Yang Jihong, Chen Beibei, Manan Sehrish, Li Penghui, Liu Chun, She Guangbiao, Zhao Shancen, Zhao Jian
State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science and Technology, Anhui Agricultural University, Hefei, 230036, China.
National Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 340070, China.
Hortic Res. 2022 Apr 21;9:uhac087. doi: 10.1093/hr/uhac087. eCollection 2022.
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 limited understanding of tea oil biosynthesis and regulation has become a significant obstacle for the breeding of high-yield and -quality oil tea varieties. By integrating metabolite and transcriptome analyses of 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-acyl carrier protein desaturases (CoSAD1 and 2) and two endoplasmic reticulum-localized FA desaturases (CoFAD2 and 3) were functionally characterized as responsible for high 18:1 and low 18:2 and 18:3 proportions in tea oils. Two diacylglycerol 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 upregulated s with downregulated and at the late seed developmental stages mainly accounted for high 18:1 levels. 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 on genes that may be used as molecular markers to breed oil tea varieties with higher oil yield and quality.
油茶能产出高品质食用油，其油酸（18:1）含量高，亚油酸（18:2）和亚麻酸（18:3）脂肪酸（FA）含量低，令人满意，但对茶油生物合成和调控的了解有限，已成为高产优质油茶品种育种的重大障碍。通过整合发育中的油茶种子的代谢物和转录组分析，我们剖析了关键代谢途径，包括糖酵解、脂肪酸和三酰甘油（TAG）生物合成，以及茶籽油生产所需的基因。两种质体硬脂酰 - 酰基载体蛋白去饱和酶（CoSAD1和2）和两种内质网定位的FA去饱和酶（CoFAD2和3）在功能上被鉴定为导致茶油中18:1含量高、18:2和18:3比例低的原因。两种可能更倾向于合成18:1 - TAG的二酰甘油酰基转移酶（CoDGAT1和2）在功能上被鉴定，它们可能对高18:1 - TAG的产生也很重要。高表达的CoWRI1a和b被鉴定并表征为糖酵解的激活剂以及发育中的油茶种子中引导源碳通量进入FA生物合成的调节剂。在种子发育后期上调而 和 下调的 主要导致了高18:1水平。两种CoDGAT可能负责用油酰基链组装TAG，而两种CoWRI1调节来自亲本来源的碳，分配到油茶胚库中的油脂生产中。本研究深入了解了茶籽油的生物合成，并提供了有关可作为分子标记用于培育具有更高油产量和质量的油茶品种的基因信息。
