Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79410, USA; email:
Annu Rev Phytopathol. 2018 Aug 25;56:225-242. doi: 10.1146/annurev-phyto-080417-045824.
Some of the most agriculturally important plant-parasitic nematodes (PPNs) harbor endosymbionts. Extensive work in other systems has shown that endosymbionts can have major effects on host virulence and biology. This review highlights the discovery, development, and diversity of PPN endosymbionts, incorporating inferences from genomic data. Cardinium, reported from five PPN hosts to date, is characterized by its presence in the esophageal glands and other tissues, with a discontinuous distribution across populations, and genomic data suggestive of horizontal gene exchange. Xiphinematobacter occurs in at least 27 species of dagger nematode in the ovaries and gut epithelial cells, where genomic data suggest it may serve in nutritional supplementation. Wolbachia, reported in just three PPNs, appears to have an ancient history in the Pratylenchidae and displays broad tissue distribution and genomic features intermediate between parasitic and reproductive groups. Finally, a model is described that integrates these insights to explain patterns of endosymbiont replacement.
一些最重要的植物寄生线虫（PPNs）携带内共生体。其他系统的广泛研究表明，内共生体对宿主的毒力和生物学特性有重大影响。本综述重点介绍了 PPN 内共生体的发现、发展和多样性，并结合了基因组数据的推断。截至目前，已在五种 PPN 宿主中发现的卡多尼亚菌以其存在于食道腺和其他组织中为特征，在种群中呈不连续分布，基因组数据提示存在水平基因交换。Xiphinematobacter 至少存在于 27 种匕首线虫的卵巢和肠道上皮细胞中，基因组数据表明它可能在营养补充中发挥作用。仅在三种 PPN 中报道的沃尔巴克氏体在 Pratylenchidae 中似乎具有古老的历史，并且表现出广泛的组织分布和介于寄生和生殖群之间的基因组特征。最后，描述了一个模型，该模型整合了这些见解来解释内共生体替换的模式。
