Transcriptional response of Pseudomonas aeruginosa to a phosphate-deficient Lolium perenne rhizosphere
- 557 Downloads
Background and aims
Plant-bacterial interactions in the rhizosphere are important in mediating soil nutrient transformations. Plants supply carbon-rich substrates to rhizobacteria as root exudates and bacteria mobilise soil-bound phosphate for plant nutrition. This study aimed to probe the specificity of the plant effect on bacterial gene expression in P-starved rhizosphere conditions.
DNA microarrays were employed to study gene expression in the rhizosphere of Lolium perenne grown under high and low phosphate regimes (330 μM vs. 3–6 μM phosphate). Root exudation under these regimes was also quantified. Phosphate-regulated gene expression of a panel of 22 genes was compared in rhizosphere, planktonic culture and during biofilm growth on an artificial root.
Plant growth and root exudation were affected by P-availability. P-limited conditions induced increased expression of bacterial genes of an aromatic degradation pathway (catA), heavy metal sensing (PA2523), and membrane proteins (glpM, crcB), while genes involved in cell motility and amino acid uptake/ metabolism were downregulated. A crcB mutant was impaired in rhizosphere survival under low phosphate conditions, though glpM and catA mutants were not affected. Several of the genes studied were induced by phosphate limitation in all three lifestyles studied.
Our results show the importance of the plant-microbe interaction in controlling the bacterial transcriptional response in a phosphate-limited rhizosphere.
KeywordsRhizosphere Phosphate deficiency Pseudomonas Perennial ryegrass Transcriptome Biofilm
This work was supported by the Natural Environment Research Council (NERC) and by a CASE studentship to AZ sponsored by the Biotechnology and Biological Sciences Research Council (BBSRC) and Macaulay Enterprises Ltd.
- Barret M, Frey-Klett P, Guillerm-Erckelboudt AY, Boutin M, Guernec G, Sarniguet A (2009) Effect of wheat roots infected with the pathogenic fungus Gaeumannomyces graminis var. tritici on gene expression of the biocontrol bacterium Pseudomonas fluorescens Pf29Arp. Mol Plant-Microbe Interact 22:1611–1623PubMedCrossRefGoogle Scholar
- Becker A, Berges H, Krol E, Bruand C, Ruberg S, Capela D, Lauber E, Meilhoc E, Ampe F, de Bruijn FJ, Fourment J, Francez-Charlot A, Kahn D, Kuster H, Liebe C, Puhler A, Weidner S, Batut J (2004) Global changes in gene expression in Sinorhizobium meliloti 1021 under microoxic and symbiotic conditions. Mol Plant-Microbe Interact 17:292–303PubMedCrossRefGoogle Scholar
- Buchan A, Crombie B, Alexandre GM (2011) Temporal dynamics and genetic diversity of chemotactic-competent microbial populations in the rhizosphere. Environ Microbiol Rep 12:3171–3184Google Scholar
- Fraud S, Campigotto AJ, Chen Z, Poole K (2008) MexCD-OprJ multidrug efflux system of Pseudomonas aeruginosa: involvement in chlorhexidine resistance and induction by membrane-damaging agents dependent upon the AlgU stress response sigma factor. Antimicrob Agents Chemother 52:4478–4482PubMedCrossRefGoogle Scholar
- Iswandi A, Bossier P, Vandenabeele J, Verstraete W (1987) Influence of the inoculation density of the rhizopseudomonad strain 7NSK2 on the growth and the composition of the root microbial community of maize (Zea mays) and barley (Hordeum vulgare). Biol Fertil Soils 4:119–123Google Scholar
- Lane DJ (1991) 16S/23S rRNA sequencing. In: Stackebrandt E, Goodefellow M (eds) Nucleic acid techniques in bacterial systematics. John Wiley & Sons, Chichester, United Kingdom, pp 115–175Google Scholar
- Mark GL, Dow JM, Kiely PD, Higgins H, Haynes J, Baysse C, Abbas A, Foley T, Franks A, Morrissey J, O’Gara F (2005) Transcriptome profiling of bacterial responses to root exudates identifies genes involved in microbe-plant interactions. Proc Natl Acad Sci USA 102:17454–17459PubMedCrossRefGoogle Scholar
- Misson J, Raghothama KG, Jain A, Jouhet J, Block MA, Bligny R, Ortet P, Creff A, Somerville S, Rolland N, Doumas P, Nacry P, Herrerra-Estrella L, Nussaume L, Thibaud MC (2005) A genome-wide transcriptional analysis using Arabidopsis thaliana Affymetrix gene chips determined plant responses to phosphate deprivation. Proc Natl Acad Sci USA 102:11934–11939PubMedCrossRefGoogle Scholar
- Richardson AE (2001) Prospects for using soil microorganisms to improve the acquisition of phosphorus by plants. Aust J Plant Physiol 28:897–906Google Scholar
- Ruffel S, Freixes S, Balzergue S, Tillard P, Jeudy C, Martin-Magniette ML, van der Merwe MJ, Kakar K, Gouzy J, Fernie AR, Udvardi M, Salon C, Gojon A, Lepetit M (2008) Systemic signaling of the plant nitrogen status triggers specific transcriptome responses depending on the nitrogen source in Medicago truncatula. Plant Physiol 146:2020–2035PubMedCrossRefGoogle Scholar
- Smyth GK (2004) Linear models and empirical Bayes for assessing differential expression in microarray experiments. Stat Appl Genet Mol Biol 3: Article 3Google Scholar