Abstract
Soil microorganisms play a key role in both plants nutrition and health. Their relation with plant varies from mutualism to parasitism, according to the balance of costs and benefits for the two partners of the interaction. These interactions involved the liberation of plant organic compounds via rhizodeposition. Modification of atmospheric CO(2) concentration may affect rhizodeposition and as a consequence trophic interactions that bind plants and microorganisms. Positive effect of elevated CO(2) on plants are rather well known but consequences for micoorganisms and their interactions with plants are still poorly understood. A gnotobiotic system has been developed to study the interaction between Medicago truncatula Jemalong J5 and the mutualistic bacteria Pseudomonas fluorescens strain C7R12 under two atmospheric CO(2) concentrations: ambient (365 ppm) versus enriched (750 ppm). Costs and benefits for each partner have been determined over time by measuring plant development and growth, the C and N contents of the various plant parts and the density of the bacteria in rhizosphere compartments. Following the increase in CO(2), there was a beneficial effect of P. fluorescens C7R12 on development, vegetative growth, and C/N content of M. truncatula. Concerning plant reproduction, an early seed production was noticed in presence of the bacterial strain combined with increased atmospheric CO(2) conditions. Paradoxically, this transient increase in seed production was correlated with a decrease in bacterial density in the rhizosphere soil, revealing a cost of increased CO(2) for the bacterial strain. This shift of costs-benefits ratio disappeared later during the plant growth. In conclusion, the increase in CO(2) concentration modifies transiently the cost-benefit balance in favor of the plant. These results may be explained either by a competition between the two partners or a change in bacterial physiology. The ecosystem functioning depends on the stability of many plant-microbe associations that abiotic factors can disrupt.
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Claims 5
Claim · model-written summary
Under elevated CO2, the bacterium benefited plant development, vegetative growth and C/N content.
- Taxon
- M. truncatula
Medicago truncatulae0 - Treatment
- increase in CO(2)e0
- Interactor
- P. fluorescens C7R12
.JPG?width=60)
Pseudomonas fluorescense0symbiont - Outcome
- development, vegetative growth, and C/N contente0
- Direction
- beneficiale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.JPG?width=500)
Verbatim
e0“Following the increase in CO(2), there was a beneficial effect of P. fluorescens C7R12 on development, vegetative growth, and C/N content of M. truncatula.”
e1“Medicago truncatula Jemalong J5 and the mutualistic bacteria Pseudomonas fluorescens strain C7R12”
Claim · model-written summary
The bacterial strain combined with increased CO2 led to earlier plant seed production.
- Taxon
- Medicago truncatulaMedicago truncatulae1
- Treatment
- increased atmospheric CO(2) conditionse0
- Interactor
- Pseudomonas fluorescens strain C7R12Pseudomonas fluorescense1symbiont
- Outcome
- seed productione0
- Direction
- earlye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an early seed production was noticed in presence of the bacterial strain combined with increased atmospheric CO(2) conditions.”
e1“Medicago truncatula Jemalong J5 and the mutualistic bacteria Pseudomonas fluorescens strain C7R12”
Claim · model-written summary
Transiently increased seed production correlated with lower bacterial density in rhizosphere soil.
- Taxon
- Medicago truncatulaMedicago truncatulae1
- Interactor
- Pseudomonas fluorescens strain C7R12Pseudomonas fluorescense1symbiont
- Outcome
- bacterial density in the rhizosphere soile0
- Direction
- decreasee0
- Qualifier
- transient increase in seed productione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this transient increase in seed production was correlated with a decrease in bacterial density in the rhizosphere soil”
e1“Medicago truncatula Jemalong J5 and the mutualistic bacteria Pseudomonas fluorescens strain C7R12”
Claim · model-written summary
The shifted cost-benefit ratio disappeared later during plant growth.
- Taxon
- Medicago truncatulaMedicago truncatulae1
- Interactor
- Pseudomonas fluorescens strain C7R12Pseudomonas fluorescense1symbiont
- Outcome
- shift of costs-benefits ratio disappearede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This shift of costs-benefits ratio disappeared later during the plant growth.”
e1“Medicago truncatula Jemalong J5 and the mutualistic bacteria Pseudomonas fluorescens strain C7R12”
Claim · model-written summary
Increased CO2 transiently shifted the cost-benefit balance in favor of the plant.
- Taxon
- Medicago truncatulaMedicago truncatulae1
- Interactor
- Pseudomonas fluorescens strain C7R12Pseudomonas fluorescense1symbiont
- Outcome
- cost-benefit balance in favor of the plante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the increase in CO(2) concentration modifies transiently the cost-benefit balance in favor of the plant.”
e1“Medicago truncatula Jemalong J5 and the mutualistic bacteria Pseudomonas fluorescens strain C7R12”