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research article
Stoichiometric N:P flexibility and mycorrhizal symbiosis favour plant resistance against drought
2017
- Drought induces changes in the nitrogen (N) and phosphorus (P) cycle but most plant species have limited flexibility to take up nutrients under such variable or unbalanced N and P availability. Both the degree of flexibility in plant N:P ratio and of root symbiosis with arbuscular mycorrhizal fungi might control plant resistance to drought-induced changes in nutrient availability, but this has not been directly tested. 2. Here, we examined the role of plant N:P stoichiometric status and mycorrhizal symbiosis in the drought-resistance of dominant and subordinate species in a semi-natural grassland. 3. We reduced water availability using rainout shelters (control vs. drought) and measured how plant biomass responded for the dominant and subordinate species. We then selected a dominant (Paspalum dilatatum) and a subordinate species (Cynodon dactylon), for which we investigated the N:P stoichiometric status, mycorrhizal root colonization and water-use efficiency. 4. The biomass of all dominant plant species, but not subordinate species, decreased under drought. Drought increased soil available nitrogen, and thus increased soil N:P ratio, due to decreasing plant N uptake. The dominant P. dilatatum showed a high degree of plant N:P homeostasis and a considerable reduction in biomass under drought. At the opposite, the more flexible subordinate species C. dactylon increased its N uptake and water-use efficiency, apparently due to stronger symbiosis with mycorrhizae, and maintained its biomass. 5. Synthesis. We conclude that the maintenance of N:P homeostasis in dominant species, possibly because of a large root nutrient foraging capacity, becomes inefficient when water stress limits N mobility in the soil. By contrast, we demonstrate that higher stoichiometric N:P flexibility coupled with stronger mutualistic association with mycorrhizae allow subordinate species to better withstand drought perturbations. Using a stoichiometric approach in a field experiment, our study provides for the first time clear and novel understandings of the mechanisms involved in drought-resistance within the plant-mycorrhizae-soil system.
Type
research article
Web of Science ID
WOS:000403549500014
Author(s)
Date Issued
2017
Publisher
Published in
Volume
105
Issue
4
Start page
958
End page
967
Peer reviewed
REVIEWED
Written at
EPFL
EPFL units
Available on Infoscience
July 10, 2017
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