title: Cyanogenic pseudomonads influence multitrophic interactions in the rhizosphere.
abstract: In the rhizosphere, plant roots cope with both pathogenic and beneficial bacterial interactions. The exometabolite production in certain bacterial species may regulate root growth and other root-microbe interactions in the rhizosphere. Here, we elucidated the role of cyanide production in pseudomonad virulence affecting plant root growth and other rhizospheric processes. Exposure of Arabidopsis thaliana Col-0 seedlings to both direct (with KCN) and indirect forms of cyanide from different pseudomonad strains caused significant inhibition of primary root growth. Further, we report that this growth inhibition was caused by the suppression of an auxin responsive gene, specifically at the root tip region by pseudomonad cyanogenesis. Additionally, pseudomonad cyanogenesis also affected other beneficial rhizospheric processes such as Bacillus subtilis colonization by biofilm formation on A. thaliana Col-0 roots. The effect of cyanogenesis on B. subtilis biofilm formation was further established by the down regulation of important B. subtilis biofilm operons epsA and yqxM. Our results show, the functional significance of pseudomonad cyanogenesis in regulating multitrophic rhizospheric interactions.
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware, United States of America.
authors.forename: Thimmaraju
authors.initials: T
authors.lastname: Rudrappa
authors.forename: Robert E
authors.initials: RE
authors.lastname: Splaine
authors.forename: Meredith L
authors.initials: ML
authors.lastname: Biedrzycki
authors.forename: Harsh P
authors.initials: HP
authors.lastname: Bais
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000382:microbiology*; D001412:Bacillus subtilis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018441:Biofilms / Q000187:drug effects; D015169:Colony Count, Microbial; D003486:Cyanides / Q000378:metabolism* / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D006790:Host-Parasite Interactions / Q000187:drug effects; D007210:Indoleacetic Acids / Q000494:pharmacology; D007700:Kinetics; D009876:Operon / Q000235:genetics; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000382:microbiology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011551:Pseudomonas fluorescens / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D036226:Seedlings / Q000187:drug effects / Q000382:microbiology; D014158:Transcription, Genetic / Q000187:drug effects; D001617:beta-Glucosidase / Q000378:metabolism
chemical_list: D003486:Cyanides; D007210:Indoleacetic Acids; D001617:beta-Glucosidase