scholarly journals Target-Site Mutations Conferring Herbicide Resistance

Plants ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 382 ◽  
Author(s):  
Brent P. Murphy ◽  
Patrick J. Tranel
Keyword(s):  
Amino Acid ◽  
Herbicide Resistance ◽  
Target Site ◽  
Single Amino Acid ◽  
Cross Resistance ◽  
Target Sites ◽  
Resistance Patterns ◽  
Experimental Approaches ◽  
Sites Of Action ◽  
Multiple Amino Acid

Mutations conferring evolved herbicide resistance in weeds are known in nine different herbicide sites of action. This review summarizes recently reported resistance-conferring mutations for each of these nine target sites. One emerging trend is an increase in reports of multiple mutations, including multiple amino acid changes at the glyphosate target site, as well as mutations involving two nucleotide changes at a single amino acid codon. Standard reference sequences are suggested for target sites for which standards do not already exist. We also discuss experimental approaches for investigating cross-resistance patterns and for investigating fitness costs of specific target-site mutations.

scholarly journals The First Report of Target-Site Resistance to Glyphosate in Sweet Summer Grass (Moorochloa eruciformis)

Plants ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1885
Author(s):  
Romesh Salgotra ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Amino Acid ◽  
Management Strategies ◽  
Glyphosate Resistance ◽  
Target Site ◽  
Single Amino Acid ◽  
Invasive Weeds ◽  
Epsps Gene ◽  
Target Site Resistance ◽  
Multiple Amino Acid ◽  
First Time

Sweet summer grass is a problematic weed in the central Queensland region of Australia. This study found glyphosate resistance in two biotypes (R1 and R2) of sweet summer grass. The level of resistance in these biotypes was greater than 8-fold. The glyphosate dose required to reduce dry matter by 50% (GR50) for the resistant populations varied from 1993 to 2100 g ha−1. A novel glyphosate resistance double point mutation in the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene was identified for the first time in sweet summer grass. Multiple mutations, including multiple amino acid changes at the glyphosate target site, as well as mutations involving two nucleotide changes at a single amino acid codon, were observed. Both resistant biotypes exhibited a nucleotide change of CAA to ACA in codon 106, which predicts an amino acid change of proline to a threonine (Pro-106-Thr). In addition, the R1 biotype also possessed a mutation at codon 100, where a nucleotide substitution of T for G occurred (GCT to TCT), resulting in a substitution of serine for alanine (Ala-100-Ser). Understanding the molecular mechanism of glyphosate resistance will help to design effective management strategies to control invasive weeds.

Target site–based penoxsulam resistance in barnyardgrass (Echinochloa crus-galli) from China

Weed Science ◽  
2019 ◽  
Vol 67 (3) ◽  
pp. 281-287 ◽  
Author(s):  
Jiapeng Fang ◽  
Tingting Liu ◽  
Yuhua Zhang ◽  
Jun Li ◽  
Liyao Dong
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Acetolactate Synthase ◽  
Target Site ◽  
Cross Resistance ◽  
Predicted Amino Acid Sequence ◽  
Sequence Analyses ◽  
Als Inhibitors ◽  
Higher Sensitivity

AbstractBarnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] is acknowledged to be the most troublesome weed in rice fields in Anhui and Jiangsu provinces of China. It cannot be effectively controlled using certain acetolactate synthase (ALS)-inhibiting herbicides, including penoxsulam. Echinochloa crus-galli samples with suspected resistance to penoxsulam were collected to identify the target site–based mechanism underlying this resistance. Populations AXXZ-2 and JNRG-2 showed 33- and 7.3-fold resistance to penoxsulam, respectively, compared with the susceptible JLGY-3 population. Cross-resistance to other ALS inhibitors was reported in AXXZ-2 but not in JNRG-2, and occasionally showed higher sensitivity than JLGY-3. In vitro ALS activity assays revealed that penoxsulam concentrations required to inhibit 50% of ALS activity were 11 and 5.2 times greater in AXXZ-2 and JNRG-2, respectively, than in JLGY-3. DNA and predicted amino acid sequence analyses of ALS revealed Ala-205-Val and Ala-122-Gly substitutions in AXXZ-2 and JNRG-2, respectively. Our results indicate that these substitutions in ALS are at least partially responsible for resistance to penoxsulam.

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 IS1630 of Mycoplasma fermentans, a Novel IS30-Type Insertion Element That Targets and Duplicates Inverted Repeats of Variable Length and Sequence during Insertion

1999 ◽  
Vol 181 (24) ◽  
pp. 7597-7607 ◽  
Author(s):  
Michael J. Calcutt ◽  
Jennifer L. Lavrrar ◽  
Kim S. Wise
Keyword(s):  
Amino Acid ◽  
Inverted Repeat ◽  
Insertion Sequence ◽  
Target Site ◽  
Inverted Repeats ◽  
Amino Acid Residues ◽  
Mycoplasma Fermentans ◽  
Is Elements ◽  
Repeat Sequences ◽  
Target Sites

ABSTRACT A new insertion sequence (IS) of Mycoplasma fermentansis described. This element, designated IS1630, is 1,377 bp long and has 27-bp inverted repeats at the termini. A single open reading frame (ORF), predicted to encode a basic protein of either 366 or 387 amino acids (depending on the start codon utilized), occupies most of this compact element. The predicted translation product of this ORF has homology to transposases of the IS30 family of IS elements and is most closely related (27% identical amino acid residues) to the product of the prototype of the group, IS30. Multiple copies of IS1630 are present in the genomes of at least two M. fermentans strains. Characterization and comparison of nine copies of the element revealed that IS1630 exhibits unusual target site specificity and, upon insertion, duplicates target sequences in a manner unlike that of any other IS element. IS1630 was shown to have the striking ability to target and duplicate inverted repeats of variable length and sequence during transposition. IS30-type elements typically generate 2- or 3-bp target site duplications, whereas those created by IS1630 vary between 19 and 26 bp. With the exception of two recently reported IS4-type elements which have the ability to generate variable large duplications (B. B. Plikaytis, J. T. Crawford, and T. M. Shinnick, J. Bacteriol. 180:1037–1043, 1998; E. M. Vilei, J. Nicolet, and J. Frey, J. Bacteriol. 181:1319–1323, 1999), such large direct repeats had not been observed for other IS elements. Interestingly, the IS1630-generated duplications are all symmetrical inverted repeat sequences that are apparently derived from rho-independent transcription terminators of neighboring genes. Although the consensus target site for IS30 is almost palindromic, individual target sites possess considerably less inverted symmetry. In contrast, IS1630appears to exhibit an increased stringency for inverted repeat recognition, since the majority of target sites had no mismatches in the inverted repeat sequences. In the course of this study, an additional copy of the previously identified insertion sequence ISMi 1 was cloned. Analysis of the sequence of this element revealed that the transposase encoded by this element is more than 200 amino acid residues longer and is more closely related to the products of other IS3 family members than had previously been recognized. A potential site for programmed translational frameshifting in ISMi 1 was also identified.

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

Point mutation in acetolactate synthase confers sulfonylurea and imidazolinone herbicide resistance in spiny annual sow-thistle [Sonchus asper (L.) Hill]

2012 ◽  
Vol 92 (2) ◽  
pp. 303-309 ◽  
Author(s):  
Kee Woong Park ◽  
Judith M. Kolkman ◽  
Carol A. Mallory-Smith
Keyword(s):  
Amino Acid ◽  
Point Mutation ◽  
Herbicide Resistance ◽  
Single Point ◽  
Acetolactate Synthase ◽  
Amino Acid Sequences ◽  
Cross Resistance ◽  
Single Point Mutation ◽  
Sonchus Asper

Park, K. W., Kolkman, J. M. and Mallory-Smith, C. A. 2012. Point mutation in acetolactate synthase confers sulfonylurea and imidazolinone herbicide resistance in spiny annual sow-thistle [Sonchus asper (L.) Hill]. Can. J. Plant Sci. 92: 303–309. Suspected thifensulfuron resistant spiny annual sow-thistle was identified near Colfax, Washington, in two fields with a winter wheat and lentil rotation. Therefore, studies were conducted to examine resistance of spiny annual sow-thistle to thifensulfuron and cross-resistance to other acetolactate synthase inhibitors and to determine the physiological and molecular basis for herbicide resistance. Whole-plant bioassay confirmed that the biotype was highly resistant to the sulfonylurea (SU) herbicides, thifensulfuron, metsulfuron, and prosulfuron. The resistant (R) biotype was also highly resistant to the imidazolinone (IMI) herbicides, imazamox and imazethapyr. An in vivo acetolactate synthase (ALS) assay indicated that the concentrations of SU and IMI herbicides required for 50% inhibition (I50) were more than 10 times greater for R biotype compared with susceptible (S) biotype. Analysis of the nucleotide and predicted amino acid sequences for ALS genes demonstrated a single-point mutation from C to T at the als1 gene, conferring the substitution of the amino acid leucine for proline in the R biotype at position197. The results of this research indicate that the resistance of spiny annual sow-thistle to SU and IMI herbicides is due to on altered target site and caused by a point mutation in the als1 gene.

Spatial Distribution of Acetolactate Synthase Resistance Mechanisms in Neighboring Populations of Silky Windgrass (Apera spica-venti)

Weed Science ◽  
2017 ◽  
Vol 65 (4) ◽  
pp. 479-490 ◽  
Author(s):  
Marielle Babineau ◽  
Solvejg K. Mathiassen ◽  
Michael Kristensen ◽  
Niels Holst ◽  
Roland Beffa ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Ethyl Ester ◽  
Acetolactate Synthase ◽  
Target Site ◽  
Cross Resistance ◽  
Spatial Gradient ◽  
Resistant Phenotype ◽  
Site Of Action ◽  
Target Site Resistance ◽  
Sites Of Action

Silky windgrass is a serious weed in central and northern Europe. Its importance has escalated in recent years because of its growing resistance to acetolactate synthase (ALS)-inhibiting herbicides. This study investigated the resistance level for three herbicide sites of action in eight silky windgrass populations, collected in fields neighboring a field where iodosulfuron sodium salt–resistant silky windgrass had previously been found. Target site resistance (TSR) and non–target site resistance (NTSR) mechanisms were identified, and a spatial gradient distribution hypothesis of ALS resistance was tested. Populations showed large variations in ED50values to iodosulfuron, with resistance indices (RIs) ranging from 0.1 to 372. No cross-resistance was found to other herbicide groups with the same site of action as iodosulfuron. In contrast, resistance was observed to the acetyl-CoA carboxylase inhibitor, fenoxaprop ethyl ester (RI from 0.7 to 776), while the activity of prosulfocarb, an inhibitor of long-chain fatty-acid synthesis, was unaffected. Iodosulfuron-resistant phenotypes were associated with NTSR, while fenoxaprop ethyl ester resistance was caused by both NTSR and TSR (Ile-1781-Leu mutation). A large-scale trend in the spatial distribution of resistance to ALS indicated a decreasing resistance with increased distance from an epicenter. After finer-scale analysis, less than 0.05% of the residual variation could be attributed to spatial autocorrelation. The spatial resistance pattern was not correlated with the dominant wind direction, while there was a correlation between the resistant phenotype and type of crop. This study underlines that NTSR mechanisms do not always confer broad resistance to different herbicide subclasses and site of action, hence the complex relationship to resistant phenotype. NTSR mechanisms, in particular detoxification, were present at different levels for the herbicides tested in the silky windgrass populations of this study. The factors contributing to the spatial distribution of resistance remain elusive.

Biochemical mechanism and molecular basis for ALS-inhibiting herbicide resistance in sugarbeet (Beta vulgaris) somatic cell selections

Weed Science ◽  
1998 ◽  
Vol 46 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Terry R. Wright ◽  
Newell F. Bascomb ◽  
Stephen F. Sturner ◽  
Donald Penner
Keyword(s):  
Amino Acid ◽  
Somatic Cell ◽  
Herbicide Resistance ◽  
Double Mutant ◽  
Acetolactate Synthase ◽  
Cross Resistance ◽  
Nucleotide Change ◽  
Wild Type ◽  
Single Nucleotide ◽  
Single Nucleotide Change

Three sugarbeet selections differing in cross-resistance to three classes of acetolactate synthase (ALS)-inhibiting herbicides have been developed using somatic cell selection. Sugarbeet selections resistant to imidazolinone herbicides,Sir-13and93R30B, do not metabolize [14C]-imazethapyr any faster or differently than sensitive, wild-type sugarbeets or a sulfonylurea-resistant/imidazolinone-sensitive selection, Sur. ALS specific activity from the three herbicide-resistant selections ranged from 73 to 93% of the wild-type enzyme extracts in the absence of herbicide, indicating enzyme overexpression was not a factor in resistance. Acetolactate synthase from Sir-13 plants showed a 40-fold resistance to imazethapyr but no resistance to chlorsulfuron or flumetsulam. Polymerase chain reaction amplification and sequencing of two regions of the ALS gene spanning all known sites for ALS-based herbicide resistance in plants indicated a single nucleotide change in theSir-13gene (G337to A337) resulting in a deduced substitution of threonine for alanine at position 113 in the sugarbeet amino acid sequence. Sur ALS was not significantly resistant to imazethapyr, but was 1,000- and 50-fold resistant to chlorsulfuron and flumetsulam, respectively.Surgene sequencing indicated a single nucleotide change(C562to T562) resulting in a serine for proline substitution at position 188 of the ALS primary structure. The93R30Bnucleotide sequence indicated two mutations resulting in two deduced amino acid substitutions: threonine for alanine at position 113 plus serine for proline at position 188. The93R30Bdouble mutant incorporated the changes observed in each of the single mutants above and correlated with higher resistance levels to imazethapyr (> 1,000-fold), chlorsulfuron (4,300-fold), and flumetsulam (200-fold) at the ALS level than observed in either of the single mutants.93R30Brepresents the first double mutant derived by a two-step selection process that incorporates two class-specific ALS-inhibitor resistance mutations to form a single broad cross-resistance trait. The interaction of the two altered amino acids is synergistic with respect to enzyme resistance vs. the resistance afforded by each of the individual mutations.

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