Classes Of Herbicides Research Articles

Ecotoxicological evaluation of poly(epsilon-caprolactone) nanocapsules containing triazine herbicides.

The triazine class of herbicides includes the compounds ametryn, atrazine, and simazine, which are used to control weeds in plantations of crops such as maize, sorghum, and sugar cane. Despite their acceptance in agriculture, these herbicides can be dangerous to the environment, depending on their toxicity, the degree of contamination, and the duration of exposure. Controlled release systems are increasingly used to mitigate problems of toxicity and minimize environmental impacts, and can also increase herbicide efficiency. The objective of this work was to prepare poly(epsilon-caprolactone) nanocapsules containing ametryn and atrazine, and evaluate their toxicity to aquatic organisms as well as in cytogenetic tests employing human lymphocyte cultures. The PCL nanocapsules were prepared according to the interfacial deposition of pre-formed polymer method. Ecotoxicological assays were performed with the alga Pseudokirchneriella subcapitata and the microcrustacean Daphnia similis. The cytogenetic tests consisted of observing mitotic index alterations after exposing lymphocyte cell cultures to different formulations. Encapsulation of the herbicides in the nanocapsules resulted in lower toxicity to the alga and higher toxicity to the microcrustacean, compared to the herbicides alone. The cytogenetic tests showed that formulations of nanocapsules containing the herbicides were less toxic than the herbicides alone. The findings indicate the potential of the nanocapsule formulations in agricultural applications, where they could help to reduce the quantities of herbicides used as well as impacts on the environment and human health.

3-(Methoxycarbonylmethylene)isobenzofuran-1-imines as a new class of potential herbicides.

A novel class of potential herbicides, the 3-(methoxycarbonylmethylene) isobenzofuran-1-imines, has been discovered. The herbicidal activity has been tested on two particular molecules, (E)-methyl 2-[3-(butylimino)isobenzofuran-1(3H)-ylidene]acetate (1) and (E)-methyl 2-phenyl-2-[3-(phenylimino)isobenzofuran-1(3H)-ylidene]acetate (2), prepared by palladium-catalyzed oxidative carbonylation of 2-alkynylbenzamides. Both compounds 1 and 2 showed a strong phytotoxic effect on both shoot and root systems of Arabidopsis thaliana. The effects observed on the shoot were similar for both molecules, but while compound 1 showed a stronger effect on root parameters (such as primary root length, root hair and density, showing lower ED50 values), compound 2 caused important malformations in root morphology. Our results indicate that these molecules are very promising synthetic herbicides.

Cyclopent-4-ene-1,3-diones: A New Class of Herbicides Acting as Potent Photosynthesis Inhibitors

In a recent paper, we reported the synthesis and photosynthesis-inhibitory activity of a series of analogues of rubrolides. From quantitative structure-activity relationship (QSAR) studies, we found that the most efficient compounds are those having higher ability to accept electrons. On the basis of those findings, we directed our effort to synthesize new analogues bearing a strong electron-withdrawing group (nitro) in the benzylidene ring and evaluate their effects on photosynthesis. However, the employed synthetic approach led to novel cyclopent-4-ene-1,3-diones as major products. Here, we report the synthesis and mechanism of action of such cyclopent-4-ene-1,3-diones as a new class of photosynthesis inhibitors. These compounds block the electron transport at the QB level by interacting at the D1 protein at the reducing side of Photosystem II and act as Hill reaction inhibitors, with higher activity than the corresponding rubrolides. To the best of our knowledge, this is the first report on the photosynthesis inhibitory activity of cyclopentenediones.

Lessons Learned From the History of Herbicide Resistance

The selection of herbicide-resistant weed populations began with the introduction of synthetic herbicides in the late 1940s. For the first 20 years after introduction, there were limited reported cases of herbicide-resistant weeds. This changed in 1968 with the discovery of triazine-resistant common groundsel. Over the next 15 yr, the cases of herbicide-resistant weeds increased, primarily to triazine herbicides. Although triazine resistance was widespread, the resistant biotypes were highly unfit and were easily controlled with specific alternative herbicides. Weed scientists presumed that this would be the case for future herbicide-resistant cases and thus there was not much concern, although the companies affected by triazine resistance were somewhat active in trying to detect and manage resistance. It was not until the late 1980s with the discovery of resistance to Acetyl Co-A carboxylase (ACCase) and acetolactate synthase (ALS) inhibitors that herbicide resistance attracted much more attention, particularly from industry. The rapid evolution of resistance to these classes of herbicides affected many companies, who responded by first establishing working groups to address resistance to specific classes of herbicides, and then by formation of the Herbicide Resistance Action Committee (HRAC). The goal of these groups, in cooperation with academia and governmental agencies, was to act as a forum for the exchange of information on herbicide-resistance selection and to develop guidelines for managing resistance. Despite these efforts, herbicide resistance continued to increase. The introduction of glyphosate-resistant crops in the 1995 provided a brief respite from herbicide resistance, and farmers rapidly adopted this relatively simple and reliable weed management system based on glyphosate. There were many warnings from academia and some companies that the glyphosate-resistant crop system was not sustainable, but this advice was not heeded. The selection of glyphosate resistant weeds dramatically changed weed management and renewed emphasis on herbicide resistance management. To date, the lesson learned from our experience with herbicide resistance is that no herbicide is invulnerable to selecting for resistant biotypes, and that over-reliance on a weed management system based solely on herbicides is not sustainable. Hopefully we have learned that a diverse weed management program that combines multiple methods is the only system that will work for the long term.

Cytochrome P450 CYP81A12 and CYP81A21 Are Associated with Resistance to Two Acetolactate Synthase Inhibitors in Echinochloa phyllopogon.

Previous studies have demonstrated multiple herbicide resistance in California populations of Echinochloa phyllopogon, a noxious weed in rice (Oryza sativa) fields. It was suggested that the resistance to two classes of acetolactate synthase-inhibiting herbicides, bensulfuron-methyl (BSM) and penoxsulam (PX), may be caused by enhanced activities of herbicide-metabolizing cytochrome P450. We investigated BSM metabolism in the resistant (R) and susceptible (S) lines of E. phyllopogon, which were originally collected from different areas in California. R plants metabolized BSM through O-demethylation more rapidly than S plants. Based on available information about BSM tolerance in rice, we isolated and analyzed P450 genes of the CYP81A subfamily in E. phyllopogon. Two genes, CYP81A12 and CYP81A21, were more actively transcribed in R plants compared with S plants. Transgenic Arabidopsis (Arabidopsis thaliana) expressing either of the two genes survived in media containing BSM or PX at levels at which the wild type stopped growing. Segregation of resistances in the F2 generation from crosses of R and S plants suggested that the resistance to BSM and PX were each under the control of a single regulatory element. In F6 recombinant inbred lines, BSM and PX resistances cosegregated with increased transcript levels of CYP81A12 and CYP81A21. Heterologously produced CYP81A12 and CYP81A21 proteins in yeast (Saccharomyces cerevisiae) metabolized BSM through O-demethylation. Our results suggest that overexpression of the two P450 genes confers resistance to two classes of acetolactate synthase inhibitors to E. phyllopogon. The overexpression of the two genes could be regulated simultaneously by a single trans-acting element in the R line of E. phyllopogon.

Evaluation of a biohybrid photoelectrochemical cell employing the purple bacterial reaction centre as a biosensor for herbicides

The Rhodobacter sphaeroides reaction centre is a relatively robust and tractable membrane protein that has potential for exploitation in technological applications, including biohybrid devices for photovoltaics and biosensing. This report assessed the usefulness of the photocurrent generated by this reaction centre adhered to a small working electrode as the basis for a biosensor for classes of herbicides used extensively for the control of weeds in major agricultural crops. Photocurrent generation was inhibited in a concentration-dependent manner by the triazides atrazine and terbutryn, but not by nitrile or phenylurea herbicides. Measurements of the effects of these herbicides on the kinetics of charge recombination in photo-oxidised reaction centres in solution showed the same selectivity of response. Titrations of reaction centre photocurrents yielded half maximal inhibitory concentrations of 208nM and 2.1µM for terbutryn and atrazine, respectively, with limits of detection estimated at around 8nM and 50nM, respectively. Photocurrent attenuation provided a direct measure of herbicide concentration, with no need for model-dependent kinetic analysis of the signal used for detection or the use of prohibitively complex instrumentation, and prospects for the use of protein engineering to develop the sensitivity and selectivity of herbicide binding by the Rba. sphaeroides reaction centre are discussed.

Evolution of resistance to phytoene desaturase and protoporphyrinogen oxidase inhibitors – state of knowledge

Two major classes of herbicides include inhibitors of protoporphyrinogen oxidase (PPO) and phytoene desaturase (PDS). Plants can evolve resistance to PPO and PDS inhibitors via several mechanisms that include physical changes, resulting in reduced uptake, physiological changes, resulting in compartmentalization or altered translocation, and biochemical changes, resulting in enhanced metabolic degradation or alterations of protein structures, leading to loss of sensitivity to the herbicides. This review discusses the involvement of some of these mechanisms in the various cases of resistance to PDS- and PPO-inhibiting herbicides, and highlights unique aspects of target-site resistance to these herbicides.

Acetohydroxyacid Synthase: A Target for Antimicrobial Drug Discovery

Acetohydroxyacid synthase (AHAS) (EC 2.2.1.6) (also known as acetolactate synthase) is the first common enzyme in the branched chain amino acid (BCAA) biosynthesis pathway. This pathway is present in microorganisms and in plants but not in animals, making it an attractive target for both drug and herbicide discovery. The function of AHAS is to catalyze the conversion of two molecules of pyruvate to 2-acetolactate or to convert one molecule of pyruvate and a molecule of 2-ketobutyrate into 2-aceto-2-hydroxybutyrate. Three cofactors are required for the activity of AHAS: thiamine diphosphate (ThDP), Mg²⁺ and flavin-adenine dinucleotide (FAD). AHAS is the target for several classes of commercial herbicides that include the sulfonylurea and imidazolinone families. These herbicides are potent and selective inhibitors of AHAS with Ki values that can be in the low nM range. Such compounds also exhibit low application rates as herbicides (typically ~3 g ha⁻¹) and have low mammalian toxicity (LD₅₀ values typically >4g/kg), thereby highlighting their utility and effectiveness as biocidal agents. However, somewhat surprisingly given the central importance of AHAS in the metabolism of microorganisms, no inhibitors of this enzyme have been commercialized into antimicrobial agents. Here we provide an overview of the biochemical characterization of AHASs from bacterial and fungal sources, analyse the structural features of these enzymes that are criticial to catalysis andprovide the current data on AHAS inhibitors that have potential to be developed into antimicrobial therapeutics.

A Novel Rice Cytochrome P450 Gene, CYP72A31, Confers Tolerance to Acetolactate Synthase-Inhibiting Herbicides in Rice and Arabidopsis

Target-site and non-target-site herbicide tolerance are caused by the prevention of herbicide binding to the target enzyme and the reduction to a nonlethal dose of herbicide reaching the target enzyme, respectively. There is little information on the molecular mechanisms involved in non-target-site herbicide tolerance, although it poses the greater threat in the evolution of herbicide-resistant weeds and could potentially be useful for the production of herbicide-tolerant crops because it is often involved in tolerance to multiherbicides. Bispyribac sodium (BS) is an herbicide that inhibits the activity of acetolactate synthase. Rice (Oryza sativa) of the indica variety show BS tolerance, while japonica rice varieties are BS sensitive. Map-based cloning and complementation tests revealed that a novel cytochrome P450 monooxygenase, CYP72A31, is involved in BS tolerance. Interestingly, BS tolerance was correlated with CYP72A31 messenger RNA levels in transgenic plants of rice and Arabidopsis (Arabidopsis thaliana). Moreover, Arabidopsis overexpressing CYP72A31 showed tolerance to bensulfuron-methyl (BSM), which belongs to a different class of acetolactate synthase-inhibiting herbicides, suggesting that CYP72A31 can metabolize BS and BSM to a compound with reduced phytotoxicity. On the other hand, we showed that the cytochrome P450 monooxygenase CYP81A6, which has been reported to confer BSM tolerance, is barely involved, if at all, in BS tolerance, suggesting that the CYP72A31 enzyme has different herbicide specificities compared with CYP81A6. Thus, the CYP72A31 gene is a potentially useful genetic resource in the fields of weed control, herbicide development, and molecular breeding in a broad range of crop species.

Rapid simultaneous determination of herbicides in human serum by UPLC-ESI-MS

A simple, rapid and reliable method is developed for the determination of 51 kinds belonging to at least 8 classes of herbicides in human serum by ultra performance liquid chromatography-electrospray ionization-mass spectrometry.

Allelopathy of Cold Water Extracts from Origanum vulgare ssp. vulgare L.

Secondary metabolites in medicinal plants could lead to discovery of new classes of herbicides. Recently aromatic plants have gained interest as a source of allelopathic secondary metabolites. Origanum vulgare ssp. vulgare L. infusions in hot water are used in folk medicine and possess proved beneficial biological activity. Plant-to-plant variability of metabolites due to genetic heterogeneity is established in Lamiaceae family. From this point of view, studies on plants from different geographic regions might reveal important sources of variability. The objective of this study was to evaluate allelopathic activity of cold water extracts made from the aerial parts of O. vulgare ssp. vulgare growing wild in Northeast Bulgaria in laboratory conditions. The allelopathic effect was evaluated using root elongation test and Allium cepa-test. Oregano extracts (17.5 g/l, 52.5 g/l) significantly decreased root length of Triticum aestivum L. (P ≤ 0.001). The root growth reduction could serve as a sign for presence of water soluble allelopathic secondary metabolites in the plant tested. Oregano (3.5 g/l) inhibited cell division in Allium root meristematic cells. The decline of the mitotic index indicates the occurrence of a cytotoxic effect. Oregano induced abnormalities in mitotic and interphase cells, so can be also considered as genotoxic. The observed macroscopic and microscopic effects of tested extracts indicated presence of water soluble allelochemicals in O. vulgare ssp. vulgare. This characteristic could be further studied as a possibility to be used in weed management programs.

Registration of ‘Clara CL’ Wheat

‘Clara CL’ (Reg. No. CV-XX; PI 665948) hard white winter wheat (Triticum aestivum L.) cultivar was developed at the Agricultural Research Center–Hays, Kansas State University and released by the Kansas Agricultural Experiment Station in 2011. Clara CL carries one Clearfield gene and has tolerance to imazamox herbicide. Clara CL was selected from a single cross of KS03HW154/KS03HW1 using a modified bulk breeding method. Both parental lines are unreleased hard white winter experimental lines from Kansas State University. The objective of the cross was to develop a hard white winter wheat variety with herbicide resistance and adaptation to the semiarid area in western Kansas. Clara CL was released because of its tolerance to imazamox herbicide, high grain yield potential under nonirrigated conditions in western Kansas, preharvest sprouting tolerance, and good disease and insect resistance. T.J. Martin and G. Zhang, Agricultural Research Center–Hays, Kansas State Univ., Hays, KS 67601; A.K. Fritz, Dep. of Agronomy, Kansas State Univ., Manhattan, KS 66506; R. Miller, Dep. of Grain Science and Industry, Kansas State Univ., Manhattan, KS 66506; M.-S. Chen, USDA–ARS, Hard Winter Wheat Genetics Research Unit, Kansas State Univ., Manhattan, KS 66506. Registration by CSSA. Received 23 July 2013. *Corresponding author (gzhang@ksu.edu). Abbreviations: ARCH, Agricultural Research Center–Hays; AYN, advanced yield nursery; HWWW, hard white winter wheat; KIN, Kansas Intra-State Nursery; KSU, Kansas State University; PPO, polyphenol oxidase; PYN, preliminary yield nursery; SBMV, Soil-borne mosaic virus; SRPN, Southern Regional Performance Nursery; WQC, Wheat Quality Council; WSMV, Wheat streak mosaic virus. ‘Clara CL’ (Reg. No. CV-XX; PI 665948) is a hard white winter wheat (Triticum aestivum L.) (HWWW) variety developed at the Agricultural Research Center–Hays (ARCH), Kansas State University (KSU), and released by the Kansas Agricultural Experiment Station in 2011. Clara CL was selected from the single cross KS03HW154/KS03HW1. Both parental lines, KS03HW154 and KS03HW1, are unreleased hard white winter experimental lines developed at ARCH. KS03HW154 is a sister line to ‘RonL’ (PI 648020) with the pedigree ‘Trego’ (PI 612576; Martin et al., 2001)/CO960293. KS03HW1 was derived from the four-way cross FS2/KS97HW150//KS97HW349/3/Trego. FS2 is a proprietary wheat germplasm developed by BASF Corporation (formerly American Cyanamid) through induced mutagenesis, and it carries Als1 locus (D genome) conferring tolerance to the imidazolinone class of herbicides (also known as Beyond herbicide) (Newhouse et al., 1992). Clara CL is an F6–derived line, which was tested as experimental line number KS08HW35-1. Clara CL was released because of its imazamox herbicide tolerance, high grain yield potential in the dryland production system in western Kansas, preharvest sprouting tolerance, and good resistance to the major diseases in western Kansas. CL in the name stands for Clearfield, the trademark for Beyond herbicide tolerance.

Fungal degradation of an acetolactate synthase (ALS) inhibitor pyrazosulfuron-ethyl in soil

Owing to reported phytotoxicity of some sulfonylurea class of herbicides in number of sensitive crops and higher persistence in soil, present study was conducted to isolate and identify pyrazosulfuron-ethyl degrading fungi from soil of rice field. Penicillium chrysogenum and Aspergillus niger, were isolated and identified from rhizospere soil of rice field, as potent pyrazosulfuron-ethyl degrading fungi. Degradation of pyrazosulfuron-ethyl by P. chrysogenum and A. niger, yielded transformation products/metabolites which were identified and characterized by LC/MS/MS. The rate of dissipation of pyrazosulfuron-ethyl was found higher in soil of rice field and soil inoculated with P. chrysogenum. This showed important route of degradation of pyrazosulfuron-ethyl by microbes apart from chemical degradation.

4‐Hydroxyphenylpyruvate Dioxygenase Inhibitors in Combination with Safeners: Solutions for Modern and Sustainable Agriculture

Inhibitors of 4-hydroxyphenylpyruvate dioxygenase (HPPD) prevent plant carotenoid pigment formation, which in turn leads to chlorophyll degradation. This "bleaching" herbicide mode of action provides weed-control products for various crops, such as rice, corn, and cereals. Combinations with suitable safeners allow the full exploitation of the potential of this compound class to selectively control major weed problems, including rapidly increasing cases of resistance against other important herbicide classes.

Bioassay-Guided Isolation of a Low Molecular Weight PHB from Burkholderia sp. with Phytotoxic Activity

This work reports on the bioassay-guided isolation and identification of the macrocyclic pentolide 1, a cyclic polyhydroxybutyrate (PHB) with low molecular weight. This metabolite is produced by Burkholderia sp. and it exhibited phytotoxic activity in a Lemna minor bioassay. Its structure was determined by (1)H and (13)C NMR, heteronuclear multiple quantum correlation, heteronuclear multiple bond correlation, IR, and electrospray ionization tandem mass spectrometry analyses. The period for maximum production of the pentolide was optimized and determined on the basis of multiple reaction monitoring experiments at 15 days. The potential of Burkholderia sp. as a producer of higher biopolymers of PHB was also investigated. The methodology employed here accelerated the isolation and characterization of a phytotoxic metabolite whose structure can serve as a model for the synthesis of new classes of herbicides.

Accurate computational prediction of the structural and vibrational properties of s-triazine derivatives in vacuo. A DFT approach

The well-known class of herbicides, s-triazine derivatives, are commonly used as reagents in the manufacture of resins and pharmaceuticals, and also of solvent-refined coals. Recently, triazine derivatives have been observed to form self-assembling nanostructures on metallic surfaces. In this paper, we present a study using a DFT approach for the computational prediction of the structural and vibrational properties in vacuo of three s-triazine derivatives, viz., atrazine (N,N′-ethyl-isopropyl-6-chloro-1,3,5-triazine,2,4-diamine), prometryn (N,N′-diisopropyl-6-methyl-thio-1,3,5-triazine,2,4-diamine) and simetryn (N,N′-diethyl-6-methyl-thio-1,3,5-triazine,2,4-diamine). In particular we show that the employment of the Becke three-parameter Lee–Yang–Parr (B3-LYP) exchange-correlation functional using the aug-cc-pVQZ basis set provides an accurate prediction of the structural and vibrational properties of atrazine, prometryn, and simetryn.

Registration of ‘WB9879CLP’ Hard Red Spring Wheat

‘WB9879CLP’ hard red spring wheat (Triticum aestivum L.) (Reg. No. CV‐1086, PI 666046) was developed by the Montana Agricultural Experiment Station and released in 2012 to the commercial partner Westbred, a subsidiary of Monsanto. WB9879CLP is a two‐gene Clearfield wheat for use with the imidazolinone herbicide Beyond (BASF). WB9879CLP was developed by backcrossing alleles for resistance to the imidazolinone herbicide class into the recurrent parent ‘Choteau’. Choteau has solid stems, which provide resistance to the wheat stem sawfly (Cephus cinctus Nort.). The wheat stem sawfly is a major yield‐reducing pest in large areas of Montana and surrounding regions. Alleles for herbicide resistance at TaAHAS1D and TaAHAS1B were selected during the backcrossing process and line derivation using polymerase chain reaction markers developed by BASF. Two years of replicated yield trials at a total of 16 sites showed that WB9879CLP is similar to Choteau in most agronomic characteristics. WB9879CLP showed no symptoms of damage at any of 13 testing sites when imidazolinone herbicide was applied at two times the recommended rate. WB9879CLP is the first Clearfield solid‐stem wheat variety for sawfly infested sites in Montana and adjoining regions.

α-(Substituted-phenoxyacetoxy)-α-heterocyclylmethylphosphonates: Synthesis, Herbicidal Activity, Inhibition on Pyruvate Dehydrogenase Complex (PDHc), and Application as Postemergent Herbicide against Broadleaf Weeds

Pyruvate dehydrogenase complex (PDHc) is the site of action of a new class of herbicides. On the basis of the previous work for O,O'-dimethyl α-(substituted-phenoxyacetoxy)alkylphosphonates (I), further synthetic modifications were made by introducing a fural and a thienyl group to structure I. A series of α-(substituted-phenoxyacetoxy)-α-heterocyclylmethylphosphonate derivatives (II) were synthesized as potential inhibitors of PDHc. The postemergent activity of the title compounds II was evaluated in greenhouse experiments. The in vitro efficacy of II against PDHc was also examined. Compounds II with fural as R(3) and 2,4-dichloro as X and Y showed significant herbicidal activity and effective inhibition against PDHc from plants. O,O'-Dimethyl α-(2,4-dichlorophenoxyacetoxy)-α-(furan-2-yl)methylphosphonate II-17 had higher inhibitory potency against PDHc from Pisum sativum than against PDHc from Oryza sativa in vitro and was most effective against broadleaf weeds at 50 and 300 ai g/ha. II-17 was safe for maize and rice even at the dose of 900-1200 ai g/ha. Field trials at different regions in China showed that II-17 (HWS) could control a broad spectrum of broad-leaved and sedge weeds at the rate of 225-375 ai g/ha for postemergent applications in maize fields. II-17 (HWS) displayed potential utility as a selective herbicide.

Resistance to herbicides caused by single amino acid mutations in acetyl‐CoA carboxylase in resistant populations of grassy weeds

Eleven spontaneous mutations of acetyl-CoA carboxylase have been identified in many herbicide-resistant populations of 42 species of grassy weeds, hampering application of aryloxyphenoxypropionate, cyclohexadione and phenylpyrazoline herbicides in agriculture. IC(50) shifts (resistance indices) caused by herbicide-resistant mutations were determined using a recombinant yeast system that allows comparison of the effects of single amino acid mutations in the same biochemical background, avoiding the complexity inherent in the in planta experiments. The effect of six mutations on the sensitivity of acetyl-CoA carboxylase to nine herbicides representing the three chemical classes was studied. A combination of partially overlapping binding sites of the three classes of herbicides and the structure of their variable parts explains cross-resistance among and between the three classes of inhibitors, as well as differences in their specificity. Some degree of resistance was detected for 51 of 54 herbicide/mutation combinations. Introduction of new herbicides targeting acetyl-CoA carboxylase will depend on their ability to overcome the high degree of cross-resistance already existing in weed populations.

Запрограмована загибель клітин у патогенезі, індукованому гербіцидами – інгібіторами ацетил-КоА-карбоксилази

Importance of pathogenesis induced by herbicides whose phytotoxic action is caused by the interaction with photosynthesis is discussed. For this class of herbicides, the participation of programmed cell death and the role of reactive oxygen species (ROS) in the induced pathogenesis are shown. However, study of pathogenesis induced by another class of herbicides, inhibitors of acetyl-CoA carboxylase is most important. Previous studies have shown that the phytotoxic action of inhibitors of acetyl-CoA carboxylase are mediated by ROS generation. This investigation showed that herbicide haloxyfop-R-metyl induced fragmentation of DNA isolated from root merystem of maize seedlings ( Zea mays L.) in mono-oligonucleosomic cites that is an important marker of the programmed cell death. These data suggest that the programmed cell death is participating in pathogenesis induced by herbicides inhibitors of acetyl-CoA-carboxylase. Keywords: Zea mays , herbicides, induced pathogenesis, acetyl-CоА-carboxy­la­se, programmed cell death, DNA degradation.