The T3SS is required for the virulence of many Gram-negative bacterial pathogens of plants and animals. This study focuses on the sensing and function of the T3SS protein HrpP during plant interactions. Our findings show that HrpP and its N-terminal truncation HrpP _1–119 can interact with MKK2, promote effector translocation, and manipulate plant immunity to facilitate bacterial infection, highlighting the P. syringae T3SS component involved in the fine-tuning of plant immunity.

Plant growth-promoting rhizobacterial strain FP607^T was isolated from the rhizosphere of beets in Wuhan, China. Strain FP607^T exhibited significant antagonism toward several phytopathogenic bacteria, indicating that FP607^T may produce antimicrobial metabolites and has a stronger biocontrol efficacy against plant pathogens. Growth-promoting tests showed that FP607^T produced indole-3-acetic acid (IAA), NH₃, and ferritin. The genome sequence of strain FP607^T was 6,590,972 bp long with 59.0% G + C content. The optimum temperature range was 25–30 °C, and the optimum pH was 7. The cells of strain FP607^T were Gram-negative, short, and rod-shaped, with polar flagella. The colonies on the King’s B (KB) agar plates were light yellow, smooth, and circular, with regular edges. A phylogenetic analysis of the 16S rRNA sequence and a multilocus sequence analysis (MLSA) showed that strain FP607^T was most closely related to the type of strain Pseudomonas farris SWRI79^T. Based on a polyphasic taxonomic approach, strain FP607^T was identified as a novel species within the genus Pseudomonas, for which the name Pseudomonas wuhanensis sp. nov. was proposed. The type of strain used was FP607^T (JCM 35688, CGMCC 27743, and ACCC 62446).

Three bacterial strains, FP250^T, FP821, and FP53, were isolated from the rhizosphere soil of oilseed rape, licorice, and habanero pepper in Anhui Province, Xinjiang Uygur Autonomous Region, and Jiangsu Province, PR China, respectively. All strains were shown to grow at 4–37 °C and pH 6.0–9.0, and in the presence of 0–4.0 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences or housekeeping genes (16S rRNA, gyrB, rpoB, and rpoD) and phylogenomic analysis showed that strains FP250^T, FP821, and FP53 belong to the genus Pseudomonas, and are closely related to Pseudomonas kilonensis DSM 13647^T, Pseudomonas brassicacearum JCM 11938^T, Pseudomonas viciae 11K1^T, and Pseudomonas thivervalensis DSM 13194^T. The DNA G+C content of strain FP205^T was 59.8 mol%. The average nucleotide identity and digital DNA–DNA hybridization values of strain FP205^T with the most closely related strain were 93.2 % and 51.4 %, respectively, which is well below the threshold for species differentiation. Strain FP205^T contained summed feature 3 (C_16 : 1  ω6c and/or C_16 : 1  ω7c), summed feature 8 (C_18 : 1  ω7c and/or C_18 : 1  ω6c) as major fatty acids, and diphosphatidylglycerol along with phosphatidylethanolamine and aminophospholipid as major polar lipids. The predominant isoprenoid quinone was ubiquinone-9. Based on these phenotypic, phylogenetic, and chemotaxonomic results, strain FP205^T represents a novel species of the genus Pseudomonas, for which the name Pseudomonas hefeiensis sp. nov. is proposed. The type strain is FP205^T (=ACCC 62447^T=JCM 35687^T).

Plant growth-promoting Pseudomonas bacteria are promising biocontrol agents whose regulatory and effector genes shape bacterial traits involved in interact