Imaging heterogeneity of membrane and storage lipids in transgenic Camelina sativa seeds with altered fatty acid profiles
Imaging heterogeneity of membrane and storage lipids in transgenic Camelina sativa seeds with altered fatty acid profiles
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DOI：
10.1111/tpj.12278
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发表时间：
2013-10-01
期刊：
影响因子：
7.2
通讯作者：
Chapman, Kent D.
中科院分区：
文献类型：
--
作者：
Horn, Patrick J.;Silva, Jillian E.;Chapman, Kent D.
油料种子中的工程化组成变化通常通过引入新的酶促步骤和/或通过以种子特异性方式阻断或增强现有的酶促步骤来实现。然而，在实践中，积累在种子中的脂质种类的量往往是不同的，从酶的表达水平预测，这些不一致性可能植根于在细胞/组织水平的种子脂质代谢的调节的不完全理解。在这里，我们表明，通过质谱成像方法，三酰甘油和它们的磷脂前体分布在子叶和下胚轴/胚根轴在胚胎的油料作物亚麻荠不同，表明组织特异性的异质性三酰甘油代谢。富含亚油酸（C18：2）的磷脂酰胆碱和三酰甘油优先定位于轴组织，而富含鳕油酸（C20：1）的脂质类优先定位于子叶。操纵种子脂质组合物的异源过表达的酰基-酰基载体蛋白硫酯酶，或通过抑制脂肪酸去饱和酶和延长酶，导致新的整体种子储存脂质组合物与改变的模式的磷脂和三酰甘油在转基因胚胎中的分布。我们的结果揭示了亚麻荠属胚胎中酰基脂质分布的先前未知差异，并表明这种空间异质性可能或可能无法在转基因种子中有效改变，具体取决于靶向酶/途径。此外，这些研究指出了解决代谢物的位置，除了它们在植物组织中的数量的重要性。
Engineering compositional changes in oilseeds is typically accomplished by introducing new enzymatic step(s) and/or by blocking or enhancing an existing enzymatic step(s) in a seed-specific manner. However, in practice, the amounts of lipid species that accumulate in seeds are often different from what one would predict from enzyme expression levels, and these incongruences may be rooted in an incomplete understanding of the regulation of seed lipid metabolism at the cellular/tissue level. Here we show by mass spectrometry imaging approaches that triacylglycerols and their phospholipid precursors are distributed differently within cotyledons and the hypocotyl/radicle axis in embryos of the oilseed crop Camelina sativa, indicating tissue-specific heterogeneity in triacylglycerol metabolism. Phosphatidylcholines and triacylglycerols enriched in linoleic acid (C18:2) were preferentially localized to the axis tissues, whereas lipid classes enriched in gadoleic acid (C20:1) were preferentially localized to the cotyledons. Manipulation of seed lipid compositions by heterologous over-expression of an acyl-acyl carrier protein thioesterase, or by suppression of fatty acid desaturases and elongases, resulted in new overall seed storage lipid compositions with altered patterns of distribution of phospholipid and triacylglycerol in transgenic embryos. Our results reveal previously unknown differences in acyl lipid distribution in Camelina embryos, and suggest that this spatial heterogeneity may or may not be able to be changed effectively in transgenic seeds depending upon the targeted enzyme(s)/pathway(s). Further, these studies point to the importance of resolving the location of metabolites in addition to their quantities within plant tissues.