根肿病是一种世界性土传病害，对鄂西高山蔬菜产业危害甚大，不少田块大白菜发病率高达60%。根际土壤微生物对抑制土传病害，维护植物健康起着重要作用。本研究拟通过盆栽试验和田间试验：测定根际土壤酶活性和土壤肥力；采用高通量测序技术，结合微生物分子生态学研究方法，解析大白菜根际土壤微生物（细菌和真菌）群落结构组成及多样性；采用Real-time PCR技术，对根肿菌，高通量测序发现的致病菌以及重要类群，进行定量分析，验证和补充高通量测序结果；监测根肿病病情。通过以上研究，揭示根肿病发生和Streptomyces alfalfae XY25T防治过程中，根际土壤性质和微生物群落结构变化规律；建立土壤性质，根际微生物群落与根肿病三者之间的联系，推断驱动微生物群落变化和根肿病发生的关键因素；阐明S. alfalfae XY25T对大白菜根肿病的防治作用及微生态机制。项目实施为根肿病的发生和防治提供依据。

Clubroot caused by Plasmodiophora brassica is one of the most important diseases of cruciferae crops in the world. It is becoming a serious threat to the vegetable industry in western Hubei, and the incidence rate of Chinese cabbage was as high as 60% in many fields. It is suggested that rhizosphere microbiota plays an important role in suppressing soil-borne diseases. However, the pathogenetic mechanism of rhizosphere microbiota caused clubroot are still unknown, and the methods of controlling clubroot are inefficient. In this study, firstly, high-throughput sequencing technologies and molecular microbial ecology methods were combined to analysis the composition of rhizosphere microorganism (bacteria and fungi) of Chinese cabbage during different stages. Secondly, real-time PCR were used to determine the copy numbers of important microbial groups, such as P. brassicae, and other pathogenic microorganism.Thirdly, the enzyme activities and fertility in rhizosphere soil were measured, and the occurrence of cubroot were recorded to discover their pathogenesis. Through the above research, we will try to explain the change rule of microbial community with the progress of cubroot, to determine the relations between soil characteristics, rhizosphere microorganism communities and clubroot, to speculate the key factors of changed rhizosphere microbiota and caused cubroot, to verify the preventive and therapeutic effects of Streptomyces alfalfae XY25T for chinese cabbage clubroot, and also to clarify the regulatory mechanism of S. alfalfae XY25T which improved soil and controlled clubroot. This program will provide theories basis for the occurrence of clubroot and the use of S. alfalfae XY25T, and will promote the sustainable development of high mountain vegetable industy.