<i>EPSPS</i> gene amplification confers resistance to glyphosate resistant populations of <scp><i>Hordeum glaucum</i></scp> Stued (northern barley grass) in South Australia

Adu-Yeboah, Patricia; Malone, Jenna; Fleet, Benjamin; Gill, Gurjeet; Preston, Christopher

doi:10.1002/ps.5671

Cited by 26 publications

(29 citation statements)

References 46 publications

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“…We must recognize, however, that doing so will not replace the necessity to practice integrated resistance management. 32-48 (53) 2.4-8.7 Hordeum glaucum 9-11 (54) 2.8-6.6 Bromus diandrus 10-36 (55) 4. 28 (56) - Table 3.…”

Section: Implications For Herbicide Discoverymentioning

confidence: 99%

Mechanisms of evolved herbicide resistance

Gaines

Duke

Morran

et al. 2020

Journal of Biological Chemistry

434

493

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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 non-target-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 non-synonymous single-nucleotide polymorphisms, but polymorphisms in more than one codon or entire codon deletions have also evolved. Some herbicides bind multiple proteins, making TSR mechanisms more difficult to evolve. Increased amounts of protein target, by increased gene expression or by gene duplication, is 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, glutathione-S-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.

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Section: Implications For Herbicide Discoverymentioning

confidence: 99%

Mechanisms of evolved herbicide resistance

Gaines

Duke

Morran

et al. 2020

Journal of Biological Chemistry

434

493

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“…Moreover, this species has evolved resistance to herbicides due to its genetic diversity and biological, physiological, and ecological adaptations [4]. The evolution of herbicide resistance in H. murinum to several sites of action (SoA) has been confirmed mainly in Australia and has made these weed species more problematic for the agricultural community [5][6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

“…This herbicide has become a popular weed control tool in agricultural systems owing to its broad spectrum weed control, high efficacy, and low cost compared with other herbicides [13], which resulted in the evolution of resistant (R) weeds around the world [19]. From an agronomic perspective, evolved herbicide resistance becomes a problem when weed control becomes "unacceptable" to a grower.…”

Section: Introductionmentioning

confidence: 99%

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Resistance Evolution to EPSPS Inhibiting Herbicides in False Barley (Hordeum murinum) Harvested in Southern Spain

et al. 2020

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A failure of the EPSPS-inhibiting herbicide glyphosate to control several populations of Hordeum murinum subsp. leporinum (or H. murinum) occurred in southern Spain after more than fifteen applications in both crop (olive, orchards, and citrus) and non-crop (dry areas, roadsides and ditches) areas. Eight out of 18 populations studied were resistant (R) to glyphosate with R factors higher than four based on GR50. These populations also had the highest values of LD50 and the lowest levels of shikimic acid accumulation. Two adjuvants tested increased glyphosate efficacy in both susceptible (S) and R populations thanks to better spray foliar retention. Moreover, PS I-, PS II-, and ACCase-inhibiting herbicides, in pre- or post-emergence, proved to be the best chemical alternatives with different sites of action (SoA) to control both S and glyphosate-R populations. This study represents the first report worldwide of glyphosate resistance in H. murinum found in very different crop and non-crop areas from southern Spain. To design chemical strategies to implement integrated weed management programs for glyphosate-R H. murinum, both adjuvants and herbicides with alternative SoA as well as application timings should be considered.

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“…6). EPSPS gene amplification is an increasingly common mechanism of glyphosate‐ resistance 38 and has been reported in five grass 34, 39–42 and four broadleaved weed species 15,35,43,44 …”

Section: Resultsmentioning

confidence: 99%

First case of glyphosate resistance in weedy sunflower (Helianthus annuus)

Singh

Etheredge

McGinty

et al. 2020

Pest Management Science

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BACKGROUND: Weedy sunflower (Helianthus annuus L.) is a troublesome weed in row-crop production fields in South Texas. Populations with suspected resistance to glyphosate were evaluated with 1X and 4X rates (X = 868 g ae ha −1) of the herbicide, followed by a dose-response assay of the most resistant population. Molecular studies were conducted to determine if targetsite mechanisms were responsible for resistance in these populations. Additionally, field experiments were conducted at two locations (Somerville and Granger, TX) to evaluate the effectiveness of different tank-mix combinations in controlling naturally infesting glyphosate-resistant (GR) weedy sunflower populations in GR corn. RESULTS: In a study conducted in the growth chamber, seven of the 11 tested populations survived up to the 4X rate of glyphosate. The most-resistant population (TX15-11) was 29-fold more resistant to glyphosate, compared to the susceptible standard. In resistant populations, 5-21 more copies of the EPSPS gene were observed compared to the susceptible standard. In the field studies, tank-mix applications of glyphosate + halosulfuron-methyl, glyphosate + prosulfuron, glyphosate + a premix of halosulfuron-methyl and dicamba or glyphosate + a premix of diflufenzopyr and dicamba effectively controlled GR weedy sunflower populations. CONCLUSION: Glyphosate-resistance was observed in 81% of the putative resistant weedy sunflower populations tested in this study. Resistance in these populations was conferred primarily by amplification of the EPSPS gene. Effective control of GR weedy sunflower can be achieved by tank-mixes tested in the current study, which provides acceptable levels of crop safety.

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EPSPS gene amplification confers resistance to glyphosate resistant populations of Hordeum glaucum Stued (northern barley grass) in South Australia

Cited by 26 publications

References 46 publications

Mechanisms of evolved herbicide resistance

Mechanisms of evolved herbicide resistance

Resistance Evolution to EPSPS Inhibiting Herbicides in False Barley (Hordeum murinum) Harvested in Southern Spain

First case of glyphosate resistance in weedy sunflower (Helianthus annuus)

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