Departamento de Protección Vegetal, Laboratorio Bacteriología, Instituto Nacional de Investigación y Tecnología Agraria (INIA), Madrid, Spain.
Centro de Investigación de Biocombustibles y Bioproductos, Instituto Tecnológico Agrario de Castilla y León (ITACyL), Villarejo de Órbigo, Leon, Spain.
PLoS One. 2019 Jul 18;14(7):e0219797. doi: 10.1371/journal.pone.0219797. eCollection 2019.
Comparative studies in Xanthomonas have provided a vast amount of data that enabled to deepen in the knowledge of those factors associated with virulence and Xanthomonas plant interaction. The species of this genus present a wide range of host plants and a large number of studies have been focused to elucidate which mechanism are involved in this characteristic. In this study, comparative genomic and phenotypic analysis were performed between X. citri subsp. citri (Xcc), one of the most studied pathogens within Xanthomonas, and X. arboricola pv. pruni (Xap), a pathogen which has aroused great interest in recent time. The work was aimed to find those elements that contribute to their host divergence despite the convergence in the symptoms that each species cause on Citrus spp. and Prunus spp., respectively. This study reveals a set of genes that could be putatively associated with the adaptation of these pathogens to their hosts, being the most remarkable those involved in environmental sensing systems such as the case of the TonB-dependent transporters, the sensors of the two-component system and the methyl accepting chemotaxis proteins. Other important variants were found in processes related to the decomposition of the cell wall as could be appreciated by their dissimilar set of cell-wall degrading enzymes. Type three effectors, as one of the most important factors in delineating the host specificity in Xanthomonas, also showed a different array when comparing both species, being some of them unique to each pathogen. On the other hand, only small variations could be connected to other features such as the motility appendages and surface adhesion proteins, but these differences were accompanied by a dissimilar capacity to attach on host and non-host leaf surface. The molecular factors found in this work provide the basis to perform a more in-depth functional analyses that unveil those actual factors associated with pathogenesis and host specificity in Xcc and Xap.
比较研究表明，黄单胞菌属的某些因素与毒性和黄单胞菌与植物互作有关，为深入了解这些因素提供了大量的数据。该属的物种有广泛的宿主植物，许多研究集中在阐明哪些机制参与了这一特性。在这项研究中，对柑橘溃疡病菌（Xcc）和李树溃疡病菌（Xap）进行了比较基因组学和表型分析。Xcc 是黄单胞菌属中研究最多的病原体之一，而 Xap 是近年来引起极大兴趣的病原体。这项工作旨在寻找导致它们宿主分化的元素，尽管它们在各自引起的柑橘和李属植物症状上存在趋同。本研究揭示了一组可能与这些病原体适应宿主相关的基因，最显著的是那些涉及环境感应系统的基因，如 TonB 依赖性转运体、双组分系统传感器和甲基接受趋化蛋白。还发现了与细胞壁分解过程相关的重要变体，这可以从它们不同的细胞壁降解酶组中得到证实。III 型效应子是黄单胞菌属中决定宿主特异性的最重要因素之一，在比较这两个物种时，也显示出不同的排列，其中一些是每个病原体所特有的。另一方面，只有一些小的差异与其他特征有关，如运动附属物和表面黏附蛋白，但这些差异伴随着在宿主和非宿主叶片表面附着能力的不同。这项工作中发现的分子因素为进行更深入的功能分析提供了基础，这些分析揭示了与 Xcc 和 Xap 发病机制和宿主特异性相关的实际因素。
