scholarly journals Target site as the main mechanism of resistance to imazamox in a Euphorbia heterophylla biotype

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Antonia M. Rojano-Delgado ◽  
João M. Portugal ◽  
Candelario Palma-Bautista ◽  
Ricardo Alcántara-de la Cruz ◽  
Joel Torra ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Root Exudation ◽  
Acetolactate Synthase ◽  
Target Site ◽  
Southern Brazil ◽  
Fresh Weight ◽  
Weed Species ◽  
Site Mutation ◽  
Principal Mechanism ◽  
Continuous Use

Abstract Euphorbia heterophylla is a weed species that invades extensive crop areas in subtropical regions of Brazil. This species was previously controlled by imazamox, but the continuous use of this herbicide has selected for resistant biotypes. Two biotypes of E. heterophylla from southern Brazil, one resistant (R) and one susceptible (S) to imazamox, were compared. The resistance of the R biotype was confirmed by dose-response assays since it required 1250.2 g ai ha−1 to reduce the fresh weight by 50% versus 7.4 g ai ha−1 for the S biotype. The acetolactate synthase (ALS) enzyme activity was studied using ALS-inhibiting herbicides from five different chemical families. The R biotype required the highest concentrations to reduce this enzyme activity by 50%. A Ser653Asn mutation was found in the ALS gene of the R biotype. The experiments carried out showed that imazamox absorption and metabolism were not involved in resistance. However, greater 14C-imazamox root exudation was found in the R biotype (~70% of the total absorbed imazamox). Target site mutation in the ALS gene is the principal mechanism that explains the imazamox resistance of the R biotype, but root exudation seems to also contribute to the resistance of this biotype.

Molecular Basis of Resistance to Herbicides Inhibiting Acetolactate Synthase in Two Rigid Ryegrass (Lolium rigidum) Populations from Australia

Weed Science ◽  
2012 ◽  
Vol 60 (2) ◽  
pp. 172-178 ◽  
Author(s):  
Shiv S. Kaundun ◽  
Richard P. Dale ◽  
Géraldine C. Bailly
Keyword(s):  
Molecular Basis ◽  
Molecular Mechanisms ◽  
Codon Position ◽  
Acetolactate Synthase ◽  
Target Site ◽  
Weed Species ◽  
Site Mutation ◽  
Sulfometuron Methyl ◽  
Whole Plant ◽  
Field Samples

Acetolactate Synthase- (ALS) inhibiting herbicides are important components for the control of ryegrass species infesting cereal-cropping systems worldwide. Although resistance to ALS herbicides in ryegrasses has evolved more than 25 yr ago, few studies have been dedicated to elucidate the molecular mechanisms involved. To this end, we have investigated the molecular basis of chlorsulfuron, sulfometuron-methyl, and imazapyr resistance in AUS5 and AUS23, two ryegrass populations from Australia. Comparison between whole-plant herbicide assays and DNA sequencing results showed that resistance to the nonmetabolizable herbicide sulfometuron-methyl was associated with four different proline mutations at ALS codon position 197 (P197) in AUS23. In addition to three P197 amino acid changes impacting on the efficacies of the two sulfonylurea herbicides, the tryptophan to leucine target-site mutation at ALS codon position 574 (W574L) was present in AUS5, conferring resistance to both sulfometuron-methyl and imazapyr. The samples were also characterized by non target-site-based resistance impacting on the metabolizable herbicide chlorsulfuron only. Interestingly, compound mutant heterozygotes threonine/serine at ALS position 197, and plants with double mutations at positions 197 and 574 were detected, thus reflecting the ability of this outcrossing species to accumulate mutant alleles. Whole-plant dose-response assays conducted on predetermined wild-type and mutant genotypes originating from the same populations allowed for a more precise estimation of the dominant and very high levels of resistance associated with the proline to serine target-site mutation at ALS codon position 197 (P197S) and W574L mutations. The two highly efficient polymerase chain reaction- (PCR) based derived cleaved amplified polymorphic sequence (dCAPS) markers developed here will allow for quick confirmation of 197 and 574 ALS target-site resistance in ryegrass species field samples and also contribute to identify populations characterized by other likely resistance mechanisms in this important weed species.

scholarly journals A Trp574Leu Target-Site Mutation Confers Imazamox Resistance in Multiple Herbicide-Resistant Wild Poinsettia Populations from Brazil

Agronomy ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1057 ◽  
Author(s):  
Rafael R. Mendes ◽  
Hudson K. Takano ◽  
Rubem S. Oliveira ◽  
Fernando S. Adegas ◽  
Todd A. Gaines ◽  
...  
Keyword(s):  
Acetolactate Synthase ◽  
Southern Brazil ◽  
Weed Species ◽  
Site Mutation ◽  
Protoporphyrinogen Oxidase ◽  
Herbicide Resistant ◽  
High Concentrations ◽  
Als Inhibitors ◽  
Biomass Reduction

Wild poinsettia (Euphorbia heterophylla L.) is an important weed species in southern Brazil, especially due to the evolution of multiple herbicide resistance (e.g., acetolactate synthase (ALS)- inhibitors, protoporphyrinogen oxidase inhibitors, and glyphosate). The mechanism of resistance to imazamox was investigated in two wild poinsettia populations (R1 and R2) from southern Brazil and compared to a known susceptible (S) population. Imazamox dose-response experiments revealed high levels of resistance: 45-fold and 224.5-fold based on dry biomass reduction, for R1 and R2, respectively. Extremely high concentrations of imazamox (20,000 µM) were not sufficient to provide 50% inhibition of ALS enzyme activity (I50) for R1 or R2. Hence, resistance levels were estimated to be greater than 123-fold for both populations based on in vitro ALS assays. The ALS gene from all R1 and R2 plants had a Trp574Leu mutation. A genotyping assay was developed to discriminate resistant and susceptible alleles based on the Trp574Leu mutation.

scholarly journals The response of weedy sunflower (Helianthus annuus L.) to nicosulfuron: An examination of vegetative parameters and acetolactate synthase activity

2019 ◽  
Vol 71 (2) ◽  
pp. 305-313
Author(s):  
Dragana Bozic ◽  
Marija Saric-Krsmanovic ◽  
Ana Matkovic ◽  
Filip Vranjes ◽  
Snezana Jaric ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Genetic Variability ◽  
Helianthus Annuus ◽  
Acetolactate Synthase ◽  
Fresh Weight ◽  
Weed Species ◽  
Row Crops ◽  
Helianthus Annuus L ◽  
Interpopulation Variability

Genetic and morphological interpopulation variability of weed species is often responsible for variable responses to herbicides. As weedy sunflower, an invasive form of Helianthus annuus L., possesses high morphological and genetic variability, very different responses of its populations to herbicides can be expected. This species is one of the dominant weed species in row crops, including maize, in many European countries in which nicosulfuron is intensively used for weed control. There are little available data about the response of this sunflower form to nicosulfuron or of the interpopulation variability of its response to other herbicides. The responses of three weedy sunflower populations to nicosulfuron were studied in field dose-response experiments, and acetolactate synthase (ALS) enzyme activity at different herbicide concentrations was determined in vitro. Interpopulation variability in the response to nicosulfuron was confirmed. Populations WS2 and WS3 were more that 20-fold and 30-fold less susceptible to nicosulfuron, respectively, than population WS1, based on fresh weight, whereas the differences were not so prominent based on other parameters, including plant height, leaf area and ALS activity, and ranged from 2 to 12-fold.

scholarly journals Point Mutations as Main Resistance Mechanism Together With P450-Based Metabolism Confer Broad Resistance to Different ALS-Inhibiting Herbicides in Glebionis coronaria From Tunisia

2021 ◽  
Vol 12 ◽  
Author(s):  
Zeineb Hada ◽  
Yosra Menchari ◽  
Antonia M. Rojano-Delgado ◽  
Joel Torra ◽  
Julio Menéndez ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Dose Response ◽  
Resistance Mechanism ◽  
Point Mutations ◽  
Acetolactate Synthase ◽  
Target Site ◽  
Cross Resistance ◽  
P450 Monooxygenase ◽  
Target Site Resistance ◽  
Sites Of Action

Resistance to acetolactate synthase (ALS) inhibiting herbicides has recently been reported in Glebionis coronaria from wheat fields in northern Tunisia, where the weed is widespread. However, potential resistance mechanisms conferring resistance in these populations are unknown. The aim of this research was to study target-site resistance (TSR) and non-target-site resistance (NTSR) mechanisms present in two putative resistant (R) populations. Dose–response experiments, ALS enzyme activity assays, ALS gene sequencing, absorption and translocation experiments with radiolabeled herbicides, and metabolism experiments were carried out for this purpose. Whole plant trials confirmed high resistance levels to tribenuron and cross-resistance to florasulam and imazamox. ALS enzyme activity further confirmed cross-resistance to these three herbicides and also to bispyribac, but not to flucarbazone. Sequence analysis revealed the presence of amino acid substitutions in positions 197, 376, and 574 of the target enzyme. Among the NTSR mechanisms investigated, absorption or translocation did not contribute to resistance, while evidences of the presence of enhanced metabolism were provided. A pretreatment with the cytochrome P450 monooxygenase (P450) inhibitor malathion partially synergized with imazamox in post-emergence but not with tribenuron in dose–response experiments. Additionally, an imazamox hydroxyl metabolite was detected in both R populations in metabolism experiments, which disappeared with the pretreatment with malathion. This study confirms the evolution of cross-resistance to ALS inhibiting herbicides in G. coronaria from Tunisia through TSR and NTSR mechanisms. The presence of enhanced metabolism involving P450 is threatening the chemical management of this weed in Tunisian wheat fields, since it might confer cross-resistance to other sites of action.

scholarly journals Multiple-Herbicide Resistance in a 2,4-D–Resistant Waterhemp (Amaranthus tuberculatus) Population from Nebraska

Weed Science ◽  
2017 ◽  
Vol 65 (6) ◽  
pp. 743-754 ◽  
Author(s):  
Roberto J. Crespo ◽  
Ana B. Wingeyer ◽  
Greg R. Kruger ◽  
Chance W. Riggins ◽  
Patrick J. Tranel ◽  
...  
Keyword(s):  
D1 Protein ◽  
Acetolactate Synthase ◽  
Mechanisms Of Action ◽  
Target Site ◽  
Site Mutation ◽  
Auxin Receptor ◽  
Application Rates ◽  
Chlorimuron Ethyl ◽  
Als Inhibitors ◽  
Susceptible Populations

A 2,4-D-resistant tall waterhemp population (FS) from Nebraska was evaluated for resistance to other TIR1 auxin receptor herbicides and to herbicides having alternative mechanisms of action using greenhouse bioassays and genetic markers. Atrazine, imazethapyr, lactofen, mesotrione, glufosinate, and glyphosate were applied in a single-dose bioassay, and tissue was collected from marked plants for genetic analysis. The FS population was not injured by atrazine or by imazethapyr. Approximately 50% of the plants survived lactofen and were actively growing 28 d after treatment. The population was susceptible to mesotrione, glufosinate, and glyphosate. Ametryn, chlorimuron-ethyl, 2,4-D, aminocyclopyraclor, aminopyralid, and picloram were applied in dose–response studies. The FS population was sensitive to ametryn, and the Ser-264-Gly substitution in the D1 protein was not detected, suggesting the lack of response to atrazine is not due to a target-site mutation. The FS population exhibited less than 50% injury to chlorimuron-ethyl at application rates 20 times the labeled use rate. The Ser-653-Asn acetolactate synthase (ALS) substitution, which confers resistance to imidazolinone herbicides, was present in the FS population. However, this does not explain the lack of response to the sulfonylurea herbicide, chlorimuron-ethyl. Sequencing of a portion of thePPX2Lgene did not show the ΔG210 mutation that confers resistance to protoporphyrinogen oxidase–inhibiting herbicides, suggesting that other factors were responsible for waterhemp survival after lactofen application. The FS population was confirmed to be at least 30-fold resistant to 2,4-D relative to the susceptible populations. In addition, it was at least 3-fold less sensitive to aminopyralid and picloram, two other TIR1 auxin receptor herbicides, than the 2,4-D-susceptible populations were. These data indicated that the FS population contains both target and non–target site mechanisms conferring resistance to herbicides spanning at least three mechanisms of action: TIR1 auxin receptors, ALS inhibitors, and photosystem II inhibitors.

Acetolactate synthase inhibitor-resistant stinkweed (Thlaspi arvense L.) in Alberta

2007 ◽  
Vol 87 (4) ◽  
pp. 965-972 ◽  
Author(s):  
H. J. Beckie ◽  
L. M. Hall ◽  
F. J. Tardif ◽  
G. Séguin-Swartz
Keyword(s):  
Herbicide Resistance ◽  
Dominant Gene ◽  
Acetolactate Synthase ◽  
Target Site ◽  
Cross Resistance ◽  
Resistance Pattern ◽  
Site Mutation ◽  
Thlaspi Arvense ◽  
Synthase Inhibitor ◽  
Als Inhibitor

Two stinkweed populations from southern and central Alberta were not controlled by acetolactate synthase (ALS)-inhibiting herbicides in 2000. This study reports on their cross-resistance to ALS-inhibiting herbicides, molecular basis of resistance, and inheritance of resistance. Both putative herbicide-resistant biotypes responded similarly to increasing doses of the herbicides. The biotypes were highly resistant to ethametsulfuron and exhibited a low level of resistance to metsulfuron and imazethapyr. However, both biotypes were not resistant to florasulam, a triazolopyrimidine ALS inhibitor, or sulfometuron, a non-selective sulfonylurea ALS inhibitor. The cross-resistance pattern was consistent with the confirmed target-site mutation. Sequence analysis of the ALS gene detected a Pro197Leu mutation in both biotypes. Similar to many other ALS inhibitor-resistant weed biotypes, resistance was conferred by a single dominant gene. This study confirms the first global occurrence of herbicide resistance in this species. Key words: ALS-inhibitor resistance, ALS sequence, herbicide resistance, target-site mutation

Acetolactate Synthase (ALS) Target-Site Mutations in ALS Inhibitor-Resistant Russian Thistle (Salsola tragus)

Weed Science ◽  
2010 ◽  
Vol 58 (3) ◽  
pp. 244-251 ◽  
Author(s):  
Suzanne I. Warwick ◽  
Connie A. Sauder ◽  
Hugh J. Beckie
Keyword(s):  
Molecular Basis ◽  
Genome Structure ◽  
Acetolactate Synthase ◽  
Molecular Techniques ◽  
Target Site ◽  
Weed Species ◽  
Single Nucleotide ◽  
Herbicide Resistant ◽  
Inhibitor Resistance ◽  
Als Inhibitor

ALS inhibitor-resistant biotypes are the fastest growing class of herbicide-resistant (HR) weeds. A Canadian ALS inhibitor-resistant biotype of Russian thistle was first reported in 1989. The molecular basis for ALS-inhibitor resistance is unknown for Canadian populations of this polyploid weed species, and was determined in this study for one Alberta and two Saskatchewan HR Russian thistle populations. HR plants survived spray application of the ALS-inhibitor mixture thifensulfuron : tribenuron in the greenhouse. All three HR Russian thistle populations were heterogeneous and contained both HR and herbicide-susceptible (HS) individuals. The molecular basis for resistance was determined by sequencing theALSgene and/or conducting a TaqMan genotyping assay for single nucleotide polymorphism (SNP) for the Trp574Leu mutation. Two target-site mutations were observed: Trp574Leu in all three biotypes (554 individuals) and Pro197Gln in one biotype (one individual), suggesting multiple-founding events for Russian thistle HR populations in western Canada. Segregation patterns among F1 and F2 progeny arrays of HR lines sprayed under greenhouse conditions varied; some segregated (i.e., had HR and HS progeny), whereas other lines were exclusively HR. In contrast, no segregation of molecular types, i.e., Trp574, Trp/Leu574and Leu574, as would be expected with heterozygosity at a single locus Trp/Leu574, was observed. Such lack of segregation is consistent with the polyploid genome structure of Russian thistle and the presence of two copies of theALSgene. The presence of more than oneALSgene confounded the ability of the molecular techniques to accurately identify “true” heterozygotes in this study.

scholarly journals Molecular Basis of Evolved Resistance to Glyphosate and Acetolactate Synthase-Inhibitor Herbicides in Kochia (Kochia scoparia) Accessions from Montana

Weed Science ◽  
2015 ◽  
Vol 63 (4) ◽  
pp. 758-769 ◽  
Author(s):  
Vipan Kumar ◽  
Prashant Jha ◽  
Darci Giacomini ◽  
Eric P. Westra ◽  
Philip Westra
Keyword(s):  
Molecular Mechanisms ◽  
Conservation Tillage ◽  
Cropping Systems ◽  
Rapid Evolution ◽  
Acetolactate Synthase ◽  
Target Site ◽  
Northern Great Plains ◽  
Site Mutation ◽  
Als Inhibitor

The rapid evolution and spread of glyphosate-resistant (GR) kochia in the Northern Great Plains is an increasing threat to GR cropping systems and conservation tillage practices common in this region. GR kochia accessions with 4.6- to 11-fold levels of resistance to glyphosate have recently been reported in Montana. Those GR kochia accessions were also suspected to be resistant to acetolactate synthase (ALS) inhibitors, i.e., multiple herbicide-resistant (MHR) kochia. In this research, the level of resistance to the ALS-inhibitor herbicides (sulfonylureas) and the molecular mechanisms conferring resistance to glyphosate and ALS-inhibitor herbicides in MHR kochia was investigated. On the basis of whole-plant dose–response assays, MHR kochia accessions (GIL01, JOP01, and CHES01) were 9.3- to 30-fold more resistant to premixed thifensulfuron methyl + tribenuron methyl + metsulfuron methyl than the susceptible (SUS) accession. In an in vivo leaf-disk shikimate assay, MHR plants accumulated less shikimate than the SUS plants at a discriminate dose of 100 μM glyphosate. Sequencing of the conserved region ofEPSPSrevealed no target-site mutation at Thr102or Pro106residue. MHR kochia accessions had increased relativeEPSPSgene copies (~ 4 to 10) compared with the SUS accession (single copy). Furthermore, MHR kochia accumulated higher EPSPS protein compared with the SUS plants. Resistance to the ALS-inhibitor herbicides was conferred by Pro197amino acid substitution (proline to glutamine).EPSPSgene amplification and a single target-site mutation at Pro197inALSgene confer resistance to glyphosate and ALS-inhibitor herbicides, respectively, in MHR kochia accessions from Montana. This is the first confirmation of occurrence of MHR kochia in Montana.

scholarly journals Herbicide resistant weeds: the case of resistance to glyphosate

2021 ◽  
Vol 63 (2) ◽  
pp. 74-80
Author(s):  
The Duc Ngo ◽  
Keyword(s):  
Weed Management ◽  
Glyphosate Resistance ◽  
Resistance Mechanisms ◽  
Management Program ◽  
Ambrosia Artemisiifolia ◽  
Target Site ◽  
Integrated Weed Management ◽  
Weed Species ◽  
Site Mutation ◽  
Sites Of Action

Glyphosate has become the most widely used herbicide worldwide since 1974 with a global use of 8.6 billion kg (glyphosate active ingredient) between 1974 and 2014. This study reports on glyphosate resistant (GR) weeds and their resistance mechanisms based on global scientifically reported cases. Forty-nine different weed species have evolved resistance to glyphosate in 29 countries with a total of 318 identified cases worldwide. Fifty percent of these resistance cases were found in glyphosate-resistant cropping systems. There were 255 identified cases (80.2%) of glyphosate resistance in the top five countries (in terms of number of cases and species), namely USA, Australia, Argentina, Brazil, and Canada. The five most popular weed species (in terms of number of cases) found to be resistant to glyphosate were Conyza canadensis, Amaranthus palmeri, Amaranthus tuberculatus, Lolium perenne ssp. Multiflorum,and Ambrosia artemisiifolia with 42, 42, 29, 26, and 21 reported cases, respectively. Out of 49 weed species, 19 GR weed species were found to not only be resistant to glyphosate but also to other herbicide sites of action (multiple herbicide resistance). Glyphosate resistance mechanisms in weeds include (1) target-site alterations: target-site mutation and target-site gene amplification; and (2) non-target-site mechanisms involving different modes of exclusion from the target site: reduced glyphosate uptake, reduced glyphosate translocation, and enhanced glyphosate metabolism. It is essential to have an integrated weed management program that includes not only smart herbicide mixtures and rotations, but also cultural, manual, mechanical, and crop-based weed management methods.

scholarly journals Herbicide Resistance in Brazil: Status, Impacts, and Future Challenges

2020 ◽  
Author(s):  
Ricardo Alcántara-de la Cruz ◽  
Guilherme Moraes de Oliveira ◽  
Leonardo Bianco de Carvalho ◽  
Maria Fátima das Graças Fernandes da Silva
Keyword(s):  
Herbicide Resistance ◽  
Resistance Management ◽  
Acetolactate Synthase ◽  
Agricultural Activity ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Crop Fields ◽  
Future Challenges ◽  
High Selection ◽  
Continuous Use

Brazil is a large producer and exporter of crops in global terms. Weeds may be responsible for ~14% of crop losses, depending on the crop system. Herbicides occupy 58% of the Brazilian pesticide market; however, the continuous use of these products and the high selection pressure have led to the emergence of weeds resistant to herbicides. Today, there are 51 weed species reported as being resistant to herbicides in Brazil, of which 17 involves cross and multiple-resistance. Acetolactate synthase (ALS), acetyl coenzyme A carboxylase (ACCase) and 5-enolpiruvylshikimate-3-phosphate synthase (EPSPs) inhibitors are the herbicidal groups with the most resistance cases. Soybean, corn, rice, wheat and cotton present 30, 12, 10, 9 and 8 cases, respectively, occurring mainly in herbicide-resistant crop fields from the Southern and Central West regions of the country. To better understand the dimensions of herbicide resistance, in this chapter, we will explore the size of agricultural activity in Brazil, the pesticide market and the use of herbicides in the main crops. In addition, the agronomic, scientific-technical and economic aspects that have contributed, directly or indirectly, to the selection of resistant weeds will be discussed in order to have an overview of the economic impact of herbicide resistance management.

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