Journal Article

Comparison of Rhizosphere Bacterial Communities in Arabidopsis thaliana Mutants for Systemic Acquired Resistance

Hein, John W., Wolfe, Gordon V., Blee, Kristopher A.

2008

Overview

Systemic acquired resistance (SAR) is an inducible systemic plant defense against a broad spectrum of plant pathogens, with the potential to secrete antimicrobial compounds into the soil. However, its impact on rhizosphere bacteria is not known. In this study, we examined fingerprints of bacterial communities in the rhizosphere of the model plant Arabidopsis thaliana to determine the effect of SAR on bacterial community structure and diversity. We compared Arabidopsis mutants that are constitutive and non-inducible for SAR and verified SAR activation by measuring pathogenesis-related protein activity via a β-glucoronidase (GUS) reporter construct driven by the β-1-3 glucanase promoter. We used terminal restriction fragment length polymorphism (T-RFLP) analysis of MspI- and HaeIII-digested 16S rDNA to estimate bacterial rhizosphere community diversity, with Lactobacillus sp. added as internal controls. T-RFLP analysis showed a clear rhizosphere effect on community structure, and diversity analysis of both rhizosphere and bulk soil operational taxonomic units (as defined by terminal restriction fragments) using richness, Shannon-Weiner, and Simpson's diversity indices and evenness confirmed that the presence of Arabidopsis roots significantly altered bacterial communities. This effect of altered soil microbial community structure by plants was also seen upon multivariate cluster analysis of the terminal restriction fragments. We also found visible differences in the rhizosphere community fingerprints of different Arabidopsis SAR mutants; however, there was no clear decrease of rhizosphere diversity because of constitutive SAR expression. Our study suggests that SAR can alter rhizosphere bacterial communities, opening the door to further understanding and application of inducible plant defense as a driving force in structuring soil bacterial assemblages.

• Publisher: New York : Springer-Verlag,Springer Science + Business Media, Inc,Springer-Verlag,Springer,Springer Nature B.V
• Subject: Acid soils / Agricultural soils / anti-infective agents / Arabidopsis / Arabidopsis - genetics / Arabidopsis - microbiology / Arabidopsis - physiology / Arabidopsis Proteins / Arabidopsis Proteins - genetics / Arabidopsis Proteins - metabolism / Arabidopsis thaliana / Bacteria / Bacteria - classification / Bacteria - isolation & purification / bacterial communities / Biodiversity / Biological and medical sciences / Biomedical and Life Sciences / classification / Cluster analysis / Community composition / Community structure / Defense mechanisms / Diversity indices / Ecology / Fingerprints / Fragments / Fundamental and applied biological sciences. Psychology / gene expression / Genes, Reporter / genetics / Genotypes / Geoecology/Natural Processes / Glucan Endo-1,3-beta-D-Glucosidase / Glucan Endo-1,3-beta-D-Glucosidase - genetics / Glucan Endo-1,3-beta-D-Glucosidase - metabolism / isolation & purification / Lactobacillus / Life Sciences / metabolism / Microbial Ecology / Microbiology / Microorganisms / multivariate analysis / Mutants / Mutation / Nature Conservation / Original Article / Pathogenesis / pathogenesis-related proteins / physiology / plant communities / plant pathogens / Plant roots / Plants / Polymorphism / Polymorphism, Restriction Fragment Length / Restriction fragment length polymorphism / Rhizome / Rhizome - microbiology / Rhizosphere / rhizosphere bacteria / ribosomal DNA / rRNA 16S / Seeds / Seeds - microbiology / Soil / Soil bacteria / Soil Microbiology / Soil microorganisms / Soil samples / soil structure / Soil treatment / Species diversity / systemic acquired resistance / Water Quality/Water Pollution