白粉病菌侵染苦瓜的生理机制

Physiological mechanism in bitter melon infected with powdery mildew fungus

对大顶苦瓜感染白粉病的发病过程和生理机制进行研究。结果发现,感病苦瓜叶片质膜透性与对照相比增加较少,其增加量与病情指数相关性不高;叶绿素a、b、总叶绿素、类胡萝卜素含量随病情加重均下降,接种15d,与对照比分别下降72.6%、68.5%、71.5%和27.1%,其中叶绿素a、b和总叶绿素含量变化与病情指数相关性很高,以叶绿素a含量变化相关性最高;氧化酶活性测定结果表明,感病苦瓜叶片中POD和PPO活性与对照比上升,且随感病时间延长活性增加更多,接种15d,POD和PPO活性较对照增加528.5%和70.4%,两个酶活性变化与病情指数的相关性也很高。

The study focused on the pathogenic process of powdery mildew and the physiological mechanism in Dading bitter melon. The result showed that the membrane permeability increased less compared with the control in pathogenic leaf, and its change wasn＇t obviously related to the pathogenic index. The contents of chlorophyll a, chlorophyll b,total chlorophyll and carotenoid all decreased gradually along with the pathogenic process developed in pathogenic leaf,which decreased by 72.6% ,68.5%, 1.50% and 27.1% respectively compared with their controls after the plant was inoculated for 15 d. Among these changes,the decreases on chlorophyll a,chlorophyll b and total chlorophyll all presented high relativity to pathogenic index,and the highest relativity was found in chlorophyll a. The test result of oxidases indicated that POD and PPO activities both increased compared with the control in pathogenic leaf, and increased more along with the pathogenic process developed, which could increased by 528.5 % and 70.4% respectively compared with their controls after the plant was inoculated for 15 d, and the change on two oxidases activities showed high relativity to pathogenic index.