具有III型分泌系统的Pseudomonas moraviensis FP1761植物益生功能及其全基因组分析

 本研究从节瓜根际分离到一株具有防病促生功能的荧光类假单胞菌FP1761。该菌株对部分植物病原真菌和细菌具有拮抗能力,能够解钾、解有机磷和无机磷,可产生氨、蛋白酶、嗜铁素、吲哚乙酸。生物测定表明菌株FP1761可显著促进小麦生长。生理生化、平均核苷酸相似度、16S rDNA和多基因分析将FP1761鉴定为摩拉维亚假单胞菌(Pseudomonas moraviensis)。菌株FP1761基因组草图全长6.12 Mb,(G+C)含量为59.9%,共编码5467个基因序列。将该菌株与种内3个代表性菌株进行泛基因组和核心基因组分析,共产生 4 357个共有基因,菌株FP1761特有基因327个。利用antiSMASH对菌株次生代谢基因簇进行预测,发现其含有8个潜在的次生代谢产物基因簇。其中两个基因簇与嗜铁素pyoverdine合成相关,未见聚酮类合成基因。基因组分析发现,该菌株具有与病原性假单胞菌相似的III型分泌系统,但丢失了效应蛋白调控因子hrpS和转运相关的hrpH和hrpK1基因。对全基因组扫描,菌株FP1761仅保留了病原性假单胞菌的保守效应蛋白AvrE和HopAA1-1。FP1761是目前已发现的唯一具有III型分泌系统的摩拉维亚假单胞菌。本研究表明摩拉维亚假单胞菌FP1761具有潜在的植物防病促生功能,但其III型分泌系统与植物益生互作机制有待进一步解析。

Characterization of plant probiotic traits and whole-genome analysis of a type III secretion system harboring bacterium Pseudomonas moraviensis FP1761

A plant probiotic strain FP1761 was isolated from the rhizosphere of hairy gourd in Shenyang Province,China.It not only strongly antagonized against plant pathogenic fungi and phytobacteria but also showed multiply plant probiotic characters,such as solubilization of potassium,organic and inorganic phospho-rus,production of ammonia,protease,siderophore,and indole-3-acetic acid.Further tests showed that strain FP1761 significantly increased wheat growth in vivo.Strain FP1761 was identified as Pseudomonas moraviensis using physiological and biochemical characterization,average nucleotide identity (ANI),16S rDNA and multi-locus sequence analysis.The draft genome of strain FP1761 contains 6.12 Mb with (G+C) content of 59.9%,which includes 5467 protein coding genes.Venn diagrams of the identified orthologous clusters of P.moraviensis FP1761 with another three sequenced P.moraviensis strains revealed up to 4357 homologous gene clusters are shared among them,and 327 orthologous clusters are only present in the genome of strain FP1761.Eight gene clusters for secondary metabolites were predicted using antiSMASH online pipeline,in which two non-ribosomal peptides (NPRSs) were proposed to encode pyoverdine,the typical siderophore possessed by fluorescent Pseudomonas.However,none polyketide synthase clusters (PKSs) were found from the FP1761 genome.A conserved type III secretion system (T3SS) gene cluster was identified from P.moraviensis FP1761,which is similar organizationally to that of pathogenic P.syringae,except that it lacks the regulator gene hrpS and the translocator genes hrpH and hrpK1.Genome scanning revealed that strain FP1761 retains only two pathogenic effector homologs AvrE and HopAA1-1.FP1761 is the only one strain of P.moraviensis having T3SS components to date.The results suggest that P.moraviensis FP1761 may be a novel plant growth-promoting agent whereas the interactions between the T3SS and planta need to be determined.