Soil ecotoxicity assessment of glyphosate use under field conditions: microbial activity and community structure of Eubacteria and ammonia‐oxidising bacteria

Zabaloy, María Celina; Carné, Ignacio; Viassolo, R.; Gómez, M. A.; Gomez, Elena V.

doi:10.1002/ps.4037

Cited by 26 publications

(8 citation statements)

References 60 publications

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“…Even after long-term glyphosate use in no-till systems, only minor changes were detected in microbial communities of the wheat rhizosphere (Lupwayi et al, 2020), even though significant negative effects recently were observed for fungi (Vázquez et al, 2021). However, the methods used to study microbial communities in soil were mostly restricted to those measuring general microbial community structure, diversity, biomass or activity so that only minor or no effects were found (Allegrini et al, 2015;Banks et al, 2014;Bottrill et al, 2020;Lupwayi et al, 2020;Zabaloy et al, 2016), probably due to the great diversity and compensatory ability of microorganisms within such large groupings.…”

Section: Effects On Microorganisms In Bulk Soil Rhizosphere and Plantsmentioning

confidence: 99%

Indirect Effects of the Herbicide Glyphosate on Plant, Animal and Human Health Through its Effects on Microbial Communities

Bruggen

Finckh

et al. 2021

Front. Environ. Sci.

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The herbicide glyphosate interferes with the shikimate pathway in plants and in major groups of microorganisms impeding the production of aromatic amino acids. Glyphosate application on plants results in a slow death, accelerated by reduced resistance to root pathogens. Extensive glyphosate use has resulted in increasing residues in soil and waterways. Although direct glyphosate effects on animals are limited, major concerns have arisen about indirect harmful side effects. In this paper, we focus on indirect effects of sublethal concentrations of glyphosate on plant, animal and human health due to shifts in microbial community compositions in successive habitats. Research results of glyphosate effects on microbial communities in soil, rhizosphere and animal guts have been contradictory due to the different integration levels studied. Most glyphosate studies have tested short-term treatment effects on microbial biomass or general community composition at higher taxonomic levels in soil, rhizosphere or animal intestinal tracts, and found little effect. More detailed studies showed reductions in specific genera or species as well as biological processes after glyphosate application. Plant growth promoting rhizobacteria and beneficial intestinal bacteria often are negatively affected, while pathogenic bacteria and fungi are enhanced. Such shifts in microbial community composition have been implicated in enhanced susceptibility of plants to Fusarium and Rhizoctonia, of birds and mammals to toxic Clostridium and Salmonella species, and of bees to Serratia and Deformed Wing Virus. In animals and humans, glyphosate exposure and concentrations in urine have been associated with intestinal diseases and neurological as well as endocrine problems, but cause-effect relationships need to be determined in more detail. Nevertheless, outbreaks of several animal and plant diseases have been related to glyphosate accumulation in the environment. Long-term glyphosate effects have been underreported, and new standards will be needed for residues in plant and animal products and the environment.

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Section: Effects On Microorganisms In Bulk Soil Rhizosphere and Plantsmentioning

confidence: 99%

Indirect Effects of the Herbicide Glyphosate on Plant, Animal and Human Health Through its Effects on Microbial Communities

Bruggen

Finckh

et al. 2021

Front. Environ. Sci.

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“…To avoid introducing errors (mainly related to an unknown number of operons per cell), we analyzed the copy numbers (Ouyang et al, 2016;Morrison et al, 2017); no attempt was made to convert these copies into cell numbers. The amplification program for AOB and AOA as well as the PCR master mix volumes and reaction setup were previously reported by Zabaloy et al (2016) and Zabaloy et al (2017), respectively. All amplifications, baseline corrections, melting curve analysis, and standard curve assessments were conducted in ABI 7500 Real− Time System and its associated software (7500 Software v2.0.3, Applied Biosystems, Foster City, CA).…”

Section: Quantitative Pcr Of Amoa Genementioning

confidence: 99%

Ammonia Oxidizing Prokaryotes Respond Differently to Fertilization and Termination Methods in Common Oat’s Rhizosphere

et al. 2021

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Cover crops (CC) have demonstrated beneficial effects on several soil properties yet questions remain regarding their effects on soil microbial communities. Among them, ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) have a key role for N cycling in soil and their responses in the rhizosphere of terminated CC deserve further investigation. A greenhouse experiment was established to assess N fertilization (with or without N) and termination methods (glyphosate, mowing, and untreated control) of common oat (Avena sativa L.) as potential drivers of AOA and AOB responses in the rhizosphere. The abundance of amoA genes was determined by quantitative real-time PCR (qPCR), the community structure was assessed with Illumina amplicon sequencing of these genes, while the function was assessed from potential nitrification activity (PNA). While N fertilization had no influence on AOA, the termination method significantly increased amoA gene copies of AOA in mowed plants relative to glyphosate termination or the untreated control (1.76 and 1.49-fold change, respectively), and shifted AOA community structure (PERMANOVA, p<0.05). Ordination methods indicated a separation between AOA communities from control and glyphosate-terminated plants relative to mowed plants for both UniFrac and Aitchison distance. Converserly, N fertilization significantly increased AOB abundance in the rhizosphere of mowed and control plants, yet not in glyphosate-treated plants. Analyses of community structure showed that AOB changed only in response to N fertilization and not to the termination method. In line with these results, significantly higher PNA values were measured in all fertilized samples, regardless of the termination methods. Overall, the results of this study indicated that bacterial and archaeal nitrifiers have contrasting responses to fertlization and plant termination methods. While AOA were responsive to the termination method, AOB were more sensitive to N additions, although, the stimulative effect of N fertilization on amoAAOB abundance was dependent on the termination method.

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“…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%

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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Soil ecotoxicity assessment of glyphosate use under field conditions: microbial activity and community structure of Eubacteria and ammonia‐oxidising bacteria

Abstract: The absence of negative effects on soil microbial communities in this study suggests that glyphosate use at recommended rates poses low risk to the microbiota.

Cited by 26 publications

References 60 publications

Indirect Effects of the Herbicide Glyphosate on Plant, Animal and Human Health Through its Effects on Microbial Communities

Indirect Effects of the Herbicide Glyphosate on Plant, Animal and Human Health Through its Effects on Microbial Communities

Ammonia Oxidizing Prokaryotes Respond Differently to Fertilization and Termination Methods in Common Oat’s Rhizosphere

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

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