scholarly journals Nontarget-Site Resistance to ALS Inhibitors in Waterhemp (Amaranthus tuberculatus)

Weed Science ◽  
2015 ◽  
Vol 63 (2) ◽  
pp. 399-407 ◽  
Author(s):  
Jiaqi Guo ◽  
Chance W. Riggins ◽  
Nicholas E. Hausman ◽  
Aaron G. Hager ◽  
Dean E. Riechers ◽  
...  
Keyword(s):  
Acetolactate Synthase ◽  
Enzyme Assays ◽  
Whole Plant ◽  
Site Of Action ◽  
Amaranthus Tuberculatus ◽  
Resistance Trait ◽  
Als Inhibitors ◽  
Moderate Resistance ◽  
Inhibitor Resistance ◽  
Als Inhibitor

A waterhemp population (MCR) previously characterized as resistant to 4-hydroxyphenylpyruvate dioxygenase and photosystem II inhibitors demonstrated both moderate and high levels of resistance to acetolactate synthase (ALS) inhibitors. Plants from the MCR population exhibiting high resistance to ALS inhibitors contained the commonly found Trp574Leu ALS amino acid substitution, whereas plants with only moderate resistance did not have this substitution. A subpopulation (JG11) was derived from the MCR population in which the moderate-resistance trait was isolated from the Trp574Leu mutation. Results from DNA sequencing and ALS enzyme assays demonstrated that resistance to ALS inhibitors in the JG11 population was not due to an altered site of action. This nontarget-site ALS-inhibitor resistance was characterized with whole-plant dose–response experiments using herbicides from each of the five commercialized families of ALS-inhibiting herbicides. Resistance ratios ranging from 3 to 90 were obtained from the seven herbicides evaluated. Nontarget-site resistance to ALS has been rarely documented in eudicot weeds, and adds to the growing list of resistance traits evolved in waterhemp.

Transfer and Expression of ALS Inhibitor Resistance from Palmer Amaranth (Amaranthus palmeri) to anA. spinosus×A. palmeriHybrid

Weed Science ◽  
2016 ◽  
Vol 64 (2) ◽  
pp. 240-247 ◽  
Author(s):  
William T. Molin ◽  
Vijay K. Nandula ◽  
Alice A. Wright ◽  
Jason A. Bond
Keyword(s):  
Field Experiments ◽  
Acetolactate Synthase ◽  
Palmer Amaranth ◽  
Enzyme Assays ◽  
Amaranthus Palmeri ◽  
Weed Species ◽  
Als Inhibitors ◽  
Inhibitor Resistance ◽  
Als Inhibitor ◽  
Interspecific Transfer

Transfer of herbicide resistance among closely related weed species is a topic of growing concern. A spiny amaranth × Palmer amaranth hybrid was confirmed resistant to several acetolactate synthase (ALS) inhibitors including imazethapyr, nicosulfuron, pyrithiobac, and trifloxysulfuron. Enzyme assays indicated that the ALS enzyme was insensitive to pyrithiobac and sequencing revealed the presence of a known resistance conferring point mutation, Trp574Leu. Alignment of the ALS gene for Palmer amaranth, spiny amaranth, and putative hybrids revealed the presence of Palmer amaranth ALS sequence in the hybrids rather than spiny amaranth ALS sequences. In addition, sequence upstream of the ALS in the hybrids matched Palmer amaranth and not spiny amaranth. The potential for transfer of ALS inhibitor resistance by hybridization has been demonstrated in the greenhouse and in field experiments. This is the first report of gene transfer for ALS inhibitor resistance documented to occur in the field without artificial/human intervention. These results highlight the need to control related species in both field and surrounding noncrop areas to avoid interspecific transfer of resistance genes.

Multiple ALS Mutations Confer Herbicide Resistance in Waterhemp (Amaranthus tuberculatus)

Weed Science ◽  
2007 ◽  
Vol 55 (5) ◽  
pp. 421-428 ◽  
Author(s):  
William L. Patzoldt ◽  
Patrick J. Tranel
Keyword(s):  
Leaf Disc ◽  
Acetolactate Synthase ◽  
Cross Resistance ◽  
Whole Plant ◽  
Amaranthus Tuberculatus ◽  
Susceptible Control ◽  
Als Inhibitors ◽  
Als Inhibitor ◽  
Disc Assay

In a survey of herbicide responses among Illinois waterhemp half-sib populations, several were observed with differential responses to imazethapyr and thifensulfuron, two acetolactate synthase (ALS)–inhibiting herbicides. Plants from two waterhemp populations were verified resistant to imazethapyr, but susceptible to chlorimuron, using a nondestructive leaf-disc assay. Sequencing of the ALS gene revealed that imazethapyr-resistant waterhemp plants from both populations had inferred amino acid substitutions at position 653 of ALS. Depending on the population, the serine at position 653 of ALS was substituted with either asparagine (S653N) or threonine (S653T). Waterhemp lines were derived from each population to create uniformly imidazolinone-resistant (IR) waterhemp biotypes, designated IR-62 and IR-101. ALS-inhibitor responses of each IR biotype were compared with a previously identified ALS inhibitor–resistant biotype with a tryptophan to leucine substitution at position 574 (W574L) and an herbicide-susceptible control. Whole-plant dose–response experiments with waterhemp biotypes containing W574L, S653N, or S653T mutations indicated that each biotype was resistant to imazethapyr, but only the biotype with a W574L mutation was resistant to thifensulfuron. In vitro ALS-activity assays revealed unique patterns of cross-resistance among protein extracts derived from each biotype in response to imazethapyr, thifensulfuron, cloransulam, and pyrithiobac. In conclusion, three different forms of target-site–based resistance to ALS inhibitors have been identified in waterhemp.

In vitro and whole-plant magnitude and cross-resistance characterization of two imidazolinone-resistant sugarbeet (Beta vulgaris) somatic cell selections

Weed Science ◽  
1998 ◽  
Vol 46 (1) ◽  
pp. 24-29 ◽  
Author(s):  
Terry R. Wright ◽  
Donald Penner
Keyword(s):  
Somatic Cell ◽  
Shoot Culture ◽  
Acetolactate Synthase ◽  
Cross Resistance ◽  
Shoot Cultures ◽  
Als Inhibitors ◽  
Whole Plants ◽  
Inhibitor Resistance ◽  
Als Inhibitor

Acetolactate synthase (ALS)-inhibiting herbicide carryover in soil can severely affect sugarbeets grown in the year(s) following application. Two newly developed imidazolinone-resistant (IMI-R) sugarbeet somatic cell selections (Sir-13 and 93R30B) were examined for magnitude of resistance and extent of cross-resistance to other classes of ALS inhibitors and compared to a previously developed sulfonylurea-resistant (SU-R) selection, Sur. In vitro shoot culture tests indicated Sir-13 resistance was specific to imidazolinone (IMI) herbicides at approximately a 100-fold resistance compared to the sensitive control sugarbeet. Sur was 10,000-fold resistant to the sulfonylurea (SU) herbicide, chlorsulfuron, and 40-fold resistant to the triazolopyrimidine sulfonanilide (TP) herbicide, flumetsulam, but not cross-resistant to the IMI herbicides. 93R30B was selected for IMI-R from a plant homozygous for the SU-R allele,Sur, and displayed similar in vitro SU-R and TP-R as Sur, but also displayed a very high resistance to various IMI herbicides (400- to 3,600-fold). Compared to the sensitive control, Sir-13 was 300- and > 250-fold more resistant to imazethapyr and imazamox residues in soil, respectively. Response by whole plants to postemergence herbicide applications was similar to that observed in shoot cultures. Sir-13 exhibited > 100-fold resistance to imazethapyr as well as imazamox, and 93R30B showed > 250-fold resistance to both herbicides. 93R30B showed great enough resistance to imazamox to merit consideration of imazamox for use as a herbicide in these sugarbeets. Sir-13 showed a two- to threefold higher level of resistance in the homozygous vs. heterozygous state, indicating that like most ALS-inhibitor resistance traits, it was semidominantly inherited.

Acetolactate Synthase Resistance in a Common Waterhemp (Amaranthus rudis) Population

1997 ◽  
Vol 11 (1) ◽  
pp. 13-18 ◽  
Author(s):  
John R. R. Hinz ◽  
Micheal D. K. Owen
Keyword(s):  
Plant Material ◽  
Resistance Mechanism ◽  
Acetolactate Synthase ◽  
Grain Amaranth ◽  
Common Waterhemp ◽  
Resistant Species ◽  
Whole Plant ◽  
Amaranthus Rudis ◽  
Inhibitor Resistance ◽  
Als Inhibitor

Research was initiated to determine (a) whether a common waterhemp population was resistant to acetolactate synthase (ALS) inhibiting herbicides, (b) the percentage of the population that was ALS-inhibitor resistant, (c) the resistance mechanism, and (d) the effectiveness of a whole plant assay to detect ALS-inhibitor resistance. ALS-inhibitor resistance was confirmed in a common waterhemp population near Davis City, IA. The Davis City common waterhemp population was cross resistant to both imidazolinone and sulfonylurea herbicides, but not to lactofen. Approximately 10% of the Davis City common waterhemp population was sensitive to a rate of imazaquin 4 times the normal field rate. Davis City common waterhemp isolated ALS was much less sensitive to imazaquin and primisulfuron inhibition than was grain amaranth or an ALS-sensitive common waterhemp isolated ALS. Imazaquin I50values were 366.4 and 3.4 μM for ALS isolated from Davis City common waterhemp and grain amaranth, respectively. Primisulfuron I50values were 3.6 and 0.007 μM for ALS isolated from Davis City common waterhemp and grain amaranth, respectively. A whole plant ALS assay was developed that allowed for much more rapid detection of an ALS-resistant species and used less plant material than a conventional ALS assay.

scholarly journals ALS–Resistant Annual Sedge (Cyperus compressus) Confirmed in Turfgrass

Weed Science ◽  
2016 ◽  
Vol 64 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Patrick E. McCullough ◽  
Jialin Yu ◽  
J. Scott McElroy ◽  
S. Chen ◽  
H. Zhang ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Acetolactate Synthase ◽  
Shoot Biomass ◽  
Resistance Level ◽  
Physiological Basis ◽  
History Of ◽  
Leaf Tissues ◽  
Als Inhibitors ◽  
Inhibitor Resistance ◽  
Als Inhibitor

Acetolactate synthase (ALS) inhibitors are widely used for POST control of sedges in turfgrass. A suspected resistant (R) biotype of annual sedge was collected from a bermudagrass turf in Georgia with a history of exclusive use of halosulfuron. Research was conducted to evaluate the resistance level of this biotype to halosulfuron, efficacy of ALS-inhibiting herbicides and other mechanisms of action for control, and the molecular and physiological basis for resistance. In greenhouse experiments, the halosulfuron rate required to reduce shoot biomass 50% in comparison with the nontreated at 8 wk after treatment (WAT) were 8 and > 1,120 g ai ha−1for the S (susceptible) and R biotypes, respectively. Imazapic, sulfosulfuron, and trifloxysulfuron reduced biomass of the S biotype greater than 60% at 8 WAT, but biomass was reduced less than 20% for the R biotype. Glufosinate, glyphosate, MSMA, and sulfentrazone reduced shoot biomass of the R biotype by 93, 86, 97, and 45%, respectively. In laboratory experiments, the halosulfuron concentration required to inhibit ALS activity by 50% in excised leaf tissues was 5.8 and > 1,000 μM for the S and R biotypes, respectively. Gene sequencing of the R biotype revealed a Pro-197-Ser substitution that confers resistance to ALS inhibitors. This is the first report of ALS-inhibitor resistance in annual sedge and herbicide resistance in a sedge species from a turfgrass system.

Acetolactate Synthase Inhibitor–Resistant False Cleavers (Galium spurium) in Western Canada

2012 ◽  
Vol 26 (1) ◽  
pp. 151-155 ◽  
Author(s):  
Hugh J. Beckie ◽  
Suzanne I. Warwick ◽  
Connie A. Sauder ◽  
Gina M. Kelln ◽  
Chris Lozinski
Keyword(s):  
Point Mutations ◽  
Low Frequency ◽  
Acetolactate Synthase ◽  
Western Canada ◽  
Resistance Factors ◽  
Als Inhibitors ◽  
Synthase Inhibitor ◽  
Inhibitor Resistance ◽  
Als Inhibitor ◽  
Galium Spurium

Cleavers species (false cleavers and catchweed bedstraw) are among the top 10 most abundant weeds across the prairie region of western Canada, and are increasing in relative abundance at the fastest rate since the 1970s. In 2008, two false cleavers populations from Tisdale and Choiceland, Saskatchewan, were suspected of acetolactate synthase (ALS) –inhibitor resistance. Dose-response experiments were conducted with the use of imazethapyr and florasulam, both ALS inhibitors, as well as fluroxypyr, a synthetic auxin. Additionally, a 1,954–base-pair region of theALSgene including sites known to conferALSresistance were sequenced. Both populations were highly resistant to imazethapyr (resistance factors greater than 100), one population (Tisdale) was highly resistant to florasulam (Choiceland population susceptible, although a second, larger screening of 200 individuals indicated low frequency [2%] florasulam resistance), and both populations were susceptible to fluroxypyr. All sequenced Tisdale individuals screened with imazethapyr posessed the Trp574Leu mutation. In contrast, three point mutations were found for Choiceland individuals sequenced: Ser653Asn, Trp574Leu, and Asp376Glu. TheseALStarget-site mutations have not been documented previously in this species.

Multiple herbicide resistance in California Italian ryegrass (Lolium perenne ssp. multiflorum): characterization of ALS-inhibiting herbicide resistance

Weed Science ◽  
2019 ◽  
Vol 67 (3) ◽  
pp. 273-280 ◽  
Author(s):  
Parsa Tehranchian ◽  
Vijay K. Nandula ◽  
Maor Matzrafi ◽  
Marie Jasieniuk
Keyword(s):  
Lolium Perenne ◽  
Herbicide Resistance ◽  
Resistance Mechanism ◽  
Acetolactate Synthase ◽  
Target Site ◽  
Italian Ryegrass ◽  
Resistance Level ◽  
Als Inhibitors ◽  
Inhibitor Resistance ◽  
Als Inhibitor

AbstractMultiple resistance to glyphosate, sethoxydim, and paraquat was previously confirmed in two Italian ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot] populations, MR1 and MR2, in northern California. Preliminary greenhouse studies revealed that both populations were also resistant to imazamox and mesosulfuron, both of which are acetolactate synthase (ALS)-inhibiting herbicides. In this study, three subpopulations, MR1-A (from seed of MR1 plants that survived a 16X rate of sethoxydim), MR1-P (from seed of MR1 plants that survived a 2X rate of paraquat), and MR2 (from seed of MR2 plants that survived a 16X rate of sethoxydim), were investigated to determine the resistance level to imazamox and mesosulfuron, evaluate other herbicide options for the control of these multiple resistant L. perenne ssp. multiflorum, and characterize the underlying ALS-inhibitor resistance mechanism(s). Based on LD50 values, the MR1-A, MR1-P, and MR2 subpopulations were 38-, 29-, 8-fold and 36-, 64-, and 3-fold less sensitive to imazamox and mesosulfuron, respectively, relative to the susceptible (Sus) population. Only MR1-P and MR2 plants were cross-resistant to rimsulfuron, whereas both MR1 subpopulations were cross-resistant to imazethapyr. Pinoxaden (ACCase inhibitor [phenylpyrazoline 'DEN']) only controlled MR2 and Sus plants at the labeled field rate. However, all plants were effectively controlled (>99%) with the labeled field rate of glufosinate. Based on I50 values, MR1-A, MR-P, and MR2 plants were 712-, 1,104-, and 3-fold and 10-, 18-, and 5-fold less responsive to mesosulfuron and imazamox, respectively, than the Sus plants. Sequence alignment of the ALS gene of resistant plants revealed a missense single-nucleotide polymorphism resulting in a Trp-574-Leu substitution in MR1-A and MR1-P plants, heterozygous in both, but not in the MR2 plants. An additional homozygous substitution, Asp-376-Glu, was identified in the MR1-A plants. Addition of malathion or piperonyl butoxide did not alter the efficacy of mesosulfuron on MR2 plants. In addition, the presence of 2,4-D had no effect on the response of mesosulfuron on the MR2 and Sus. These results suggest an altered target site is the mechanism of resistance to ALS inhibitors in MR1-A and MR1-P plants, whereas a non–target site based resistance apparatus is present in the MR2 plants.

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.

A kochia (Kochia scoparia) biotype resistant to triazine and ALS-inhibiting herbicides

Weed Science ◽  
1999 ◽  
Vol 47 (1) ◽  
pp. 20-27 ◽  
Author(s):  
Matthew J. Foes ◽  
Lixin Liu ◽  
Gerald Vigue ◽  
Edward W. Stoller ◽  
Loyd M. Wax ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
D1 Protein ◽  
Acetolactate Synthase ◽  
Enzyme Assays ◽  
Kochia Scoparia ◽  
Gene Encoding ◽  
Reading Frame ◽  
Whole Plant ◽  
Site Of Action

A kochia biotype from McDonough County, Illinois, was suspected to be resistant to both triazine and acetolactate synthase (ALS)-inhibiting herbicides. We performed greenhouse and laboratory experiments to confirm, quantify, and determine the molecular basis of multiple herbicide resistance in this biotype. Whole-plant phytotoxicity assays confirmed that the biotype was resistant to triazine (atrazine), imidazolinone (imazethapyr), and sulfonylurea (thifensulfuron and chlorsulfuron) herbicides. Relative to a susceptible kochia biotype, resistance to these herbicides ranged from 500- to > 28,000-fold. The kochia biotype from McDonough County also displayed high levels of resistance (2,000- to 9,000-fold) to ALS-inhibiting herbicides in in vivo ALS enzyme assays, indicating that resistance to these herbicides was site-of-action mediated. Results from chlorophyll fluorescence assays indicated that triazine resistance was also site-of-action mediated. Foliar applications of atrazine had little or no effect on photosynthesis in the resistant biotype, even when atrazine concentrations were 108-fold higher than needed to inhibit photosynthesis in the susceptible biotype. A region of the gene encoding the D1 protein of photosystem II and all of the open reading frame of the gene encoding ALS were sequenced and compared between the resistant and susceptible biotypes. Resistance to triazine and ALS-inhibiting herbicides in the kochia biotype from McDonough County was conferred by, respectively, a glycine for serine substitution at residue 264 of the D1 protein and a leucine for tryptophan substitution at residue 570 of ALS.

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.

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