start-ver=1.4 cd-journal=joma no-vol=26 cd-vols= no-issue=11 article-no= start-page=e70168 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=202511 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Comparative Genomic Analysis Identifies FleQ and GcbB as Virulence-Associated Factors in Pseudomonas syringae pv. tabaci Strains en-subtitle= kn-subtitle= en-abstract= kn-abstract=Pseudomonas syringae pv. tabaci (Pta) is an important plant pathogen, which causes wildfire disease in Nicotiana species. However, the genetic basis underlying strain-level differences in virulence remains largely unresolved. To address this, we performed a comparative genomic analysis between a highly virulent strain Pta6605 and a less virulent strain Pta7375. Despite high overall genome similarity, we identified key single-nucleotide polymorphisms, including premature stop-codon mutations in seven open reading frames in Pta7375. Notably, point mutations in two regulatory genes, such as fleQ, which encodes a transcription factor essential for flagellar biogenesis and biofilm formation, and gcbB, which encodes a GGDEF domain-containing diguanylate cyclase responsible for cyclic dimeric guanosine monophosphate (c-di-GMP) synthesis, were implicated in virulence disparity. Functional analyses using deletion and locus replacement mutants in the Pta6605 background revealed that the disruption of fleQ markedly reduced motility, flagellin production, c-di-GMP accumulation, biofilm formation and virulence level mirroring the Pta7375 phenotype. The gcbB replacement mutant showed reduced disease symptom development, although c-di-GMP levels remained comparable to the Pta6605 wild type. Locus replacement between strains confirmed that a point mutation in fleQ was the primary driver of reduced motility and flagellin expression in Pta7375. These findings indicate that the reduced virulence of Pta7375 is associated with impaired regulation of flagella-related genes and disruption of the FleQ-mediated c-di-GMP signalling, underscoring the value of comparative genomics in disentangling the complex regulatory networks that govern virulence in plant pathogens. en-copyright= kn-copyright= en-aut-name=HidayatMuhammad Taufiq en-aut-sei=Hidayat en-aut-mei=Muhammad Taufiq kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=YoshiokaKei en-aut-sei=Yoshioka en-aut-mei=Kei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=NishimuraTakafumi en-aut-sei=Nishimura en-aut-mei=Takafumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=AsaiShuta en-aut-sei=Asai en-aut-mei=Shuta kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=MasudaSachiko en-aut-sei=Masuda en-aut-mei=Sachiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=ShirasuKen en-aut-sei=Shirasu en-aut-mei=Ken kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 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=7 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=8 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=9 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=10 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=11 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=12 ORCID= affil-num=1 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Faculty of Agriculture, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Center for Sustainable Resource Science, RIKEN-TRIP kn-affil= affil-num=6 en-affil=Center for Sustainable Resource Science, RIKEN-TRIP kn-affil= affil-num=7 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=8 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=9 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=10 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=11 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=12 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= en-keyword=comparative genomics kn-keyword=comparative genomics en-keyword=cyclic-di- GMP kn-keyword=cyclic-di- GMP en-keyword=fleQ kn-keyword=fleQ en-keyword=gcbB kn-keyword=gcbB en-keyword=Pseudomonas syringae kn-keyword=Pseudomonas syringae END