Oil tea trees produce high-quality edible oils with desirably high oleic acid (18:1) and low linoleic (18:2) and linolenic (18:3) fatty acid (FA) levels, but the limited understanding of tea oil biosynthesis and regulation has become a significant obstacle for breeding of high-yield and quality oil tea varieties. By integrating metabolite and transcriptome analyses of the developing oil tea seeds, we dissected the critical metabolic pathways including glycolysis, fatty acid and triacylglycerol (TAG) biosynthesis, as well as genes essential for tea seed oil production. Two plastidic stearoyl-ACP desaturases (CoSAD1 and 2) and two ER-localized FA deasturases (CoFAD2 and 3) were functionally characterized responsible for high-18:1 and low-18:2 and-18:3 proportions in tea oils. Two diacylglycerols O-acyltransferases (CoDGAT1 and 2) that may prefer to synthesize 18:1-TAG were functionally characterized and might be also important for high 18:1-TAG production. The highly expressed CoWRI1a and b were identified and characterized as activators of glycolysis and regulators of directing source carbon flux into FA biosynthesis in developing oil tea seeds. The up-regulated CoSADs with down-regulated CoFAD2 and CoFAD3 at the late seed developmental stages mainly accounted for high 18:1 level. Two CoDGATs might be responsible for assembling TAGs with oleoyl acyl chains, whilst two CoWRI1s regulated carbons from parental sources partitioning into oil production in oil tea embryo sinks. This study provides a deep understanding of the biosynthesis of tea seed oils and information of genes that may be used as molecular markers to breed oil tea varieties with higher oil yield and quality.

中文翻译：

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关键代谢途径和 SAD/FAD、WRI1 和 DGAT 在开发油茶 (Camellia oleifera) 种子中协同生产高油酸油

油茶树生产的优质食用油具有理想的高油酸 (18:1) 和低亚油酸 (18:2) 和亚麻酸 (18:3) 脂肪酸 (FA) 水平，但对茶油生物合成和监管已成为高产优质油茶品种选育的重大障碍。通过整合发育中的油茶种子的代谢物和转录组分析，我们剖析了关键的代谢途径，包括糖酵解、脂肪酸和三酰基甘油 (TAG) 生物合成，以及茶籽油生产所必需的基因。两种质体硬脂酰-ACP 去饱和酶（CoSAD1 和 2）和两种 ER 定位的 FA 去饱和酶（CoFAD2 和 3）在功能上表征了茶油中高 18:1 和低 18:2 和 18:3 的比例。可能更喜欢合成 18:1-TAG 的两种二酰基甘油 O-酰基转移酶（CoDGAT1 和 2）在功能上进行了表征，并且可能对高 18:1-TAG 生产也很重要。在油茶种子发育过程中，高表达的 CoWRI1a 和 b 被鉴定并表征为糖酵解的激活剂和将源碳通量引导至 FA 生物合成的调节剂。在种子发育后期，CoFAD2和CoFAD3上调，CoFAD3下调，主要占18：1的高水平。两个 CoDGAT 可能负责组装具有油酰基链的 TAG，而两个 CoWRI1 调节来自亲本来源的碳，分配到油茶胚槽中的石油生产中。