Herbicide Dicamba Research Articles

Two herbicides, two fungicides and spore-associated bacteria affect Funneliformis mosseae extraradical mycelium structural traits and viability.

The extraradical mycelium (ERM) produced by arbuscular mycorrhizal fungi is fundamental for the maintenance of biological fertility in agricultural soils, representing an important inoculum source, together with spores and mycorrhizal root fragments. Its viability and structural traits, such as density, extent and interconnectedness, which are positively correlated with the growth and nutrition of host plants, may be affected by different agronomic practices, including the use of pesticides and by different mycorrhizospheric communities. This work, carried out using a whole-plant experimental model system, showed that structural traits of ERM, such as length and density, were strongly decreased by the herbicides dicamba and glufosinolate and the fungicides benomyl and fenhexamid, while anastomosis frequency and hyphal branching were differentially modulated by singly inoculated mycorrhizospheric bacteria, depending on their identity.

Subdoses of Dicamba Herbicide on Yield Componentes in Function of the Soybean Growth Stage

Soybean cultivars without tolerance can suffer injury from exposure to tank herbicide residues. This study aimed at assessing the potential effects of the broad spectrum herbicide dicamba on sensitive soybean during its vegetative and reproductive stages. The trial was performed in a randomized complete block design with four replications. Six rates (1.4, 2.8, 5.6, 11.2, 16.8 and 28.0 g ae ha-1) of dicamba were applied at two soybean growth stages (V3 and R2). The soybeans were planted in Passo Fundo, Rio Grande do Sul state in 2015/16 agricultural year. The dicamba induced symptoms of soybean phytotoxicity showed a steady rise at all the assessment times. The soybean decreased in height as the subdose of the herbicide increased. Dicamba was observed to negatively affect the number of nodes alone, during the V3 and R2 stages. The grain yield was adversely affected at the 28.0 g ae ha-1 subdose, in the V3 application stage, and in response to the 16.8 and 28.0 g ae ha-1 subdoses in the R2 stage.

Redox-Based Synthetic Biology Enables Electrochemical Detection of the Herbicides Dicamba and Roundup via Rewired Escherichia coli.

Synthetic biology is typically exploited to endow bacterial cells with new biosynthetic capabilities. It can also serve to create "smart" bacteria such as probiotics that detect and treat disease. Here, we show how minimally rewiring the genetic regulation of bacterial cells can enable their ability to recognize and report on chemical herbicides, including those routinely used to clear weeds from gardens and crops. In so doing, we demonstrate how constructs of synthetic biology, in this case redox-based synthetic biology, can serve as a vector for information flow mediating molecular communication between biochemical systems and microelectronics. We coupled the common genetic reporter, β-galactosidase, with the E. coli superoxide response regulon promoter pSoxS, for detection of the herbicides dicamba and Roundup. Both herbicides activated our genetic construct in a concentration dependent manner. Results indicate robust detection using spectrophotometry, via the Miller assay, and electrochemistry using the enzymatic cleavage of 4-aminophenyl β-d-galactopyranoside into the redox active molecule p-aminophenol. We found that environmental components, in particular, the availability of glucose, are important factors for the cellular detection of dicamba. Importantly, both herbicides were detected at concentrations relevant for aquatic toxicity.

A new process to prepare 3,6-dichloro-2-hydroxybenzoic acid, the penultimate intermediate in the synthesis of herbicide dicamba

Glyphosate [N-(phosphonomethyl)glycine] is a broad spectrum, post-emergent herbicide that is among the most widely used agrochemicals globally. Over the past 30 years, there has been a development of glyphosate-resistant weeds, which pose a significant challenge to growers and crop scientists, resulting in lower crop yields and increased costs. 3,6-Dichloro-2-methoxybenzoic acid (dicamba) is the active ingredient in XtendiMax®, a standalone herbicide developed by Bayer Crop Science to control broadleaf weeds, including glyphosate-resistant species. 3,6-Dichloro-2-hydroxybenzoic acid (3,6-DCSA) is the penultimate intermediate in the synthesis of dicamba. Existing dicamba manufacturing routes utilize a high temperature, high pressure Kolbe-Schmitt carboxylation to prepare 3,6-DCSA. Described in this Letter is a new, non-Kolbe-Schmitt process to prepare 3,6-DCSA from salicylic acid in four chemical steps.

Influence of Weed Manipulation in Field Borders on Brown Stink Bug (Hemiptera: Pentatomidae) Densities and Damage in Field Corn.

Brown stink bug, Euschistus servus (Say), is a damaging pest of corn, Zea mays L. (Cyperales: Poaceae), in the southeastern United States. In North Carolina, during the spring, winter-planted wheat, Triticum aestivum L. (Cyperales: Poaceae), serves as the earliest available crop host, and E. servus seems to prefer this crop over seedling corn. In the absence of wheat in the agroecosystem, weeds serve as a bridge host for a portion of overwintered E. servus populations until they move to corn and other subsequent crops. Our objective was to reduce densities of E. servus in corn by manipulating the weedy field borders with mowing and applications of dicamba herbicide. During the study, multiple species of stink bugs (n =16) were found associated with weed plots. However, E. servus was the predominant (>94%) stink bug species in the corn. In this farmscape, density of E. servus adults in the unmanaged weed plots began declining around the second week of May, followed by an increase in density in adjacent corn plots. This movement coincided with the seedling growth of corn. In 2016, applications of dicamba in the weedy field border resulted in a lower density of E. servus in herbicide-treated weed plots compared with untreated plots. Despite this difference, manipulations of weeds did not lead to any significant changes in density of E. servus adults in corn. Further evidence suggested that a prominent external source of E. servus, other than field-bordering weeds, in the farmscape was likely driving densities in corn.

Members of the GH3 Family of Proteins Conjugate 2,4-D and Dicamba with Aspartate and Glutamate.

Auxin homeostasis is a highly regulated process that must be maintained to allow auxin to exert critical growth and developmental controls. Auxin conjugase and hydrolase family proteins play important roles in auxin homeostasis through means of storage, activation, inactivation, response inhibition and degradation of auxins in plants. We systematically evaluated 60 GRETCHEN HAGEN3 (GH3) proteins from diverse plant species for amino acid conjugation activity with the known substrates jasmonic acid (JA), IAA and 4-hydroxybenzoate (4-HBA). While our results largely confirm that Group II conjugases prefer IAA, we observed no clear substrate preference among Group III proteins, and only three of 11 Group I proteins showed the expected preference for JA, indicating that sequence similarity does not always predict substrate specificity. Such a sequence-substrate relationship held true when sequence similarity at the acyl acid-binding site was used for grouping. Several GH3 proteins could catalyze formation of the potentially degradation-destined aspartate (Asp) and glutamate (Glu) conjugates of IAA and the synthetic auxins 2,4-D and dicamba. We found that 2,4-D-Asp/Glu conjugates, but not dicamba and IAA conjugates, were hydrolyzed in Arabidopsis and soybean by AtILL5- and AtIAR3-like amidohydrolases, releasing free 2,4-D in plant cells when conjugates were exogenously applied to seedlings. Dicamba-Asp or dicamba-Glu conjugates were not hydrolyzed in vivo in infiltrated plants nor in vitro with recombinant amidohydrolases. These findings could open the door for exploration of a dicamba herbicide tolerance strategy through conjugation.

3,6-Dichlorosalicylate Catabolism Is Initiated by the DsmABC Cytochrome P450 Monooxygenase System in Rhizorhabdus dicambivorans Ndbn-20.

The degradation of the herbicide dicamba is initiated by demethylation to form 3,6-dichlorosalicylate (3,6-DCSA) in Rhizorhabdusdicambivorans Ndbn-20. In the present study, a 3,6-DCSA degradation-deficient mutant, Ndbn-20m, was screened. A cluster, dsmR1DABCEFGR2, was lost in this mutant. The cluster consisted of nine genes, all of which were apparently induced by 3,6-DCSA. DsmA shared 30 to 36% identity with the monooxygenase components of reported three-component cytochrome P450 systems and formed a monophyletic branch in the phylogenetic tree. DsmB and DsmC were most closely related to the reported [2Fe-2S] ferredoxin and ferredoxin reductase, respectively. The disruption of dsmA in strain Ndbn-20 resulted in inactive 3,6-DCSA degradation. When dsmABC, but not dsmA alone, was introduced into mutant Ndbn-20m and Sphingobium quisquiliarum DC-2 (which is unable to degrade salicylate and its derivatives), they acquired the ability to hydroxylate 3,6-DCSA. Single-crystal X-ray diffraction demonstrated that the DsmABC-catalyzed hydroxylation occurred at the C-5 position of 3,6-DCSA, generating 3,6-dichlorogentisate (3,6-DCGA). In addition, DsmD shared 51% identity with GtdA (a gentisate and 3,6-DCGA 1,2-dioxygenase) from Sphingomonas sp. strain RW5. However, unlike GtdA, the purified DsmD catalyzed the cleavage of gentisate and 3-chlorogentisate but not 6-chlorogentisate or 3,6-DCGA in vitro Based on the bioinformatic analysis and gene function studies, a possible catabolic pathway of dicamba in R. dicambivorans Ndbn-20 was proposed.IMPORTANCE Dicamba is widely used to control a variety of broadleaf weeds and is a promising target herbicide for the engineering of herbicide-resistant crops. The catabolism of dicamba has thus received increasing attention. Bacteria mineralize dicamba initially via demethylation, generating 3,6-dichlorosalicylate. However, the catabolism of 3,6-dichlorosalicylate remains unknown. In this study, we cloned a gene cluster, dsmR1DABCEFGR2, involved in 3,6-dichlorosalicylate degradation from R. dicambivorans Ndbn-20, demonstrated that the cytochrome P450 monooxygenase system DsmABC was responsible for the 5-hydroxylation of 3,6-dichlorosalicylate, and proposed a dicamba catabolic pathway. This study provides a basis to elucidate the catabolism of dicamba and has benefits for the ecotoxicological study of dicamba. Furthermore, the hydroxylation of salicylate has been previously reported to be catalyzed by single-component flavoprotein or three-component Rieske non-heme iron oxygenase, whereas DsmABC was the only cytochrome P450 monooxygenase system hydroxylating salicylate and its methyl- or chloro-substituted derivatives.

Adsorption of Dicamba herbicide onto a carbon replica obtained from a layered double hydroxide.

In this work, a carbon replica derived from a vinylbenzenesulfonate-intercalated layered double hydroxide (CR-LDH) was applied to remove the Dicamba organochlorine herbicide from aqueous solution. The samples were characterized by several experimental techniques such as X-ray diffraction (XRD), thermogravimetric analysis coupled with differential scanning calorimetry and mass spectrometry (TGA-DSC-MS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Raman spectroscopy, N2 adsorption/desorption and zeta potential analysis. The CR-LDH sample presents a very high specific surface area (2345 m2 g-1). The adsorption experiment typically followed the Langmuir isotherm model and the adsorption kinetics was best fitted with a pseudo second-order model. The maximum adsorption capacity of Dicamba herbicide onto CR-LDH was 279 mg g-1. CR-LDH presented a higher adsorption capacity than other carbon adsorbent materials reported in the literature.

Increased chalcone synthase (CHS) expression is associated with dicamba resistance in Kochia scoparia.

Resistance to the synthetic auxin herbicide dicamba is increasingly problematic in Kochia scoparia. The resistance mechanism in an inbred dicamba-resistant K. scoparia line (9425R) was investigated using physiological and transcriptomics (RNA-Seq) approaches. No differences were found in dicamba absorption or metabolism between 9425R and a dicamba-susceptible line, but 9425R was found to have significantly reduced dicamba translocation. Known auxin-responsive genes ACC synthase (ACS) and indole-3-acetic acid amino synthetase (GH3) were transcriptionally induced following dicamba treatment in dicamba-susceptible K. scoparia but not in 9425R. Chalcone synthase (CHS), the gene regulating synthesis of the flavonols quertecin and kaemperfol, was found to have twofold higher transcription in 9425R both without and 12 h after dicamba treatment. Increased CHS transcription co-segregated with dicamba resistance in a forward genetics screen using an F2 population. Prior work has shown that the flavonols quertecin and kaemperfol compete with auxin for intercellular movement and vascular loading via ATP-binding cassette subfamily B (ABCB) membrane transporters. The results of this study support a model in which constitutively increased CHS expression in the meristem produces more flavonols that would compete with dicamba for intercellular transport by ABCB transporters, resulting in reduced dicamba translocation. © 2017 Society of Chemical Industry.

Fate and Impact of Pesticides

Fate and Impact of Pesticides

EPA restricts dicamba herbicide

In the wake of thousands of complaints of damage to crops in the U.S. from the herbicide dicamba drifting off neighboring fields, the U.S. Environmental Protection Agency and pesticide makers have reached an agreement to impose restrictions on the herbicide’s use. Dicamba products sold for the 2018 growing season will be classified as restricted use, meaning they can be applied only by a certified applicator with special training. Other changes include limiting dicamba spraying to when winds are less than 16 km/hour, restricting spraying to certain times of the day, and requiring farmers to keep records of dicamba use. Farmers are increasingly spraying dicamba on soybeans and cotton that have been genetically engineered to tolerate it, as weeds are becoming resistant to other herbicides such as glyphosate. But soybeans that have not been genetically engineered to tolerate dicamba are particularly susceptible to its damage. State agencies in Arkansas, Illinois, Missouri,

SPECTRUM OF WEED CONTROL WITH 2,4-D AND DICAMBA HERBICIDES ASSOCIATED TO GLYPHOSATE OR NOT

ABSTRACT The possibility of using auxin mimics herbicides in culture postemergence applications contributes to weed management. This study aimed at evaluating and comparing the effectiveness of 2,4-D and dicamba herbicides on glyphosate resistant or tolerant weeds. The treatments were dicamba and 2,4-D doses with or without glyphosate. The evaluated weeds in the experiment were Richardia brasiliensis, Commelina benghalensis, Conyza sp. and Ipomoea nil. Herbicides were applied when weeds were in 4 to 6 and 10 to 12 leaves stages. Data referring to evaluations on day 30 after application were submitted to analysis of variance. Response-dose curves were obtained for herbicides, and C85 and C95 values were identified. Weed species showed different tolerance to dicamba and 2,4-D, and differences were more evident for C. benghalensis. The addition of glyphosate to the auxin mimic reduced the differences between them. For plants in less developed stages, regardless of the species, mixtures of glyphosate + 2,4-D or glyphosate + dicamba provided excellent levels of control. In general, considering equivalent doses, for R. brasiliensis, C. benghalensis and I. nil, 2,4-D herbicide was superior to dicamba. As for Conyza bonariensis, dicamba showed better control percentages.

Dicamba disaster fuels controversy

This year farmers across the U.S. Midwest planted soybeans genetically engineered to tolerate the herbicide dicamba. The seeds were so popular they were used on an area about the size of South Carolina. For many growers it was a huge relief to finally have a tool that kills several fierce weeds that have become resistant to the herbicide glyphosate, also known as Roundup. But other farmers are not happy; in fact, they are downright angry. They opted to plant other varieties of soybeans, which are sensitive to dicamba. After their neighbors began spraying dicamba, these farmers discovered that their own soybean fields displayed the classic signs of dicamba-induced damage, including wrinkled and cupped leaves and stunted growth. State agriculture agencies—particularly in Arkansas, Illinois, Missouri, Ohio, and Tennessee—are now investigating thousands of reports of purported dicamba injury. And herbicide companies are at odds with university weed scientists over why the damage

States ban dicamba herbicide

In response to escalating concerns about alleged misuse of the herbicide dicamba, Arkansas and Missouri have halted the sale and use of the chemical. The states received hundreds of complaints this year from farmers who say dicamba spray drifted onto their property from neighboring fields and damaged their soybeans that have not been genetically engineered to tolerate the herbicide. On July 7, the Missouri Department of Agriculture banned the sale and use of all dicamba products labeled for agricultural use in the state, effective immediately. Also on July 7, the Arkansas Agriculture Department halted the sale of dicamba for agricultural use in that state for 120 days, effective on July 11. Chris Chinn, director of the Missouri Department of Agriculture, says Missouri’s ban will be lifted once companies, the state, and the U.S. Environmental Protection Agency agree to new restrictions to be printed on dicamba product labels. Dicamba (3,6-dichloro-2-methoxybenzoic acid)

Dicamba drift sows trouble in Arkansas

Arkansas is considering a 120-day ban on the use of dicamba herbicide on cotton and soybeans. The ban would be a response to farmers who say dicamba drifted to their fields and damaged crops. Dicamba is used to control broad-leaved weeds, including those such as Palmer amaranth that have developed resistance to the herbicide glyphosate. Herbicide-resistant weeds have become a major problem for farmers, particularly in the southern U.S. This year, cotton and soybean farmers had the option to plant crops genetically modified to tolerate being sprayed with dicamba. The Arkansas State Plant Board approved a new dicamba formulation—BASF’s Engenia—for use during the growing season. Engenia is an N,N-bis-(3-aminopropyl)methylamine salt of dicamba developed by BASF to reduce drift. Farmers are required to use Engenia rather than older formulations and follow detailed application instructions. Even with those controls in place, the Arkansas plant board has received 135 complaints from farmers alleging

Wpływ herbicydów na biomasę chwastów, plon ziarna i wybrane elementy plonowania prosa zwyczajnego (Panicum miliaceum L.)

This paper shows results of studies conducted at the same time in Belarus and in Poland (over the period of 2014–2016) on the tolerance of millet towards some foliar herbicides (2,4-D + fluroxypyr; tribenuron-methyl + fluroxypyr; dicamba + triasulfuron) applied at rates reduced by 1/3 relative to the recommended rates for oats crops. Plots without herbicide application (mechanical weed control) were the control treatment.  The experiment was set up with the same design (one-factional) under the soil and climatic conditions of central-eastern Belarus (Priluki near Minsk) and the central Lublin region (Czesławice, Poland), respectively. The Belarussian soil was characterized by medium nutrient availability (soil class III), whereas the soil in Poland had higher nutrient availability (soil class II). In both places, the same agricultural practices were used (tillage system, previous crop, seeding rate, and row spacing), while mineral NPK fertilization was adjusted to the initial soil nutrient availability in both study areas. It was proved that the foliar herbicides applied in the experiment (at the tillering stage of millet) had high weed control efficacy and that the low level of weed infestation contributed to the high productivity of millet compared to the mechanical weed control treatment (without herbicides). The action of the herbicides 2,4-D + fluroxypyr and tribenuron-methyl + fluroxypyr was evaluated particularly positively, since they did not induce a phytotoxic response in millet plants, but eliminated weeds biomass from the crop almost completely. In turn, the herbicide dicamba + triasulfuron exhibited a slightly lower weed-killing ability and, moreover, caused damage to millet plants in a small percentage. Some differences (though statistically insignificant) in weeds biomass and millet yield which were found between the experiments in Belarus and Poland should be attributed to the difference in the soils and more favorable weather conditions for the growth of millet in Belarus.

Optimization of Fenton\u2019s oxidation of herbicide dicamba in water using response surface methodology

In this study Fenton’s oxidation of dicamba in aqueous medium was investigated by using the response surface methodology. The influence of H2O2/COD (A), H2O2/Fe2+ (B), pH (C) and reaction time (D) as independent variables were studied on two responses (COD and dicamba removal efficiency). The dosage of H2O2 (5.35–17.4 mM) and Fe2+ (0.09–2.13 mM) were varied and optimum percentage removal of dicamba of 84.01% with H2O2 and Fe2+ dosage of 11.38 and 0.33 mM respectively. The whole oxidation process was monitored by high performance liquid chromatography (HPLC) along with liquid chromatography/mass spectrometry (LC/MS). It was found that 82% of dicamba was mineralized to oxalic acid, chloride ion, CO2 and H2O, which was confirmed with COD removal of 81.53%. The regression analysis was performed, in which standard deviation (<4%), coefficient of variation (<8), F value (Fisher’s Test) (>2.74), coefficient of correlation (R2 = R_{text{adj}}^{2}) and adequate precision (>12) were in good agreement with model values. Finally, the treatment process was validated by performing the additional experiments.

Transcriptomic analysis of basidiocarp development in Ustilago maydis (DC) Cda.

Previously, we demonstrated that when Ustilago maydis (DC) Cda., a phytopathogenic basidiomycete and the causal agent of corn smut, is grown in the vicinity of maize embryogenic calli in a medium supplemented with the herbicide Dicamba, it developed gastroid-like basidiocarps. To elucidate the molecular mechanisms involved in the basidiocarp development by the fungus, we proceeded to analyze the transcriptome of the process, identifying a total of 2002 and 1064 differentially expressed genes at two developmental stages, young and mature basidiocarps, respectively. Function of these genes was analyzed with the use of different databases. MIPS analysis revealed that in the stage of young basidiocarp, among the ca. two thousand differentially expressed genes, there were some previously described for basidiocarp development in other fungal species. Additional elements that operated at this stage included, among others, genes encoding the transcription factors FOXO3, MIG3, PRO1, TEC1, copper and MFS transporters, and cytochromes P450. During mature basidiocarp development, important up-regulated genes included those encoding hydrophobins, laccases, and ferric reductase (FRE/NOX). The demonstration that a mapkk mutant was unable to form basidiocarps, indicated the importance of the MAPK signaling pathway in this developmental process.

Palmer Amaranth (&amp;lt;i&amp;gt;Amaranthus palmeri&amp;lt;/i&amp;gt; S. Wats.) and Pitted Morningglory (&amp;lt;i&amp;gt;Ipomoea lacunosa&amp;lt;/i&amp;gt; L.) Control in Dicamba Tolerant Soybean (&amp;lt;i&amp;gt;Glycine max&amp;lt;/i&amp;gt; L.)

Palmer amaranth and pitted morningglory are difficult to manage weeds present in South Carolina soybean production fields. Glyphosate and ALS-resistant Palmer amaranth biotypes have spread rapidly throughout South Carolina making the control of these weeds more difficult. Recently, soybean varieties with tolerance to dicamba have been introduced along with several new ultra-low volatility formulations of dicamba to help with the problem. Field experiments were conducted near Blackville, SC in 2012 and 2013 to evaluate dicamba herbicide programs for broadleaf weed management in dicamba tolerant soybean. At 2 weeks after POST1 (2 WAP1), Palmer amaranth control ranged from 93% to 100% across the PRE followed by POST treatments in 2012 and 2013. By 2 weeks after POST2 (2 WAP2), control was 95% or better. Treatments containing two or three herbicide applications (PRE, POST1 and POST2) offered good to excellent (92% - 100%) pitted morningglory control. No differences in weed control were observed among treatments with 3 application times compared to those applied twice. In general, all treatments with a PRE followed by at least one POST application provided good to excellent control of Palmer amaranth and pitted morningglory. Overall, a PRE (either dicamba or flumioxazin) followed by a dicamba or a non-dicamba containing POST treatment provided good to excellent control of Palmer amaranth and pitted morningglory when applied at the correct growth stage.

A Tetrahydrofolate-Dependent Methyltransferase Catalyzing the Demethylation of Dicamba in Sphingomonas sp. Strain Ndbn-20

Sphingomonas sp. strain Ndbn-20 degrades and utilizes the herbicide dicamba as its sole carbon and energy source. In the present study, a tetrahydrofolate (THF)-dependent dicamba methyltransferase gene, dmt, was cloned from the strain, and three other genes, metF, dhc, and purU, which are involved in THF metabolism, were found to be located downstream of dmt A transcriptional study revealed that the four genes constituted one transcriptional unit that was constitutively transcribed. Lysates of cells grown with glucose or dicamba exhibited almost the same activities, which further suggested that the dmt gene is constitutively expressed in the strain. Dmt shared 46% and 45% identities with the methyltransferases DesA and LigM from Sphingomonas paucimobilis SYK-6, respectively. The purified Dmt catalyzed the transfer of methyl from dicamba to THF to form the herbicidally inactive metabolite 3,6-dichlorosalicylic acid (DCSA) and 5-methyl-THF. The activity of Dmt was inhibited by 5-methyl-THF but not by DCSA. The introduction of a codon-optimized dmt gene into Arabidopsis thaliana enhanced resistance against dicamba. In conclusion, this study identified a THF-dependent dicamba methyltransferase, Dmt, with potential applications for the genetic engineering of dicamba-resistant crops. Dicamba is a very important herbicide that is widely used to control more than 200 types of broadleaf weeds and is a suitable target herbicide for the engineering of herbicide-resistant transgenic crops. A study of the mechanism of dicamba metabolism by soil microorganisms will benefit studies of its dissipation, transformation, and migration in the environment. This study identified a THF-dependent methyltransferase, Dmt, capable of catalyzing dicamba demethylation in Sphingomonas sp. Ndbn-20, and a preliminary study of its enzymatic characteristics was performed. Introduction of a codon-optimized dmt gene into Arabidopsis thaliana enhanced resistance against dicamba, suggesting that the dmt gene has potential applications for the genetic engineering of herbicide-resistant crops.