Journal ArticleDOI
Carbon flow in the rhizosphere: carbon trading at the soil–root interface
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TLDR
Due to the importance of rhizodeposition in regulating ecosystem functioning, it is critical that future research focuses on resolving the quantitative importance of the different C and N fluxes operating in the rhizosphere and the ways in which these vary spatially and temporally.Abstract:
The loss of organic and inorganic carbon from roots into soil underpins nearly all the major changes that occur in the rhizosphere. In this review we explore the mechanistic basis of organic carbon and nitrogen flow in the rhizosphere. It is clear that C and N flow in the rhizosphere is extremely complex, being highly plant and environment dependent and varying both spatially and temporally along the root. Consequently, the amount and type of rhizodeposits (e.g. exudates, border cells, mucilage) remains highly context specific. This has severely limited our capacity to quantify and model the amount of rhizodeposition in ecosystem processes such as C sequestration and nutrient acquisition. It is now evident that C and N flow at the soil–root interface is bidirectional with C and N being lost from roots and taken up from the soil simultaneously. Here we present four alternative hypotheses to explain why high and low molecular weight organic compounds are actively cycled in the rhizosphere. These include: (1) indirect, fortuitous root exudate recapture as part of the root’s C and N distribution network, (2) direct re-uptake to enhance the plant’s C efficiency and to reduce rhizosphere microbial growth and pathogen attack, (3) direct uptake to recapture organic nutrients released from soil organic matter, and (4) for inter-root and root–microbial signal exchange. Due to severe flaws in the interpretation of commonly used isotopic labelling techniques, there is still great uncertainty surrounding the importance of these individual fluxes in the rhizosphere. Due to the importance of rhizodeposition in regulating ecosystem functioning, it is critical that future research focuses on resolving the quantitative importance of the different C and N fluxes operating in the rhizosphere and the ways in which these vary spatially and temporally.read more
Citations
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Journal ArticleDOI
Going back to the roots: the microbial ecology of the rhizosphere.
TL;DR: Recent developments in rhizosphere research are discussed in relation to assessing the contribution of the micro- and macroflora to sustainable agriculture, nature conservation, the development of bio-energy crops and the mitigation of climate change.
Journal ArticleDOI
Structure and functions of the bacterial microbiota of plants
Davide Bulgarelli,Klaus Schlaeppi,Stijn Spaepen,Stijn Spaepen,Emiel Ver Loren van Themaat,Paul Schulze-Lefert +5 more
TL;DR: The plant microbiota emerges as a fundamental trait that includes mutualism enabled through diverse biochemical mechanisms, as revealed by studies on plant growth- Promoting and plant health-promoting bacteria.
Journal ArticleDOI
The rhizosphere microbiome: significance of plant beneficial, plant pathogenic, and human pathogenic microorganisms
TL;DR: The main functions of rhizosphere microorganisms and how they impact on health and disease are reviewed and several strategies to redirect or reshape the rhizospheric microbiome in favor of microorganisms that are beneficial to plant growth and health are highlighted.
Journal ArticleDOI
Embracing the unknown: disentangling the complexities of the soil microbiome.
TL;DR: Although most soil microorganisms remain undescribed, the field is now poised to identify how to manipulate and manage the soil microbiome to increase soil fertility, improve crop production and improve the understanding of how terrestrial ecosystems will respond to environmental change.
Journal ArticleDOI
Plant growth-promoting bacteria in the rhizo- and endosphere of plants: Their role, colonization, mechanisms involved and prospects for utilization
TL;DR: The individual steps of plant colonization are described and the known mechanisms responsible for rhizosphere and endophytic competence are surveyed to better predict how bacteria interact with plants and whether they are likely to establish themselves in the plant environment after field application as biofertilisers or biocontrol agents.
References
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Journal ArticleDOI
Plant growth promoting rhizobacteria as biofertilizers
TL;DR: This review focuses on the known, the putative, and the speculative modes-of-action of PGPR, which include fixing N2, increasing the availability of nutrients in the rhizosphere, positively influencing root growth and morphology, and promoting other beneficial plant–microbe symbioses.
Journal ArticleDOI
Bioavailability of soil inorganic P in the rhizosphere as affected by root-induced chemical changes: A review
TL;DR: In this paper, the authors give an overview of those chemical processes that are directly induced by plant roots and which can affect the concentration of P in the soil solution and, ultimately, the bioavailability of soil inorganic P to plants.
Journal ArticleDOI
Microbial interactions and biocontrol in the rhizosphere
TL;DR: Multiple microbial interactions involving bacteria and fungi in the rhizosphere are shown to provide enhanced biocontrol in many cases in comparison with biocOntrol agents used singly.
Journal ArticleDOI
Large-scale forest girdling shows that current photosynthesis drives soil respiration
Peter Högberg,Anders Nordgren,Nina Buchmann,Andy F. S. Taylor,Alf Ekblad,Alf Ekblad,Mona N. Högberg,Gert Nyberg,Mikaell Ottosson-Löfvenius,David Read +9 more
TL;DR: Girdling reduced soil respiration within 1–2 months by about 54% relative to respiration on ungirdled control plots, and that decreases of up to 37% were detected within 5 days, which clearly show that the flux of current assimilates to roots is a key driver of soil resppiration.
Journal ArticleDOI
Mycorrhizas and nutrient cycling in ecosystems – a journey towards relevance?
David Read,Jesús Pérez-Moreno +1 more
TL;DR: The results support the hypothesis that selection has favoured ericoid and ectomycorrhizal systems with well developed saprotrophic capabilities in those ecosystems characterized by retention of N and P as organic complexes in the soil.
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