Diacylglycerol acyltransferases (DGAT) catalyze the final committed step of de novo biosynthesis of triacylglycerol (TAG) in plant seeds. This study was to functionally characterize DGAT3 genes in Camelina sativa, an important oil crops accumulating high levels of unsaturated fatty acids (UFAs) in seeds. Three camelina DGAT3 genes (CsDGAT3-1, CsDGAT3-2 and CsDGAT3-3) were identified, and the encoded proteins were predicted to be cytosolic-soluble proteins present as a homodimer containing the 2Fe-2S domain. They had divergent expression patterns in various tissues, suggesting that they may function in tissue-specific manner with CsDGAT3-1 in roots, CsDGAT3-2 in flowers and young seedlings, and CsDGAT3-3 in developing seeds. Functional complementation assay in yeast demonstrated that CsDGAT3-3 restored TAG synthesis. TAG content and UFAs, particularly eicosenoic acid (EA, 20:1n-9) were largely increased by adding exogenous UFAs in the yeast medium. Further heterogeneously transient expression in N. benthamiana leaves and seed-specific expression in tobacco seeds indicated that CsDGAT3-3 significantly enhanced oil and UFA accumulation with much higher level of EA. Overall, CsDGAT3-3 exhibited a strong abilty catalyzing TAG synthesis and high substrate preference for UFAs, especially for 20:1n-9. The present data provide new insights for further understanding oil biosynthesis mechanism in camelina seeds, indicating that CsDGAT3-3 may have practical applications for increasing both oil yield and quality.

中文翻译：

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来自亚麻荠的新型酰基辅酶A：二酰基甘油酰基转移酶3-3（CsDGAT3-3）基因的功能表征

二酰基甘油酰基转移酶 (DGAT) 催化植物种子中三酰基甘油 (TAG) 从头生物合成的最后一步。本研究旨在对亚麻籽中的 DGAT3 基因进行功能表征，亚麻籽是一种重要的油料作物，在种子中积累了高水平的不饱和脂肪酸 (UFAs)。鉴定了三个亚麻荠 DGAT3 基因（CsDGAT3-1、CsDGAT3-2 和 CsDGAT3-3），并且预测编码的蛋白质是胞质可溶性蛋白质，以含有 2Fe-2S 结构域的同型二聚体形式存在。它们在各种组织中具有不同的表达模式，表明它们可能以组织特异性方式发挥作用，CsDGAT3-1 在根中，CsDGAT3-2 在花和幼苗中，CsDGAT3-3 在发育种子中。酵母中的功能互补测定表明 CsDGAT3-3 恢复了 TAG 合成。TAG 内容和 UFA，尤其是二十碳烯酸 (EA, 20:1n-9) 通过在酵母培养基中添加外源 UFA 大大增加。此外，本氏烟草叶片中的异质瞬时表达和烟草种子中的种子特异性表达表明，CsDGAT3-3 显着增强了油和 UFA 的积累，同时具有更高水平的 EA。总体而言，CsDGAT3-3 表现出强大的催化 TAG 合成能力和对 UFA 的高底物偏好，尤其是对于 20:1n-9。目前的数据为进一步了解亚麻籽油的生物合成机制提供了新的见解，表明 CsDGAT3-3 可能具有提高油产量和质量的实际应用。本生烟叶和烟草种子中的种子特异性表达表明，CsDGAT3-3 显着增强了油和 UFA 的积累，并具有更高水平的 EA。总体而言，CsDGAT3-3 表现出强大的催化 TAG 合成能力和对 UFA 的高底物偏好，尤其是对于 20:1n-9。目前的数据为进一步了解亚麻籽油的生物合成机制提供了新的见解，表明 CsDGAT3-3 可能具有提高油产量和质量的实际应用。本生烟叶和烟草种子中的种子特异性表达表明，CsDGAT3-3 显着增强了油和 UFA 的积累，并具有更高水平的 EA。总体而言，CsDGAT3-3 表现出强大的催化 TAG 合成能力和对 UFA 的高底物偏好，尤其是对于 20:1n-9。目前的数据为进一步了解亚麻籽油的生物合成机制提供了新的见解，表明 CsDGAT3-3 可能具有提高油产量和质量的实际应用。