Generating Pennycress (Thlaspi arvense) Seed Triacylglycerols and Acetyl-Triacylglycerols Containing Medium-Chain Fatty Acids

Thlaspi arvense L. (pennycress) is a cold-tolerant Brassicaceae that produces large amounts of seeds rich in triacylglycerols and protein, making it an attractive target for domestication into offseason oilseed cash cover crop. Pennycress easily genetically transformed, enabling synthetic biology approaches to tailor oil properties specific biofuel industrial applications. To test the feasibility pennycress producing TAGs acetyl-TAGs medium-chain fatty acids (MCFAs; C6–C14) industrial, biojet fuel improved biodiesel applications, we generated transgenic lines with seed-specific expression unique acyltransferase ( LPAT diacylglycerol ) genes thioesterase FatB isolated from Cuphea viscosissima , avigera var. pulcherrima hookeriana Coco nucifera Umbellularia californica . Wild-type seed accumulate no shorter than 16C less 5 mol percent C16 as palmitic acid (16:0). Co-expressing UcFatB CnLPAT produced up 17 mol% accumulation lauric (12:0) TAGs, whereas CvFatB1 CvLPAT2 CpDGAT1 combinatorial 27 medium chain FAs Medium Chain Fatty Acids mostly form capric (10:0). CpFatB2 ChFatB2 predominantly produced, equal parts, 28 myristic (14:0) acid. Genetically crossing constructs elongation1 fae1 mutant 22:1 erucic acid, Euonymus alatus acetyltransferase EaDAcT )-expressing line 60 acetyl-TAGs, had or relatively minor effects on MCFAs accumulation, suggesting fluxes were largely unaltered. Seed germination assays revealed delays most lines, exception being -expressing which substantially slower rates. Taken together, these data show can be engineered produce accumulating modest varying carbon-chain length rates delayed only some cases. We hypothesize increasing further may require functional reductions endogenous transferases and/or other FA elongases.