应用荧光定量PCR的方法对茶树咖啡碱合成酶基因在PEG胁迫下的表达情况进行分析。结果显示，与对照相比，PEG胁迫下咖啡碱合成酶基因表达量随着胁迫时间延长呈现出先升高后降低的变化特点，胁迫的12 h内表达量明显上调，胁迫6 h表达量最大，之后明显下降，相对表达量变化范围为0.13~10.97。

The differential expression of the caffeine synthase gene in tea plant under polyethylene glycol(PEG ) stress was analyzed by fluorescence quantitative polymerase chain reaction. The results indicated that comparing with control, the caffeine synthase gene expression increased significantly in the 12 hours and reached the maximum level 6 hours after PEG stress, and then decreased. The caffeine synthase gene transcription level in tea leaves follows a high-low pattern under PEG stress.The relative expression ratios ranged from 0.13 to 10.97.