Bacterial distribution in the rhizosphere of wild barley under contrasting microclimates

Salme Timmusk, Viiu Paalme, Tomas Pavlicek, Jonas Bergquist, Ameraswar Vangala, Triin Danilas, Eviatar Nevo, Salme Timmusk, Viiu Paalme, Tomas Pavlicek, Jonas Bergquist, Ameraswar Vangala, Triin Danilas, Eviatar Nevo

Abstract

Background: All plants in nature harbor a diverse community of rhizosphere bacteria which can affect the plant growth. Our samples are isolated from the rhizosphere of wild barley Hordeum spontaneum at the Evolution Canyon ('EC'), Israel. The bacteria which have been living in close relationship with the plant root under the stressful conditions over millennia are likely to have developed strategies to alleviate plant stress.

Methodology/principal findings: We studied distribution of culturable bacteria in the rhizosphere of H. spontaneum and characterized the bacterial 1-aminocyclopropane-1-carboxylate deaminase (ACCd) production, biofilm production, phosphorus solubilization and halophilic behavior. We have shown that the H. spontaneum rhizosphere at the stressful South Facing Slope (SFS) harbors significantly higher population of ACCd producing biofilm forming phosphorus solubilizing osmotic stress tolerant bacteria.

Conclusions/significance: The long-lived natural laboratory 'EC' facilitates the generation of theoretical testable and predictable models of biodiversity and genome evolution on the area of plant microbe interactions. It is likely that the bacteria isolated at the stressful SFS offer new opportunities for the biotechnological applications in our agro-ecological systems.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1. Cross section of the ‘Evolution…
Figure 1. Cross section of the ‘Evolution Canyon’ indicating the collection sites on South Facing Slope (SFS) 1 and 2 and North Facing Slope (NFS) 5 and 7.
Figure 2. Solid surface assay of the…
Figure 2. Solid surface assay of the South Facing Slope (SFS) and North Facing Slope (NFS) bacterial biofilm formation.
The crystal violet assay was used to measure solid surface biofilm formation at 30C. Preparation and analysis were as described in Material and Methods.

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