Phenazine-producing Pseudomonas spp. in the rhizosphere

假单胞菌是需氧的革兰氏阴性细菌，普遍存在于土壤中。它们特别适合于植物根部定殖，并且许多植物有益的菌株通过各种机制（包括寄生作用）显示出对植物病原体的生物防治活性。在由对植物有益的假单胞菌属产生的各种抗生素中，吩嗪显示出广谱抗微生物活性。不同的吩嗪衍生物已被证明在各种植物系统中的几种病原体的生物防治中起着至关重要的作用，以及参与根际能力（即定殖根际的能力）和根际生物膜的形成。植物有益假单胞菌属具有大的基因组，其显示嵌合结构，其中基因在核心基因组和辅助基因组之间分离，核心基因组负责基本细胞过程，辅助基因组通常为一个或几个菌株所独有，并且负责菌株之间观察到的变异性。植物有益假单胞菌的基因组多样性和可塑性。来自于它们的附属基因组最近，我们的实验室组装了世界上最大的收集植物有益的吩嗪生产假单胞菌。从18个国家分离的63种代表性生物的集合被选择来解释宿主植物和环境的巨大多样性，它们在世界范围内的分布，它们的分类多样性，以及产生的吩嗪衍生物的阵列。我们的实验室最近完成了它们基因组的测序和注释。这一独特的大型数据集将被用作本研究项目的起点。这项研究的主要目标是更好地表征和了解如何植物有益的吩嗪生产假单胞菌。影响根际生态，从而改善植物健康，并保护植物免受各种疾病的侵害。具体目标是：1）表征和比较世界范围内的植物有益的吩嗪生产假单胞菌的多样性。在基因组学和功能水平上。2)表征和对比植物有益的吩嗪生产假单胞菌的机制。抗细菌、卵菌和真菌植物病原体。3)确定植物有益的吩嗪生产假单胞菌属的关键遗传决定因素。更好地了解对植物有益的产吩嗪假单胞菌属的多样性、生态学和基因组学，以及涉及其根际能力和植物病原体生物防治的机制，以确保这些生物体中的一些作为生物杀虫剂的成功开发、配制和商业化。该研究计划将解决这一知识差距。

Pseudomonas spp. are aerobic, Gram-negative bacteria ubiquitously found in soils. They are particularly well suited for plant root colonization and many plant-beneficial strains display biocontrol activity against plant pathogens through various mechanisms, including antibiosis. Among the wide array of antibiotics produced by plant-beneficial Pseudomonas spp., phenazines display broad-spectrum antimicrobial activity. Different phenazine derivatives have been shown to play a crucial role in the biocontrol of several pathogens in various plant systems as well as being involved in rhizocompetence (i.e. the capacity to colonize the rhizosphere) and biofilm formation in the rhizosphere. Plant-beneficial Pseudomonas spp. possess a large genome which displays a mosaic structure with genes segregating between the core genome, responsible for essential cellular processes, and the accessory genome, often unique to one or few strains, and responsible for the variability observed among strains. The genomic diversity and plasticity of plant-beneficial Pseudomonas spp. come from their accessory genomes. Recently, our laboratory assembled the largest worldwide collection of plant-beneficial phenazine-producing Pseudomonas spp. A collection of 63 representative organisms isolated from 18 countries were chosen to account for the large diversity of host plants and environments from where they were isolated, their worldwide distribution, their taxonomical diversity, and the array of phenazine derivatives produced. The sequencing and annotation of their genomes has recently been completed by our laboratory. This unique large data set will be used as a starting point for this research project. The primary goal of this research is to better characterize and understand how plant-beneficial phenazine-producing Pseudomonas spp. influence the ecology of the rhizosphere, leading to improved plant health, and protection against various plant diseases. The specific goals are to: 1) Characterize and compare the worldwide diversity of plant-beneficial phenazine-producing Pseudomonas spp. at the genomics and functional levels. 2) Characterize and contrast the mechanisms employed by plant-beneficial phenazine-producing Pseudomonas spp. against bacterial, oomycete and fungal plant pathogens. 3) Identify key genetic determinants in plant-beneficial phenazine-producing Pseudomonas spp. involved in rhizocompetence.A better understanding of the diversity, ecology and genomics of plant-beneficial phenazine-producing Pseudomonas spp., as well as the mechanisms involved in their rhizocompetence and biocontrol of plant pathogens is required to ensure the successful development, formulation and commercialisation of some of these organisms as biopesticides. This research program will address this gap in knowledge.