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Article|21 Apr 2022|OPEN
 Critical metabolic pathways and SAD/FADs, WRI1s, and DGATs cooperate for high-oleic acid oil production in developing oil tea (Camellia oleifera) seeds
Jihong Yang1 , Beibei Chen2 , Sehrish Manan2,4 , Penghui Li1 , Chun Liu3 , Guangbiao She1 and Shancen Zhao3 , Jian Zhao,1 ,
1State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science and Technology, Anhui Agricultural University, Hefei, 230036, China
2National Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 340070, China
3BGI Institute of Applied Agriculture, BGI–Shenzhen, Shenzhen 518083, China
4Present address: Biofuel Institute, Jiangsu University, Zhenjiang, China
*Corresponding author. E-mail: jianzhao@ahau.edu.cn

Horticulture Research 9,
Article number: uhac087 (2022)
doi: https://doi.org/10.1093/hr/uhac087
Views: 191

Received: 08 Nov 2021
Accepted: 30 Mar 2022
Published online: 21 Apr 2022

Abstract

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 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 upregulated CoSADs with downregulated CoFAD2 and CoFAD3 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.