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Article|19 Feb 2022|OPEN
Transcription factor CsWRKY40 regulates L-theanine hydrolysis by activating the CsPDX2.1 promoter in tea leaves during withering
Haiyan Cheng1,2 , Wei Wu2,3 and Xiaofen Liu2,3 , Yuefei Wang1,2 , Ping Xu,1,2 ,
1Institute of Tea Science, Zhejiang University, Hangzhou 310058, Zhejiang, China
2Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Ministry of Agriculture, Hangzhou 310058, Zhejiang, China
3Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zhejiang University, Hangzhou 310058, Zhejiang, China
*Corresponding author. E-mail: zdxp@zju.edu.cn

Horticulture Research 9,
Article number: uhac025 (2022)
doi: https://doi.org/10.1093/hr/uhac025
Views: 199

Received: 30 Nov 2021
Revised: 16 Jun 2022
Accepted: 26 Jan 2022
Published online: 19 Feb 2022

Abstract

L-Theanine is a crucial secondary metabolite in tea and positively determines the potential quality and health benefits of tea products. Previous work found that the content of L-theanine decreased during the withering process, although the specific mechanism is still unknown. Here, weighted gene co-expression network analysis (WGCNA) was performed based on transcriptome data obtained previously. The key hydrolysis gene CsPDX2.1 in L-theanine metabolism and seven candidate transcription factors were screened out. Among these transcription factors, CsWRKY40 displayed the strongest activation on the CsPDX2.1 promoter (373.18-fold) by binding to the W box element, based on dual luciferase assay and EMSA results. The CsWRKY40 protein was located in the nucleoplasm, whereas CsPDX2.1 was found in both the nucleoplasm and cytoplasm. Analysis of withering, water-retention, and water-loss treatments confirmed that water loss from tea leaves was the critical factor that affected ABA and L-theanine contents by activating the expression of CsWRKY40 and CsPDX2.1. Our results provide a new insight into the regulatory mechanism of L-theanine hydrolysis metabolism.