PDF(Pubmed)
Abstract：
Plant-beneficial Pseudomonas bacteria hold the potential to be used as inoculants in agriculture to promote plant growth and health through various mechanisms. The discovery of new strains tailored to specific agricultural needs remains an open area of research. In this study, we report the isolation and characterization of four novel Pseudomonas species associated with the wheat rhizosphere. Comparative genomic analysis with all available Pseudomonas type strains revealed species-level differences, substantiated by both digital DNA-DNA hybridization and average nucleotide identity, underscoring their status as novel species. This was further validated by the phenotypic differences observed when compared to their closest relatives. Three of the novel species belong to the P. fluorescens species complex, with two representing a novel lineage in the Pseudomonas phylogeny. Functional genome annotation revealed the presence of specific features contributing to rhizosphere colonization, including flagella and components for biofilm formation. The novel species have the genetic potential to solubilize nutrients by acidifying the environment, releasing alkaline phosphatases and their metabolism of nitrogen species, indicating potential as biofertilizers. Additionally, the novel species possess traits that may facilitate direct promotion of plant growth through the modulation of the plant hormone balance, including the ACC deaminase enzyme and auxin metabolism. The presence of biosynthetic clusters for toxins such as hydrogen cyanide and non-ribosomal peptides suggests their ability to compete with other microorganisms, including plant pathogens. Direct inoculation of wheat roots significantly enhanced plant growth, with two strains doubling shoot biomass. Three of the strains effectively antagonized fungal phytopathogens (Thielaviopsis basicola, Fusarium oxysporum, and Botrytis cinerea), demonstrating their potential as biocontrol agents. Based on the observed genetic and phenotypic differences from closely related species, we propose the following names for the four novel species: Pseudomonas grandcourensis sp. nov., type strain DGS24T ( = DSM 117501T = CECT 31011T), Pseudomonas purpurea sp. nov., type strain DGS26T ( = DSM 117502T = CECT 31012T), Pseudomonas helvetica sp. nov., type strain DGS28T ( = DSM 117503T = CECT 31013T) and Pseudomonas aestiva sp. nov., type strain DGS32T ( = DSM 117504T = CECT 31014T).
摘要：
对植物有益的假单胞菌细菌具有在农业中用作接种剂的潜力，可以通过各种机制促进植物生长和健康。发现适合特定农业需求的新菌株仍然是一个开放的研究领域。在这项研究中,我们报告了与小麦根际相关的四种新型假单胞菌属物种的分离和表征。与所有可用的假单胞菌型菌株的比较基因组分析揭示了物种水平差异，由数字DNA-DNA杂交和平均核苷酸同一性证实，强调它们作为新物种的地位。当与它们的近亲相比时观察到的表型差异进一步证实了这一点。三个新物种属于荧光假单胞菌物种复合物，其中两个代表假单胞菌系统发育中的新谱系。功能基因组注释揭示了有助于根际定植的特定特征的存在，包括鞭毛和生物膜形成的成分。这种新物种具有通过酸化环境来溶解营养物质的遗传潜力，释放碱性磷酸酶及其氮物种的代谢，表明作为生物肥料的潜力。此外,新物种具有通过调节植物激素平衡可以促进直接促进植物生长的性状，包括ACC脱氨酶酶和生长素代谢。毒素如氰化氢和非核糖体肽的生物合成簇的存在表明它们能够与其他微生物竞争，包括植物病原体。直接接种小麦根系显著促进了植物生长，两个菌株的芽生物量加倍。其中三个菌株有效地拮抗了真菌植物病原体（Thielaviopsisbasicola，尖孢镰刀菌,和灰葡萄孢)，证明了它们作为生物防治剂的潜力。根据观察到的遗传和表型差异密切相关的物种，我们为这四个新物种提出了以下名称：绿脓杆菌。11月。,型应变DGS24T(=DSM117501T=CECT31011T),紫菜假单胞菌。11月。,型应变DGS26T(=DSM117502T=CECT31012T),蠕虫假单胞菌。11月。,型菌株DGS28T（=DSM117503T=CECT31013T）和假单胞菌。11月。,型菌株DGS32T(=DSM117504T=CECT31014T)。
