红树林植物根际真菌的物种多样性、代谢产物的分子多样性及抗农业病害菌活性研究

Mangroves are rare plant resources living in coastal tidal regions, and their rhizospheric environments, which differed from that of the non-rhizospheric environments, have unique and complicated physical, chemical, and biological characteristics, making the mangroves as a very important resource for finding bioactive substances. During our previous study we collected samples from mangrove rhizospheres and obtained a series of fungi. By systematic screening some of these fungi displayed potent activity against agro-pathogens, and a number of active secondary metabolites were characterized. Further works disclosed that many metabolitic pathways of these fungi are silent under the normal culture conditions, and by changing the culture manner (e.g., with static or shaking fermentation) or by changing the cultural conditions (e.g., with various culture media composition, various pH values, or with different fermentation temperature) could effectively active the silent pathways and therefore affected the metabolitic profiles as well as the activity. On the basis of the previous works, the current proposal will dedicate to a systematic investigation on the bio- and molecular-diversity of the fungi from mangrove rhizospheres. By using the epigenetic strategies and with stressed fermentation factors, the silent metabolitic pathways are expected to be activated and the structurally unique and biologically active secondary metabolites will be obtained. The molecular diversity and inhibitory activity of these metabolites will be evaluated and some of them are expected to have potential for application for agro-chemicals. The results from this study will provide scientific basis for the usage of mangrove rhizospheres.

红树林是生长在海岸潮间带的珍稀植物资源，其根际环境区别于非根际环境，具有独特、复杂的物理、化学、生物学特性，是发现新活性物质的重要来源。我们在前期研究中对红树林植物根际真菌进行了系统的样品采集、分离鉴定与活性筛选，获得了一系列具有抗农业病害菌活性的菌株资源和代谢产物。进一步的研究发现，许多次生代谢途径在通常情况下处于沉默状态，改变培养方式（静置培养、摇床培养）或改变培养条件（不同的培养基组成、不同的酸碱度、不同的温度等）能激活这些沉默途径，进而显著影响其代谢产物的组成与活性。拟在前期工作的基础上，系统开展红树林植物根际真菌的物种多样性与次生代谢产物的分子多样性研究，采用表观遗传修饰的研究策略，通过施加外部胁迫因子激活其沉默的次生代谢途径，诱导红树林根际真菌产生结构新颖的代谢产物，阐明其分子结构多样性与抗农业病害菌活性，获得有应用价值的代谢产物，为红树林根际真菌资源的有效利用提供科学依据。

本项目以我国海南东寨港红树林保护区为重点研究区域，获得了研究样品26种，开展了其真菌物种多样性研究，采用真菌分离方法从中分离获得菌株55种；对获得的真菌进行了系统的抗农业病害菌活性筛选，并根据筛选结果优选2株代谢产物丰富、活性显著的菌株（简青霉MA-332和多色青霉MA-327）进行了系统的次生代谢产物分子多样性研究，通过表观遗传修饰的技术手段激活其潜在的沉默次生代谢途径，诱导其产生结构新颖、活性显著的代谢产物。到目前为止已经从中分离获得代谢产物26种，采用现代波谱技术鉴定了其中21个化合物的分子结构，发现新化合物6个，新天然产物1个。活性筛选发现多个化合物对人类病原菌、水产病害菌和农业病害菌有较好的抑制活性。研究成果发表论文SCI论文3篇、中文核心期刊论文1篇、申请发明专利1项。