植物ω-7脂肪酸的系统代谢工程

ω-7脂肪酸(C16:1Δ9, C18:1Δ11, C20:1Δ13), 特别是棕榈油酸(C16:1Δ9)具有重要的工业、营养和医药价值。这些珍稀脂肪酸大多在一些野生植物的种子中合成, 不能商业化生产。对普通油料作物的油脂代谢途径进行遗传修饰, 使其种子大量合成并积累ω-7脂肪酸, 已成为生物技术和可再生资源研究的一个热点领域。基因操作的主要靶标包括: 不同来源的Δ9脱氢酶的应用、提高底物(C16:0)的浓度、共表达质体型和内质网型Δ9脱氢酶以及代谢物流的优化等。该文在解析ω-7脂肪酸生物合成途径及其调控网络的基础上, 重点论述了ω-7脂肪酸代谢工程的技术策略、研究进展和存在的问题, 并进一步讨论了油脂物组学和转基因组学等组学技术在鉴定参与ω-7脂肪酸生物合成途径及其调控的特异基因和优化油脂代谢工程设计上的应用前景。

Systematic Metabolic Engineering of ω-7 Fatty Acids in Plants

Omega-7(ω-7) fatty acids (FAs) such as C16:1Δ9, C18:1Δ11 and C20:1Δ13, particularly palmitoleate (C16:1Δ9), are an important contributor to human health and are highly valued in pharmaceutical and industrial applications. A number of natural wild plants can synthesize high levels of these unusual FAs in seeds, but low yields and poor agronomic properties of those plants preclude their commercial use for ω-7 FA production. The lipid metabolic pathway has been genetically modified to develop engineered common oil crops that can highly produce and accumulate ω-7 FAs in seeds and represents a key hot-spot in biotechnology and renewable bio-based resources. The major targets for modification in the oil biosynthesis pathway include expression of various Δ9 desaturases, increasing substrate (C16:0) levels, co-expression of plastidial and endoplasmic reticulum Δ9 desaturases and optimizing the metabolic flux into triacylglycerols (TAGs). Here, we summarize our current understanding of ω-7 FA biosynthesis and its regulation and describe the advances in ω-7 FA metabolic engineering. We also discuss the current “bottleneck” in this field and potential breakthroughs by combining lipidomics, transgenics and other “-omics”. These new tools will provide a valued platform for mining genes involved in ω-7 FA biosynthesis and regulation. With this knowledge, we will develop more rational designs for metabolically engineering the commercial production of ω-7 FA in established oilseeds for human health and sustainable development of the related industry.