{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T13:43:33Z","timestamp":1792590213766,"version":"4.5.0"},"reference-count":33,"publisher":"American Society for Microbiology","issue":"10","license":[{"start":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T00:00:00Z","timestamp":1792540800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T00:00:00Z","timestamp":1792540800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["22KJ0057"],"award-info":[{"award-number":["22KJ0057"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["22H05068"],"award-info":[{"award-number":["22H05068"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["Appl Environ Microbiol"],"published-print":{"date-parts":[[2026,10,21]]},"abstract":"ABSTRACT<\/jats:title>\n \n \n \n Many plants and animals form specific symbioses with microorganisms, relying on bidirectional host\u2013bacteria interactions. However, knowledge about the evolution of symbiont traits enabling such specificity remains limited. The bean bug\n Riptortus pedestris<\/jats:italic>\n acquires\n Caballeronia<\/jats:italic>\n from environmental soil and harbors it in its gut symbiotic organ. This bug-\n Caballeronia<\/jats:italic>\n symbiosis is an ideal model to clarify the evolutionary process of symbiotic bacteria because members of outgroups, such as\n Paraburkholderia<\/jats:italic>\n and\n Pandoraea<\/jats:italic>\n , can also colonize the host symbiotic organ but are outcompeted when co-inoculated with the native symbiont,\n Caballeronia<\/jats:italic>\n . Here, we investigated mechanisms underlying the competitive performance of\n Caballeronia<\/jats:italic>\n within the insect gut. Spatial analyses revealed that wild-type\n Caballeronia<\/jats:italic>\n showed directional localization toward the symbiotic organ and colonized the M4 region faster than related bacteria. A\n cheA<\/jats:italic>\n insertion mutant exhibited delayed early colonization and reduced competitive performance in co-infection assays although both strains ultimately reached similar levels of crypt colonization. In addition, microscopic observations revealed strain-specific aggregation patterns within the symbiotic organ, providing additional insight into bacterial spatial organization during host colonization. Together, these findings suggest that chemotaxis accelerates early symbiotic organ colonization and enhances competitive performance during the initial stages of symbiont establishment. More broadly, our results highlight the importance of spatial and temporal dynamics in shaping host\u2013microbe associations and provide a framework for understanding how bacterial traits contribute to the evolution of symbiotic specificity.\n <\/jats:p>\n \n IMPORTANCE<\/jats:title>\n \n Riptortus pedestris<\/jats:italic>\n , a major soybean pest in East Asia, acquires symbiotic bacteria from the environment every generation, yet its gut is consistently and specifically colonized by\n Caballeronia<\/jats:italic>\n species. The evolutionary traits that underlie this strong symbiotic specificity remain poorly understood. Here, we demonstrate that chemotaxis accelerates early colonization of the symbiotic organ by\n Caballeronia<\/jats:italic>\n and enhances its competitive performance relative to closely related bacteria. Using comparative colonization assays with wild-type, chemotaxis-deficient mutants, closely related bacteria, and an out-group species, we show that chemotaxis contributes to competitive performance during the initial stages of symbiotic organ colonization. Our findings indicate that ecological and behavioral traits, including chemotaxis, contribute to the establishment of exclusive symbiotic associations, providing new insight into how symbiotic specificity may evolve in horizontally transmitted systems.\n <\/jats:p>\n <\/jats:sec>\n <\/jats:sec>","DOI":"10.1128\/aem.01364-26","type":"journal-article","created":{"date-parts":[[2026,9,14]],"date-time":"2026-09-14T13:01:16Z","timestamp":1789390876000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Chemotaxis promotes early colonization and microbiogeography of\n Caballeronia insecticola<\/i>\n in the gut symbiotic organ of\n Riptortus pedestris<\/i>"],"prefix":"10.1128","volume":"92","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8670-5858","authenticated-orcid":true,"given":"Kota","family":"Ishigami","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02z1n9q24","id-type":"ROR","asserted-by":"publisher"}],"name":"Faculty of Agriculture, University of the Ryukyus","place":["Ginowan, Japan"]},{"id":[{"id":"https:\/\/ror.org\/01703db54","id-type":"ROR","asserted-by":"publisher"}],"name":"Biomanufacturing Process Research Center, National Institute of Advanced Industrial Science and Technology (AIST)","place":["Sapporo, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5347-0872","authenticated-orcid":true,"given":"Antoine-Olivier","family":"Lirette","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/01703db54","id-type":"ROR","asserted-by":"publisher"}],"name":"Biomanufacturing Process Research Center, National Institute of 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Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1651-2532","authenticated-orcid":true,"given":"Yoshitomo","family":"Kikuchi","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/01703db54","id-type":"ROR","asserted-by":"publisher"}],"name":"Biomanufacturing Process Research Center, National Institute of Advanced Industrial Science and Technology (AIST)","place":["Sapporo, Japan"]},{"id":[{"id":"https:\/\/ror.org\/02e16g702","id-type":"ROR","asserted-by":"publisher"}],"name":"Graduate School of Agriculture, Hokkaido University","place":["Sapporo, 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