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1. Taxonomic Profiling of Microbes in Glyphosate-Treated Sediment Microcosms

   https://doi.org/10.1128/mra.01183-22  

   Newman, Madison R.; Sanchez, Darlenys; Acosta, Anna M.; Connors, Bernadette J. (January 2023, Microbiology Resource Announcements)

   Newton, Irene L. (Ed.)

   ABSTRACT Here, we report the impact of glyphosate on bacterial populations in sediment microcosms, determined using 16S amplicon sequencing and shotgun metagenomics with source material from a suburban creek. The 16S amplicon and metagenomic data reveal that members of the genus Pseudomonas are increased by the treatment. 

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2. Extrachromosomal DNA‐mediated glyphosate resistance in Italian ryegrass

   https://doi.org/10.1002/ps.7626  

   Koo, Dal‐Hoe; Ju, Yoonha; Putta, Karthik; Sathishraj, Rajendran; Burgos, Nilda; Jugulam, Mithila; Friebe, Bernd; Gill, Bikram S. (January 2023, Pest Management Science)
3. Draft Genome Sequences of Pseudomonas Isolates Derived from Glyphosate-Treated Sediments

   https://doi.org/10.1128/mra.01147-22  

   Cadavillo, Sabryna C.; Stroud, Morgan P.; Newman, Madison; Zigic, Jovan; Roman, Samuel D.; Connors, Bernadette J. (April 2023, Microbiology Resource Announcements)

   Maresca, Julia A. (Ed.)

   ABSTRACT Reported here are the genome sequences of Pseudomonas isolates that were derived from glyphosate-treated sediment microcosms. Genomes were assembled using workflows available through the Bacterial and Viral Bioinformatics Resource Center (BV-BRC). The genomes of eight Pseudomonas isolates were sequenced, with genomes ranging from 5.9 to 6.3 Mb. 

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4. The Glyphosate Assemblage: Herbicides, Uneven Development, and Chemical Geographies of Ubiquity

   https://doi.org/10.1080/24694452.2021.1898322  

   Werner, Marion; Berndt, Christian; Mansfield, Becky (May 2021, Annals of the American Association of Geographers)

   null (Ed.)

   This article develops a dialogue between agrarian political economy, critical commodity chains research, and chemical geographies through a case study of the world’s most widely used agrochemical: glyphosate, commonly known as Monsanto’s Roundup. In the 1980s, glyphosate triumphed as a benign biocide that promised both safety and effectiveness. This construct made possible a capitalist agricultural assemblage characterized by chemical pervasiveness, first as a chemical replacement for mechanical tillage and since the 1990s as the chemical input for genetically modified seed packages. The ubiquity that characterizes the glyphosate assemblage is also a geography of uneven development comprising shifting firm networks, policies, and trade. Central to this assemblage since 2000, yet largely ignored, is the outsized expansion of second- and third-tier generic pesticide producers, especially in China, for whom glyphosate is part of a network entry and upgrading development strategy. Today, the glyphosate assemblage faces unprecedented challenges from weed resistance and health controversies. Whether and how the herbicide assemblage restabilizes will be determined by the complex environmental and developmental challenges of chemical agriculture and pervasive chemicals broadly, which highlights the need for a transdisciplinary dialogue that cuts across these domains. 

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5. Root Microbiome Modulates Plant Growth Promotion Induced by Low Doses of Glyphosate

   https://doi.org/10.1128/mSphere.00484-20  

   Ramirez-Villacis, Dario X.; Finkel, Omri M.; Salas-González, Isai; Fitzpatrick, Connor R.; Dangl, Jeffery L.; Jones, Corbin D.; Leon-Reyes, Antonio (August 2020, mSphere)

   Fischer, Reinhard (Ed.)

   ABSTRACT Glyphosate is a commonly used herbicide with a broad action spectrum. However, at sublethal doses, glyphosate can induce plant growth, a phenomenon known as hormesis. Most glyphosate hormesis studies have been performed under microbe-free or reduced-microbial-diversity conditions; only a few were performed in open systems or agricultural fields, which include a higher diversity of soil microorganisms. Here, we investigated how microbes affect the hormesis induced by low doses of glyphosate. To this end, we used Arabidopsis thaliana and a well-characterized synthetic bacterial community of 185 strains (SynCom) that mimics the root-associated microbiome of Arabidopsis . We found that a dose of 3.6 × 10 −6 g acid equivalent/liter (low dose of glyphosate, or LDG) produced an ∼14% increase in the shoot dry weight (i.e., hormesis) of uninoculated plants. Unexpectedly, in plants inoculated with the SynCom, LDG reduced shoot dry weight by ∼17%. We found that LDG enriched two Firmicutes and two Burkholderia strains in the roots. These specific strains are known to act as root growth inhibitors (RGI) in monoassociation assays. We tested the link between RGI and shoot dry weight reduction in LDG by assembling a new synthetic community lacking RGI strains. Dropping RGI strains out of the community restored growth induction by LDG. Finally, we showed that individual RGI strains from a few specific phyla were sufficient to switch the response to LDG from growth promotion to growth inhibition. Our results indicate that glyphosate hormesis was completely dependent on the root microbiome composition, specifically on the presence of root growth inhibitor strains. IMPORTANCE Since the introduction of glyphosate-resistant crops, glyphosate has become the most common and widely used herbicide around the world. Due to its intensive use and ability to bind to soil particles, it can be found at low concentrations in the environment. The effect of these remnants of glyphosate in plants has not been broadly studied; however, glyphosate 1,000 to 100,000 times less concentrated than the recommended field dose promoted growth in several species in laboratory and greenhouse experiments. However, this effect is rarely observed in agricultural fields, where complex communities of microbes have a central role in the way plants respond to external cues. Our study reveals how root-associated bacteria modulate the responses of Arabidopsis to low doses of glyphosate, shifting between growth promotion and growth inhibition. 

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