Tung oil obtained from tung tree (Vernicia fordii) seeds is highly valued for its high unsaturation due to α-eleostearic acid. Tung tree can accumulate oil even during late-stage seed maturation under cold waves. Understanding unsaturated fatty acid formation in tung tree under low temperatures is crucial. Previous research identified three types of fatty acid desaturases in plants, but their roles in tung tree remain unclear. Our study shows that VfSCD, a stearoyl-CoA desaturase in tung tree, increases oil content and enhances cold tolerance by promoting unsaturated fatty acid accumulation. VfSCD is highly expressed in leaves and developing seeds, correlating with increased oil and unsaturated fatty acids. Localization studies reveal VfSCD in the endoplasmic reticulum. Heterologous overexpression of VfSCD in E. coli, yeast, and tobacco increases oil content by raising unsaturated fatty acids while reducing saturated ones. Knockdown of VfSCD decreases oil content due to reduced unsaturated fatty acids. Overexpression of VfSCD also improves tobacco's cold tolerance, similar to wild-type plants under low temperatures. In summary, we propose that, in addition to the stearoyl-ACP desaturase (SAD) pathway in plastids, a distinct pathway regulated by VfSCD in endoplasmic reticulum of tung tree enhances cold tolerance by increasing unsaturated fatty acid contents.

中文翻译：

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VfSCD 通过先前发现的不饱和脂肪酸合成途径增强桐树的抗寒性

从桐树 （Vernicia fordii） 种子中获得的桐油因其 α-eleostearic acid 的高不饱和度而受到高度重视。即使在寒潮下的种子成熟后期，桐树也会积油。了解低温下桐树中不饱和脂肪酸的形成至关重要。以前的研究在植物中确定了三种类型的脂肪酸去饱和酶，但它们在桐树中的作用仍不清楚。我们的研究表明，VfSCD 是桐树中的硬脂酰辅酶 A 去饱和酶，通过促进不饱和脂肪酸积累来增加含油量并增强耐寒性。VfSCD 在叶子和发育中的种子中高度表达，与油和不饱和脂肪酸的增加有关。定位研究显示 VfSCD 位于内质网中。VfSCD 在大肠杆菌 、酵母和烟草中的异源过表达通过提高不饱和脂肪酸同时减少饱和脂肪酸来增加含油量。由于不饱和脂肪酸减少，VfSCD 的敲除会降低油含量。过表达 VfSCD 还可以提高烟草的耐寒性，类似于低温下的野生型植物。综上所述，除了质体中的硬脂酰-ACP 去饱和酶 （SAD） 途径外，桐树内质网中受 VfSCD 调节的独特途径通过增加不饱和脂肪酸含量来增强耐寒性。