Abstract
Arbuscular mycorrhizal fungi (AMF) are important symbionts for plant nutrient uptake, but their exact role in plant nitrogen (N) nutrition is unclear. Protists on the other hand play an acknowledged role in plant N acquisition, and there is increasing evidence for a close interaction with AMF. In a split root set up, we investigated the distinct roles of mycorrhiza (Rhizophagus irregularis), protists (Acanthamoeba castellanii), and their interaction on plant N uptake, within-root system allocation patterns, and shoot-to-root ratio of winter wheat. In addition, we applied a quantitative metabolomics approach to characterize associated changes in soil microbial communities by microbial phospholipid fatty acid (PLFA) analysis from rhizosphere soil. AMF markedly altered plant shoot-to-root allometry by reducing root biomass of wheat, and mycorrhiza partly took over root system functioning. Protists promoted shoot and root growth, and improved plant N uptake by the release of N from consumed bacterial biomass, a mechanism known as microbial loop. The shoot system however responded little to these alterations of the root system and of the rhizosphere community composition, indicating that the plants optimized shoot growth despite varying investment into roots. Mycorrhiza reduced root biomass and plant N, especially in the combined treatments with protists by changing within root system allocation of N and root biomass. These systemic effects on root allocation pattern suggest that mycorrhiza also gained control over N provided by protist grazers. Protists and mycorrhiza altered rhizosphere bacterial communities in contrasting but consistent ways as shown by quantitative shifts in microbial PLFA profiles. Remarkably, the changes in bacterial community composition were systemically conveyed within the root system to the split-root chamber where the symbionts were lacking. Accordingly the synergistic effects of protists and mycorrhiza indicated systemic effects on nutrient- and on root-allocation within root systems as an emergent property that could not be predicted from single treatments with mycorrhiza or protists alone. The tight plant and microbial feed backs uncovered in this study have far reaching implications for understanding the assembly of plant microbiomes, and testify central roles of both protists and mycorrhizas in the assembly process.
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Claims 11
Claim · model-written summary
AMF reduced wheat root biomass and changed shoot-to-root allometry.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- AMFe0
- Interactor
- AMFe0symbiont
- Outcome
- root biomasse0
- Direction
- reducinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AMF markedly altered plant shoot-to-root allometry by reducing root biomass of wheat”
Claim · model-written summary
Protists promoted wheat shoot and root growth.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- Protistse0
- Interactor
- Protistse0other
- Outcome
- shoot and root growthe0
- Direction
- promotede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“Protists promoted shoot and root growth”
Claim · model-written summary
Protists improved plant nitrogen uptake through release of nitrogen from consumed bacteria.
- Taxon
- winter wheatTriticum aestivumt0
- Interactor
- Protistse0other
- Outcome
- plant N uptakee0
- Direction
- improvede0
- Qualifier
- release of N from consumed bacterial biomasse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“Protists promoted shoot and root growth, and improved plant N uptake by the release of N from consumed bacterial biomass”
Claim · model-written summary
Shoot growth responded little to root-system and rhizosphere-community changes.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- shoot systeme0
- Direction
- responded littlee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“The shoot system however responded little to these alterations of the root system and of the rhizosphere community composition”
Claim · model-written summary
Mycorrhiza reduced wheat root biomass, especially when combined with protists.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- Mycorrhizae0
- Interactor
- Mycorrhizae0symbiont
- Outcome
- root biomasse0
- Direction
- reducede0
- Qualifier
- especially in the combined treatments with protistse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“Mycorrhiza reduced root biomass and plant N, especially in the combined treatments with protists by changing within root system allocation of N and root biomass”
Claim · model-written summary
Mycorrhiza reduced plant nitrogen, especially in combination with protists.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- Mycorrhizae0
- Interactor
- Mycorrhizae0symbiont
- Outcome
- plant Ne0
- Direction
- reducede0
- Qualifier
- especially in the combined treatments with protistse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“Mycorrhiza reduced root biomass and plant N, especially in the combined treatments with protists by changing within root system allocation of N and root biomass”
Claim · model-written summary
Mycorrhiza changed within-root allocation of nitrogen and root biomass.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- Mycorrhizae0
- Interactor
- Mycorrhizae0symbiont
- Outcome
- within root system allocation of N and root biomasse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“Mycorrhiza reduced root biomass and plant N, especially in the combined treatments with protists by changing within root system allocation of N and root biomass”
Claim · model-written summary
Protists altered rhizosphere bacterial communities.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- Protistse0
- Interactor
- Protistse0other
- Outcome
- rhizosphere bacterial communitiese0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“Protists and mycorrhiza altered rhizosphere bacterial communities in contrasting but consistent ways as shown by quantitative shifts in microbial PLFA profiles”
Claim · model-written summary
Mycorrhiza altered rhizosphere bacterial communities.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- mycorrhizae0
- Interactor
- mycorrhizae0symbiont
- Outcome
- rhizosphere bacterial communitiese0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“Protists and mycorrhiza altered rhizosphere bacterial communities in contrasting but consistent ways as shown by quantitative shifts in microbial PLFA profiles”
Claim · model-written summary
Changes in bacterial community composition spread within the root system to a split-root chamber lacking symbionts.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- changes in bacterial community composition were systemically conveyed within the root systeme0
- Qualifier
- split-root chamber where the symbionts were lackinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“the changes in bacterial community composition were systemically conveyed within the root system to the split-root chamber where the symbionts were lacking”
Claim · model-written summary
Combined protists and mycorrhiza had synergistic systemic effects on nutrient and root allocation that single treatments did not predict.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- protists and mycorrhizae0
- Interactor
- mycorrhizae0symbiont
- Second interactor
- protistse0other
- Outcome
- nutrient- and on root-allocation within root systemse0
- Comparator
- single treatments with mycorrhiza or protists alonee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“the synergistic effects of protists and mycorrhiza indicated systemic effects on nutrient- and on root-allocation within root systems as an emergent property that could not be predicted from single treatments with mycorrhiza or protists alone”
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See all 82 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.