Tea Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory for Plant Biology and Resource Application of Tea, The Ministry of Agriculture, Hangzhou, 310008, China.
College of Horticulture, Qingdao Agricultural University, Qingdao Key Laboratory of Genetic Improvement and Breeding in Horticultural Plants, Qingdao, China.
Plant Physiol Biochem. 2019 May;138:48-57. doi: 10.1016/j.plaphy.2019.02.017. Epub 2019 Feb 22.
Widely distributed in tea plants, the flavonoid flavonol and its glycosylated derivatives have important roles in determining tea quality. However, the biosynthesis and accumulation of these compounds has not been fully studied, especially in response to nitrogen (N) supply. In the present study, 'Longjing 43' potted tea seedlings were subjected to N deficiency (0g/pot), normal N (4g/pot) or excess N (16g/pot). Quantitative analyses using Ultra Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry (UPLC-QqQ-MS/MS) revealed that most flavonol glycosides (e.g., Quercetin-3-glucoside, Kaempferol-3-rgalactoside and Kaempferol-3-glucosyl-rhamnsoyl-glucoside) accumulated to the highest levels when treated with normal N. Results from metabolomics using Gas Chromatography-Mass Spectrometer (GC-MS) suggested that the levels of carbohydrate substrates of flavonol glycosides (e.g., sucrose, sucrose-6-phosphate, D-fructose 1,6-bisphosphate and glucose-1-phosphate) were positively correlated with flavonol glycoside content in response to N availability. Furthermore, Quantitative Real-time PCR analysis of 28 genes confirmed that genes related to flavonoid (e.g., flavonol synthase 1, flavonol 3-O-galactosyltransferase) and carbohydrate (e.g., sucrose phosphate synthase, sucrose synthase and glucokinase) metabolism have important roles in regulating the biosynthesis and accumulation of flavonol glycosides. Collectively, our results suggest that normal N levels promote the biosynthesis of flavonol glycosides through gene regulation and the accumulation of substrate carbohydrates, while abnormal N availability has inhibitory effects, especially excess N.
广泛分布于茶树中的类黄酮黄酮醇及其糖基化衍生物在决定茶叶品质方面具有重要作用。然而，这些化合物的生物合成和积累尚未得到充分研究，特别是在氮（N）供应方面。在本研究中，对盆栽龙井 43 茶苗进行了缺氮（0g/盆）、正常氮（4g/盆）或过量氮（16g/盆）处理。使用超高效液相色谱-三重四极杆质谱联用仪（UPLC-QqQ-MS/MS）进行定量分析显示，在正常氮处理下，大多数黄酮醇糖苷（如槲皮素-3-葡萄糖苷、山柰酚-3-半乳糖苷和山柰酚-3-葡萄糖基鼠李糖基葡萄糖苷）积累水平最高。使用气相色谱-质谱联用仪（GC-MS）进行代谢组学分析表明，黄酮醇糖苷的碳水化合物底物水平（如蔗糖、蔗糖-6-磷酸、D-果糖 1,6-二磷酸和葡萄糖-1-磷酸）与黄酮醇糖苷含量呈正相关，这与 N 供应的可用性有关。此外，对 28 个基因的定量实时 PCR 分析证实，与类黄酮（如黄酮醇合酶 1、黄酮醇 3-O-半乳糖基转移酶）和碳水化合物（如蔗糖磷酸合酶、蔗糖合酶和葡萄糖激酶）代谢相关的基因在调节黄酮醇糖苷的生物合成和积累方面具有重要作用。总的来说，我们的研究结果表明，正常的 N 水平通过基因调控和底物碳水化合物的积累促进黄酮醇糖苷的生物合成，而异常的 N 可用性具有抑制作用，尤其是过量的 N。
