套作大豆根际土壤微生物群落解析及根腐病抑制菌筛选

Soybean root rot is a worldwide soil-borne fungal disease which is characterized by complicated pathogens and difficult control and causes large loss in yield and quality of soybean. Relay intercropping can change soil microbial community and reduce the soil-borne disease incidence. Our previous studies showed that relay intercropping changed the population and pathogenicity of the pathogens causing soybean root rot, but also affected the structure of soil microbial community and enzymes related to metabolic processes. However, the correlation of soil microbial community with the pathogen population, and with disease occurrence of soybean root rot is still unclear. In this study, the rhizosphere soil were collected from location test field of monocultural or intercropped soybean, the population, pathogenicity and genetic diversity of Fusarium spp. associated with soybean root rot were studied using traditional microbial isolation, pathogenicity test and PCR-based DNA sequence analysis, the structure of soil microbial community were analyzed by high-throughput sequencing based on 16SrRNA or ITS, the suppressing soil fungi of root rot were screened and identified, and then the suppression ability were examined. In addition, the growth parameters and defense responses of soybean after inoculation with suppressing soil fungi were examined. This study will the biological regulation mechanism of intercropping on the occurrence of soybean root rot, and will provide important reference for this disease management and also for popularization and application of intercropping soybean with maize.

根腐病是世界性的大豆土传真菌病害，其病原菌复杂，防治困难，严重影响大豆产量和品质。间套作能够改变土壤微生物结构，降低土传病害发生。前期研究发现，套作改变了大豆根腐病菌的种群及致病性，降低了大豆根腐病发生，同时也影响了根际土壤微生物群落及代谢相关酶活性，但是否根际土壤微生物群落的改变影响根腐病菌的种群发生尚不清楚。本项目拟采用田间定位试验，以玉米大豆套作为研究对象，结合传统真菌分离与鉴定技术、致病性检测、核酸序列分析、16SrRNA/ITS高通量测序等方法，研究套作大豆根际土壤中根腐病镰孢菌的种群、致病性及遗传多样性，同时，通过土壤微生物群落结构解析，明确套作根际土壤微生物群落结构多样性，并筛选获得根腐病高效抑制性真菌类群；进一步通过盆栽试验，研究高效抑制性真菌对大豆生长及抗病防卫反应的影响，从而探明套作大豆根际土壤微生物调控根腐病发生的机制，为根腐病的生物防治及套作大豆推广应用奠定基础。

根腐病是世界性的大豆土传真菌病害，其病原菌复杂、防治困难，严重影响我国大豆增产和品质提升。间套作具有改变土壤微生物群落结构，抑制土传病害发生的作用，是当前土传病害绿色生态防控的重要农业措施。根际有益土壤微生物具有抑制或杀死土传病菌，促进植物健康生长的功效，是土传病害根际微生物调控的关键角色。前期研究发现，玉米大豆带状套作抑制大豆根腐病发生,但其根际微生物调控机制尚不清楚。本项目基于多年田间定位实验，首先系统调查明确了带状套作抑制了根腐病发生，改变了其病原镰孢菌的种类。然后从根际土壤微生物入手，比较分析了带状套作和单作大豆健康植株和根腐病病株的根际土壤微生物群落结构多样性，明确了带状套作显著影响了根际土壤真菌和细菌结构多样性。接着对两种栽培方式下根际土壤镰孢菌进行了分离鉴定，明确了根际土壤镰孢菌菌群与根腐病致病优势菌群一致，且能够侵染大豆引起根腐病；同时，带状套作显著提高了根际土壤木霉菌丰度。在此基础上，鉴定筛选获得了根腐病抑制效果良好的3株木霉菌，研究了这些木霉菌的生物学特性，初步明确了其抑制杀死病原菌及诱导大豆免疫抗性的功能。本项目成果为理解玉米大豆带状套作调控根腐病的根际微生物机制及根腐病的生物防治提供了支撑，对于玉米大豆带状套作推广应用及大豆增产具有重要意义。