start-ver=1.4 cd-journal=joma no-vol=40 cd-vols= no-issue=3 article-no= start-page=ME25019 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=2025 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Role of Formate Chemoreceptor in Pseudomonas syringae pv. tabaci 6605 in Tobacco Infection en-subtitle= kn-subtitle= en-abstract= kn-abstract=Chemotaxis is essential for infection by plant pathogenic bacteria. The causal agent of tobacco wildfire disease, Pseudomonas syringae pv. tabaci 6605 (Pta6605), is known to cause severe leaf disease and is highly motile. The requirement of chemotaxis for infection has been demonstrated through the inoculation of mutant strains lacking chemotaxis sensory component proteins. Pta6605 possesses 54 genes that encode chemoreceptors (known as methyl-accepting chemotaxis proteins, MCPs). Chemoreceptors are classified into several groups based on the type and localization of ligand-binding domains (LBD). Cache LBD-type chemoreceptors have been reported to recognize formate in several bacterial species. In the present study, we identified Cache_3 Cache_2 LBD-type Mcp26 encoded by Pta6605_RS00335 as a chemoreceptor for formate using a quantitative capillary assay, and named it McpF. Although the deletion mutant of mcpF (ΔmcpF) retained attraction to 1% yeast extract, its chemotactic response to formate was markedly reduced. Swimming and swarming motilities were also impaired in the mutant. To investigate the effects of McpF on bacterial virulence, we conducted inoculations on tobacco plants using several methods. The ΔmcpF mutant exhibited weaker virulence in flood and spray assays than wild-type and complemented strains, highlighting not only the involvement of McpF in formate recognition, but also its critical role in leaf entry during the early stages of infection. en-copyright= kn-copyright= en-aut-name=NguyenPhuoc Quy Thang en-aut-sei=Nguyen en-aut-mei=Phuoc Quy Thang kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=WatanabeYuta en-aut-sei=Watanabe en-aut-mei=Yuta kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=MatsuiHidenori en-aut-sei=Matsui en-aut-mei=Hidenori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=SakataNanami en-aut-sei=Sakata en-aut-mei=Nanami kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=NoutoshiYoshiteru en-aut-sei=Noutoshi en-aut-mei=Yoshiteru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=ToyodaKazuhiro en-aut-sei=Toyoda en-aut-mei=Kazuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=IchinoseYuki en-aut-sei=Ichinose en-aut-mei=Yuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= affil-num=1 en-affil=The Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=The Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=The Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=The Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=The Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=6 en-affil=The Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=7 en-affil=The Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= en-keyword=chemoreceptor kn-keyword=chemoreceptor en-keyword=formate kn-keyword=formate en-keyword=mcpF kn-keyword=mcpF en-keyword=Pseudomonas syringae kn-keyword=Pseudomonas syringae en-keyword=virulence kn-keyword=virulence END start-ver=1.4 cd-journal=joma no-vol=37 cd-vols= no-issue=1 article-no= start-page=ME21076 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=2022 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Identification of Aerotaxis Receptor Proteins Involved in Host Plant Infection by Pseudomonas syringae pv. tabaci 6605 en-subtitle= kn-subtitle= en-abstract= kn-abstract=Pseudomonas syringae pv. tabaci 6605 (Pta6605) is a foliar plant pathogen that causes wildfire disease on tobacco plants. It requires chemotaxis to enter plants and establish infection. While chemotactic signals appear to be the main mechanism by which Pta6605 performs directional movement, the involvement of aerotaxis or energy taxis by this foliar pathogen is currently unknown. Based on domain structures and similarity with more than 50 previously identified putative methyl-accepting chemotaxis proteins (MCPs), the genome of Pta6605 encodes three potential aerotaxis transducers. We identified AerA as the main aerotaxis transducer and found that it possesses a taxis-to-serine-and-repellent (Tsr)-like domain structure that supports a periplasmic 4HB-type ligand-binding domain (LBD). The secondary aerotaxis transducer, AerB, possesses a cytosolic PAS-type LBD, similar to the Aer of Escherichia coli and Pseudomonas aeruginosa. Aerotaxis ability by single and double mutant strains of aerA and aerB was weaker than that by wild-type Pta6605. On the other hand, another cytosolic PAS-type LBD containing MCP did not make a major contribution to Pta6605 aerotaxis in our assay system. Furthermore, mutations in aerotaxis transducer genes did not affect surface motility or chemotactic attraction to yeast extract. Single and double mutant strains of aerA and aerB showed less colonization in the early stage of host plant infection and lower biofilm production than wild-type Pta6605. These results demonstrate the presence of aerotaxis transducers and their contribution to host plant infection by Pta6605. en-copyright= kn-copyright= en-aut-name=TumewuStephany Angelia en-aut-sei=Tumewu en-aut-mei=Stephany Angelia kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=WatanabeYuta en-aut-sei=Watanabe en-aut-mei=Yuta kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=MatsuiHidenori en-aut-sei=Matsui en-aut-mei=Hidenori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=YamamotoMikihiro en-aut-sei=Yamamoto en-aut-mei=Mikihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=NoutoshiYoshiteru en-aut-sei=Noutoshi en-aut-mei=Yoshiteru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=ToyodaKazuhiro en-aut-sei=Toyoda en-aut-mei=Kazuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=IchinoseYuki en-aut-sei=Ichinose en-aut-mei=Yuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= affil-num=1 en-affil=Graduate School of Environmental and Life Science, Okayama University kn-affil= affil-num=2 en-affil=Faculty of Agriculture, Okayama University kn-affil= affil-num=3 en-affil=Faculty of Agriculture, Okayama University kn-affil= affil-num=4 en-affil=Faculty of Agriculture, Okayama University kn-affil= affil-num=5 en-affil=Graduate School of Environmental and Life Science, Okayama University kn-affil= affil-num=6 en-affil=Graduate School of Environmental and Life Science, Okayama University kn-affil= affil-num=7 en-affil=Graduate School of Environmental and Life Science, Okayama University kn-affil= en-keyword=aerotaxis kn-keyword=aerotaxis en-keyword=aeroreceptor kn-keyword=aeroreceptor en-keyword=MCP kn-keyword=MCP en-keyword=Pseudomonas syringae kn-keyword=Pseudomonas syringae en-keyword=virulence kn-keyword=virulence END start-ver=1.4 cd-journal=joma no-vol=35 cd-vols= no-issue=4 article-no= start-page=ME20114 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2020 dt-pub=2020 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Requirement of γ-Aminobutyric Acid Chemotaxis for Virulence of Pseudomonas syringae pv. tabaci 6605 en-subtitle= kn-subtitle= en-abstract= kn-abstract=γ-Aminobutyric acid (GABA) is a widely distributed non-proteinogenic amino acid that accumulates in plants under biotic and abiotic stress conditions. Recent studies suggested that GABA also functions as an intracellular signaling molecule in plants and in signals mediating interactions between plants and phytopathogenic bacteria. However, the molecular mechanisms underlying GABA responses to bacterial pathogens remain unknown. In the present study, a GABA receptor, named McpG, was conserved in the highly motile plant-pathogenic bacteria Pseudomonas syringae pv. tabaci 6605 (Pta6605). We generated a deletion mutant of McpG to further investigate its involvement in GABA chemotaxis using quantitative capillary and qualitative plate assays. The wild-type strain of Pta6605 was attracted to GABA, while the ΔmcpG mutant abolished chemotaxis to 10‍ ‍mM GABA. However, ΔmcpG retained chemotaxis to proteinogenic amino acids and succinic semialdehyde, a structural analog of GABA. Furthermore, ΔmcpG was unable to effectively induce disease on host tobacco plants in three plant inoculation assays: flood, dip, and infiltration inoculations. These results revealed that the GABA sensing of Pta6605 is important for the interaction of Pta6605 with its host tobacco plant. en-copyright= kn-copyright= en-aut-name=TumewuStephany Angelia en-aut-sei=Tumewu en-aut-mei=Stephany Angelia kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=MatsuiHidenori en-aut-sei=Matsui en-aut-mei=Hidenori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=YamamotoMikihiro en-aut-sei=Yamamoto en-aut-mei=Mikihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=NoutoshiYoshiteru en-aut-sei=Noutoshi en-aut-mei=Yoshiteru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=ToyodaKazuhiro en-aut-sei=Toyoda en-aut-mei=Kazuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=IchinoseYuki en-aut-sei=Ichinose en-aut-mei=Yuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil=Graduate School of Environmental and Life Science, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Environmental and Life Science, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Environmental and Life Science, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Environmental and Life Science, Okayama University kn-affil= affil-num=5 en-affil=Graduate School of Environmental and Life Science, Okayama University kn-affil= affil-num=6 en-affil=Graduate School of Environmental and Life Science, Okayama University kn-affil= en-keyword= bacterial virulence kn-keyword= bacterial virulence en-keyword=chemotaxis kn-keyword=chemotaxis en-keyword=GABA kn-keyword=GABA en-keyword=plant-microbe interaction kn-keyword=plant-microbe interaction en-keyword=Pseudomonas kn-keyword=Pseudomonas END