title: Transkingdom signaling based on bacterial cyclodipeptides with auxin activity in plants.
abstract: Microorganisms and their hosts communicate with each other through an array of signals. The plant hormone auxin (indole-3-acetic acid; IAA) is central in many aspects of plant development. Cyclodipeptides and their derivative diketopiperazines (DKPs) constitute a large class of small molecules synthesized by microorganisms with diverse and noteworthy activities. Here, we present genetic, chemical, and plant-growth data showing that in Pseudomonas aeruginosa, the LasI quorum-sensing (QS) system controls the production of three DKPs--namely, cyclo(L-Pro-L-Val), cyclo(L-Pro-L-Phe), and cyclo(L-Pro-L-Tyr)--that are involved in plant growth promotion by this bacterium. Analysis of all three bacterial DKPs in Arabidopsis thaliana seedlings provided detailed information indicative of an auxin-like activity, based on their efficacy at modulating root architecture, activation of auxin-regulated gene expression, and response of auxin-signaling mutants tir1, tir1 afb2 afb3, arf7, arf19, and arf7arf19. The observation that QS-regulated bacterial production of DKPs modulates auxin signaling and plant growth promotion establishes an important function for DKPs mediating prokaryote/eukaryote transkingdom signaling.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, CP 58030 Morelia, Michoacán, Mexico.
authors.forename: Randy
authors.initials: R
authors.lastname: Ortiz-Castro
authors.forename: César
authors.initials: C
authors.lastname: Díaz-Pérez
authors.forename: Miguel
authors.initials: M
authors.lastname: Martínez-Trujillo
authors.forename: Rosa E
authors.initials: RE
authors.lastname: del Río
authors.forename: Jesús
authors.initials: J
authors.lastname: Campos-García
authors.forename: José
authors.initials: J
authors.lastname: López-Bucio
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000378:metabolism*; D009154:Mutation; D010456:Peptides, Cyclic / Q000737:chemistry / Q000494:pharmacology; D011550:Pseudomonas aeruginosa / Q000737:chemistry*; D036226:Seedlings / Q000235:genetics / Q000254:growth & development*; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D007210:Indoleacetic Acids; D010456:Peptides, Cyclic