A double EPSPS gene mutation endowing glyphosate resistance shows a remarkably high resistance cost

Due to the overdependence on glyphosate to manage weeds in fallow conditions, glyphosate resistance has developed in various biotypes of several grass weeds, including Chloris virgata Sw. The first case of glyphosate resistance in C. virgata was found in 2015 in Australia, and since then several cases have been confirmed in several biotypes across Australia. Pot studies were conducted with 10 biotypes of C. virgata to determine glyphosate resistance levels. The biotypes were identified as either susceptible, moderately resistant or highly resistant based on the glyphosate dose required to kill 50% of plants. Two glyphosate-susceptible (GS) and two glyphosate-resistant (GR) biotypes were identified by the dose-response study and analyzed for the presence of target-site mutation in the 5–enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene. Performance of alternative herbicides to glyphosate as well as the double-knock herbicide approach was evaluated on the two GS (Ch and SGM2) and two GR (SGW2 and CP2) biotypes. Three herbicides, clethodim, haloxyfop and paraquat, were found to be effective (100% control) against all four biotypes when applied at the 4–5 leaf stage. All the sequential herbicide treatments, such as glyphosate followed by paraquat and glufosinate-ammonium followed by paraquat, provided 100% control of all four biotypes of C. virgata. This study identified effective herbicide options for the control of GR C. virgata and showed that target-site mutations were involved in the resistance of two biotypes to glyphosate (SGW2 and CP2). Results could aid farmers in selecting herbicides to manage C. virgata in their fields.

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The Triple Amino Acid Substitution TAP-IVS in the EPSPS Gene Confers High Glyphosate Resistance to the Superweed Amaranthus hybridus

International Journal of Molecular Sciences ◽

10.3390/ijms20102396 ◽

2019 ◽

Vol 20 (10) ◽

pp. 2396 ◽

Cited By ~ 15

Author(s):

Maria J. García ◽

Candelario Palma-Bautista ◽

Antonia M. Rojano-Delgado ◽

Enzo Bracamonte ◽

João Portugal ◽

...

Keyword(s):

Amino Acid ◽

Amino Acid Substitution ◽

Glyphosate Resistance ◽

Wild Type ◽

Triple Mutant ◽

Resistance Level ◽

Amaranthus Hybridus ◽

Susceptible Population ◽

Epsps Gene ◽

Wide Range

The introduction of glyphosate-resistant (GR) crops revolutionized weed management; however, the improper use of this technology has selected for a wide range of weeds resistant to glyphosate, referred to as superweeds. We characterized the high glyphosate resistance level of an Amaranthus hybridus population (GRH)—a superweed collected in a GR-soybean field from Cordoba, Argentina—as well as the resistance mechanisms that govern it in comparison to a susceptible population (GSH). The GRH population was 100.6 times more resistant than the GSH population. Reduced absorption and metabolism of glyphosate, as well as gene duplication of 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) or its overexpression did not contribute to this resistance. However, GSH plants translocated at least 10% more 14C-glyphosate to the rest of the plant and roots than GRH plants at 9 h after treatment. In addition, a novel triple amino acid substitution from TAP (wild type, GSH) to IVS (triple mutant, GRH) was identified in the EPSPS gene of the GRH. The nucleotide substitutions consisted of ATA102, GTC103 and TCA106 instead of ACA102, GCG103, and CCA106, respectively. The hydrogen bond distances between Gly-101 and Arg-105 positions increased from 2.89 Å (wild type) to 2.93 Å (triple-mutant) according to the EPSPS structural modeling. These results support that the high level of glyphosate resistance of the GRH A. hybridus population was mainly governed by the triple mutation TAP-IVS found of the EPSPS target site, but the impaired translocation of herbicide also contributed in this resistance.

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VERIFICATION OF THE MECHANISM OF GLYPHOSATE RESISTANCE IN ITALIAN RYEGRASS BIOTYPES

Planta Daninha ◽

10.1590/s0100-83582016340300017 ◽

2016 ◽

Vol 34 (3) ◽

pp. 565-573 ◽

Cited By ~ 3

Author(s):

L. VARGAS ◽

Q. RUCHEL ◽

D. AGOSTINETTO ◽

F.P. LAMEGO ◽

A.C. LANGARO ◽

...

Keyword(s):

Point Mutation ◽

Weed Control ◽

Glyphosate Resistance ◽

Italian Ryegrass ◽

Piperonyl Butoxide ◽

P450 Monooxygenase ◽

Epsps Gene ◽

Site Of Action

ABSTRACT The intense use of glyphosate for weed control led to the emergence of several cases of resistance to this herbicide. Weeds can survive the application of herbicides due to several factors, which may or may not be related to the herbicide site of action. The objectives of this study were to quantify the accumulation of shikimate in ryegrass biotypes in response to glyphosate application; investigate possible mutations on the EPSPs gene in susceptible and resistant biotypes; and evaluate the response of ryegrass biotypes to the application of glyphosate after treatment with a metabolism inhibitor of cyt P450 monooxygenase. The seeds of ryegrass biotypes with suspected resistance came from the municipality of São Valentim, RS (SVA 1 and SVA 4) and Passo Fundo, RS (PFU 5) and the seeds of the susceptible biotype (SVA 2), from São Valentim. The results demonstrated that, SVA biotype 2 accumulated more shikimate than any of the resistant biotypes, regardless of the herbicide dose used. The EPSPs gene showed no point mutation previously associated with the resistance to glyphosate, and the evaluated biotypes show no metabolism of glyphosate by the cyt P450 complex concerning inhibition by piperonyl butoxide (PBO) and malathion.

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No fitness cost of glyphosate resistance endowed by massive EPSPS gene amplification in Amaranthus palmeri

Planta ◽

10.1007/s00425-013-2022-x ◽

2014 ◽

Vol 239 (4) ◽

pp. 793-801 ◽

Cited By ~ 64

Author(s):

Martin M. Vila-Aiub ◽

Sou S. Goh ◽

Todd A. Gaines ◽

Heping Han ◽

Roberto Busi ◽

...

Keyword(s):

Gene Amplification ◽

Glyphosate Resistance ◽

Fitness Cost ◽

Amaranthus Palmeri ◽

Epsps Gene

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A Multistate Study of the Association Between Glyphosate Resistance and EPSPS Gene Amplification in Waterhemp (Amaranthus tuberculatus)

Weed Science ◽

10.1614/ws-d-14-00149.1 ◽

2015 ◽

Vol 63 (3) ◽

pp. 569-577 ◽

Cited By ~ 31

Author(s):

Laura A. Chatham ◽

Kevin W. Bradley ◽

Greg R. Kruger ◽

James R. Martin ◽

Micheal D. K. Owen ◽

...

Keyword(s):

Gene Amplification ◽

Copy Number ◽

Quantitative Relationship ◽

Glyphosate Resistance ◽

Epsps Gene ◽

Number Magnitude ◽

Site Of Action ◽

Amaranthus Tuberculatus ◽

Polymerase Chain ◽

The Relationship

Waterhemp is an increasingly problematic weed in the U.S. Midwest, having now evolved resistances to herbicides from six different site-of-action groups. Glyphosate-resistant waterhemp in the Midwest is especially concerning given the economic importance of glyphosate in corn and soybean production. Amplification of the target-site gene, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) was found to be the mechanism of glyphosate resistance in Palmer amaranth, a species closely related to waterhemp. Here, the relationship between glyphosate resistance and EPSPS gene amplification in waterhemp was investigated. Glyphosate dose response studies were performed at field sites with glyphosate-resistant waterhemp in Illinois, Kansas, Kentucky, Missouri, and Nebraska, and relative EPSPS copy number of survivors was determined via quantitative real-time polymerase chain reaction (qPCR). Waterhemp control increased with increasing glyphosate rate at all locations, but no population was completely controlled even at the highest rate (3,360 g ae ha−1). EPSPS gene amplification was present in plants from four of five locations (Illinois, Kansas, Missouri, and Nebraska) and the proportion of plants with elevated copy number was generally higher in survivors from glyphosate-treated plots than in plants from the untreated control plots. Copy number magnitude varied by site, but an overall trend of increasing copy number with increasing rate was observed in populations with gene amplification, suggesting that waterhemp plants with more EPSPS copies are more resistant. Survivors from the Kentucky population did not have elevated EPSPS copy number. Instead, resistance in this population was attributed to the EPSPS Pro106Ser mutation. Results herein show a quantitative relationship between glyphosate resistance and EPSPS gene amplification in some waterhemp populations, while highlighting that other mechanisms also confer glyphosate resistance in waterhemp.

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Evolved Glyphosate Resistance in Plants: Biochemical and Genetic Basis of Resistance

Weed Technology ◽

10.1614/wt-04-142r.1 ◽

2006 ◽

Vol 20 (2) ◽

pp. 282-289 ◽

Cited By ~ 153

Author(s):

Stephen B. Powles ◽

Christopher Preston

Keyword(s):

Amino Acid ◽

Resistance Mechanism ◽

Nuclear Gene ◽

Glyphosate Resistance ◽

The United States ◽

Resistance Mechanisms ◽

Italian Ryegrass ◽

Weed Species ◽

Epsps Gene ◽

Rigid Ryegrass

Resistance to the herbicide glyphosate is currently known in at least eight weed species from many countries. Some populations of goosegrass from Malaysia, rigid ryegrass from Australia, and Italian ryegrass from Chile exhibit target site–based resistance to glyphosate through changes at amino acid 106 of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene. Mutations change amino acid 106 from proline to either serine or threonine, conferring an EPSPS weakly resistant to glyphosate. The moderate level of resistance is sufficient for commercial failure of the herbicide to control these plants in the field. Conversely, a nontarget site resistance mechanism has been documented in glyphosate-resistant populations of horseweed and rigid ryegrass from the United States and Australia, respectively. In these resistant plants, there is reduced translocation of glyphosate to meristematic tissues. Both of these mechanisms are inherited as a single, nuclear gene trait. Although at present only two glyphosate-resistance mechanisms are known, it is likely that other mechanisms will become evident. The already very large and still increasing reliance on glyphosate in many parts of the world will inevitably result in more glyphosate-resistant weeds, placing the sustainability of this precious herbicide resource at risk.

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Prediction of glyphosate resistance level based on EPSPS gene copy number in Kochia scoparia

10.1101/047878 ◽

2016 ◽

Author(s):

Todd A. Gaines ◽

Abigail L. Barker ◽

Eric L. Patterson ◽

Philip Westra ◽

Eric P. Westra ◽

...

Keyword(s):

Gene Duplication ◽

Empirical Model ◽

Copy Number ◽

Gene Copy Number ◽

Glyphosate Resistance ◽

Gene Copy ◽

Kochia Scoparia ◽

Resistance Level ◽

Epsps Gene ◽

Fallow Systems

AbstractGlyphosate-resistant (GR) Kochia scoparia has evolved in dryland chemical fallow systems throughout North America and the mechanism involves 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene duplication. Sugarbeet fields in four states were surveyed for K. scoparia in 2013 and tested for glyphosate-resistance level and EPSPS gene copy number. Glyphosate resistance was confirmed in K. scoparia populations collected from sugarbeet fields in Colorado, Wyoming, and Nebraska. The GR samples all had increased EPSPS gene copy number, with median population values up to 11. An empirical model was developed to estimate the level of glyphosate-resistance in K. scoparia based on EPSPS gene copy number. The results suggested that glyphosate susceptibility can be accurately diagnosed using EPSPS gene copy number, and further increases in EPSPS gene copy number could increase resistance levels up to 8-fold relative to susceptible K. scoparia. These trends suggest that continued glyphosate selection pressure is selecting for higher EPSPS copy number and higher resistance levels in K. scoparia. By including multiple K. scoparia samples lacking EPSPS gene duplication, our empirical model provides a more realistic estimate of fold-resistance due to EPSPS gene copy number compared to methods that do not account for normal variation of herbicide response in susceptible biotypes.

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An intragenic approach to confer glyphosate resistance in chile (Capsicum annuum) by introducing an in vitro mutagenized chile EPSPS gene encoding for a glyphosate resistant EPSPS protein

PLoS ONE ◽

10.1371/journal.pone.0194666 ◽

2018 ◽

Vol 13 (4) ◽

pp. e0194666 ◽

Cited By ~ 3

Author(s):

Jose Luis Ortega ◽

Wathsala Rajapakse ◽

Suman Bagga ◽

Kimberly Apodaca ◽

Yvonne Lucero ◽

...

Keyword(s):

Capsicum Annuum ◽

Glyphosate Resistance ◽

Gene Encoding ◽

Epsps Gene

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EPSPS Gene Amplification is Present in the Majority of Glyphosate-Resistant Illinois Waterhemp (Amaranthus tuberculatus) Populations

Weed Technology ◽

10.1614/wt-d-14-00064.1 ◽

2015 ◽

Vol 29 (1) ◽

pp. 48-55 ◽

Cited By ~ 31

Author(s):

Laura A. Chatham ◽

Chenxi Wu ◽

Chance W. Riggins ◽

Aaron G. Hager ◽

Bryan G. Young ◽

...

Keyword(s):

Gene Amplification ◽

High Throughput Screening ◽

Glyphosate Resistance ◽

The State ◽

Molecular Test ◽

Molecular Assay ◽

Epsps Gene ◽

Whole Plant ◽

Alternative Means ◽

Amaranthus Tuberculatus

With the frequency of glyphosate-resistant waterhemp increasing throughout the Midwest, the identification of resistant populations has become important for managing this species. However, high-throughput screening for glyphosate resistance in the greenhouse is tedious and inefficient. Research was conducted to document the occurrence of glyphosate-resistant waterhemp throughout the state of Illinois, and to determine whether a molecular assay for 5-enolypyruvyl-shikimate-3-phosphate synthase (EPSPS) gene amplification can be used as an alternative means to detect resistant populations. Populations throughout the state of Illinois were collected in 2010 and screened for glyphosate resistance using a whole-plant assay in a greenhouse, and survivors were examined for EPSPS gene amplification. Of 80 populations investigated, 22 were glyphosate resistant based on the greenhouse screen, and gene amplification was identified in 20 (91%) of the resistant populations. Although there are multiple mechanisms for glyphosate resistance in waterhemp, a molecular test for EPSPS gene amplification provides a rapid alternative for identification of glyphosate resistance in most populations.

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