Department of Tea Science , Zhejiang University , Hangzhou 310058 , People's Republic of China.
Agricultural Experiment Station , Zhejiang University , Zijingang Campus, Hangzhou , People's Republic of China.
J Agric Food Chem. 2020 Feb 26;68(8):2528-2538. doi: 10.1021/acs.jafc.9b08212. Epub 2020 Feb 13.
Albino became a novel kind of tea cultivar in China recently. In this study, transcriptome and whole-genome bisulfite sequencing (WGBS) were employed to investigate the shading effects on leaf color conversion and biosynthesis of three major secondary metabolites in the albino tea cultivar "Yujinxiang". The increased leaf chlorophyll level was likely the major cause for shaded leaf greening from young pale or yellow leaf. In comparison with the control, the total catechin level of the shading group was significantly decreased and the abundance of caffeine was markedly increased, while the theanine level was nearly not influenced. Meanwhile, differentially expressed genes (DEGs) enriched in some biological processes and pathways were identified by transcriptome analysis. Furthermore, whole-genome DNA methylation analysis revealed that the global genomic DNA methylation patterns of the shading period were remarkably altered in comparison with the control. In addition, differentially methylated regions (DMRs) and the DMR-related DEG analysis indicated that the DMR-related DEGs were the critical participants in biosynthesis of the major secondary metabolites. These findings suggest that DNA methylation is probably responsible for changes in the contents of the major secondary metabolites in Yujinxiang.
白化茶最近成为中国一种新型的茶叶品种。在这项研究中，采用转录组和全基因组亚硫酸氢盐测序（WGBS）技术，研究了遮荫对白化茶品种“玉金香”叶片颜色转化和三种主要次生代谢产物生物合成的影响。增加的叶片叶绿素水平可能是导致嫩叶从淡色或黄色变绿的主要原因。与对照相比，遮荫组儿茶素总含量显著降低，咖啡因含量显著增加，而茶氨酸含量几乎不受影响。同时，通过转录组分析鉴定了参与一些生物过程和途径的差异表达基因（DEGs）。此外，全基因组 DNA 甲基化分析表明，与对照相比，遮荫期的全基因组 DNA 甲基化模式发生了显著改变。此外，差异甲基化区域（DMRs）和 DMR 相关 DEG 分析表明，DMR 相关 DEGs 是主要次生代谢产物生物合成的关键参与者。这些发现表明，DNA 甲基化可能是导致玉金香主要次生代谢产物含量变化的原因。
