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氮素供应对茶树叶片中黄酮醇糖苷合成和积累的影响

2019-07-05  作者: admin  来源: 未知  已阅读

黄酮类黄酮醇及其糖基化衍生物在茶树中广泛存在并且对茶叶品质具有决定性作用。在本研究中,作者对‘龙井43’盆栽苗进行不同程度的氮肥(尿素)处理(N1: 0g/pot; N2: 4g/pot; N3:16g/pot),其中春茶采收后施30%、秋茶采收前施40%、来年春茶前施30%。利用超高效液相色谱-三重四极杆串联质谱(UPLC-QqQ-MS/MS)对不同处理下的黄酮醇糖苷类定量检测发现正常氮素(N2)水平供应下它们中的大多数都大量积累,而基于气相色谱-质谱(GC-MS)的代谢组学结果表明在这个过程中黄酮醇糖苷类的积累与碳水化合物类基质的水平呈正相关;进一步对类黄酮和碳水化合物代谢相关的关键基因定量分析显示这些基因在调控黄酮醇糖苷类的合成与积累中发挥着积极作用。结果表明正常的氮素供应能够通过基因表达调控以及碳水化合物类基质的积累来促进茶树叶片中黄酮醇糖苷类的合成,而在氮素供应异常尤其是过量情况下则能抑制这种效应。

 

 

 


Abstract

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.

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