Pseudomonas fluorescens 2P24 is a plant growth-promoting rhizobacterium (PGPR) isolated from wheat take-all decline soil. Genomic analysis of strain 2P24 revealed the presence of a complete SPI-1 type III secretion system (T3SS) gene cluster on the chromosome with an organization and orientation similar to the SPI-1 T3SS gene clusters of Salmonella enterica and P. kilonensis F113. Phylogenetic analysis revealed that the SPI-1 T3SS gene cluster of strain 2P24 might be obtained from Salmonella and Shigella by horizontal gene transfer. Two transcriptional regulator homologs of HilA and InvF were found from the SPI-1 T3SS gene cluster of strain 2P24. HilA regulated the expression of the structural genes positively, such as invG, sipB, sipD, prgI, and prgK. Prediction of transcriptional binding sites and RNA-seq analysis revealed 14 genes were up-regulated by InvF in strain 2P24. Exploring potential roles of SPI-1 T3SS revealed that it was not associated with motility. However, 2P24ΔinvF reduced resistance against Fusarium graminearum significantly. 2P24ΔhilA enhanced formation of biofilm significantly at 48 h. All three mutants 2P24ΔhilA, 2P24ΔinvF, and 2P24ΔinvE-C reduced the chemotactic responses to glucose significantly. Finally, the determination of SPI-1 mutants to trigger innate immunity in Nicotiana benthamiana showed that 2P24ΔinvE-C reduced the ability to induce the production of reactive oxygen species compared with the wild type strain 2P24.

荧光假单胞菌2P24 是一种从小麦全麦衰退土壤中分离出来的植物促生长根际细菌 (PGPR)。菌株 2P24 的基因组分析显示染色体上存在完整的 SPI-1 III 型分泌系统 (T3SS) 基因簇，其组织和方向类似于 SPI-1 T3SS 基因簇沙门氏菌 和 昆曲F113。系统发育分析表明，菌株 2P24 的 SPI-1 T3SS 基因簇可能来自沙门氏菌 和 志贺氏菌通过水平基因转移。从菌株 2P24 的 SPI-1 T3SS 基因簇中发现了 HilA 和 InvF 的两个转录调节同源物。HilA 正调控结构基因的表达，如invG, SIPB, SIPD, 程序， 和 程序. 转录结合位点的预测和 RNA-seq 分析显示 14 个基因在菌株 2P24 中被 InvF 上调。探索 SPI-1 T3SS 的潜在作用表明它与运动无关。然而，2P24Δ输入法 抵抗力下降 禾谷镰刀菌显着地。2P24Δ希拉48 小时显着增强生物膜的形成。所有三个突变体 2P24Δ希拉, 2P24Δ输入法, 和 2P24ΔinvE-C显着降低对葡萄糖的趋化反应。最后，确定 SPI-1 突变体触发先天免疫本氏烟草 表明 2P24ΔinvE-C 与野生型菌株 2P24 相比，降低了诱导活性氧产生的能力。