5mC DNA methylation modification-mediated regulation in tissue functional differentiation and important flavor substance synthesis of tea plant (Camellia sinensis L.)

In plants, 5mC DNA methylation is an important and conserved epistatic mark involving genomic stability, gene transcriptional regulation, developmental regulation, abiotic stress response, metabolite synthesis, etc. However, the roles of 5mC DNA methylation modification (5mC methylation) in tea plant growth and development (in pre-harvest) and flavor substance synthesis in pre- and post-harvest is unknown.

This article has been published on Horticulture Research with title: 5mC DNA methylation modification-mediated regulation in tissue functional differentiation and important flavor substance synthesis of tea plant (Camellia sinensis L.).

In this study, we therefore conducted a comprehensive methylation analysis of four key pre-harvest tissues (root, leaf, flower, and fruit) and two processed leaves during oolong tea postharvest processing. We found that differential 5mC methylation among four key tissues are closely related to tissue functional differentiation and that tissue-specific expressed genes responsible for tissue-specific functions maintain relatively low 5mC methylation levels relative to non-tissue-specific expressed genes. Importantly, hypomethylation modifications of CsAlaDC and TS/GS genes in roots provided the molecular basis for the dominant synthesis of theanine in roots.

In addition, integrating of 5mC DNA methylationomics, metabolomics, and transcriptomics of postharvest leaf revealed that content changes in flavor metabolites during oolong tea processing were closely associated with transcription level changes in corresponding metabolite synthesis genes, and changes in transcript levels of these important synthesis genes were strictly regulated by 5mC methylation. We further reported that some key genes during processing are regulated by 5mC methylation, which can effectively explain the content changes of important aroma metabolites, including α-farnesene, nerolidol, lipids, and taste substances such as catechins.

In total, our results not only highlight the key roles of 5mC methylation in important flavor substance synthesis in pre- and post-harvest, but also provide epimutation-related gene targets for future improvement of tea quality or breeding of whole-tissue high theanine varieties.

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References

Authors

Weilong Kong, Qiufang Zhu, Qing Zhang, Yiwang Zhu, Jingjing Yang, Kun Chai, Wenlong Lei, Mengwei Jiang, Shengcheng Zhang, Jinke Lin, and Xingtan Zhang

Affiliations

National Key Laboratory for Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, Guangzhou

About Xingtan Zhang

Dr. Xingtan Zhang is a research professor and doctoral supervisor at the Agricultural Genomics Institute at Shenzhen (AGIS), Chinese Academy of Agricultural Sciences. He is also the deputy director of the National Key Laboratory for Tropical Crop Breeding and a recipient of the National Science Fund for Distinguished Young Scholars and the Chinese Academy of Agricultural Sciences' Leading Talent B. He graduated with a bachelor's degree from Harbin Institute of Technology (HIT) in 2009 and obtained a Ph.D. in Botany from Chongqing University in 2015. He has been engaged in research on plant genomics for a long time and is proficient in genome assembly and bioinformatics analysis of plant complex genomes. In the past five years, his relevant achievements have been published as first or corresponding author (including co-authorship) in journals such as Cell, Nature, Nature Genetics, and Nature Plants.