大豆根内特异微生物及疫霉病菌侵染后根招募微生物代谢活性化合物研究

本实验室从病虫害侵染植物及相邻正常植物的根际、根内筛选微生物，已高效发现44个放线菌新种、属，200多个新结构活性化合物，3个产业化菌株。植物根内是否存在一类特异微生物，和植物被病虫害侵染后根能招募微生物，且它们能代谢农用活性化合物？为探明这一科学假设，拟采用16S rRNA宏基因组测序，明确土壤、大豆及被疫霉病菌侵染大豆根际、根内微生物群落组成及丰度，确定大豆根内存在的特异微生物和侵染后招募的微生物，选择专用、特殊培养基及方法分离这类菌株；然后以参与主要抗生素生物合成的非核糖体多肽合成酶腺苷酰作用模块、PKS I型酮基合成酶模块、烯二炔聚酮合成酶的3个基因，进行基因探针扫描菌株基因组，聚类分析生物合成化合物结构的多样性，纯化、表征新型化合物并评估活性。研究将全面、深入探明大豆根内特异微生物和被疫霉病菌侵染后根招募的微生物代谢活性化合物的能力，对引领发现新型农用抗生素有重大科学和应用价值。

Microbes have been screened from rhizosphere and roots of the disease- and insect pest- caused plants as well as the adjacent normal plants for many years in our lab. 44 new genera and species of actinomycetes, over 200 active compounds with novel structures and three commercialized strains have been obtained. For exploring the specific microbes within roots and those recruited by disease and insect pest infestation with the remarkable abilities of synthesizing active compounds, the 16S rRNA metagenomes of microbiota residing in the soil, soybean (normal and Phytophthora-infected) rhizosphere and roots will be sequenced to define the composition and abundance of different genera, therefore, leading to their identification of these specific microbes. According to the distribution of different genera colonizing the roots, special media and separation methods are employed for isolating specific strains. The isolated specific strains will be screened by PCR for genes associated with secondary-metabolite biosynthesis. Three primer sets were used to specifically target adenylation domains associated with nonribosomal peptide synthetases (NRPSs) and ketosynthase (KS) domains associated with type I modular, iterative, hybrid, and enediyne polyketide synthases (PKSs). Subsequently, sequence clustering patterns were conducted to provide an estimate of PKS pathway diversity and to evaluate the biosynthetic richness of individual strains. Furthermore, novel purified compounds will be identified and their activities will be assessed. This study exploits the potential of antibiotic biosynthesis of specific microbes within roots and those recruited by infestation comprehensively and deeply, thus contributing great scientific significance and applicable value to the discovery of novel agroantibiotics.