The importance of a sterile rhizosphere when phenotyping for root exudation

Kuijken, R.C.P.; Snel, J.; Heddes, Martijn M.; Bouwmeester, Harro J.; Marcelis, L.F.M.

doi:10.1007/s11104-014-2283-6

Cited by 54 publications

(38 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There is at present no way of reconciling the discrepancy between methods. It might be that organic acids were taken up intact but rapidly metabolized such that none of the U-13 C isotopologue remained within root tissues, or it could be that the decrease in U-13 C isotopologues from the hydroponic solution was due to microbial contamination or rhizoplane microbes (Jones and Darrah 1994;Kuijken et al 2015). Either way, we can conclude that if uptake of organic acids occurs it is slower than uptake of amino acids and sugars.…”

Section: Discussionmentioning

confidence: 99%

“…Wheat was grown in a sterile hydroponic system so as to exclude complications from microbes (Kuijken et al 2015), whereas in soil efflux and uptake are affected by soil processes (e.g., adsorption, mass flow, diffusion, microbial competition) and could also be modified by specific microbial metabolites (Phillips et al 2004). Root uptake could be a means of re-capturing some (or all) of the metabolites that Bleaked^out of root cells (Jones et al 2005;Warren 2015).…”

Section: Ecological Implicationsmentioning

confidence: 99%

See 1 more Smart Citation

Simultaneous efflux and uptake of metabolites by roots of wheat

Warren

2016

Plant Soil

View full text Add to dashboard Cite

Background & aims Some metabolites (e.g. amino acids) present in root exudates can be taken up by roots, but we do not know if this ability extends to the broader suite of metabolites found in exudates. The aim of this study was to examine the ability of wheat (Triticum aestivum L.) to efflux and take up a broad suite of small metabolites. Methods Four-week-old plants were placed into an uptake solution that contained a broad suite of 13 C-labelled metabolites. Uptake was estimated from the decrease in concentration of the 13 C isotopologue in the solution; and from the appearance of 13 C isotopologues within roots. Efflux was estimated from appearance of 12 C isotopologues in solution.Results When wheat plants were placed in 13 C-metabolite solutions the concentration of U-13 C isotopologues of 37 metabolites decreased -as would be expected if plants were taking up the U-13 C metabolites. After 4 h immersion in 13 C metabolite solution, roots contained detectable amounts of U-13 C isotopologues of 55 metabolites. U-13 C isotopologues of organic acids were not detected within roots.Conclusions These findings indicate that wheat can take up a broad suite of N-containing metabolites and some sugars, but there was no evidence for uptake of organic acids.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Ecological Implicationsmentioning

confidence: 99%

Simultaneous efflux and uptake of metabolites by roots of wheat

Warren

2016

Plant Soil

View full text Add to dashboard Cite

show abstract

“…Although these compounds are exuded in high quantities by roots (Rudrappa et al ., ; Ziegler et al ., ; van Dam and Bouwmeester, ), the microbial activity in the rhizosphere will quickly metabolize them, and the C18‐UPLC separation is not optimal for the separation of (often very polar) primary metabolites. Above all, we stress that our method is not suitable for quantitative analysis of primary and secondary root exudates, for which sterile root cultivation systems are more appropriate (Kuijken et al ., ; Strehmel et al ., ). Our method should only be used for the profiling, identification and/or quantification of rhizosphere chemicals.…”

Section: Discussionmentioning

confidence: 99%

Metabolite profiling of non‐sterile rhizosphere soil

et al. 2017

View full text Add to dashboard Cite

SummaryRhizosphere chemistry is the sum of root exudation chemicals, their breakdown products and the microbial products of soil‐derived chemicals. To date, most studies about root exudation chemistry are based on sterile cultivation systems, which limits the discovery of microbial breakdown products that act as semiochemicals and shape microbial rhizosphere communities. Here, we present a method for untargeted metabolic profiling of non‐sterile rhizosphere soil. We have developed an experimental growth system that enables the collection and analysis of rhizosphere chemicals from different plant species. High‐throughput sequencing of 16S rRNA genes demonstrated that plants in the growth system support a microbial rhizosphere effect. To collect a range of (a)polar chemicals from the system, we developed extraction methods that do not cause detectable damage to root cells or soil‐inhabiting microbes, thus preventing contamination with cellular metabolites. Untargeted metabolite profiling by UPLC‐Q‐TOF mass spectrometry, followed by uni‐ and multivariate statistical analyses, identified a wide range of secondary metabolites that are enriched in plant‐containing soil, compared with control soil without roots. We show that the method is suitable for profiling the rhizosphere chemistry of Zea mays (maize) in agricultural soil, thereby demonstrating the applicability to different plant–soil combinations. Our study provides a robust method for the comprehensive metabolite profiling of non‐sterile rhizosphere soil, which represents a technical advance towards the establishment of causal relationships between the chemistry and microbial composition of the rhizosphere.

show abstract

“…Wheat was grown in a sterile hydroponic system so as to exclude complications from microbes (Kuijken et al 2015), whereas in soil the efflux and uptake of N from roots could be modified by specific microbial metabolites (Phillips et al 2004) and a suite of soil processes (e.g., adsorption, mass flow, diffusion, microbial competition). For example, many studies have shown that microbes out-compete plants for inorganic and organic forms of N (Hodge et al 2000;Bardgett et al 2003;Jones et al 2005), and thus while plants may be able to salvage effluxed compounds in sterile hydroponic solution this capability may not be fully realized in soil.…”

Section: Methodological Considerationsmentioning

confidence: 99%

Wheat roots efflux a diverse array of organic N compounds and are highly proficient at their recapture

Warren

2015

Plant Soil

View full text Add to dashboard Cite

Background & aims Small organic N compounds could contribute to N nutrition, but an alternative view is that root uptake may serve to recapture compounds that efflux out of roots. However, it is unclear if plants can recapture leaked organic N compounds because no studies have examined quantitative relationships between efflux and uptake at sub-micromolar concentrations. Methods This study examines efflux and uptake of a broad suite of small organic N compounds by wheat (Triticum aestivum L.).15 N-labeling and capillary electrophoresis-mass spectrometry were used to estimate efflux and uptake. Results One hundred and ten organic N compounds were detected in exudates. Amino acids were abundant but accounted for less than half of organic N. Other abundant compound classes were amines and polyamines, quaternary ammonium compounds, nucleobases and nucleosides. Uptake occurred simultaneously with efflux for all 45 compounds for which rates of efflux could be reliably determined, even though concentrations were 0.01 to 0.5 μM.Conclusions These findings indicate that wheat is highly proficient at recapturing much of the diverse array of organic N compounds in root exudates. The ability to salvage effluxed compounds present at very low concentrations means that wheat might also be able to take up organic N compounds from the soil solution.

show abstract

The importance of a sterile rhizosphere when phenotyping for root exudation

Cited by 54 publications

References 64 publications

Simultaneous efflux and uptake of metabolites by roots of wheat

Simultaneous efflux and uptake of metabolites by roots of wheat

Metabolite profiling of non‐sterile rhizosphere soil

Wheat roots efflux a diverse array of organic N compounds and are highly proficient at their recapture

Contact Info

Product

Resources

About