Transkingdom signaling based on bacterial cyclodipeptides with auxin activity in plants

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 108; no. 17; pp. 7253 - 7258
• Main Authors: Ortiz-Castro, Randy, Diaz-Perez, Cesar, Martinez-Trujillo, Miguel, del Rio, Rosa E, Campos-Garcia, Jesus, Lopez-Bucio, Jose
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 26.04.2011; National Acad Sciences
• Subjects: Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Auxins; Bacteria; Bacterial Proteins - chemistry; Bacterial Proteins - pharmacology; Biological Sciences; Data processing; diketopiperazines; eukaryotic cells; Flowers & plants; Gene expression; Gene expression regulation; growth promotion; Hormones; hosts; indole acetic acid; Indoleacetic Acids - metabolism; Microorganisms; Molecules; mutants; Mutation; Peptides; Peptides, Cyclic - chemistry; Peptides, Cyclic - pharmacology; Physiology; plant development; Plant growth; Plant growth regulators; Plant roots; Plants; Prokaryotes; prokaryotic cells; Pseudomonas aeruginosa; Pseudomonas aeruginosa - chemistry; quorum sensing; Root growth; Roots; Seedlings; Seedlings - genetics; Seedlings - growth & development; Signal Transduction - drug effects
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1006740108

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.