The triacylglycerols (TAGs; i.e. oils) that accumulate in plants represent the most energy-dense form of biological carbon storage, and are used for food, fuels, and chemicals. The increasing human population and decreasing amount of arable land have amplified the need to produce plant oil more efficiently. Engineering plants to accumulate oils in vegetative tissues is a novel strategy, because most plants only accumulate large amounts of lipids in the seeds. Recently, tobacco (Nicotiana tabacum) leaves were engineered to accumulate oil at 15% of dry weight due to a push (increased fatty acid synthesis)-and-pull (increased final step of TAG biosynthesis) engineering strategy. However, to accumulate both TAG and essential membrane lipids, fatty acid flux through nonengineered reactions of the endogenous metabolic network must also adapt, which is not evident from total oil analysis. To increase our understanding of endogenous leaf lipid metabolism and its ability to adapt to metabolic engineering, we utilized a series of in vitro and in vivo experiments to characterize the path of acyl flux in wild-type and transgenic oil-accumulating tobacco leaves. Acyl flux around the phosphatidylcholine acyl editing cycle was the largest acyl flux reaction in wild-type and engineered tobacco leaves. In oil-accumulating leaves, acyl flux into the eukaryotic pathway of glycerolipid assembly was enhanced at the expense of the prokaryotic pathway. However, a direct Kennedy pathway of TAG biosynthesis was not detected, as acyl flux through phosphatidylcholine preceded the incorporation into TAG. These results provide insight into the plasticity and control of acyl lipid metabolism in leaves.

中文翻译：

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通过积油烟叶中的脂质代谢网络重组酰基通量。

在植物中积累的三酰基甘油（TAGs；即油）代表了生物碳储存的能量密度最高的形式，并用于食品、燃料和化学品。随着人口的增加和耕地数量的减少，更需要更有效地生产植物油。工程植物在营养组织中积累油是一种新策略，因为大多数植物只在种子中积累大量脂质。最近，由于推动（增加脂肪酸合成）和拉动（增加 TAG 生物合成的最后一步）工程策略，烟草（Nicotiana tabacum）叶子被设计为以干重的 15% 积累油。然而，为了积累 TAG 和必需的膜脂，通过内源性代谢网络的非工程反应的脂肪酸流量也必须适应，这在总油分析中并不明显。为了增加我们对内源性叶脂代谢及其适应代谢工程的能力的理解，我们利用一系列体外和体内实验来表征野生型和转基因积油烟叶中酰基通量的路径。围绕磷脂酰胆碱酰基编辑循环的酰基通量是野生型和工程化烟叶中最大的酰基通量反应。在积油的叶子中，进入甘油脂组装真核途径的酰基通量以原核途径为代价增强。然而，未检测到 TAG 生物合成的直接肯尼迪途径，因为通过磷脂酰胆碱的酰基通量先于并入 TAG。这些结果提供了对叶片中酰基脂质代谢的可塑性和控制的深入了解。