College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
Int J Mol Sci. 2019 Jan 9;20(2):237. doi: 10.3390/ijms20020237.
Tea ( (L.) O. Kuntze), one of the main crops in China, is high in various bioactive compounds including flavonoids, catechins, caffeine, theanine, and other amino acids. is also known as an accumulator of fluoride (F), and the bioactive compounds are affected by F, however, the mechanism remains unclear. Here, the effects of F treatment on the accumulation of F and major bioactive compounds and gene expression were investigated, revealing the molecular mechanisms affecting the accumulation of bioactive compounds by F treatment. The results showed that F accumulation in tea leaves gradually increased under exogenous F treatments. Similarly, the flavonoid content also increased in the F treatment. In contrast, the polyphenol content, free amino acids, and the total catechins decreased significantly. Special amino acids, such as sulfur-containing amino acids and proline, had the opposite trend of free amino acids. Caffeine was obviously induced by exogenous F, while the theanine content peaked after two day-treatment. These results suggest that the F accumulation and content of bioactive compounds were dramatically affected by F treatment. Furthermore, differentially expressed genes (DEGs) related to the metabolism of main bioactive compounds and amino acids, especially the pivotal regulatory genes of catechins, caffeine, and theanine biosynthesis pathways, were identified and analyzed using high-throughput Illumina RNA-Seq technology and qRT-PCR. The expression of pivotal regulatory genes is consistent with the changes of the main bioactive compounds in leaves, indicating a complicated molecular mechanism for the above findings. Overall, these data provide a reference for exploring the possible molecular mechanism of the accumulation of major bioactive components such as flavonoid, catechins, caffeine, theanine and other amino acids in tea leaves in response to fluoride treatment.
茶（(L.) O. Kuntze）是中国的主要作物之一，富含多种生物活性化合物，包括类黄酮、儿茶素、咖啡因、茶氨酸和其他氨基酸。茶也被认为是氟化物（F）的积累者，生物活性化合物受 F 的影响，但机制尚不清楚。本研究探讨了 F 处理对 F 积累和主要生物活性化合物及基因表达的影响，揭示了 F 处理影响生物活性化合物积累的分子机制。结果表明，外源 F 处理下，茶叶中 F 积累逐渐增加。同样，类黄酮含量也在 F 处理下增加。相比之下，多酚含量、游离氨基酸和总儿茶素含量显著下降。特殊氨基酸，如含硫氨基酸和脯氨酸，游离氨基酸的趋势相反。咖啡因明显被外源 F 诱导，而茶氨酸含量在处理两天后达到峰值。这些结果表明，F 积累和生物活性化合物含量受 F 处理的显著影响。此外，利用高通量 Illumina RNA-Seq 技术和 qRT-PCR 技术，鉴定和分析了与主要生物活性化合物和氨基酸代谢相关的差异表达基因（DEGs），特别是儿茶素、咖啡因和茶氨酸生物合成途径的关键调控基因。关键调控基因的表达与叶片中主要生物活性化合物的变化一致，表明存在复杂的分子机制。总体而言，这些数据为探索茶叶中主要生物活性成分（如类黄酮、儿茶素、咖啡因、茶氨酸和其他氨基酸）在氟化物处理下积累的可能分子机制提供了参考。
