美洲剑线虫组（Xiphinema americanum group）内线虫系一类形态上极为相似、重要的植物外寄生线虫，其内包括一些植物病毒的传播介体，在相当长的一个阶段一直是植物检疫界关注的一个重要的线虫类群。本申请项目拟对我国不同典型的地理生态地区美洲剑线虫组内的的主要地理种群的形态学研究，核糖体RNA基因中编码区和非编码区、线粒体细胞色素C氧化酶亚基I基因等的克隆及序列分析，以及对美洲剑线虫组内主要种群伴生的内生细菌定位、与寄主的特异性关系及协同进化研究等。明确我国美洲剑线虫组的主要种群、种间及种内的形态学、核糖体RNA基因和线粒体细胞色素C氧化酶亚基I 基因及其内共生细菌等的主要特性和系统学关系、筛选一些重要种鉴定特征的分子靶标。研究结果将填补我国该领域空白，对该类群线虫的分子分类及系统学、有害生物风险评估及检验检疫部门针对性的采取相应的预警和检疫有重要的理论意义和直接的应用价值。

Nematodes in Xiphinema americanum group is a gorup of important ecto-paraistes of plants, in which consist of some plant virus vectors.The group are world concerned by plant quarantine for a long period of time.In this study the gerogiphical species and populations in the group will be sampled from different bio-type regions of China. Morphological and molecular identification, including cloning and sequenceing of rDNA and mitochondrial COI gene, Localization of endosymbionts and co-evolution within the X.americanum group species and populations, will be made. To characterize the major Xihinema americanum group species and populations occurring in China, morphological variations of inter- and intro-species populations, rDNA and mitochondrial COI characters,and the phylogeny relation of the species , specific and co-evolution of endosymbionets with the Xiphimena americanum group species and populations will be confirmed. Based on screening the speices specific molecular markers, a stand species-specific molecular identification method for the important Xiphinema americanum group species will be constrcuted. The research results will provided some new data, and it will be very helpful and usful for molecular identification and taxonomy of plant parasitic nematodes, pest risk analysis, and proper intergreted management methods to the plant quarantine, agriculture and forestry departments in China.