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International Journal of Molecular... Apr 2022Glyphosate, a non-selective systemic biocide with broad-spectrum activity, is the most widely used herbicide in the world. It can persist in the environment for days or... (Review)
Review
Glyphosate, a non-selective systemic biocide with broad-spectrum activity, is the most widely used herbicide in the world. It can persist in the environment for days or months, and its intensive and large-scale use can constitute a major environmental and health problem. In this systematic review, we investigate the current state of our knowledge related to the effects of this pesticide on the nervous system of various animal species and humans. The information provided indicates that exposure to glyphosate or its commercial formulations induces several neurotoxic effects. It has been shown that exposure to this pesticide during the early stages of life can seriously affect normal cell development by deregulating some of the signaling pathways involved in this process, leading to alterations in differentiation, neuronal growth, and myelination. Glyphosate also seems to exert a significant toxic effect on neurotransmission and to induce oxidative stress, neuroinflammation and mitochondrial dysfunction, processes that lead to neuronal death due to autophagy, necrosis, or apoptosis, as well as the appearance of behavioral and motor disorders. The doses of glyphosate that produce these neurotoxic effects vary widely but are lower than the limits set by regulatory agencies. Although there are important discrepancies between the analyzed findings, it is unequivocal that exposure to glyphosate produces important alterations in the structure and function of the nervous system of humans, rodents, fish, and invertebrates.
Topics: Animals; Central Nervous System Depressants; Glycine; Herbicides; Neurotoxicity Syndromes; Glyphosate
PubMed: 35562999
DOI: 10.3390/ijms23094605 -
International Journal of Environmental... Oct 2020Glyphosate is a non-specific organophosphate pesticide, which finds widespread application in shielding crops against the weeds. Its high solubility in hydrophilic... (Review)
Review
Glyphosate is a non-specific organophosphate pesticide, which finds widespread application in shielding crops against the weeds. Its high solubility in hydrophilic solvents, especially water and high mobility allows the rapid leaching of the glyphosate into the soil leading to contamination of groundwater and accumulation into the plant tissues, therefore intricating the elimination of the herbicides. Despite the widespread application, only a few percentages of the total applied glyphosate serve the actual purpose, dispensing the rest in the environment, thus resulting in reduced crop yields, low quality agricultural products, deteriorating soil fertility, contributing to water pollution, and consequently threatening human and animal life. This review gives an insight into the toxicological effects of the herbicide glyphosate and current approaches to track and identify trace amounts of this agrochemical along with its biodegradability and possible remediating strategies. Efforts have also been made to summarize the biodegradation mechanisms and catabolic enzymes involved in glyphosate metabolism.
Topics: Biodegradation, Environmental; Glycine; Herbicides; Humans; Plant Weeds; Glyphosate
PubMed: 33076575
DOI: 10.3390/ijerph17207519 -
The Journal of Biological Chemistry Jul 2020The widely successful use of synthetic herbicides over the past 70 years has imposed strong and widespread selection pressure, leading to the evolution of herbicide... (Review)
Review
The widely successful use of synthetic herbicides over the past 70 years has imposed strong and widespread selection pressure, leading to the evolution of herbicide resistance in hundreds of weed species. Both target-site resistance (TSR) and nontarget-site resistance (NTSR) mechanisms have evolved to most herbicide classes. TSR often involves mutations in genes encoding the protein targets of herbicides, affecting the binding of the herbicide either at or near catalytic domains or in regions affecting access to them. Most of these mutations are nonsynonymous SNPs, but polymorphisms in more than one codon or entire codon deletions have also evolved. Some herbicides bind multiple proteins, making the evolution of TSR mechanisms more difficult. Increased amounts of protein target, by increased gene expression or by gene duplication, are an important, albeit less common, TSR mechanism. NTSR mechanisms include reduced absorption or translocation and increased sequestration or metabolic degradation. The mechanisms that can contribute to NTSR are complex and often involve genes that are members of large gene families. For example, enzymes involved in herbicide metabolism-based resistances include cytochromes P450, GSH -transferases, glucosyl and other transferases, aryl acylamidase, and others. Both TSR and NTSR mechanisms can combine at the individual level to produce higher resistance levels. The vast array of herbicide-resistance mechanisms for generalist (NTSR) and specialist (TSR and some NTSR) adaptations that have evolved over a few decades illustrate the evolutionary resilience of weed populations to extreme selection pressures. These evolutionary processes drive herbicide and herbicide-resistant crop development and resistance management strategies.
Topics: Acclimatization; Cytochrome P-450 Enzyme System; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Herbicide Resistance; Herbicides; Plant Proteins; Plants
PubMed: 32430396
DOI: 10.1074/jbc.REV120.013572 -
Toxins Apr 2021Fungal phytotoxic secondary metabolites are poisonous substances to plants produced by fungi through naturally occurring biochemical reactions. These metabolites exhibit... (Review)
Review
Fungal phytotoxic secondary metabolites are poisonous substances to plants produced by fungi through naturally occurring biochemical reactions. These metabolites exhibit a high level of diversity in their properties, such as structures, phytotoxic activities, and modes of toxicity. They are mainly isolated from phytopathogenic fungal species in the genera of , , , , , and . Phytotoxins are either host specific or non-host specific phytotoxins. Up to now, at least 545 fungal phytotoxic secondary metabolites, including 207 polyketides, 46 phenols and phenolic acids, 135 terpenoids, 146 nitrogen-containing metabolites, and 11 others, have been reported. Among them, aromatic polyketides and sesquiterpenoids are the main phytotoxic compounds. This review summarizes their chemical structures, sources, and phytotoxic activities. We also discuss their phytotoxic mechanisms and structure-activity relationships to lay the foundation for the future development and application of these promising metabolites as herbicides.
Topics: Animals; Fungi; Herbicides; Humans; Molecular Structure; Mycotoxins; Plants; Secondary Metabolism; Structure-Activity Relationship
PubMed: 33917534
DOI: 10.3390/toxins13040261 -
Protein Science : a Publication of the... Jun 20194-Hydroxyphenylpyruvate dioxygenase (HPPD) catalyzes the second reaction in the tyrosine catabolism and is linked to the production of cofactors plastoquinone and...
4-Hydroxyphenylpyruvate dioxygenase (HPPD) catalyzes the second reaction in the tyrosine catabolism and is linked to the production of cofactors plastoquinone and tocopherol in plants. This important biological role has put HPPD in the focus of current herbicide design efforts including the development of herbicide-tolerant mutants. However, the molecular mechanisms of substrate binding and herbicide tolerance have yet to be elucidated. In this work, we performed molecular dynamics simulations and free energy calculations to characterize active site gating by the C-terminal helix H11 in HPPD. We compared gating equilibria in Arabidopsis thaliana (At) and Zea mays (Zm) wild-type proteins retrieving the experimentally observed preferred orientations from the simulations. We investigated the influence of substrate and product binding on the open-closed transition and discovered a ligand-mediated conformational switch in H11 that mediates rapid substrate access followed by active site closing and efficient product release through H11 opening. We further studied H11 gating in At mutant HPPD, and found large differences with correlation to experimentally measured herbicide tolerance. The computational findings were then used to design a new At mutant HPPD protein that showed increased tolerance to six commercially available HPPD inhibitors in biochemical in vitro experiments. Our results underline the importance of protein flexibility and conformational transitions in substrate recognition and enzyme inhibition by herbicides.
Topics: 4-Hydroxyphenylpyruvate Dioxygenase; Arabidopsis; Binding Sites; Dose-Response Relationship, Drug; Enzyme Inhibitors; Herbicides; Models, Molecular; Molecular Dynamics Simulation; Molecular Structure; Mutation; Structure-Activity Relationship; Substrate Specificity; Thermodynamics; Zea mays
PubMed: 30945368
DOI: 10.1002/pro.3612 -
Pest Management Science Apr 2021Chemical weed control has been widely adopted and has led to increased efficiency and reduced crop production costs. With the increased use of herbicides and the...
Chemical weed control has been widely adopted and has led to increased efficiency and reduced crop production costs. With the increased use of herbicides and the introduction of herbicide-tolerant crops we have also seen an increase in herbicide resistant weeds which presents a challenge for farmers and land managers. It is incumbent upon the agriculture industry to be an indispensable partner in leading policy, research, education, and best management practices related to herbicide resistance. Corteva Agriscience is an active, engaged partner in herbicide resistance research, education, and communication globally to enable the long-term sustainable use of herbicide-tolerant crop traits and herbicides. Some of the key components of our commitment are highlighted in this Perspective paper and include memberships, partnerships, close involvement with CropLife International (and regional CropLife organizations), and Herbicide Resistance Action Committees at the Global, regional and country level, technical leadership and engagement in multiple scientific societies, and collaboration with universities and research institutes. Corteva is committed to advancing sustainable agriculture to enrich lives and our planet for generations to come and this drives our action through the entire product lifecycle and with our customers and consumers.
Topics: Crops, Agricultural; Herbicide Resistance; Herbicides; Plant Weeds; Weed Control
PubMed: 33284501
DOI: 10.1002/ps.6214 -
Journal of Agricultural and Food... Jun 2011Since 1996, genetically modified herbicide-resistant (HR) crops, particularly glyphosate-resistant (GR) crops, have transformed the tactics that corn, soybean, and... (Review)
Review
Since 1996, genetically modified herbicide-resistant (HR) crops, particularly glyphosate-resistant (GR) crops, have transformed the tactics that corn, soybean, and cotton growers use to manage weeds. The use of GR crops continues to grow, but weeds are adapting to the common practice of using only glyphosate to control weeds. Growers using only a single mode of action to manage weeds need to change to a more diverse array of herbicidal, mechanical, and cultural practices to maintain the effectiveness of glyphosate. Unfortunately, the introduction of GR crops and the high initial efficacy of glyphosate often lead to a decline in the use of other herbicide options and less investment by industry to discover new herbicide active ingredients. With some exceptions, most growers can still manage their weed problems with currently available selective and HR crop-enabled herbicides. However, current crop management systems are in jeopardy given the pace at which weed populations are evolving glyphosate resistance. New HR crop technologies will expand the utility of currently available herbicides and enable new interim solutions for growers to manage HR weeds, but will not replace the long-term need to diversify weed management tactics and discover herbicides with new modes of action. This paper reviews the strengths and weaknesses of anticipated weed management options and the best management practices that growers need to implement in HR crops to maximize the long-term benefits of current technologies and reduce weed shifts to difficult-to-control and HR weeds.
Topics: Crops, Agricultural; Glycine; Herbicide Resistance; Herbicides; Plant Weeds; Weed Control; Glyphosate
PubMed: 20586458
DOI: 10.1021/jf101286h -
Genes Nov 2022Herbicides have become one of the most widespread weed-control tools in the world since their advent in the mid-20th century [...].
Herbicides have become one of the most widespread weed-control tools in the world since their advent in the mid-20th century [...].
Topics: Herbicide Resistance; Plant Weeds; Weed Control; Herbicides
PubMed: 36360259
DOI: 10.3390/genes13112025 -
Pest Management Science Oct 2018Herbicides classified as synthetic auxins have been most commonly used to control broadleaf weeds in a variety of crops and in non-cropland areas since the first... (Review)
Review
Herbicides classified as synthetic auxins have been most commonly used to control broadleaf weeds in a variety of crops and in non-cropland areas since the first synthetic auxin herbicide (SAH), 2,4-D, was introduced to the market in the mid-1940s. The incidence of weed species resistant to SAHs is relatively low considering their long-term global application with 30 broadleaf, 5 grass, and 1 grass-like weed species confirmed resistant to date. An understanding of the context and mechanisms of SAH resistance evolution can inform management practices to sustain the longevity and utility of this important class of herbicides. A symposium was convened during the 2nd Global Herbicide Resistance Challenge (May 2017; Denver, CO, USA) to provide an overview of the current state of knowledge of SAH resistance mechanisms including case studies of weed species resistant to SAHs and perspectives on mitigating resistance development in SAH-tolerant crops. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Topics: Herbicide Resistance; Herbicides; Indoleacetic Acids; Plant Weeds; Weed Control
PubMed: 29235732
DOI: 10.1002/ps.4823 -
Pest Management Science Apr 2021The evolution of weed resistance to herbicides is an ever-increasing problem that affects crop yield and food production. In Syngenta, we believe that this difficult and...
The evolution of weed resistance to herbicides is an ever-increasing problem that affects crop yield and food production. In Syngenta, we believe that this difficult and complex issue can be most efficiently addressed through a deep understanding of the evolutionary dynamics and mechanism of resistance. A profound knowledge of resistance is key to developing the next generation of resistance-breaking compounds with existing or novel herbicide sites of action. We use a multidisciplinary laboratory-based, glasshouse and field biology approach to study herbicide resistance and provide strong science-based solutions to delay the onset and manage resistance. We have developed and implemented simple early-season resistance detection methods to allow farmers make an informed decision for effective weed control. We have built mechanistic, individual-based computer models to design profitable, long-term sustainable weed management programs. Our zero tolerance approaches employ herbicides with different sites of action, applied in mixtures and sequences, to minimise the risk of resistance evolution. Weeds are targeted at the right growth stage with optimal herbicide formulation and spray technology for maximising weed control and depleting the seed bank. We are promoting the use of competitive crop varieties and other nonchemical methods for an integrated weed management strategy. We have a global web of external collaborations for studying and managing herbicide resistance. We are committed to farmers' education and training on herbicide resistance, and regularly share our methods and findings via conferences and peer-reviewed scientific publications for the benefit of the wider weed science community and field practitioners. © 2020 Society of Chemical Industry.
Topics: Farmers; Herbicide Resistance; Herbicides; Humans; Plant Weeds; Weed Control
PubMed: 32893405
DOI: 10.1002/ps.6072