感染晚疫病菌马铃薯中化学防御性成分研究

Potato as one of the most important food and cash crops in China is crucial for adjusting the structure of cultivation and increasing agricultural efficiency. China is the largest country in terms of potato production which is seriously affected by the late blight disease (LBD) caused by pathogenic fungus (Phytophthora infestans) infection. Chemical fungicides including metalaxyl-mancozeb and oxadixyl mancozeb, etc. are the major prevention methods; however, its application is limited due to the high toxicity and contamination to the environment. Defensive metabolites from plants are important sources for modern agricultural chemicals. According to the previous investigation, a series of sesquiterpenes including phytuberin, phytuberol, rishitin, and oxyglutinosone, etc. had been isolated from the fungus-infected potatoes, of which only several cases were revealed with anti-LBD or antifungal activity. Currently, the correlations between sesquiterpenes and LBD are still unclear, which need further investigation. Our recent investigation suggested that the chemical constituents of potatoes were varied significantly after infected by Phytophthora infestans. A series of sesquiterpenes (MW 200-300) and other components (MW>400) were detected in the LBD infected potatoes instead of the healthy ones according to the LCMS analyses. Furthermore, the antifungal activity test showed that the crude extract of LBD-infected potatoes can efficiently inhibit the mycelium growth of the fungus Phytophthora infestans, with inhibition ratio of 69.0% (1 mg/mL). Further investigation suggested that the most potent ethylacetate extract exhibited inhibition ratio of 80.1%. Therefore, it will be very significant to clarify the anti-LBD active constituents in LBD infected potatoes. In this project, pathogenic fungus (Phytophthora infestans) will be initially isolated and used to infect the healthy potatoes for inducing the chemical defensive components. The chemical difference between the LBD-infected potatoes and healthy ones will be compared by LCMS to designate the defensive components produced after LBD infection. With the guidance of LCMS analysis, systematically chemical and biological investigation will be conducted on the LBD-infected potatoes. The successful implementation of this project (if granted) will provide scientific basis not only for clarifying the chemical defensive components in LBD-infected potatoes but also for searching novel LBD inhibitors from natural sources.

由晚疫病菌Phytophthora infestans引起的晚疫病是影响马铃薯产量的最主要因素，人工合成农药作为主要防治手段，其毒性大，长期应用对人体及环境造成严重危害。植物化学防御成分是现代农药研究的重要方向，早年国外学者从染病马铃薯中分离得到系列倍半萜，但其化学防御功能及是否具有抗晚疫病菌活性尚不清楚，国内尚未开展相关研究。我们通过LCMS分析发现健康和感染晚疫病马铃薯化学成分存在明显差异，特别是从染病马铃薯中新发现系列分子量在200至300(倍半萜)和>400的色谱峰。活性研究显示染病马铃薯提取物(1mg/mL)对晚疫病菌菌丝体生长抑制率为69.0%，活性最强的乙酸乙酯部位抑制率为80.1%。本研究在此基础上，利用晚疫病菌感染健康马铃薯诱导产生化学防御成分，以LCMS分析为导向对其进行系统的抗晚疫病菌活性成分研究，为揭示马铃薯化学防御性成分以及寻找高效低毒晚疫病菌天然抑制剂提供依据。

由晚疫病菌Phytophthora infestans引起的晚疫病是影响马铃薯产量的最主要因素，人工合成农药作为主要防治手段，其毒性大，长期应用对人体及环境造成严重危害。植物化学防御成分是现代农药研究的重要方向，早年国外学者从染病马铃薯中分离得到系列倍半萜，但其化学防御功能及是否具有抗晚疫病菌活性尚不清楚，国内尚未开展相关研究。本研究以LCMS分析为导向对感染晚疫病的马铃薯植株进行系统的抗晚疫病菌活性成分研究，为揭示马铃薯化学防御性成分以及寻找高效低毒晚疫病菌天然抑制剂提供依据。根据研究计划，本研究共分离单体化合物45个，完成结构鉴定33个，发现新化合物4个，并对这4个新化合物的抗菌活性进行了评价，发现其均表现出中等抑菌活性，在500ppm浓度下，对晚疫病菌菌丝体生长的抑制率分别为30.1%、52.4%、42.5%、60.1%。