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Article|28 Jan 2022|OPEN
Function and transcriptional regulation of CsKCS20 in the elongation of very-long-chain fatty acids and wax biosynthesis in Citrus sinensis flavedo
Yang Wang1,2 , Xianpeng Yang3 , Zhaoxing Chen4 , Jin Zhang1,2 , Kai Si1,2 and Rangwei Xu1,2 , Yizhong He1,2 , Feng Zhu1,2 , Yunjiang Cheng,1,2 ,
1Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China
2National R&D Center for Citrus Postharvest Technology, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China
3College of Life Sciences, Shandong Normal University, Jinan 250014, China
4Institute of Citrus Science Research of Ganzhou, Ganzhou 341000, China
*Corresponding author. E-mail: yjcheng@mail.hzau.edu.cn

Horticulture Research 9,
Article number: uhab027 (2022)
doi: https://doi.org/10.1093/hr/uhab027
Views: 20

Received: 22 Jun 2021
Revised: 18 Jan 2022
Accepted: 15 Sep 2021
Published online: 28 Jan 2022

Abstract

Cuticular wax on plant aerial surfaces plays a vital role in the defense against various stresses, and the genes related to wax metabolism have been well documented in several model plants. However, there is very limited research on the key enzymes and transcription factors (TFs) associated with carbon chain distribution and wax biosynthesis in citrus fruit. In this study, an analysis of wax metabolites indicated that even carbon-chain (C24-C28) metabolites are the dominant wax components in citrus fruit, and a 3-ketoacyl-CoA synthase (KCS) family gene (CsKCS20) plays an important role in the carbon chain distribution during wax biosynthesis in a wax-deficient mutant (MT). Expression of CsKCS20 in yeast indicated that CsKCS20 can catalyze the biosynthesis of C22 and C24 very-long-chain fatty acids (VLCFAs). In addition, transcriptome and sequence analysis indicated that the differential expression of CsKCS20 between the wild-type (WT) and MT fruit can be partly attributed to the regulation of CsMYB96, which was further confirmed by yeast one-hybrid (Y1H) assays, electrophoretic mobility shift assays (EMSAs) and dual luciferase assays. The functions of CsMYB96 and CsKCS20 in wax biosynthesis were further validated by heterologous expression in Arabidopsis. In summary, this study elucidates the important roles of CsKCS20 and CsMYB96 in regulating VLCFA elongation and cuticular wax biosynthesis, which provides new directions for the improvement of citrus fruit wax quality in genetic breeding programs.