Root exudates mediated interactions belowground

Haichar, Feth el Zahar; Santaella, Catherine; Heulin, Thierry; Achouak, Wafa

doi:10.1016/j.soilbio.2014.06.017

Cited by 752 publications

(408 citation statements)

References 148 publications

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“…A significantly greater abundance of anammox bacteria was also observed in rhizosphere compared to bulk soils, possibly as a result of root exudates. Roots exudates, including sugars, amino acids, various LMWOAs such as succinate, malate and fumarate, may act as chemo-attractants for bacteria or simply stimulate bacterial growth (Haichar et al, 2014). Root exudates have a direct impact on carbon and nitrogen cycling through a priming effect, and are part of the rhizo-deposition process, which is the major source of soil organic carbon released by plant root, leading to a proliferation of microorganisms in the rhizosphere (Haichar et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

“…Roots exudates, including sugars, amino acids, various LMWOAs such as succinate, malate and fumarate, may act as chemo-attractants for bacteria or simply stimulate bacterial growth (Haichar et al, 2014). Root exudates have a direct impact on carbon and nitrogen cycling through a priming effect, and are part of the rhizo-deposition process, which is the major source of soil organic carbon released by plant root, leading to a proliferation of microorganisms in the rhizosphere (Haichar et al, 2014). Plant roots excrete a compositionally diverse array of more than 100,000 different low-molecular mass natural products, which comprise a broad range of substrates and signaling molecules for rhizosphereassociated microorganisms (Bais et al, 2004;Haichar et al, 2014), possibly including anammox bacteria.…”

Section: Discussionmentioning

confidence: 99%

“…Root exudates have a direct impact on carbon and nitrogen cycling through a priming effect, and are part of the rhizo-deposition process, which is the major source of soil organic carbon released by plant root, leading to a proliferation of microorganisms in the rhizosphere (Haichar et al, 2014). Plant roots excrete a compositionally diverse array of more than 100,000 different low-molecular mass natural products, which comprise a broad range of substrates and signaling molecules for rhizosphereassociated microorganisms (Bais et al, 2004;Haichar et al, 2014), possibly including anammox bacteria. The significant correlation between hzsB gene copies and succinate could indicate a potential role of succinate in anammox bacterial metabolism.…”

Section: Discussionmentioning

confidence: 99%

“…The significant correlation between hzsB gene copies and succinate could indicate a potential role of succinate in anammox bacterial metabolism. Succinic acid is a chelator of poorly dissolved mineral nutrients (Haichar et al, 2014), which may be important for anammox bacterial growth.…”

Section: Discussionmentioning

confidence: 99%

“…Ammonium is obviously a main substrate of anammox bacteria Yang et al, 2015), but citrate and formate are not recognized as having a direct influence on anammox composition. However, the use of these LMWOAs as a nutrient source for anammox bacteria (Badri and Vivanco, 2009) or as a mechanism to reduce the toxicity of aluminum (Haichar et al, 2014), may explain this correlation.…”

Section: Discussionmentioning

confidence: 99%

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The phenological stage of rice growth determines anaerobic ammonium oxidation activity in rhizosphere soil

Yang

Weng

et al. 2016

Soil Biology and Biochemistry

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a b s t r a c tAnaerobic oxidation of ammonium (anammox) plays an important role in nitrogen (N) loss from agricultural systems. Recently, the rice rhizosphere was demonstrated to be a hotspot for anammox, yet the dynamics of anammox activity and the distribution of anammox bacteria in rhizosphere soil at different phenological stages of rice growth are still unknown. In this study, the activity, diversity and abundance of anammox bacteria in both rhizosphere and bulk soils were investigated over the entire rice growth season. From tillering to ripening stage, significantly higher anammox bacterial abundance was detected in rhizosphere soils compared to bulk soils. The rhizosphere soils also had significantly higher anammox rates at tillering and booting stages (0.71 and 0.32 nmol N g À1 dry soil h À1 , respectively) compared to bulk soils. The anammox rate in rhizosphere soil was positively correlated to the concentrations of NO x À (total of nitrate and nitrite) and acetate. The abundance of anammox bacteria was significantly correlated with the concentration of succinate in rhizosphere soils. A total of five anammox genera of Brocadia, Kuenenia, Anammoxoglobus, Jettenia and Scalindua were detected, with Brocadia predominating in all examined samples. The distribution of anammox bacteria in rhizosphere and bulk soils varied with phenological stages. Statistical analysis indicated that C/N ratio, formate, citrate and ammonium were key factors influencing the composition of anammox bacteria. Variations in activity, abundance and distribution of anammox bacteria in rhizosphere were observed over the phenological progression, demonstrating that the root exudates might be influential for the anammox process. This study implies that future efforts in estimating the rate of anammox should consider the temporal variation during plant life cycles.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 3 more Smart Citations

The phenological stage of rice growth determines anaerobic ammonium oxidation activity in rhizosphere soil

Yang

Weng

et al. 2016

Soil Biology and Biochemistry

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Does mycorrhizal inoculation improve plant survival, aggregate stability, and fine root development on a coarse‐grained soil in an alpine eco‐engineering field experiment?

et al. 2016

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Steep vegetation‐free talus slopes in high mountain environments are prone to superficial slope failures and surface erosion. Eco‐engineering measures can reduce slope instabilities and thus contribute to risk mitigation. In a field experiment, we established mycorrhizal and nonmycorrhizal research plots and determined their biophysical contribution to small‐scale soil fixation. Mycorrhizal inoculation impact on plant survival, aggregate stability, and fine root development was analyzed. Here we present plant survival (ntotal = 1248) and soil core (ntotal = 108) analyses of three consecutive years in the Swiss Alps. Soil cores were assayed for their aggregate stability coefficient (ASC), root length density (RLD), and mean root diameter (MRD). Inoculation improved plant survival significantly, but it delayed aggregate stabilization relative to the noninoculated site. Higher aggregate stability occurred only after three growing seasons. Then also RLD tended to be higher and MRD increased significantly at the mycorrhizal treated site. There was a positive correlation between RLD, ASC, and roots <0.5 mm, which had the strongest impact on soil aggregation. Our results revealed a temporal offset between inoculation effects tested in laboratory and field experiments. Consequently, we recommend to establish an intermediate to long‐term field experimental monitoring before transferring laboratory results to the field.

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Roots: Contribution to the Rhizosphere

Curlango‐Rivera

Gunawardena

Wen

et al. 2016

Encyclopedia of Life Sciences

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Diverse compounds exuded by different parts of the root system create a unique environment known as the rhizosphere. Interactions among microorganisms found within the rhizosphere and communication between these microorganisms and plant roots play an important role in maintaining plant health. In 2004, the discovery of deoxyribonucleic acid (DNA)‐based neutrophil extracellular traps (NETs) have transformed our understanding of mammalian immune responses. Subsequent studies revealed that plant roots express a similar mechanism in the rhizosphere, where root border cells secrete extracellular DNA together with antibiotic amino acids, enzymes and other proteins, to trap pathogens and prevent their invasion of the root system. As in animals, the defense response is impaired if extracellular proteins and/or extracellular DNA are degraded by protease and/or by DNase at the time of inoculation with fungal or bacterial pathogens. Defining species‐specific mechanisms of plant extracellular trapping may yield new avenues for engineering the rhizosphere to improve crop production. Key Concepts Extracellular DNA (exDNA) in the rhizosphere has long been observed, and was presumed to result from cell death. Recent studies have revealed that exDNA is a key component of an extracellular matrix involved in trapping and immobilisation of pathogens. The specificity of exDNA‐based trapping may play a critical role in microbial population structure in the rhizosphere. The discovery that DNA‐based extracellular trapping operates in animals and plants suggests that this previously unrecognised process is an ancient underpinning of eukaryotic defence. Efforts to engineer the rhizosphere may be facilitated by a better understanding of how plants control the environment surrounding their roots.

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Root exudates mediated interactions belowground

Cited by 752 publications

References 148 publications

The phenological stage of rice growth determines anaerobic ammonium oxidation activity in rhizosphere soil

The phenological stage of rice growth determines anaerobic ammonium oxidation activity in rhizosphere soil

Does mycorrhizal inoculation improve plant survival, aggregate stability, and fine root development on a coarse‐grained soil in an alpine eco‐engineering field experiment?

Roots: Contribution to the Rhizosphere

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