Arg-128-Leu target-site mutation in PPO2 evolves in wild poinsettia (Euphorbia heterophylla) with cross-resistance to PPO-inhibiting herbicides

Weed Science ◽  
2020 ◽  
Vol 68 (5) ◽  
pp. 437-444 ◽  
Author(s):  
Rafael R. Mendes ◽  
Hudson K. Takano ◽  
Fernando S. Adegas ◽  
Rubem S. Oliveira ◽  
Todd A. Gaines ◽  
...  

AbstractWild poinsettia (Euphorbia heterophylla L.) is a troublesome broadleaf weed in grain production areas in South America. Herbicide resistance to multiple sites of action has been documented in this species, including protoporphyrinogen oxidase (PPO) inhibitors. We investigated the physiological and molecular bases for PPO-inhibitor resistance in a E. heterophylla population (RPPO) from Southern Brazil. Whole-plant dose–response experiments revealed a cross-resistance profile to three different chemical groups of PPO inhibitors. Based on dose–response parameters, RPPO was resistant to lactofen (47.7-fold), saflufenacil (8.6-fold), and pyraflufen-ethyl (3.5-fold). Twenty-four hours after lactofen treatment (120 g ha−1) POST, RPPO accumulated 27 times less protoporphyrin than the susceptible population (SPPO). In addition, RPPO generated 5 and 4.5 times less hydrogen peroxide and superoxide than SPPO, respectively. The chloroplast PPO (PPO1) sequences were identical between the two populations, whereas 35 single-nucleotide polymorphisms were found for the mitochondrial PPO (PPO2). Based on protein homology modeling, the Arg-128-Leu (homologous to Arg-98-Leu in common ragweed [Ambrosia artemisiifolia L.] was the only one located near the catalytic site, also in a conserved region of PPO2. The cytochrome P450 monooxygenase inhibitor malathion did not reverse resistance to lactofen in RPPO, and both populations showed similar levels of PPO1 and PPO2 expression, suggesting that metabolic resistance and PPO overexpression are unlikely. This is the first report of an Arg-128-Leu mutation in PPO2 conferring cross-resistance to PPO inhibitors in E. heterophylla.

2021 ◽  
Vol 12 ◽  
Author(s):  
Zeineb Hada ◽  
Yosra Menchari ◽  
Antonia M. Rojano-Delgado ◽  
Joel Torra ◽  
Julio Menéndez ◽  
...  

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.


2020 ◽  
pp. 1-5
Author(s):  
Wyatt Coffman ◽  
Tom Barber ◽  
Jason K. Norsworthy ◽  
Greg R. Kruger

Abstract Throughout eastern Arkansas, Palmer amaranth resistant to protoporphyrinogen oxidase (PPO)-inhibiting herbicides (Group 14 herbicides) has become widespread. Most PPO-resistant Palmer amaranth biotypes possess a target-site mutation, but a metabolic resistance mechanism to fomesafen (Group 14) has also been identified. Once metabolic resistance manifests, plants may also be tolerant to other herbicides and sites of action. To evaluate whether varying spray parameters affected control of PPO-resistant Palmer amaranth in dicamba-tolerant crops, field trials were conducted in 2017 and 2018 at the Lon Mann Cotton Research Station near Marianna, AR, and on-farm in Marion, AR. The experiment included split plot factors of dicamba rate, nozzle type, and carrier volume, with a whole plot factor of population. Dicamba was applied at 560 or 1120 g ae ha−1 through 110015 TTI or AirMix nozzles at 70 or 140 L ha−1 to PPO-resistant or PPO-susceptible Palmer amaranth. Palmer amaranth control 14 d after treatment (DAT) was influenced by an interaction between population and carrier volume. PPO-resistant Palmer amaranth control 14 DAT was 81% regardless of carrier volume, compared with 90% and 95% control at 70 and 140 L ha−1, respectively, of the PPO-susceptible population. An interaction between nozzle type and carrier volume influenced Palmer amaranth control 21 DAT, whereas AirMix nozzles at 140 L ha−1 controlled Palmer amaranth at a greater level (94%) than any other nozzle and carrier volume combination (≤90%). An interaction between population and dicamba rate influenced the relative density of Palmer amaranth 21 DAT. PPO-resistant Palmer amaranth density was less affected by dicamba at either rate than PPO-susceptible Palmer amaranth, relative to the nontreated check. Results concur with those of other research that suggest PPO-resistant Palmer amaranth is harder to control with dicamba. Otherwise, increasing carrier volume affected overall Palmer amaranth control to a greater degree than any other factor.


2021 ◽  
pp. 1-28
Author(s):  
Charles M. Geddes ◽  
Mallory L. Owen ◽  
Teandra E. Ostendorf ◽  
Julia Y. Leeson ◽  
Shaun M. Sharpe ◽  
...  

Abstract Herbicide-resistant (HR) kochia is a growing problem in the Great Plains region of Canada and the United States (U.S.). Resistance to up to four herbicide sites of action, including photosystem II inhibitors, acetolactate synthase inhibitors, synthetic auxins, and the 5-enolpyruvylshikimate-3-phosphate synthase inhibitor glyphosate have been reported in many areas of this region. Despite being present in the U.S. since 1993/1994, auxinic-HR kochia is a recent and growing phenomenon in Canada. This study was designed to characterize (a) the level of resistance and (b) patterns of cross-resistance to dicamba and fluroxypyr in 12 putative auxinic-HR kochia populations from western Canada. The incidence of dicamba-resistant individuals ranged among populations from 0% to 85%, while fluroxypyr-resistant individuals ranged from 0% to 45%. In whole-plant dose-response bioassays, the populations exhibited up to 6.5-fold resistance to dicamba and up to 51.5-fold resistance to fluroxypyr based on visible injury 28 days after application. Based on plant survival estimates, the populations exhibited up to 3.7-fold resistance to dicamba and up to 72.5-fold resistance to fluroxypyr. Multiple patterns of synthetic auxin resistance were observed, where one population from Cypress County, Alberta was resistant to dicamba but not fluroxypyr, while another from Rocky View County, Alberta was resistant to fluroxypyr but not dicamba based on single-dose population screening and dose-response bioassays. These results suggest that multiple mechanisms may confer resistance to dicamba and/or fluroxypyr in Canadian kochia populations. Further research is warranted to determine these mechanisms. Farmers are urged to adopt proactive non-chemical weed management tools in an effort to preserve efficacy of the remaining herbicide options available for control of HR kochia.


Weed Science ◽  
1996 ◽  
Vol 44 (3) ◽  
pp. 476-481 ◽  
Author(s):  
Bruce G. Murray ◽  
Anita L. Brûlé-Babel ◽  
Ian N. Morrison

The objectives of this study were to determine the inheritance of aryloxyphenoxypropionate (APP) resistance in the wild oat population UM33 and to determine the genetic relationship between resistance in UM33 and another population, UM1, which has a different cross-resistance pattern. Reciprocal crosses were made between UM33 and a susceptible population UM5, and between UM33 and UM1. Initial screenings of F1and F2Is populations derived from crosses between UM33 and UM5 were conducted over a range of fenoxaprop-P rates to determine a discriminatory dosage. F2populations and F2-derived F3families were then screened at this dosage (1200 g ai ha−1) to determine segregation patterns. Results from reciprocal UM33 x UM5 F1dose-response experiments, and F2and F2-derived F3segregation experiments indicated that UM33 resistance to fenoxaprop-P was governed by a single, partially dominant nuclear gene system. To determine if resistance in UM1 and UM33 results from alterations at the same gene locus, 584 F2plants derived from reciprocal UM33 x UM1 crosses were screened with 150 g ha−1fenoxaprop-P. This dosage was sufficient to kill susceptible plants (UM5), but was not sufficient to kill plants with a resistance allele from either parent. None of the treated F2plants exhibited injury or death, indicating that UM1 and UM33 resistance genes did not segregate independently. From this it was concluded that resistance in both populations is encoded at the same gene locus.


Weed Science ◽  
1998 ◽  
Vol 46 (5) ◽  
pp. 604-607 ◽  
Author(s):  
Stephen B. Powles ◽  
Debrah F. Lorraine-Colwill ◽  
James J. Dellow ◽  
Christopher Preston

Following 15 yr of successful use, glyphosate failed to control a population of the widespread grass weed rigid ryegrass in Australia. This population proved to be resistant to glyphosate in pot dose-response experiments conducted outdoors, exhibiting 7- to 11-fold resistance when compared to a susceptible population. Some cross-resistance to diclofop-methyl (about 2.5-fold) was also observed. Similar levels of control of the resistant and susceptible populations were obtained following application of amitrole, chlorsulfuron, fluazifop-P-butyl, paraquat, sethoxydim, sirnazine, or tralkoxydim. The presence of glyphosate resistance in a major weed species indicates a need for changes in glyphosate use patterns.


2015 ◽  
Vol 29 (3) ◽  
pp. 380-389 ◽  
Author(s):  
Annemarie C. Van Wely ◽  
Nadar Soltani ◽  
Darren E. Robinson ◽  
David C. Hooker ◽  
Mark B. Lawton ◽  
...  

Field trials were conducted in Ontario in 2013 and 2014 in soybean to determine the efficacy of POST herbicides on common ragweed resistant to group 2 and group 9 herbicides. Glyphosate dose-response experiments were conducted in the field on two resistant common ragweed populations and one susceptible population. None of the POST herbicides evaluated provided 80% control of glyphosate-resistant (GR) common ragweed. The most effective POST herbicide mixture was glyphosate (Monsanto Canada Inc., 67 Scurfield Blvd., Winnipeg, Manitoba, Canada) plus fomesafen(Syngenta Canada Inc., 140 Research Lane, Research Park Guelph, Ontario, Canada), which provided 68 to 98% control of GR common ragweed. Chlorimuron, cloransulam, imazethapyr, and thifensulfuron provided control similar to glyphosate alone. An application of glyphosate/fomesafen reduced biomass by as much as 95%. Glyphosate plus acifluorfen reduced GR common ragweed biomass by as much as 92%. The remaining POST herbicide tank mixes evaluated reduced GR common ragweed biomass by less than 80%. Glyphosate plus bentazon, glyphosate plus chlorimuron, and glyphosate plus thifensulfuron resulted in soybean yields similar to the weedy control, with yield reductions of 70, 62, and 73%, respectively. An application of glyphosate plus fomesafen or glyphosate/fomesafen had the lowest soybean yield reductions of 29 and 34%, respectively. The resistant biotype required a 2- to 28-fold increase in glyphosate dose compared to the susceptible population to achieve 50% control.


2021 ◽  
Vol 63 (2) ◽  
pp. 74-80
Author(s):  
The Duc Ngo ◽  

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.


2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Dilpreet S. Riar ◽  
Jason K. Norsworthy ◽  
Jason A. Bond ◽  
Mohammad T. Bararpour ◽  
Michael J. Wilson ◽  
...  

ThreeEchinochloa crus-galli(barnyardgrass) populations from rice fields in Arkansas (AR1 and AR2) and Mississippi (MS1), USA, were recently confirmed to be resistant to imazethapyr. Experiments were conducted to characterize cross-resistance to acetolactate synthase- (ALS-) inhibiting herbicides and determine if malathion, a known cytochrome P450 monooxygenase (CYP) inhibitor, would overcome resistance. The AR1 and MS1 populations were cross-resistant to bispyribac-sodium; however, AR2 was sensitive to bispyribac-sodium. The AR1, AR2, and MS1 populations were >94, >94, and 3.3 times, respectively, more resistant to imazamox; >94, 30, and 9.4 times, respectively, more resistant to penoxsulam; and 15, 0.9, and 7.2 times, respectively, more resistant to bispyribac-sodium compared to a susceptible population. Addition of malathion to penoxsulam reduced dry weight of all populations and increased mortality of AR2 and MS1 populations compared to penoxsulam alone. Addition of malathion to imazethapyr and bispyribac-sodium increased the mortality of MS1 population in mixture with imazethapyr and AR1 population in mixture with bispyribac-sodium compared to treatments with imazethapyr and bispyribac-sodium applied alone. Synergism of ALS-inhibiting herbicides with malathion indicates increased herbicide degradation by CYP as partial mechanism of resistance to penoxsulam in all resistant populations and probably to imazethapyr in MS1 and bispyribac-sodium in AR1 populations.


2021 ◽  
Vol 12 ◽  
Author(s):  
Joel Torra ◽  
José María Montull ◽  
Andreu Taberner ◽  
Nawaporn Onkokesung ◽  
Neil Boonham ◽  
...  

Lolium rigidum is one the worst herbicide resistant (HR) weeds worldwide due to its proneness to evolve multiple and cross resistance to several sites of action (SoA). In winter cereals crops in Spain, resistance to acetolactate synthase (ALS)- and acetyl-CoA carboxylase (ACCase)-inhibiting herbicides has become widespread, with farmers having to rely on pre-emergence herbicides over the last two decades to maintain weed control. Recently, lack of control with very long-chain fatty acid synthesis (VLCFAS)-inhibiting herbicides has been reported in HR populations that are difficult to manage by chemical means. In this study, three Spanish populations of L. rigidum from winter cereals were confirmed as being resistant to ALS- and ACCase-inhibiting herbicides, with broad-ranging resistance toward the different chemistries tested. In addition, reduced sensitivity to photosystem II-, VLCFAS-, and phytoene desaturase-inhibiting herbicides were confirmed across the three populations. Resistance to ACCase-inhibiting herbicides was associated with point mutations in positions Trp-2027 and Asp-2078 of the enzyme conferring target site resistance (TSR), while none were detected in the ALS enzyme. Additionally, HR populations contained enhanced amounts of an ortholog of the glutathione transferase phi (F) class 1 (GSTF1) protein, a functional biomarker of non-target-site resistance (NTSR), as confirmed by enzyme-linked immunosorbent assays. Further evidence of NTSR was obtained in dose-response experiments with prosulfocarb applied post-emergence, following pre-treatment with the cytochrome P450 monooxygenase inhibitor malathion, which partially reversed resistance. This study confirms the evolution of multiple and cross resistance to ALS- and ACCase inhibiting herbicides in L. rigidum from Spain by mechanisms consistent with the presence of both TSR and NTSR. Moreover, the results suggest that NTSR, probably by means of enhanced metabolism involving more than one detoxifying enzyme family, confers cross resistance to other SoA. The study further demonstrates the urgent need to monitor and prevent the further evolution of herbicide resistance in L. rigidum in Mediterranean areas.


Weed Science ◽  
2012 ◽  
Vol 60 (2) ◽  
pp. 167-171 ◽  
Author(s):  
Ibrahim A. Mohamed ◽  
Runzhi Li ◽  
Zhenguo You ◽  
Zhaohu Li

Japanese foxtail is one of the most common and competitive annual grass weeds of wheat in China. Whole-plant dose-response experiments were conducted with fenoxaprop and pinoxaden to confirm and characterize resistant and susceptible Japanese foxtail populations and to elucidate the basis of resistance to these herbicides. The resistant Japanese foxtail population was 49-fold resistant to fenoxaprop and 16-fold (cross) resistant to pinoxaden relative to the susceptible population, which was susceptible to both fenoxaprop and pinoxaden herbicides. Molecular analysis of resistance confirmed that the Ile1781to Leu mutation in the resistant population conferred resistance to both fenoxaprop and pinoxaden. This is the first report of cross resistance of Japanese foxtail to pinoxaden in the world and of a target site mutation that corresponded to resistance to both fenoxaprop and pinoxaden in Japanese foxtail. Prior selection pressure from fenoxaprop could result in evolution of resistance to fenoxaprop and cross resistance to pinoxaden in Japanese foxtail population.


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