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Stephen B Powles - One of the best experts on this subject based on the ideXlab platform.

  • aldo keto reductase metabolizes Glyphosate and confers Glyphosate resistance in echinochloa colona
    Plant Physiology, 2019
    Co-Authors: Lang Pan, Heping Han, Lingfeng Mao, Alex Nyporko, Longjiang Fan, Lianyang Bai, Stephen B Powles
    Abstract:

    Glyphosate, the most commonly used herbicide in the world, controls a wide range of plant species, mainly because plants have little capacity to metabolize (detoxify) Glyphosate. Massive Glyphosate use has led to world-wide evolution of Glyphosate-resistant (GR) weed species, including the economically damaging grass weed Echinochloa colona. An Australian population of E. colona has evolved resistance to Glyphosate with unknown mechanisms that do not involve the Glyphosate target enzyme 5-enolpyruvylshikimate-3-P synthase. GR and Glyphosate-susceptible (S) lines were isolated from this population and used for resistance gene discovery. RNA sequencing analysis and phenotype/genotype validation experiments revealed that one aldo-keto reductase (AKR) contig had higher expression and higher resultant AKR activity in GR than S plants. Two full-length AKR (EcAKR4-1 and EcAKR4-2) complementary DNA transcripts were cloned with identical sequences between the GR and S plants but were upregulated in the GR plants. Rice (Oryza sativa) calli and seedlings overexpressing EcAKR4-1 and displaying increased AKR activity were resistant to Glyphosate. EcAKR4-1 expressed in Escherichia coli can metabolize Glyphosate to produce aminomethylphosphonic acid and glyoxylate. Consistent with these results, GR E. colona plants exhibited enhanced capacity for detoxifying Glyphosate into aminomethylphosphonic acid and glyoxylate. Structural modeling predicted that Glyphosate binds to EcAKR4-1 for oxidation, and metabolomics analysis of EcAKR4-1 transgenic rice seedlings revealed possible redox pathways involved in Glyphosate metabolism. Our study provides direct experimental evidence of the evolution of a plant AKR that metabolizes Glyphosate and thereby confers Glyphosate resistance.

  • Pest Management Science Pest Manag Sci 64:360–365 (2008) Review Evolved Glyphosate-resistant weeds around the world: lessons to be learnt
    2015
    Co-Authors: Stephen B Powles
    Abstract:

    Abstract: Glyphosate is the world’s most important herbicide, with many uses that deliver effective and sustained control of a wide spectrum of unwanted (weedy) plant species. Until recently there were relatively few reports of weedy plant species evolving resistance to Glyphosate. Since 1996, the advent and subsequent high adoption of transgenic Glyphosate-resistant crops in the Americas has meant unprecedented and often exclusive use of Glyphosate forweed control over very large areas. Consequently, in regions of theUSAwhere transgenic Glyphosate-resistant crops dominate, there are now evolved Glyphosate-resistant populations of the economically damaging weed species Ambrosia artemissifolia L., Ambrosia trifida L., Amaranthus palmeri S Watson, Amaranthus rudis JD Sauer, Amaranthus tuberculatus (Moq) JD Sauer and various Conyza and Lolium spp. Likewise, in areas of transgenic Glyphosate-resistant crops in Argentina and Brazil, there are now evolved Glyphosate-resistant populations of Sorghumhalepense (L.) Pers andEuphorbia heterophyllaL. respectively. As transgenic Glyphosate-resistant crops will remain very popular with producers, it is anticipated that Glyphosate-resistant biotypes of other prominent weed species will evolve over the next few years. Therefore, evolved Glyphosate-resistant weeds are a major risk for the continued success of Glyphosate and transgenic Glyphosate-resistant crops. However, Glyphosate-resistant weeds are not yet a problem in many parts of the world, and lessons can be learnt and actions taken to achieve Glyphosate sustainability. A major lesson is that maintenance of diversity in weed management systems is crucial for Glyphosate to be sustainable. Glyphosate is essential for present and future world food production, and action to secure its sustainability for future generations is a global imperative

  • Glyphosate resistant rigid ryegrass lolium rigidum populations in the western australian grain belt
    Weed Technology, 2010
    Co-Authors: Mechelle J Owen, Stephen B Powles
    Abstract:

    Abstract Glyphosate-resistance evolution in weeds is evident globally, especially in areas where transgenic Glyphosate-resistant crops dominate. Resistance to Glyphosate is currently known in 16 weed species, including rigid ryegrass in Australia. Following the first report of Glyphosate resistance in 1998, there are now 78 documented Glyphosate-resistant populations of rigid ryegrass in grain-growing regions of southern Australia. In some regions where Glyphosate-resistance evolution has already occurred in rigid ryegrass, transgenic Glyphosate-resistant canola was introduced in 2008, further highlighting the need to monitor Glyphosate-resistance evolution in weeds. A rigid ryegrass population (WALR70) was collected in 2005 from a crop field in Esperance, Western Australia, after it had survived applications of Glyphosate. Dose–response experiments confirmed resistance in the population, with the Glyphosate rate resulting in 50% mortality (LD50) for WALR70 being 11 times greater than that for a susceptib...

  • evolved Glyphosate resistant weeds around the world lessons to be learnt
    Pest Management Science, 2008
    Co-Authors: Stephen B Powles
    Abstract:

    Glyphosate is the world's most important herbicide, with many uses that deliver effective and sustained control of a wide spectrum of unwanted (weedy) plant species. Until recently there were relatively few reports of weedy plant species evolving resistance to Glyphosate. Since 1996, the advent and subsequent high adoption of transgenic Glyphosate-resistant crops in the Americas has meant unprecedented and often exclusive use of Glyphosate forweedcontroloververylarge areas.Consequently, in regionsoftheUSA wheretransgenic Glyphosate- resistant crops dominate, there are now evolved Glyphosate-resistant populations of the economically damaging weed species Ambrosia artemissifolia L., Ambrosia trifida L., Amaranthus palmeri SW atson,Amaranthus rudis JD Sauer, Amaranthus tuberculatus (Moq) JD Sauer and various Conyza and Lolium spp. Likewise, in areas of transgenic Glyphosate-resistant crops in Argentina and Brazil, there are now evolved Glyphosate-resistant populations ofSorghum halepense (L.) Pers andEuphorbia heterophylla L. respectively. As transgenic Glyphosate- resistant crops will remain very popular with producers, it is anticipated that Glyphosate-resistant biotypes of other prominent weed species will evolve over the next few years. Therefore, evolved Glyphosate-resistant weeds are a major risk for the continued success of Glyphosate and transgenic Glyphosate-resistant crops. However, Glyphosate-resistant weeds are not yet a problem in many parts of the world, and lessons can be learnt and actions taken to achieve Glyphosate sustainability. A major lesson is that maintenance of diversity in weed management systems is crucial for Glyphosate to be sustainable. Glyphosate is essential for present and future world food production, and action to secure its sustainability for future gene rations is ag lobal imperative.  2008 Society of Chemical Industry

  • Glyphosate a once in a century herbicide
    Pest Management Science, 2008
    Co-Authors: Stephen O Duke, Stephen B Powles
    Abstract:

    Since its commercial introduction in 1974, Glyphosate [N-(phosphonomethyl)glycine] has become the dominant herbicide worldwide. There are several reasons for its success. Glyphosate is a highly effective broad-spectrum herbicide, yet it is very toxicologically and environmentally safe. Glyphosate translocates well, and its action is slow enough to take advantage of this. Glyphosate is the only herbicide that targets 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPS), so there are no competing herbicide analogs or classes. Since Glyphosate became a generic compound, its cost has dropped dramatically. Perhaps the most important aspect of the success of Glyphosate has been the introduction of transgenic, Glyphosate-resistant crops in 1996. Almost 90% of all transgenic crops grown worldwide are Glyphosate resistant, and the adoption of these crops is increasing at a steady pace. Glyphosate/Glyphosate-resistant crop weed management offers significant environmental and other benefits over the technologies that it replaces. The use of this virtually ideal herbicide is now being threatened by the evolution of Glyphosate-resistant weeds. Adoption of resistance management practices will be required to maintain the benefits of Glyphosate technologies for future generations. Copyright © 2008 Society of Chemical Industry

Manuel Tejada - One of the best experts on this subject based on the ideXlab platform.

  • evolution of soil biological properties after addition of Glyphosate diflufenican and Glyphosate diflufenican herbicides
    Chemosphere, 2009
    Co-Authors: Manuel Tejada
    Abstract:

    Abstract The aim of this paper was to study in laboratory the degradation and the effects on biological properties in two soils after the addition of Glyphosate, diflufenican and Glyphosate+diflufenican. One hundred grams of sieved soil ( ® (16% Glyphosate and 4% diflufenican) prepared in a water solution of 1 L (0.52 g of Glyphosate and 2.08 g of diflufenican), (ii) 5.2 mL of Round up ® (40% Glyphosate), prepared in a water solution of 1 L (0.52 g of Glyphosate), and (iii) 1.19 mL of Brodal ® (43.5% diflufenican), prepared in a water solution of 1 L (2.08 g of diflufenican). Soil samples were collected after 0, 1, 5, 10, 15, 30, 60, 120 and 180 d of incubation and analyzed for microbial biomass-C and dehydrogenase, urease, β-glucosidase, phosphatase, arylsulphatase activities and Glyphosate and diflufenican contents. At the end of the experiment, in the clayey texture soil the Glyphosate and diflufenican contents were higher 50% and 30.7%, respectively, for the Glyphosate+diflufenican treatment compared to Glyphosate and diflufenican treatments, respectively. In the sandy loam texture soil the Glyphosate and diflufenican contents were higher (38.9% and 39.4%, respectively) when the Glyphosate and diflufenican were added as Zarpa ® than Round up ® or Brodal ® . The application of Glyphosate+diflufenican mixture to soil increased the toxic effects of both herbicides in the soil biological activity and the individual soil persistence of each herbicide.

  • Evolution of soil biological properties after addition of Glyphosate, diflufenican and Glyphosate+diflufenican herbicides.
    Chemosphere, 2009
    Co-Authors: Manuel Tejada
    Abstract:

    Abstract The aim of this paper was to study in laboratory the degradation and the effects on biological properties in two soils after the addition of Glyphosate, diflufenican and Glyphosate+diflufenican. One hundred grams of sieved soil ( ® (16% Glyphosate and 4% diflufenican) prepared in a water solution of 1 L (0.52 g of Glyphosate and 2.08 g of diflufenican), (ii) 5.2 mL of Round up ® (40% Glyphosate), prepared in a water solution of 1 L (0.52 g of Glyphosate), and (iii) 1.19 mL of Brodal ® (43.5% diflufenican), prepared in a water solution of 1 L (2.08 g of diflufenican). Soil samples were collected after 0, 1, 5, 10, 15, 30, 60, 120 and 180 d of incubation and analyzed for microbial biomass-C and dehydrogenase, urease, β-glucosidase, phosphatase, arylsulphatase activities and Glyphosate and diflufenican contents. At the end of the experiment, in the clayey texture soil the Glyphosate and diflufenican contents were higher 50% and 30.7%, respectively, for the Glyphosate+diflufenican treatment compared to Glyphosate and diflufenican treatments, respectively. In the sandy loam texture soil the Glyphosate and diflufenican contents were higher (38.9% and 39.4%, respectively) when the Glyphosate and diflufenican were added as Zarpa ® than Round up ® or Brodal ® . The application of Glyphosate+diflufenican mixture to soil increased the toxic effects of both herbicides in the soil biological activity and the individual soil persistence of each herbicide.

Samawar Mansur - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis and properties of zirconium Glyphosate and monochromatic zirconium Glyphosate-Eu
    Microporous and Mesoporous Materials, 2008
    Co-Authors: Yaqing Zhang, Yuan Yuan, Samawar Mansur
    Abstract:

    Abstract A series of layered compounds of zirconium Glyphosate and zirconium phosphate–Glyphosates were synthesized with ZrOCl2, N-(phosphonomethyl)glycine and H3PO4 for the first time. It was found that the morphologies of zirconium phosphate–Glyphosates had a strong variational rule from hexagon to sphere and sphere to lamella when n H 3 PO 4 / n Glyphosate changed from ∞ to 0, and also it was found that the product of zirconium Glyphosate could be decomposed gradually in basic condition with pH value of lye increased. A monochromatic body of ZrGPEu under illumination of UV light was obtained by Eu3+ exchanged and coordinated with imido and carbonyl groups in the gallery of the layers.

Yaqing Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis and properties of zirconium Glyphosate and monochromatic zirconium Glyphosate-Eu
    Microporous and Mesoporous Materials, 2008
    Co-Authors: Yaqing Zhang, Yuan Yuan, Samawar Mansur
    Abstract:

    Abstract A series of layered compounds of zirconium Glyphosate and zirconium phosphate–Glyphosates were synthesized with ZrOCl2, N-(phosphonomethyl)glycine and H3PO4 for the first time. It was found that the morphologies of zirconium phosphate–Glyphosates had a strong variational rule from hexagon to sphere and sphere to lamella when n H 3 PO 4 / n Glyphosate changed from ∞ to 0, and also it was found that the product of zirconium Glyphosate could be decomposed gradually in basic condition with pH value of lye increased. A monochromatic body of ZrGPEu under illumination of UV light was obtained by Eu3+ exchanged and coordinated with imido and carbonyl groups in the gallery of the layers.

Stephen O Duke - One of the best experts on this subject based on the ideXlab platform.

  • Glyphosate-Resistant and Conventional Canola (Brassica napus L.) Responses to Glyphosate and Aminomethylphosphonic Acid (AMPA) Treatment
    Journal of Agricultural and Food Chemistry, 2016
    Co-Authors: Elza Alves Corrêa, Daniel K. Owens, Agnes M. Rimando, Franck E Dayan, Stephen O Duke
    Abstract:

    Glyphosate-resistant (GR) canola contains two transgenes that impart resistance to the herbicide Glyphosate: (1) the microbial Glyphosate oxidase gene (gox) encoding the Glyphosate oxidase enzyme (GOX) that metabolizes Glyphosate to aminomethylphosphonic acid (AMPA) and (2) cp4 that encodes a GR form of the Glyphosate target enzyme 5-enolpyruvylshikimic acid-3-phosphate synthase. The objectives of this research were to determine the phytotoxicity of AMPA to canola, the relative metabolism of Glyphosate to AMPA in GR and conventional non-GR (NGR) canola, and AMPA pool sizes in Glyphosate-treated GR canola. AMPA applied at 1.0 kg ha–1 was not phytotoxic to GR or NGR. At this AMPA application rate, NGR canola accumulated a higher concentration of AMPA in its tissues than GR canola. At rates of 1 and 3.33 kg ae ha–1 of Glyphosate, GR canola growth was stimulated. This stimulatory effect is similar to that of much lower doses of Glyphosate on NGR canola. Both shikimate and AMPA accumulated in tissues of these ...

  • Glyphosate degradation in Glyphosate-resistant and -susceptible crops and weeds
    Journal of Agricultural and Food Chemistry, 2011
    Co-Authors: Stephen O Duke
    Abstract:

    High levels of aminomethylphosphonic acid (AMPA), the main Glyphosate\nmetabolite, have been found in Glyphosate-treated, Glyphosate-resistant\n(GR) soybean, apparently due to plant Glyphosate oxidoreductase\n(GOX)-like activity. AMPA is mildly phytotoxic, and under some\nconditions the AMPA accumulating in GR soybean correlates with\nGlyphosate-caused phytotoxicity. A bacterial GOX is used in GR canola,\nand an altered bacterial Glyphosate N-acetyltransferase is planned for a\nnew generation of GR crops. In some weed species, Glyphosate degradation\ncould contribute to natural resistance. Neither an isolated plant GOX\nenzyme nor a gene for it has yet been reported in plants. Gene mutation\nor amplification of plant genes for GOX-like enzyme activity or\nhorizontal transfer of microbial genes from Glyphosate-degrading enzymes\ncould produce GR weeds. Yet, there is no evidence that metabolic\ndegradation plays a significant role in evolved resistance to\nGlyphosate. This is unexpected, considering the extreme selection\npressure for evolution of Glyphosate resistance in weeds and the\ndifficulty in plants of evolving Glyphosate resistance via other\nmechanisms.

  • Glyphosate tolerance mechanism in italian ryegrass lolium multiflorum from mississippi
    Weed Science, 2008
    Co-Authors: Vijay K Nandula, Agnes M. Rimando, Krishna N. Reddy, Daniel H Poston, Stephen O Duke
    Abstract:

    T1 population absorbed less 14 C-Glyphosate (43% of applied) compared to the susceptible (S) population (59% of applied) at 48 h after treatment (HAT). The T2 population absorbed 14 C-Glyphosate at levels (56% of applied at 48 HAT) that were similar to both T1 and S populations, but tended to be more comparable to the S population. The amount of 14 CGlyphosate that remained in the treated leaf was significantly higher in both T1 (67% of absorbed) and T2 (65% of absorbed) populations compared to the S population (45% of absorbed) at 48 HAT. The amount of 14 C-Glyphosate that moved out of treated leaf to shoot and root was lower in both T1 (25% of absorbed in shoot and 9% of absorbed in root) and T2 (25% of absorbed in shoot and 11% of absorbed in root) populations compared to the S population (40% of absorbed in shoot and 16% of absorbed in root) at 48 HAT. There were no differences in epicuticular wax mass among the three populations. Treating a single leaf with Glyphosate solution at the field use rate (0.84 kg ae ha 21 )a s 10 1- ml droplets killed the S plant but not the T1 and T2 plants (33 and 55% shoot fresh-weight reduction, respectively). Shikimic acid accumulated rapidly at higher levels in Glyphosate-treated leaf segments of the S population compared to the T1 population up to 100 mM Glyphosate. However, above 500 mM Glyphosate, the levels of shikimate were similar in both the S and T1 populations. Furthermore, shikimic acid content was three- to sixfold more in whole plants of the S population treated with 0.22 kg ae ha 21 Glyphosate compared to the T1 and T2 populations. No degradation of Glyphosate to aminomethylphosphonic acid was detected among the tolerant and susceptible populations. These results indicate that tolerance to Glyphosate in the T1 population is partly due to reduced absorption and translocation of Glyphosate and in the T2 population it is partly due to reduced translocation of Glyphosate. Nomenclature: Glyphosate; Italian ryegrass, Lolium multiflorum Lam.

  • Glyphosate a once in a century herbicide
    Pest Management Science, 2008
    Co-Authors: Stephen O Duke, Stephen B Powles
    Abstract:

    Since its commercial introduction in 1974, Glyphosate [N-(phosphonomethyl)glycine] has become the dominant herbicide worldwide. There are several reasons for its success. Glyphosate is a highly effective broad-spectrum herbicide, yet it is very toxicologically and environmentally safe. Glyphosate translocates well, and its action is slow enough to take advantage of this. Glyphosate is the only herbicide that targets 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPS), so there are no competing herbicide analogs or classes. Since Glyphosate became a generic compound, its cost has dropped dramatically. Perhaps the most important aspect of the success of Glyphosate has been the introduction of transgenic, Glyphosate-resistant crops in 1996. Almost 90% of all transgenic crops grown worldwide are Glyphosate resistant, and the adoption of these crops is increasing at a steady pace. Glyphosate/Glyphosate-resistant crop weed management offers significant environmental and other benefits over the technologies that it replaces. The use of this virtually ideal herbicide is now being threatened by the evolution of Glyphosate-resistant weeds. Adoption of resistance management practices will be required to maintain the benefits of Glyphosate technologies for future generations. Copyright © 2008 Society of Chemical Industry