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Stone BW, Blazewicz SJ, Koch BJ, Dijkstra P, Hayer M, Hofmockel KS, Liu XJA, Mau RL, Pett-Ridge J, Schwartz E, Hungate BA. Nutrients strengthen density dependence of per-capita growth and mortality rates in the soil bacterial community. Oecologia 2023; 201:771-782. [PMID: 36847885 DOI: 10.1007/s00442-023-05322-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/15/2023] [Indexed: 03/01/2023]
Abstract
Density dependence in an ecological community has been observed in many macro-organismal ecosystems and is hypothesized to maintain biodiversity but is poorly understood in microbial ecosystems. Here, we analyze data from an experiment using quantitative stable isotope probing (qSIP) to estimate per-capita growth and mortality rates of bacterial populations in soils from several ecosystems along an elevation gradient which were subject to nutrient addition of either carbon alone (glucose; C) or carbon with nitrogen (glucose + ammonium-sulfate; C + N). Across all ecosystems, we found that higher population densities, quantified by the abundance of genomes per gram of soil, had lower per-capita growth rates in C + N-amended soils. Similarly, bacterial mortality rates in C + N-amended soils increased at a significantly higher rate with increasing population size than mortality rates in control and C-amended soils. In contrast to the hypothesis that density dependence would promote or maintain diversity, we observed significantly lower bacterial diversity in soils with stronger negative density-dependent growth. Here, density dependence was significantly but weakly responsive to nutrients and was not associated with higher bacterial diversity.
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Affiliation(s)
- Bram W Stone
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA.
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA.
| | - Steven J Blazewicz
- Physical and Life Sciences Directorate, Lawrence Livermore National Lab, Livermore, CA, USA
| | - Benjamin J Koch
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Paul Dijkstra
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Michaela Hayer
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
| | - Kirsten S Hofmockel
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA
- Department of Agronomy, Iowa State University, Ames, IA, USA
| | - Xiao Jun Allen Liu
- Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, USA
| | - Rebecca L Mau
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
| | - Jennifer Pett-Ridge
- Physical and Life Sciences Directorate, Lawrence Livermore National Lab, Livermore, CA, USA
- Life and Environmental Sciences Department, University of California Merced, Merced, CA, USA
| | - Egbert Schwartz
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Bruce A Hungate
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
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Williams A, Pétriacq P, Beerling DJ, Cotton TEA, Ton J. Impacts of Atmospheric CO 2 and Soil Nutritional Value on Plant Responses to Rhizosphere Colonization by Soil Bacteria. FRONTIERS IN PLANT SCIENCE 2018; 9:1493. [PMID: 30405655 PMCID: PMC6204664 DOI: 10.3389/fpls.2018.01493] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 09/25/2018] [Indexed: 05/24/2023]
Abstract
Concerns over rising atmospheric CO2 concentrations have led to growing interest in the effects of global change on plant-microbe interactions. As a primary substrate of plant metabolism, atmospheric CO2 influences below-ground carbon allocation and root exudation chemistry, potentially affecting rhizosphere interactions with beneficial soil microbes. In this study, we have examined the effects of different atmospheric CO2 concentrations on Arabidopsis rhizosphere colonization by the rhizobacterial strain Pseudomonas simiae WCS417 and the saprophytic strain Pseudomonas putida KT2440. Rhizosphere colonization by saprophytic KT2440 was not influenced by sub-ambient (200 ppm) and elevated (1,200 ppm) concentrations of CO2, irrespective of the carbon (C) and nitrogen (N) content of the soil. Conversely, rhizosphere colonization by WCS417 in soil with relatively low C and N content increased from sub-ambient to elevated CO2. Examination of plant responses to WCS417 revealed that plant growth and systemic resistance varied according to atmospheric CO2 concentration and soil-type, ranging from growth promotion with induced susceptibility at sub-ambient CO2, to growth repression with induced resistance at elevated CO2. Collectively, our results demonstrate that the interaction between atmospheric CO2 and soil nutritional status has a profound impact on plant responses to rhizobacteria. We conclude that predictions about plant performance under past and future climate scenarios depend on interactive plant responses to soil nutritional status and rhizobacteria.
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Affiliation(s)
- Alex Williams
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
- P Institute for Translational Plant and Soil Biology, Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Pierre Pétriacq
- P Institute for Translational Plant and Soil Biology, Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
- UMR 1332 Fruit Biology and Pathology, INRA-Bordeaux & University of Bordeaux, Villenave d’Ornon, France
- Plateforme Métabolome du Centre de Génomique Fonctionnelle de Bordeaux, INRA – Bordeaux, Villenave d’Ornon, France
| | - David J. Beerling
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
| | - T. E. Anne Cotton
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Jurriaan Ton
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
- P Institute for Translational Plant and Soil Biology, Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
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