Architecture and Dynamics of the Wounding-Induced Gene Regulatory Network During the Oolong Tea Manufacturing Process (Camellia sinensis).

Yucheng Zheng,Yun Sun,Huili Deng,Liangyu Wu,Pengjie Wang,Naixing Ye,Yun Yang,Zongjie Wu,Qingcai Hu

doi:10.3389/fpls.2021.788469

Abstract

Understanding extensive transcriptional reprogramming events mediated by wounding during the oolong tea manufacturing process is essential for improving oolong tea quality. To improve our comprehension of the architecture of the wounding-induced gene regulatory network, we systematically analyzed the high-resolution transcriptomic and metabolomic data from wounding-treated (after turnover stage) tea leaves at 11 time points over a 220-min period. The results indicated that wounding activates a burst of transcriptional activity within 10 min and that the temporal expression patterns over time could be partitioned into 18 specific clusters with distinct biological processes. The transcription factor (TF) activity linked to the TF binding motif participated in specific biological processes within different clusters. A chronological model of the wounding-induced gene regulatory network provides insight into the dynamic transcriptional regulation event after wounding treatment (the turnover stage). Time series data of wounding-induced volatiles reveal the scientific significance of resting for a while after wounding treatment during the actual manufacturing process of oolong tea. Integrating information-rich expression data with information on volatiles allowed us to identify many high-confidence TFs participating in aroma formation regulation after wounding treatment by using weighted gene co-expression network analysis (WGCNA). Collectively, our research revealed the complexity of the wounding-induced gene regulatory network and described wounding-mediated dynamic transcriptional reprogramming events, serving as a valuable theoretical basis for the quality formation of oolong tea during the post-harvest manufacturing process.

Highlights

Oolong tea products with rich aromas usually have better economic benefits than those without these aromas
The results showed that the peak area of cis-3-hexen-1-ol at each time point after wounding treatment was positively correlated with the cyan, blue, royal blue, yellow, and brown modules, while the indole, E-nerolidol, and ocimene modules were positively correlated with the dark red, grey60, dark green, and orange modules, indicating that these modules play an important role in aroma formation during the oolong tea process (Figure 5B)
The comprehensive transcriptional reprogramming events mediated by wounding treatment are poorly understood within the post-harvest process of oolong tea

Summary

Introduction

Oolong tea products with rich aromas usually have better economic benefits than those without these aromas. Recent studies have shown that the turnover process leads to the accumulation of indole, E-nerolidol, and jasmine lactone, which are the representative volatile constituents of oolong tea, by activating the expression of key genes in the related pathway (Baldermann et al, 2014; Zeng et al, 2019b). These three representative substances are synthesized from different pathways, which suggests that the molecular regulatory network driven by wounding stress is comprehensive and complex. All of the above actions pose challenges to the standardization and refinement of the quality of oolong tea in the future

Methods

Results

Conclusion