Mechanism Underlying the Shading-Induced Chlorophyll Accumulation in Tea Leaves

Jiaming Chen; Shuhua Wu; Fang Dong; Jianlong Li; Lanting Zeng; Jinchi Tang; Dachuan Gu

doi:10.3389/fpls.2021.779819

Mechanism Underlying the Shading-Induced Chlorophyll Accumulation in Tea Leaves

Front Plant Sci. 2021 Dec 2:12:779819. doi: 10.3389/fpls.2021.779819. eCollection 2021.

Authors

Jiaming Chen^{1

2}, Shuhua Wu^{1

2}, Fang Dong³, Jianlong Li⁴, Lanting Zeng¹, Jinchi Tang⁴, Dachuan Gu¹

Affiliations

¹ Guangdong Provincial Key Laboratory of Applied Botany & Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
² College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
³ Guangdong Food and Drug Vocational College, Guangzhou, China.
⁴ Laboratory of Tea Plant Resources Innovation and Utilization, Tea Research Institute, Guangdong Academy of Agricultural Sciences & Guangdong Provincial Key, Guangzhou, China.

Abstract

Besides aroma and taste, the color of dry tea leaves, tea infusion, and infused tea leaves is also an important index for tea quality. Shading can significantly increase the chlorophyll content of tea leaves, leading to enhanced tea leaf coloration. However, the underlying regulatory mechanism remains unclear. In this study, we revealed that the expressions of chlorophyll synthesis genes were significantly induced by shading, specially, the gene encoding protochlorophyllide oxidoreductase (CsPOR). Indoor control experiment showed that decreased light intensity could significantly induce the expression of CsPOR, and thus cause the increase of chlorophyll content. Subsequently, we explored the light signaling pathway transcription factors regulating chlorophyll synthesis, including CsPIFs and CsHY5. Through expression level and subcellular localization analysis, we found that CsPIF3-2, CsPIF7-1, and CsHY5 may be candidate transcriptional regulators. Transcriptional activation experiments proved that CsHY5 inhibits CsPORL-2 transcription. In summary, we concluded that shading might promote the expression of CsPORL-2 by inhibiting the expression of CsHY5, leading to high accumulation of chlorophyll in tea leaves. The results of this study provide insights into the mechanism regulating the improvements to tea plant quality caused by shading.

Keywords: Camellia sinensis; chlorophyll accumulation; light intensity; shading; transcription regulation.