Reorganization of Acyl Flux through the Lipid Metabolic Network in Oil-Accumulating Tobacco Leaves
Reorganization of Acyl Flux through the Lipid Metabolic Network in Oil-Accumulating Tobacco Leaves
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DOI：
10.1104/pp.19.00667
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发表时间：
2020-02-01
期刊：
影响因子：
7.4
通讯作者：
Bates, Philip D.
中科院分区：
文献类型：
--
作者：
Zhou, Xue-Rong;Bhandari, Sajina;Bates, Philip D.
在植物中积累的三酰基甘油（标签，即油）是生物碳储存中能量密度最高的形式，用于食品、燃料和化学品。人口的增加和可耕地的减少使得提高植物油生产效率的需求变得更加迫切。工程植物在营养组织中积累油脂是一种新颖的策略，因为大多数植物只在种子中积累大量的脂质。最近，烟草（Nicotiana tabacum）叶片通过推（增加脂肪酸合成）和拉（增加TAG生物合成的最后一步）工程策略，在干重的15%处积累油脂。然而，为了积累TAG和必需的膜脂，脂肪酸通量通过内源性代谢网络的非工程反应也必须适应，这在总油分析中并不明显。为了进一步了解内源叶片脂质代谢及其适应代谢工程的能力，我们利用一系列体外和体内实验来表征野生型和转基因烟叶中酰基通量的途径。在野生型和工程型烟叶中，围绕磷脂酰胆碱酰基编辑周期的酰基通量是最大的酰基通量反应。在积油的叶片中，酰基进入甘油脂组装真核途径的通量增加，而原核途径的通量减少。然而，没有检测到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纳入TAG。这些结果为叶片酰基脂质代谢的可塑性和调控提供了新的思路。
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.