DGAT1s from Camelina sativa, Physaria fendleri, and Ricinus communis. Foreign gene expression was contextualized by the minimal expression unit containing the promoter/5’ UTR and first intron of native AtDGAT1 that are essential for pollen expression. Next, we crossed homozygous lines with a DGAT1/DGAT1/PDAT1/pdat1-2 parent. • Ricinus communis DGAT1 was active in dgat1-1 seeds, but produced unique oil profiles, lipid metabolic gene expression alterations, and failed to rescue the dgat1-1/pdat1-2 lethality. Camelina sativa and Physaria fendleri DGAT1s restored FA compositions and transcriptional changes to near wild-type, complementing the lethality. • This study confirms the promoter and first intron of AtDGAT1 can properly express foreign DGAT1s at the right time and place to replace endogenous TAG biosynthesis. Furthermore, it demonstrates an additional layer of unexpected incompatibility between oilseed lineages which may complicate bioengineering approaches that seek to replace essential genes with orthologs.