Differential regulatory mechanisms of secondary metabolites revealed at different leaf positions in two related tea cultivars

文献类型： 外文期刊

第一作者： Zhang, Yazhen

作者： Zhang, Yazhen;Wang, Liyuan;Wei, Kang;Ruan, Li;Wu, Liyun;He, Mengdi;Cheng, Hao;Zhang, Yazhen;Tong, Huarong

作者机构：

关键词： Tea plant; Leaf position; Theanine; Caffeine; Catechins; Gene expression; Correlation analysis

期刊名称：SCIENTIA HORTICULTURAE （ 影响因子：3.463； 五年影响因子：3.672 ）

ISSN： 0304-4238

年卷期： 2020 年 272 卷

页码：

收录情况： SCI

摘要： In this study, 'Zhongchal08' (ZC) and its offspring cultivar 'Zhongming7' (ZM) were used to investigate the variation in characteristic compounds at different leaf positions. The results showed that there were differences between the two cultivars beyond the leaf position. The concentrations of theanine and caffeine were significantly higher in ZM, whereas more catechins accumulated in ZC. The expression levels of genes related to the theanine, caffeine and catechin pathways were determined by quantitative real time PCR. Compared with ZC, ZM showed higher expression levels of genes involved in theanine biosynthesis and transport, including GOGAT, GS(TS), AlaAT, AspAT, AS and AAP, suggesting that effective biosynthesis and translocation facilitate theanine accumulation in ZM. The caffeine content in ZC was positively correlated with the gene expression of TCS. However, such a correlation was not observed in ZM, which might be related to highly expressed genes involved in caffeine degradation, including CYP1A2, ALN and XO. Furthermore, catechin biosynthesis was regulated by different structural genes in the two cultivars. Higher catechins contents in ZC were related to higher genes expression levels, particularly for PAL, 4CL, F3H, FLS and MR. A correlation analysis among key genes involved in theanine, caffeine, and catechin biosynthesis also showed consistent results. In ZC, catechins biosynthesis was more active, which inhibited the biosynthesis of nitrogen-rich metabolites, particularly for theanine. The balance of secondary metabolisms in ZM was shifted toward increasing the synthesis of nitrogen-containing compounds, i.e., theanine and caffeine. Taken together, these data reveal different regulatory mechanisms of theanine, caffeine, and catechins within two genetically similar tea cultivars. This work provides an important basis for further research on the characteristic metabolites of tea plants.

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