由寄生疫霉（Phytophthora parasitica）引起的柑橘根腐病是柑橘生产上普遍发生、对柑橘危害较为严重的一种病害。本研究的目的是建立一种简易快速的结合侧流层析技术判定结果的重组酶聚合酶扩增（lateral flow strip-based recombinase polymerase amplification, LF-RPA）方法检测寄生疫霉，为诊断和防治寄生疫霉引起的柑橘根腐病提供技术支撑。以Ypt1基因为检测的靶标序列，通过多序列比对分析，设计寄生疫霉的特异性引物和探针，建立并优化LF-RPA检测方法，并与简易核酸提取技术相结合，对该检测方法的特异性、灵敏度和实际应用效果进行评估。对LF-RPA体系中的温度、引物和探针比例、时间进行了优化，使得LF-RPA在40°C孵育温度下反应20分钟后即可肉眼判断检测结果。特异性试验中，LF-RPA能特异性地检测出不同来源的寄生疫霉，而其它亲缘关系相近的卵菌病原菌均未检测出。灵敏度试验结果显示，LF-RPA的最低检测灵敏度为1 pg。为了使LF-RPA检测方法更适宜基层使用，对四种不同的简易核酸提取技术进行了比较评估，发现基于PEG-NaOH的简易核酸提取技术更适合本研究。将LF-RPA与PEG-NaOH核酸提取技术相结合，不需要特定的仪器设备，只需要能维持40°C的保温杯，即可在30分钟内完成从发病植株的核酸提取到结果判定的整个检测过程。利用该方法，成功地从接种寄生疫霉的柑橘叶片、枝条和果实上检测出寄生疫霉；此外也从田间采集的10份柑橘发病样品中检测出其中3份样品含有寄生疫霉本研究成功建立了一种针对寄生疫霉的LF-RPA快速检测方法，该方法与简易核酸提取技术相结合，非常适宜于基层使用，为柑橘根腐病的快速诊断奠定了技术基础。

The relationship between the amount of tea cream and the chemical components contents in the original green tea infusion was investigated. The results showed that the amounts of tea cream in the green tea infusions obtained from different cultivars and different parts of new shoots were varied. There were many chemical components participating in the formation of green tea cream. However, there were only the contents of caffeine (Y=0.85, P<0.01) and polyphenols (Y=0.65,P<0.05) in the original green tea infusion highly correlated with the amount of green tea cream. Stepwise regression analysis of overall chemical components indicated that the contents of caffeine and gallated catechins in the original green tea infusion had a significant effect (P<0.01) on green tea cream levels. Cream (g L^-1)=-172.071+ 0.129 x C_caffeine+0.024xG_{gallated catechins} (R²=0.936). The amount of green tea cream can be predicted by the contents of gallated catechins and caffeine in the original tea infusion. Principal component analysis also indicated that catechins, minerals, and polysaccharides were the important chemical components in the formation of green tea cream.