低钾胁迫对茶树(Camellia sinensis var.sinensis cv.)叶片低萜类化合物合成的影响及其机制研究

According to the fact that the content of rapid available potassium in the tea-cultivated soil was lower than critical value and low-molecule terpene was an important component to form volatile aroma in tea leaves, this subject aimed to investigate the effect of low-content potassium stress on synthesis of low-molecule terpene and discussion of procedural mechanism during synthesis pathway employing water-culture experiment. Due to mevalonate pathway (MVA pathway) and 1-deoxy-D-xylulose 5-phosphate/ 2C-methyl-D-erythritol 4-phosphate pathway (DOXP/MEP pathway) were principal path for synthesis of low-molecule terpene in the specie of advanced plant, the key enzymes and intermediates would be changed during the two pathways in leaves at the condition of low-content potassium stress. Thus it is possible to quantify the change of the contents of intermediate and low-molecule terpene under different levels of stress using chromatographic separation and identification method, and to characterize the difference of key enzymes using gene expression technique. Relational network will be constructed among the intermediate, low-molecule terpene, and key enzyme by combining the chemical method and the biological technique, and that the velocity-controlled step and rate-limiting enzyme were confirmed. Based on water-culture experiment, soil-culture experiment and field plot trial were developed in order to investigate the effect of rapid available potassium at the levels of different deficiency and abundant on synthesis of low-molecule terpene and discussion of procedural mechanism. Those purposes were to construct relational network among intermediate, low-molecule terpene, and key enzyme, and to find the velocity-controlled step and rate-limiting enzyme were, in reality. This research will provide of foundation for high-quality tea production, and rich the fundamental theory of tea plant nutrition and physiology.

针对茶园土壤速效钾含量多低于临界值以及低萜类化合物是茶树叶片香气形成重要组分的实际，本项目采用水培方法研究低钾胁迫对低萜类合成的影响及过程机制探讨。甲羟戊酸途径和5-磷酸脱氧木酮糖/2C-甲4-磷酸-4D-赤藓糖醇途径是高等植物中低萜类合成的主要途径，低钾胁迫下，叶片中两条代谢途径的相应关键酶及中间体发生不同程度改变，采用色谱分离与鉴定技术跟踪定性定量分析合成中间体及低萜类含量变化，用基因表达手段表征关键酶的差异，以化学方法结合生物学手段，构建三者之间的关系网络，确定不同程度钾胁迫的控速步骤与限速酶。在水培试验为基础上，进一步开展低钾胁迫下土培实验及田间小区实验，研究速效钾在不同亏缺及丰富水平下对低萜类的影响及其合成过程机制探讨，在实践中寻求关键酶、合成中间体及低萜类关系网络，探明不同含量钾素对低萜类合成影响的控速步骤及相应限速酶。为优质茶叶生产提供依据，丰富茶树营养与生理基础理论。

摘要：针对安徽茶园土壤普遍缺钾、镁的现状，以及低萜类化合物是茶叶中优质香气成分的实际，在分析了钾镁营养生理功能的基础上，本项目采用了盆栽的方法研究了不同水平的钾镁对茶树叶片中低萜类化合物合成的影响，分析了影响机理。证实钾镁是低萜类化合物合成的重要营养元素，钾镁在较低的水平下抑制萜类化合物的生成，高钾也抑制萜类的合成，只有土壤钾镁含量维持在合理的水平下才有助于低萜类物质形成。确定了甲羟戊酸途径合成萜烯类化合物过程的酶，HMG-CoA还原酶可能是关键酶，钾镁对该酶均具有潜在的调节作用。