Phenazine-producing Pseudomonas spp. in the rhizosphere

假单胞菌属是土壤中普遍存在的需氧的革兰氏阴性细菌。它们特别适合于植物的根部定植，许多对植物有益的菌株通过包括抗生素在内的各种机制对植物病原菌表现出生物防治活性。在对植物有益的假单胞菌产生的多种抗生素中，吩嗪类化合物显示出广谱的抗菌活性。不同的吩嗪类化合物已被证明在不同植物系统中对几种病原菌的生物防治以及参与根际能力(即根际定植能力)和根际生物膜的形成起着至关重要的作用。*植物益生型假单胞菌拥有一个大基因组，呈现镶嵌结构，基因分离在负责基本细胞过程的核心基因组和附属基因组之间，通常是一个或几个菌株所独有的，并负责在菌株之间观察到的变异性。植物益生型假单胞菌的基因组多样性和可塑性来自它们的附属基因组。最近，我们的实验室收集了世界上最大的有益于植物生产吩嗪的假单胞菌。选择了从18个国家分离的63种代表性生物的集合，以说明它们所在的寄主植物和环境的巨大多样性、它们在世界各地的分布、它们的分类多样性以及产生的吩嗪衍生物的阵列。我们实验室最近已经完成了它们基因组的测序和注释。这一独特的大数据集将作为这一研究项目的起点。这项研究的主要目标是更好地表征和了解对植物有益的吩嗪产生假单胞菌是如何产生的。影响根际生态，改善植物健康，保护植物免受各种疾病侵袭。具体目标是：*1)表征和比较有益于植物生产吩嗪的假单胞菌的全球多样性。在基因组学和功能层面上。*2)对植物有益的产吩嗪假单胞菌的作用机制进行表征和对比。抗细菌、卵菌和真菌植物病原体。*3)确定有益于植物生产吩嗪的假单胞菌的关键遗传决定因素。*需要更好地了解产生吩嗪的有益植物假单胞菌的多样性、生态学和基因组学，以及它们对植物病原菌的生根能力和生防机制，以确保其中一些生物作为生物杀虫剂的成功开发、配制和商业化。这项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.**