Stimulation of bacteria and protists in rhizosphere of glyphosate-treated barley

Imparato, Valentina; Santos, Susana; Johansen, Anders; Geisen, Stefan; Winding, Anne

doi:10.1016/j.apsoil.2015.09.007

Cited by 35 publications

(23 citation statements)

References 49 publications

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“…Other recent studies have observed subtle or insignificant impacts of glyphosate on bacterial communities, though in a more limited number of soils or with little experimental replication (11,14,18,26). For example, Newman et al (11) described slight increases in the relative abundances of Proteobacteria and decreases in Acidobacteria, consistent with the concept of copiotrophic bacteria being favored over oligotrophs in the rhizospheres of glyphosate-treated plants (28). However, there are few investigations of how a history of glyphosate use impacts the microbial community response to additional herbicide applications.…”

Section: Discussionmentioning

confidence: 96%

“…Because some taxa are glyphosate sensitive, whereas others are insensitive or may benefit from it as a nutrient source, glyphosate is likely to have negative, neutral, or positive effects on soil microbial populations and to modify the microbiomes of crop plants. Consequently, it is not surprising that studies on the effects of glyphosate on microbial populations have yielded conflicting evidence, suggesting detrimental effects (9)(10)(11)(18)(19)(20), minimal or no effects (21)(22)(23)(24)(25)(26)(27), or stimulatory effects (23,(28)(29)(30)(31) on bacterial abundance, activity, and diversity.…”

mentioning

confidence: 99%

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Impacts of Repeated Glyphosate Use on Wheat-Associated Bacteria Are Small and Depend on Glyphosate Use History

Schlatter

Yin

Hulbert

et al. 2017

Appl Environ Microbiol

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Glyphosate is the most widely used herbicide worldwide and a critical tool for weed control in no-till cropping systems. However, there are concerns about the nontarget impacts of long-term glyphosate use on soil microbial communities. We investigated the impacts of repeated glyphosate treatments on bacterial communities in the soil and rhizosphere of wheat in soils with and without long-term history of glyphosate use. We cycled wheat in the greenhouse using soils from 4 paired fields under no-till (20+-year history of glyphosate) or no history of use. At each cycle, we terminated plants with glyphosate (2× the field rate) or by removing the crowns, and soil and rhizosphere bacterial communities were characterized. Location, cropping history, year, and proximity to the roots had much stronger effects on bacterial communities than did glyphosate, which only explained 2 to 5% of the variation. Less than 1% of all taxa were impacted by glyphosate, more in soils with a long history of use, and more increased than decreased in relative abundance. Glyphosate had minimal impacts on soil and rhizosphere bacteria of wheat, although dying roots after glyphosate application may provide a "greenbridge" favoring some copiotrophic taxa. Glyphosate (Roundup) is the most widely used herbicide in the world and the foundation of Roundup Ready soybeans, corn, and the no-till cropping system. However, there have been recent concerns about nontarget impacts of glyphosate on soil microbes. Using next-generation sequencing methods and glyphosate treatments of wheat plants, we described the bacterial communities in the soil and rhizosphere of wheat grown in Pacific Northwest soils across multiple years, different locations, and soils with different histories of glyphosate use. The effects of glyphosate were subtle and much less than those of drivers such as location and cropping systems. Only a small percentage of the bacterial groups were influenced by glyphosate, and most of those were stimulated, probably because of the dying roots. This study provides important information for the future of this important tool for no-till systems and the environmental benefits of reducing soil erosion and fossil fuel inputs.

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Section: Discussionmentioning

confidence: 96%

mentioning

confidence: 99%

Impacts of Repeated Glyphosate Use on Wheat-Associated Bacteria Are Small and Depend on Glyphosate Use History

Schlatter

Yin

Hulbert

et al. 2017

Appl Environ Microbiol

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“…, Imparato et al. ]) influenced by plants, but in most cases the possible existence of such mechanisms remains to be determined. The different Nebela species were strongly correlated to habitat‐type also corresponding to contrasting vascular plant and bryophyte communities.…”

Section: Discussionmentioning

confidence: 99%

“…Community patterns of soil micro-organisms including testate amoebae may be directly (e.g., through facilitation or allelopathy) or indirectly (e.g., through plant-induced modification of the environment [Philippot et al 2013, Imparato et al 2016) influenced by plants, but in most cases the possible existence of such mechanisms remains to be determined. The different Nebela species were strongly correlated to habitat-type also corresponding to contrasting vascular plant and bryophyte communities.…”

Section: Environmental Gradients Vegetation and Driving Factors Of Mmentioning

confidence: 99%

Environmental filtering and phylogenetic clustering correlate with the distribution patterns of cryptic protist species

Singer

Kosakyan

Seppey

et al. 2018

Ecology

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The community composition of any group of organisms should theoretically be determined by a combination of assembly processes including resource partitioning, competition, environmental filtering, and phylogenetic legacy. Environmental DNA studies have revealed a huge diversity of protists in all environments, raising questions about the ecological significance of such diversity and the degree to which they obey to the same rules as macroscopic organisms. The fast-growing cultivable protist species on which hypotheses are usually experimentally tested represent only a minority of the protist diversity. Addressing these questions for the lesser known majority can only be inferred through observational studies. We conducted an environmental DNA survey of the genus Nebela, a group of closely related testate (shelled) amoeba species, in different habitats within Sphagnum-dominated peatlands. Identification based on the mitochondrial cytochrome c oxidase 1 gene, allowed species-level resolution as well as phylogenetic reconstruction. Community composition varied strongly across habitats and associated environmental gradients. Species showed little overlap in their realized niche, suggesting resource partitioning, and a strong influence of environmental filtering driving community composition. Furthermore, phylogenetic clustering was observed in the most nitrogen-poor samples, supporting phylogenetic inheritance of adaptations in the group of N. guttata. This study showed that the studied free-living unicellular eukaryotes follow to community assembly rules similar to those known to determine plant and animal communities; the same may be true for much of the huge functional and taxonomic diversity of protists.

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“…This also comes true for statements on side effects from herbicides, e.g. the influence of glyphosate on the composition of the microorganism flora of both the soil and of endophytic communities in the plant (Kuklinsky-Sobrel et al, 2005;Imparato et al, 2016;Newman et al, 2016). The current body of evidence does not allow one to draw clear conclusions on the direction of the effects or their impact.…”

Section: Fastidiosamentioning

confidence: 99%

Four statements questioning the EU control strategy against Xylella fastidiosa

Bragard¹,

Caffier²,

Candresse³

et al. 2016

EFS2

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This opinion addresses questions concerning the EU control strategy against Xylella fastidiosa: i) factors affecting symptom expression and spread of X. fastidiosa; ii) the aetiology of the CoDiRO (Complesso del Disseccamento Rapido dell'Olivo) disease; iii) host plant removal as an option for containment or eradication; and iv) secondary effects of pesticides. Xylella fastidiosa subsp. pauca was shown to be the causal agent of the CoDiRO disease of olives by recent biological assays fulfilling Koch's postulates. Symptoms in X. fastidiosa infected plants develop because of wilting from water stress induced by bacteria clogging the xylem vessels. Therefore, interventions supporting vigorous growth and development of the plant may improve its health status, its resilience, prolong its productive phase and extend the symptomless phase of the disease. The Panel considers removal of infected plants, in a system‐based approach, as the only option to prevent further spread of the pathogen to new areas. In the outer strip of the containment area bordering the buffer zone, removal of infected plants and stringent monitoring can be effective in preventing pathogen spread into the buffer zone. In areas of recent introduction, such as new outbreaks in the buffer zone, the stringent removal of both infected plants and all host plants irrespective of their health status within a radius, as described in current EU legislation, can be effective in reducing pathogen spread, when rigorously administered and new infections are detected in time. Finally, the reduction of vector populations by application of chemical or biological means, mechanical treatments, or other sustainable methods, can have effects in slowing down the pathogen spread. Concerning the use of pesticides, there is currently no evidence of negative effects of such treatments on the interaction of X. fastidiosa with infected olive trees, the severity of symptoms and the outcome of the infection.

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Stimulation of bacteria and protists in rhizosphere of glyphosate-treated barley

Cited by 35 publications

References 49 publications

Impacts of Repeated Glyphosate Use on Wheat-Associated Bacteria Are Small and Depend on Glyphosate Use History

Impacts of Repeated Glyphosate Use on Wheat-Associated Bacteria Are Small and Depend on Glyphosate Use History

Environmental filtering and phylogenetic clustering correlate with the distribution patterns of cryptic protist species

Four statements questioning the EU control strategy against Xylella fastidiosa

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