基于土壤线虫群落特征的连作番茄根结线虫病发生机制

根结线虫病是蔬菜生产中的重要病害之一，连作是该病害加重的主要原因。根结线虫群体作为土壤线虫群落的组成，在连作过程与土壤中其它线虫群体之间关系如何？土壤中线虫微生物天敌群体如何演替？它们之间的联动效应等均不清楚。本研究利用微生物分子生态学原理结合传统研究方法，基于土壤线虫群落结构和微生物天敌的多样性，研究连作番茄根结线虫病灾变机理。前期研究明确了连作土壤自由生活线虫与根结线虫群体之间关系，在此基础上有必要利用土壤线虫群落结构、线虫微生物天敌与根结线虫群体关系深入研究连作土壤根结线虫群体上升的机制。主要研究内容包括：1、应用末端限制性酶切片段长度多态性（T-RFLP）技术和传统分类学对连作土壤线虫多样性分析；2、连作土壤线虫和微生物群落的演替分析；3、根结线虫群体数量与病情关系研究；4、土壤线虫、微生物天敌群落及与根结线虫群体关系研究，为进一步获得根结线虫病早期预警的分子标记研究提供理论基础。

Root-knot nematodes, one of the most important agricultural pests of vegetables, are responsible for large yield losses in several horticultural crops. The root knot nematode population is one of population in soil nematode communities. However, little is known about the relationship between root knot nematodes and other soil nematodes, the changes in the diversity of the soil nematode population and natural microbial enemies during cotinuous cropping. Likewise, coupling effects of root knot nematodes and microbial enemies is not well understood. Therefore, this project will study the outbreak mechanism of root-knot nematodes based on the diversity of soil nematodes and their natural microbial enemies using molecular microbial ecology and traditonal taxonomy methods. In addition, we will further study the reason for the large root-knot nematode populations in long-term continously cropped soil based on the community dynamics of the soil nematodes and their natural microbial enemies using the results of a previous study we conducted, which showed the relationship between root-knot nematodes and free-living nematodes in the soil to different durations of continuous cropping. The experiment will be carried out in field scale and pots experiment to study the soil of continously cropped tomato. The objectives of the current study are: (1) to determine the dynamics of the soil nematode community diversity with increasing durations of continous cropping using terminal restriction fragment length polymorphism (T-RFLP) and traditional taxonomy techniques; (2) to determine the dynamics of soil microbial community diversity with increasing duration of continous cropping using T-RFLP; (3) to study and analyze relationship between the disease index of root-knot nematode and nematode population; and (4) to assess the relationship between root-knot nematodes, the soil nematode community, and the natural microbial enemy community in the soil. The research results will provide important theoretical information on molecular markers of root-knot nematodes that can serve as early warning systems of disease outbreaks.