A Target-Site Point Mutation in Henbit (Lamium amplexicaule) Confers High-Level Resistance to ALS-Inhibitors

Weed Science ◽  
2016 ◽  
Vol 64 (2) ◽  
pp. 231-239 ◽  
Author(s):  
Vijay K. Varanasi ◽  
Amar S. Godar ◽  
Dallas E. Peterson ◽  
Doug Shoup ◽  
Mithila Jugulam
Keyword(s):  
Point Mutation ◽  
Resistance Index ◽  
Acetolactate Synthase ◽  
Common Mutation ◽  
First Case ◽  
Winter Annual ◽  
Rapid Amplification ◽  
Als Inhibitors ◽  
High Level ◽  
Dna Ends

Henbit is a facultative broadleaf winter annual in the Lamiaceae family. Acetolactate synthase (ALS) inhibitors are primarily used to control a broad spectrum of weeds, including henbit. During 2012 to 2013, field applications of ALS-inhibiting herbicides were ineffective in controlling a henbit population from Marion County, KS (MCK). To confirm field-evolved resistance to ALS inhibitors, response of MCK henbit and a known susceptible henbit population from Kansas (DPS) to varying doses of three different ALS inhibitors were examined: chlorsulfuron, imazamox, and propoxycarbazone. Results of the dose–response experiments suggest that the MCK population is highly resistant to chlorsulfuron (resistance index [R/S] > 1,000) and propoxycarbazone (R/S = 331) but is susceptible to imazamox. A full-lengthALSgene sequence obtained using the 5′- and 3′- rapid amplification of complementary DNA ends approach revealed a Pro197to Arg point mutation (a common mutation that confers resistance to sulfonylurea herbicides, e.g., chlorsulfuron) in the MCK henbit. No other known resistance-conferring mutations were found in the study. Evolved resistance to major classes of ALS inhibitors in the MCK henbit will reduce herbicide options for its control. To our knowledge, this is the first case of evolution of herbicide resistance in henbit.

scholarly journals Confirmation and Characterization of the First Case of Acetolactate Synthase (ALS)-Inhibitor—Resistant Wild Buckwheat (Polygonum convolvulus L.) in the United States

Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1496
Author(s):  
Balaji Aravindhan Pandian ◽  
Abigail Friesen ◽  
Martin Laforest ◽  
Dallas E. Peterson ◽  
P. V. Vara Prasad ◽  
...  
Keyword(s):  
Acetolactate Synthase ◽  
The United States ◽  
Cross Resistance ◽  
Wheat Field ◽  
Wild Buckwheat ◽  
Polygonum Convolvulus ◽  
First Case ◽  
Als Inhibitors ◽  
High Level ◽  
Als Inhibitor

Wild buckwheat (Polygonum convolvulus L.) is a problem weed and ALS-inhibitors (e.g., chlorsulfuron) are commonly used for its management. Recently, a population of wild buckwheat (KSW-R) uncontrolled with ALS-inhibitors was found in a wheat field in Kansas, USA. The objectives of this research were to determine the level and mechanism of resistance to chlorsulfuron and cross resistance to other ALS-inhibitors in the KSW-R population. In response to chlorsulfuron rates ranging from 0 to 16x (x = 18 g ai/ha), the KSW-R wild buckwheat was found >100-fold more resistant compared to a known ALS-inhibitor susceptible (KSW-S) wild buckwheat. Also, >90% of KSW-R plants survived field recommended rates of sulfonylurea but not imidazolinone family of ALS-inhibitors. A portion of the ALS gene covering all previously reported mutations known to bestow resistance to ALS-inhibitors was sequenced from both KSW-R and KSW-S plants. The Pro-197-Ser substitution that confers resistance to the sulfonylurea herbicides was found in KSW-R plants. Our results support the evolution of high level of chlorsulfuron resistance as a result of a mutation in the ALS-gene in KSW-R buckwheat. This is the first case of resistance to any herbicides in wild buckwheat in the US.

Multiple resistance to PPO and ALS inhibitors in redroot pigweed (Amaranthus retroflexus)

Weed Science ◽  
2019 ◽  
pp. 1-8
Author(s):  
Hao Wang ◽  
Hengzhi Wang ◽  
Ning Zhao ◽  
Baolin Zhu ◽  
Penglei Sun ◽  
...  
Keyword(s):  
Resistance Mechanism ◽  
Resistance Index ◽  
Acetolactate Synthase ◽  
Amaranthus Retroflexus ◽  
Target Site ◽  
Multiple Resistance ◽  
Redroot Pigweed ◽  
First Case ◽  
Als Inhibitors

Abstract A redroot pigweed (Amaranthus retroflexus L.) population (HN-02) collected from Nenjiang County, Heilongjiang Province, exhibited multiple resistance to fomesafen and nicosulfuron. The purposes of this study were to characterize the herbicide resistance status of an HN-02 population for both acetolactate synthase (ALS) and protoporphyrinogen oxidase (PPO) inhibitors and the response to other herbicides and to investigate the target site-based mechanism governing fomesafen and nicosulfuron resistance. Three mutations, Ala-205-Val and Trp-574-Leu mutations in the ALS gene and an Arg-128-Gly mutation in the PPX2 gene, were identified in individual resistant plants. An HN-02F1-1 subpopulation homozygous for the Ala-205-Val and Arg-128-Gly mutations was generated, and whole-plant experiments confirmed multiple resistance to PPO inhibitors (fomesafen, fluoroglycofen-ethyl, and acifluorfen) and ALS inhibitors (imidazolinones [IMI], sulfonylureas [SU], and triazolopyrimidines [TP]) in the HN-02F1-1 plants, which presented resistance index values ranging from 8.3 to 110; however, these plants were sensitive to flumioxazin, fluroxypyr-meptyl, and 2,4-D butylate. In vitro ALS enzyme activity assays revealed that, compared with ALS from susceptible plants, ALS from the HN-02F1-1 plants was 15-, 28- and 320-fold resistant to flumetsulam, nicosulfuron, and imazethapyr, respectively. This study confirms the first case of multiple resistance to PPO and ALS inhibitors in A. retroflexus and determines that the target-site resistance mechanism was produced by Ala-205-Val and Arg-128-Gly mutations in the ALS gene and PPX2 gene, respectively. In particular, the Ala-205-Val mutation was found to endow resistance to three classes of ALS inhibitors: TP, SU, and IMI.

scholarly journals Target Site Resistance to Acetolactate Synthase Inhibitors in Diplotaxis erucoides and Erucaria hispanica–Mechanism of Resistance and Response to Alternative Herbicides

Agronomy ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 471 ◽  
Author(s):  
Maor Matzrafi ◽  
Ofri Gerson ◽  
Moshe Sibony ◽  
Baruch Rubin
Keyword(s):  
Management Strategies ◽  
Acetolactate Synthase ◽  
Poor Control ◽  
First Case ◽  
Evolution Of Resistance ◽  
Target Site Resistance ◽  
Excellent Control ◽  
Diplotaxis Erucoides ◽  
Als Inhibitors ◽  
Two Populations

Diplotaxis erucoides and Erucaria hispanica are common weeds of the Mediterranean region; they infest various habitats including cultivated fields and roadsides. In several fields across Israel, farmers have reported on poor control of D. erucoides and E. hispanica plants using acetolactate synthase (ALS) inhibitors. Greenhouse experiments were conducted to determine the effect of various ALS inhibitors on plants from two potentially resistant D. erucoides and E. hispanica populations. Additionally, alternative management strategies using auxinic herbicides were studied. Plants from both populations exhibited resistance to all tested ALS inhibitors, up to 20-fold the label field rate, as compared with ALS sensitive populations of D. erucoides and E. hispanica. Sequencing of the ALS gene revealed Trp574 to Leu substitution in ALS-resistant D. erucoides plants, whereas a Pro197 to Ser substitution was detected in ALS-resistant E. hispanica plants. Although high levels of resistance were observed in individuals from both putative resistant populations, sensitive individuals were also detected, suggesting the evolution of resistance in these two populations is still in progress. Auxinic herbicides, 2,4-D, and mecoprop-P, provided excellent control of plants from both ALS-resistant populations. This study documents and confirms the first case of evolution of resistance to ALS inhibitors in D. erucoides and E. hispanica populations.

Molecular Basis of Resistance to Tribenuron in Water Starwort (Myosoton aquaticum) Populations from China

Weed Science ◽  
2013 ◽  
Vol 61 (3) ◽  
pp. 390-395 ◽  
Author(s):  
Weitang Liu ◽  
Yaling Bi ◽  
Lingxu Li ◽  
Guohui Yuan ◽  
Jinxin Wang
Keyword(s):  
Molecular Basis ◽  
Inhibitory Concentration ◽  
Acetolactate Synthase ◽  
Susceptible Population ◽  
Documented Case ◽  
Whole Plant ◽  
Winter Annual ◽  
High Level ◽  
Plant Bioassays

Populations of water starwort, a winter annual or biennial weed in the pink family (Caryophyllaceae), can no longer be controlled by tribenuron following successive use of this herbicide over several years. Whole-plant bioassays have established that the resistant water starwort populations JS17, JS08, JS16, and JS07 showed high-level (from 203-fold to 565-fold) resistance to tribenuron. In vitro acetolactate synthase (ALS) assays revealed that resistance was due to reduced sensitivity of the ALS enzyme to tribenuron. The half-maximal inhibitory concentration (I50) values for JS17, JS08, JS16, and JS07 were 72, 71, 70, and 76 times greater, respectively, than were those of the susceptible population JS24. This altered ALS sensitivity in the resistant populations was due to a mutation in the ALS gene resulting in a Pro197to Ser substitution (JS17, JS08, and JS16) and a Pro197to Leu substitution (JS07). This study established the first documented case, to our knowledge, of evolved tribenuron resistance in water starwort and concluded that the molecular basis of resistance is due, at least in part, to a target-site modification at Pro197in the ALS gene.

Multiple herbicide-resistant Palmer amaranth (Amaranthus palmeri) in Connecticut: confirmation and response to POST herbicides

2021 ◽  
pp. 1-7
Author(s):  
Jatinder S. Aulakh ◽  
Parminder S. Chahal ◽  
Vipan Kumar ◽  
Andrew J. Price ◽  
Karl Guillard
Keyword(s):  
Cropping Systems ◽  
Acetolactate Synthase ◽  
Palmer Amaranth ◽  
Effective Control ◽  
Herbicide Resistant ◽  
First Case ◽  
Whole Plant ◽  
Chlorimuron Ethyl ◽  
Als Inhibitors ◽  
Als Inhibitor

Abstract Palmer amaranth is the latest pigweed species documented in Connecticut; it was identified there in 2019. In a single-dose experiment, the Connecticut Palmer amaranth biotype survived the field-use rates of glyphosate (840 g ae ha−1) and imazaquin (137 g ai ha−1) herbicides applied separately. Additional experiments were conducted to (1) determine the level of resistance to glyphosate and acetolactate synthase (ALS) inhibitors in the Connecticut-resistant (CT-Res) biotype using whole-plant dose-response bioassays, and (2) evaluate the response of the CT-Res biotype to POST herbicides commonly used in Connecticut cropping systems. Based on the effective dose required for 90% control (ED90), the CT-Res biotype was 10-fold resistant to glyphosate when compared with the Kansas-susceptible (KS-Sus) biotype. Furthermore, the CT-Res biotype was highly resistant to ALS-inhibitor herbicides; only 18% control was achieved with 2,196 g ai ha−1 imazaquin. The CT-Res biotype was also cross-resistant to other ALS-inhibitor herbicides, including chlorimuron-ethyl (13.1 g ai ha−1), halosulfuron-methyl (70 g ai ha−1), and sulfometuron-methyl (392 g ai ha−1). The CT-Res Palmer amaranth was controlled 75% to 100% at 21 d after treatment (DAT) with POST applications of 2,4-D (386 g ae ha−1), carfentrazone-ethyl (34 g ai ha−1), clopyralid (280 g ae ha−1), dicamba (280 g ae ha−1), glufosinate (595 g ai ha−1), lactofen (220 g ai ha−1), oxyfluorfen (1,121g ai ha−1), and mesotrione (105 g ai ha−1) herbicides. Atrazine (2,240 g ai ha−1) controlled the CT-Res biotype only 52%, suggesting the biotype is resistant to this herbicide as well. Here we report the first case of Palmer amaranth from Connecticut with multiple resistance to glyphosate and ALS inhibitors. Growers should proactively use all available weed control tactics, including the use of effective PRE and alternative POST herbicides (tested in this study), for effective control of the CT-Res biotype.

Resistance to acetolactate synthase inhibitors and quinclorac in a biotype of false cleavers (Galium spurium)

Weed Science ◽  
1998 ◽  
Vol 46 (4) ◽  
pp. 390-396 ◽  
Author(s):  
Linda M. Hall ◽  
Kim M. Stromme ◽  
Geoff P. Horsman ◽  
Malcolm D. Devine
Keyword(s):  
Herbicide Resistance ◽  
Acetolactate Synthase ◽  
Field Analysis ◽  
Cross Resistance ◽  
Weed Species ◽  
Mechanism Of Resistance ◽  
Als Inhibitors ◽  
High Level ◽  
Galium Spurium ◽  
Moderately Resistant

A false cleavers population that survived treatment with triasulfuron/bromoxynil in 1996 was identified in central Alberta, Canada, in a field that had been treated with acetolactate synthase (ALS) inhibitors in 3 of the previous 6 yr. In greenhouse studies, this biotype was highly resistant to the ALS inhibitors triasulfuron, thifensulfuron/tribenuron, and sulfometuron and moderately resistant to imazethapyr; GR50, values were > 16, > 5, > 1.0, and 9.9, respectively. In addition, cross-resistance was identified to the auxin-type herbicide quinclorac (GR50 value > 6.7) but not to fluroxypyr (GR50 value 1) or MCPA/mecoprop/dicamba. Quinclorac had not been used previously in this field. Analysis of ALS extracted from the resistant biotype and a susceptible biotype from a nearby location indicated that resistance to ALS inhibitors was due to an altered target site with reduced sensitivity to a broad range of ALS inhibitors. The ALS I50 values for triasulfuron, metsulfuron, chlorsulfuron, thifensulfuron, and imazethapyr were 36, 34, 92, 96, and 14 times higher, respectively, for the resistant compared to the susceptible biotype. The mechanism of resistance to quinclorac is unknown. This is the first report of high-level herbicide resistance in this weed species.

Cross-Resistance of Eclipta (Eclipta prostrata) in China to ALS Inhibitors Due to a Pro-197-Ser Point Mutation

Weed Science ◽  
2017 ◽  
Vol 65 (5) ◽  
pp. 547-556 ◽  
Author(s):  
Dan Li ◽  
Xiangju Li ◽  
Huilin Yu ◽  
Jingjing Wang ◽  
Hailan Cui
Keyword(s):  
Gene Sequence ◽  
Resistance Index ◽  
Acetolactate Synthase ◽  
Cross Resistance ◽  
Eclipta Prostrata ◽  
Whole Plant ◽  
Plant Assays ◽  
Als Inhibitors ◽  
Als Inhibitor

Eclipta, widespread in tropical, subtropical, and temperate regions, is one of the main malignant broadleaf weeds and thrives in moist and dryland fields. Field rates of acetolactate synthase (ALS) inhibitors have failed to control eclipta in some farmlands in China. One ALS inhibitor–resistant population (R) collected from Jiangsu province in China was confirmed in the greenhouse in our preliminary work. Whole-plant assays revealed that this R population was highly resistant to four sulfonylureas (pyrazosulfuron-ethyl, 134-fold; bensulfuron-methyl, 172-fold; metsulfuron-methyl, 30-fold; and tribenuron-methyl, 195-fold), two triazolopyrimidines (pyroxsulam, 98-fold; penoxsulam, 30-fold), and one pyrimidinylthio-benzoate (bispyribac-sodium, 166-fold) and was moderately resistant to two imidazolinones (imazethapyr, 10-fold; imazapic, 19-fold). ALS enzyme-activity assays showed insensitivity of the ALS from the R population (resistance index values ranged from 12 to 293) to all of the above ALS inhibitors in vitro. Chromatograms fromALSgene sequence analysis detected a homozygous Pro-197-Ser amino acid substitution in the R population. These results confirmed that the Pro-197-Ser substitution results in broad-spectrum cross-resistance to ALS inhibitors in the eclipta R population. To our knowledge, this study is the first to report broad cross-resistance to ALS inhibitors in eclipta and to obtain the full-lengthALSgene sequence.

scholarly journals ALS Gene Mutations in Apera Spica-Venti Confer Broad-Range Resistance to Herbicides

2011 ◽  
Vol 51 (3) ◽  
pp. 261-267 ◽  
Author(s):  
Michał Krysiak ◽  
Stanisław Gawroński ◽  
Kazimierz Adamczewski ◽  
Roman Kierzek
Keyword(s):  
Gene Mutations ◽  
Pcr Amplification ◽  
Acetolactate Synthase ◽  
Nucleotide Polymorphisms ◽  
Molecular Tests ◽  
Whole Plant ◽  
Plant Bioassay ◽  
Resistance To Herbicides ◽  
Als Inhibitors ◽  
High Level

ALS Gene Mutations in Apera Spica-Venti Confer Broad-Range Resistance to Herbicides Several biotypes of wind bentgrass in Poland have been identified as being resistant to acetolactate synthase (ALS) inhibitors. We screened these weeds with chlorsulfuron and performed a whole-plant bioassay with a range of doses based on these four herbicides: chlorsulfuron, sulfosulfuron, propoxycarbazone-sodium and mesosulfuron-methyl + iodosulfuron-methyl-sodium mixture. Ten biotypes, diverse in their levels of resistance, were submitted for molecular tests. PCR amplification and sequencing of als domains demonstrated numerous single nucleotide polymorphisms. Nine biotypes showed non-synonymous substitutions in codon Pro197, changing it to Ser or Thr. Mutation in Pro197 conferred a high level of resistance to the tested herbicides. Analysis of four biotypes also revealed a substitution in the Ala122 codon, changing it to Val. In one biotype this substitution was not accompanied by Pro197 mutation and this biotype was resistant to chlorsulfuron and mesosulfuron + iodosulfuron, but not to sulfosulfuron or propoxycarbazone-sodium. Correspondence between mutations and levels of resistan ce to ALS inhibitors may support management of resistant weeds with the existing palette of herbicides.

ALS resistance in several smooth pigweed (Amaranthus hybridus) biotypes

Weed Science ◽  
2006 ◽  
Vol 54 (5) ◽  
pp. 828-832 ◽  
Author(s):  
Cory M. Whaley ◽  
Henry P. Wilson ◽  
James H. Westwood
Keyword(s):  
Acetolactate Synthase ◽  
Amino Acid Position ◽  
Cross Resistance ◽  
Similar Response ◽  
Somerset County ◽  
Increased Sensitivity ◽  
Plant Level ◽  
Als Inhibitors ◽  
High Level ◽  
Smooth Pigweed

Experiments were conducted to identify acetolactate synthase (ALS, EC 2.2.1.6 [formerly EC 4.1.3.18]) mutation sites in eight biotypes of smooth pigweed and correlate these mutations with patterns of herbicide cross-resistance. Four herbicide-resistant smooth pigweed biotypes (R5, R6, R7, R8) collected from fields in Virginia, Delaware, and Maryland, showed a similar response to postemergence applications of the ALS-inhibitors imazethapyr, pyrithiobac, chlorimuron, thifensulfuron, and cloransulam. These R biotypes ranged from 261- to 537-fold resistant to imazethapyr and 29- to 88-fold resistant to pyrithiobac. The biotypes also had reduced sensitivity to chlorimuron and thifensulfuron of 2- to 14-fold and 10- to 25-fold, respectively, relative to a susceptible smooth pigweed biotype (S). Biotypes R6, R7, and R8 had reduced sensitivity of 3- to 10-fold to cloransulam relative to the S biotype, whereas R5 had increased sensitivity. All of these biotypes were found to have a serine to asparagine substitution at amino acid position 653, as numbered relative to the protein sequence ofArabidopsis thaliana. This stands in contrast to four other imidazolinone (IMI)-resistant smooth pigweed biotypes (R1, R2, R3, R4) that were collected from fields in Somerset County, Maryland. These biotypes were found to have an alanine to threonine substitution at position 122 of the ALS enzyme and were previously characterized at the whole-plant level with high-level resistance to IMI herbicides, increased sensitivity to pyrimidinylthiobenzoate and triazolopyrimidine sulfonanilide herbicides, and low to no cross-resistance to sulfonylurea herbicides.

scholarly journals Characterization of Acetolactate Synthase (ALS)-Inhibitor Resistance in Pennsylvania smartweed (Persicaria pensylvanica)

Weed Science ◽  
2018 ◽  
Vol 66 (6) ◽  
pp. 710-714
Author(s):  
Vijay K. Varanasi ◽  
Jason K. Norsworthy ◽  
Chad Brabham ◽  
Robert C. Scott
Keyword(s):  
United States ◽  
Resistance Mechanism ◽  
Resistance Index ◽  
Acetolactate Synthase ◽  
Reduced Tillage ◽  
Tillage Systems ◽  
Als Inhibitors ◽  
Inhibitor Resistance ◽  
Als Inhibitor

AbstractPennsylvania smartweed [Persicaria pensylvanica(L.) M. Gómez] is a common weed of rice (Oryza sativaL.) in the midsouthern United States and has recently become a concern for farmers because of reduced tillage systems. Acetolactate synthase (ALS) inhibitors have been extensively used for controlling smartweeds in imidazolinone-resistant and conventional rice. In the present study, we confirmed resistance to commonly used ALS inhibitors in rice and characterized the underlying resistance mechanism in aP. pensylvanicabiotype from southeast Missouri. A dose–response experiment was conducted in the greenhouse using bensulfuron-methyl, imazethapyr, and bispyribac-sodium to determine the resistance index (resistance/susceptibility [R/S]) based on GR50estimates. The target-siteALSgene was amplified from R and S plants, and sequences were analyzed for mutations known to confer ALS-inhibitor resistance. TheP. pensylvanicabiotype in question was found to be resistant to bensulfuron-methyl (R/S=2,330), imazethapyr (R/S=12), and bispyribac-sodium (R/S=6). Sequencing of theALSgene from R plants revealed two previously known mutations (Pro-197-Ser, Ala-122-Ser) conferring resistance to sulfonylureas and imidazolinones. This is the first report of ALS-inhibitor resistance inP. pensylvanica.

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