Donald Danforth Plant Science Center, St. Louis, Missouri 63132 (W.Y., G.W., J.L., X.W., D.K.A.); USDA-ARS, Plant Genetics Research Unit, St. Louis, Missouri 63132 (W.Y., D.K.A.); Department of Biology, University of Missouri, St. Louis, Missouri 63121 (G.W., X.W.); and Department of Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg, Mississippi 39406 (P.D.B.).
Donald Danforth Plant Science Center, St. Louis, Missouri 63132 (W.Y., G.W., J.L., X.W., D.K.A.); USDA-ARS, Plant Genetics Research Unit, St. Louis, Missouri 63132 (W.Y., D.K.A.); Department of Biology, University of Missouri, St. Louis, Missouri 63121 (G.W., X.W.); and Department of Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg, Mississippi 39406 (P.D.B.)
Plant Physiol. 2017 May;174(1):110-123. doi: 10.1104/pp.17.00026. Epub 2017 Mar 21.
Plant seeds are the primary source of triacylglycerols (TAG) for food, feed, fuel, and industrial applications. As TAG is produced from diacylglycerol (DAG), successful engineering strategies to enhance TAG levels have focused on the conversion of DAG to TAG. However, the production of TAG can be limited by flux through the enzymatic reactions that supply DAG. In this study, two genes ( and ) were coexpressed in to test whether the conversion of phosphatidylcholine to DAG impacts TAG levels in seeds. The resulting transgenic plants produced 2% to 3% more TAG as a component of total seed biomass and had increased 18:3 and 20:1 fatty acid levels relative to wild type. Increased DAG and decreased PC levels were examined through the kinetics of lipid assembly by [C]acetate and [C]glycerol incorporation into glycerolipids. [C]acetate was rapidly incorporated into TAG in both wild-type and overexpression lines, indicating a significant flux of nascent and elongated acyl-CoAs into the -3 position of TAG. Stereochemical analysis revealed that newly synthesized fatty acids were preferentially incorporated into the -2 position of PC, but the -1 position of de novo DAG and indicated similar rates of nascent acyl groups into the Kennedy pathway and acyl editing. [C]glycerol studies demonstrated PC-derived DAG is the major source of DAG for TAG synthesis in both tissues. The results emphasize that the interconversions of DAG and PC pools can impact oil production and composition.
植物种子是三酰基甘油（TAG）的主要来源，可用于食品、饲料、燃料和工业应用。由于 TAG 是由二酰基甘油（DAG）产生的，因此提高 TAG 水平的成功工程策略集中在将 DAG 转化为 TAG。然而，TAG 的生产可能受到供应 DAG 的酶促反应通量的限制。在这项研究中，我们在 中共同表达了两个基因（ 和 ），以测试将磷脂酰胆碱转化为 DAG 是否会影响种子中的 TAG 水平。结果表明，与野生型相比，转基因植物的 TAG 作为总种子生物量的一部分增加了 2%至 3%，18:3 和 20:1 脂肪酸水平也增加了。通过 [C]乙酸盐和 [C]甘油掺入甘油脂质来研究脂质组装的动力学，检查了 DAG 的增加和 PC 的减少。[C]乙酸盐在野生型和过表达系中均迅速掺入 TAG，表明新生和伸长的酰基辅酶 A 大量流入 TAG 的 -3 位。立体化学分析表明，新合成的脂肪酸优先掺入 PC 的 -2 位，但新合成的 DAG 的 -1 位和表明新生酰基基团进入 Kennedy 途径和酰基编辑的速率相似。[C]甘油研究表明，PC 衍生的 DAG 是两种组织中 TAG 合成的主要 DAG 来源。这些结果强调了 DAG 和 PC 池的相互转化可以影响油脂的生产和组成。
