Response of Arabidopsis thaliana to N-hexanoyl-dl-homoserine-lactone, a bacterial quorum sensing molecule produced in the rhizosphere

Abstract

The bacterial quorum sensing signals N-acyl-L: -homoserine lactones enable bacterial cells to regulate gene expression depending on population density, in order to undertake collective actions such as the infection of host cells. Only little is known about the molecular ways of plants reacting to these bacterial signals. In this study we show that the contact of Arabidopsis thaliana roots with N-hexanoyl-DL: -homoserine-lactone (C6-HSL) resulted in distinct transcriptional changes in roots and shoots, respectively. Interestingly, unlike most other bacterial signals, C6-HSL influenced only a few defense-related transcripts. Instead, several genes associated with cell growth as well as genes regulated by growth hormones showed changes in their expression after C6-HSL treatment. C6-HSL did not induce plant systemic resistance against Pseudomonas syringae. The inoculation of roots with different types of AHLs led predominantly for short chain N-butyryl-DL: -homoserine lactone and C6-HSL to root elongation. Determination of plant hormone concentrations in root and shoot tissues supported alterations of auxin to cytokinin ratio. Finally, we provide evidence that Arabidopsis takes up bacterial C6-HSL and allows systemic distribution throughout the plant. In sum, the bacterial quorum sensing signal C6-HSL does induce transcriptional changes in Arabidopsis and may contribute to tuning plant growth to the microbial composition of the rhizosphere.

N-3-Oxo-Decanoyl-l-Homoserine-Lactone Activates Auxin-Induced Adventitious Root Formation via Hydrogen Peroxide- and Nitric Oxide-Dependent Cyclic GMP Signaling in Mung Bean

“…These results add further support to the observation that the structure of branched chains in the AHL family affects the auxin transport. These data also help explain why 3-O-C10-HL activated auxin-regulated gene expression in Medicago (Mathesius et al, 2003) and why C10-HL showed an auxin-independent effect on inducing lateral root development in Arabidopsis (Ortíz-Castro et al, 2008;von Rad et al, 2008;Shi et al, 2010), where it is likely that the presence or absence of the C3 branch chain differentiates between these two responses.…”

“…Recently, more evidence demonstrate that AHLs are able to modulate plant growth and development (Mathesius et al, 2003;Ortíz-Castro et al, 2008;von Rad et al, 2008;Méndez-Bravo et al, 2010;MorquechoContreras et al, 2010). In Arabidopsis, treatment with AHLs alters primary growth, lateral root formation, and root hair development; specifically, AHLs with different lengths of unmodified branched chains differentially affect the root architecture.…”

“…Recent evidence indicates that plants are able to perceive AHLs; the application of AHLs to Arabidopsis or Medicago truncatula results in distinct transcriptional changes in the roots and shoots and affects primary root growth, lateral root formation, and root hair development (Mathesius et al, 2003;Ortíz-Castro et al, 2008;von Rad et al, 2008;Morquecho-Contreras et al, 2010). Similar to the structure of AHLs, the fatty acid amides, including N-acyl-ethanolamines (NAEs) and alkamides in plants, are also capable of regulating root and shoot architecture (Laxalt and Munnik, 2002;Campos-Cuevas et al, 2008;Morquecho-Contreras et al, 2010), and the Arabidopsis recessive mutant decanamide-resistant root1 (drr1) was isolated based on its continuous primary root and reduced lateral root formation in response to decanamide (an alkamide) or AHLs (Morquecho-Contreras et al, 2010).…”

Future research trends in the major chemical language of bacteria

“…More precisely, experiments with Serratia liquefaciens, a strain that is capable of protecting plants against fungal pathogens, showed that AHL production in the rhizosphere of tomato plant roots was responsible for increasing systemic resistance against the fungal leaf pathogen Alternaria alternata . In another study, the response of the model plant Arabidopsis thaliana to different AHLs was investigated via microarray analysis (von Rad et al, 2008). It was established that AHLs are taken up by A. thaliana and are distributed throughout the plant and that they cause distinct changes in transcription profile in roots and shoots.…”

Enhancement of the expression of defense genes in tomato against Ralstonia solanacearum by N-octanoyl-L-homoserine lactone

“…Similar to AHL molecules produced by bacteria, commercially available pure AHL molecules also induce priming. The transport of AHLs within plants has been studied initially in Barley and Arabidopsis (Gotz et al, 2007;von Rad et al, 2008) by using radioactive labelled AHLs. Mathesius et al (2003) observed that the legume plant, Medicago truncatula are able to respond to nanomolar concentrations of synthetic and purified AHLs and these compounds elicit major changes in protein expression.…”