Acetyl-CoA Carboxylase—a Graminicide Target Site

Acetyl-CoA carboxylase catalyses the first committed step in fatty acid (and acyl lipid) formation. The enzyme has been shown to exert a high degree of flux control for lipid biosynthesis in leaves and, therefore, it is not surprising that chemicals which can inhibit it effectively are successful herbicides. These chemicals belong mainly to the cyclohexanedione and aryloxyphenoxypropionate classes and are graminicides. The reason for the selectivity of these herbicides towards grasses lies in the nature of the target site, acetyl-CoA carboxylase. Recent advances in our knowledge of acetyl-CoA carboxylases from sensitive and resistant plants has revealed some important facts. Dicotyledons, which are resistant, have a multi-enzyme complex type of carboxylase in their chloroplasts while grasses have a multifunctional protein. Both divisions of plants have two isoforms of the enzyme, the second being in the cytosol. Detailed study of multifunctional forms of acetyl-CoA carboxylases, which have different sensitivities to herbicides, suggests that herbicide resistance is correlated with cooperativity of herbicide binding to the native dimeric form of the carboxylase. © 1997 SCI.     

Harelish负向调控棉铃虫性信息素生物合成机制的初步研究

性信息素是蛾类昆虫通讯的关键信号分子,其生物合成机制已在家蚕Bombyx mori、棉铃虫Helicoverpa armigera和亚洲玉米螟Ostrinia furnacalis等蛾类中明确了,但其负向调控机制尚不明确。本文探索了Harelish基因在棉铃虫雌蛾性信息素生物合成中的作用。结果发现,Harelish基因在棉铃虫雌蛾中肠、表皮、脑、触角、脂肪体、肌肉和性信息素腺体等7个组织中均有表达,且在羽化后随着性信息素生物的合成和释放而高丰度表达。基于RNAi降低Harelish基因转录水平的表达量后,其性信息素含量和钙调磷酸酶活性均显著上升,表明Harelish通过抑制钙调磷酸酶活性负向调控了性信息素的生物合成。该研究为利用性信息素生物合成的终止信号为分子靶标来防控害虫奠定理论基础。     

Phytotoxic sites of action for molecular design of modern herbicides (Part 2): Amino acid, lipid and cell wall biosynthesis, and other targets for future herbicides

A bird's eye review was tried in Part 2 of this series, 'Phytotoxic sites of action for molecular design of modern herbicides', in order to select the best selection of known and some novel plant-specific targets for molecular design of modern herbicides, which affect amino acid, lipid and cell wall biosynthesis. Although amino acid biosynthesis pathways, particularly those for aromatic amino acids, ammonia assimilation and branched amino acids, have been confirmed as reasonable herbicidal target domains, the other targets affecting plant growth more markedly than inhibition of 5-enolpyruvylshikimate-3-phosphate synthase, glutamine synthetase and acetolactate synthase are discussed. In three essential enzymes involved in fatty acid biosynthesis in or in the vicinity of chloroplasts, acetyl-CoA carboxylase (ACCase), elongase(s) for very long chain fatty acids (VLCFA) and linolate monogalactosyldiacylglycerol desaturase, ACCase and elongase are more important targets for new herbicides. Although the effect of cellulose biosynthesis inhibitors is restricted to cell wall formation in growing plant cells only, there is a good chance to design the low-use rate herbicides also in this class of inhibitors. Other possible targets for new herbicides are also discussed.     

Studies on the effect of different cyclohexane-1,3-diones on de-novo fatty acid biosynthesis in poaceae

Cyclohexane-1,3-diones such as the herbicides cycloxydim, sethoxydim, alloxydim and clethodim are known to be specific inhibitors of the plastid-located acetyl-CoA carboxylase (ACCase) in Poaceae, a key enzyme of de-novo fatty acid biosynthesis in higher plants. Using several new cyclohexane-1,3-dione derivatives and known herbicides, the relationships between chemical structure and enzyme inhibition have been studied. The basic cyclohexane-1,3-dione structure was modified at three different positions. These compounds were tested for inhibition of the de novo fatty-acid biosynthesis in test systems of etioplasts isolated from Avena sativa L. and Hordeum vulgare L. seedlings and also for inhibition of the isolated barley ACCase. The I₅₀ values of these cyclohexane-1,3-diones were determined. The influence of the modification of alkyl chains (length and type of substituent) on the degree of ACCase-inhibition is discussed. Several new compounds were found that were about two orders more active than the known herbicides cycloxydim or sethoxydim in the etioplast and ACCase test systems but not necessarily on the level of whole plants.     

Cross-resistance profile of mesosulfuron-methyl-resistant Italian ryegrass in the southern United States

Diclofop-resistant Lolium species (ryegrass) is a major weed problem in wheat production worldwide. This study was conducted to determine the resistance pattern of diclofop-resistant ryegrass accessions from the southern United States to mesosulfuron-methyl, a recently commercialized herbicide for ryegrass control in wheat; to determine the cross-resistance pattern of a Lolium multiflorum Lam. (Italian ryegrass) accession, 03-1, to acetolactate synthase (ALS) and acetyl-CoA carboxylase (ACCase) inhibitors; and to determine the resistance mechanism of Italian ryegrass to mesosulfuron-methyl. Seventeen ryegrass accessions from Arkansas and Louisiana, including standard resistant and susceptible accessions, were used in this experiment. Fourteen of the 17 accessions were more resistant (four- to > 308-fold) to diclofop than the standard susceptible biotype. One accession, 03-1, was resistant to mesosulfuron-methyl as well as to other ALS inhibitor herbicides such as chlorsulfuron, imazamox and sulfometuron. Accession 03-1, however, did not show multiple resistance to the ACCase inhibitor herbicides diclofop, fluazifop, clethodim, sethoxydim and pinoxaden, nor to glyphosate. The in vivo ALS activity of the 03-1 biotype was less affected by mesosulfuron-methyl than the susceptible biotype. This indicates that the resistance mechanism of Italian ryegrass to mesosulfuron-methyl is partly due to an alteration in the target enzyme, ALS. It is concluded that diclofop-resistant ryegrass in the southern United States can be generally controlled by mesosulfuron-methyl. However, mesosulfuron-methyl must be used with caution because not all ryegrass populations are susceptible to it. There is a need for more thorough profiling of ryegrass resistance to herbicides.     

Structure-activity relationships of pheromonostasis induced by ACCase-inhibitor herbicides in the moth Helicoverpa armigera

Many moth sex pheromone blends are derived from fatty acids and their production is regulated by a Pheromone Biosynthesis Activating Neuropeptide (PBAN). In prior work we showed that the herbicide Diclofop-acid, an acetyl-coenzyme A carboxylase (ACCase) inhibitor, inhibits PBAN-induced sex pheromone production in vitro. In this work we extend our study showing that several other herbicides, belonging to the 2-aryloxyphenoxypropionate (‘FOP’) and the cyclohexandione-oxime (‘DIM’) families significantly inhibit pheromone production by adult females whilst survival is unaffected by treatment. Enzyme activity in vitro and kinetic analysis revealed a K_m of 0.35 μM with K_i values of 0.1 and 0.28 μM due to Tralkoxydim and Diclofop inhibition, respectively. Inhibitory activity on PBAN-induced pheromone production by all herbicides tested revealed a potency order: Tralkoxydim > Clodinafop > Cycloxidim > Haloxyfop > Diclofop > Fenoxaprop > Fluazifop > Quizalofop, Quizalofop being inactive. Differences in inhibition efficiencies may be attributed to different binding sites on the enzyme or to the polarity and solubility of these compounds.     

Susceptibility of a broad-leaved weed, Acanthospermum hispidum, to the grass herbicide fluazifop-butyl

Broad-leaved plants are generally resistant to aryloxyphenoxypropionate (AOPP) and cyclohexanedione (CHD) herbicides. In laboratory experiments, however, we confirmed that Acanthospermum hispidum , a Compositae weed, was susceptible to one of the AOPP herbicides, fluazifop-butyl, but tolerant to other AOPP herbicides (quizalofop-ethyl and fenoxaprop-ethyl) and a CHD herbicide (sethoxydim). The symptoms induced by fluazifop-butyl in A. hispidum (wilting and necrosis) were distinctly different from those induced in oat (chlorosis). The period required to cause seedling death of A. hispidum (48–72 h) was shorter than that of oat ( ca 15 days). The ( R )-enantiomer of fluazifop-butyl was more active on this weed. In oat, lipid biosynthesis and acetyl-CoA carboxylase (ACCase) activity were inhibited, and electrolyte leakage from the shoots was increased by fluazifop-butyl and sethoxydim. In the case of A. hispidum , the membrane permeability increased and the lipid biosynthesis was inhibited only by fluazifop-butyl. These results indicate that A. hispidum is particularly sensitive to fluazifop-butyl, and its mechanism of action in the plant may be different from its mechanism of action in oat.     

吡啶甲酸类除草剂应用研究进展

吡啶甲酸类除草剂属合成激素类, 目前登记使用的有效成分包括氨氯吡啶酸、二氯吡啶酸和氯氨吡啶酸, 分别于1963年、1977年和2005年上市, 主要用于阔叶杂草和灌木的茎叶处理防控, 其中氯氨吡啶酸具有土壤封闭活性。吡啶甲酸类除草剂的作用靶标仍未明确, 有可能来自生长素结合蛋白家族。全世界报道的抗吡啶甲酸类除草剂杂草共涉及7种8个生物型。目前, 我国登记的除草剂品种中共有13个复配剂含氨氯吡啶酸和二氯吡啶酸, 1个含氨氯吡啶酸、氯氨吡啶酸和二氯吡啶酸;国外登记的吡啶甲酸类除草剂复配剂主要为与其他激素型除草剂、ALS(乙酰乳酸合酶)抑制剂、ACCase(乙酰辅酶A羧化酶)抑制剂的组合。该类除草剂仍然具有较好的应用前景, 在主要应用场景下常见杂草对氨氯吡啶酸、二氯吡啶酸、氯氨吡啶酸的敏感性仍需系统研究, 该类除草剂主要靶标杂草种群的抗药性水平也亟须检测。     

杂草对ACCase抑制剂的抗性

以乙酰辅酶A羧化酶（ACCase）为作用靶标的除草剂是高效、选择性的禾本科杂草除草剂,其在全球范围内的广泛、重复使用,导致了抗药性杂草的发生和发展。到目前为止,已经在30个国家有37种抗此类除草剂的杂草生物型。抗药性杂草严重威胁杂草治理和农业生产,由此引发的生态问题及粮食安全问题引起了广泛的关注。文章概述了ACCase抑制剂抗药性杂草的发生现状,从杂草ACCase突变、代谢解毒等几个方面综述了杂草抗ACCase抑制剂的抗性机制,以期为ACCase抑制剂抗性研究提供参考。最后讨论了阻止或延缓抗药性发生的杂草管理措施。     

Effect of fluazifop-p-butyl treatment on pigments and polyamines level within tissues of non-target maize plants

Fluazifop-p-butyl (FL) is one of the most popular graminicides from arylophenoxypropionate group. These herbicides act as inhibitors of acetyl-CoA carboxylase (ACCase) that catalyzes the formation of malonyl-CoA during metabolism of lipids and/or of some secondary compounds. On the other hand arylopropionates and cyclohexanediones cause phytotoxic effects by stimulating free-radicals generation and causing oxidative stress in susceptible plants. However, the importance of disturbances in plant pigments and polyamines accumulation for this effect is not clear. The aim of this work is to quantify the phytotoxicity of FL to non target maize plant and to explain how photosynthetic pigments, anthocyanins (ANC) and polyamines participate in this interaction.     

靶标为原卟啉原氧化酶的高效除草剂品种

原卟啉原ＩＸ氧化酶是血红素和叶绿素生物合成中的关键酶，是过氧化型除草剂的分子靶标，当植物用二苯醚类，酞酰亚胺以及一些吡啶衍生物等除草剂处理后，造成原卟啉原ＩＸ积累，膜脂质破坏，最终细胞死亡，同ＡＬＳ抑制剂一样，作用靶标为原卟啉原化酶的除草剂，具有用药量低，活性高，杀草谱广，对哺乳动物低毒，对环境影响较小等良好特性，本文介绍了作用靶标为原卟啉原氧化酶的代表性品种。     

杀虫剂对蛾类昆虫生殖行为影响的研究进展

综述了近年来国内外关于杀虫剂对蛾类昆虫求偶、性信息素合成及释放、定向行为、交配和产卵等生殖行为影响的研究进展。经杀虫剂处理后,许多雌蛾的求偶行为受到抑制、性信息素含量降低,雄蛾对性信息素的反应和交配成功率下降,但药剂对产卵量和卵孵化率没有明显影响。而部分药剂可增强雄蛾对性信息素的反应,刺激雌蛾信息素含量异常增高和使活性组的比例发生漂移。     

Herbicide-resistant barnyardgrass (Echinochloa crus-galli) in global rice production

Barnyardgrass (Echinochloa crus-galli (L.) Beauv.), an annual species of the family Poaceae, is a major weed problem in rice-producing countries throughout the globe. Synthetic herbicides can effectively control this grass in rice paddies, but the development of resistant biotypes after the continuous use of the same active ingredients has led to low herbicide efficacy and yield losses. In this review, a summary of resistant-barnyardgrass cases in global rice production is reported based on data from the International Herbicide-Resistant Weed Database. The first case of resistant barnyardgrass in rice paddies was to the photosystem-II inhibitor propanil in the late 1980s. Eighty-five (85) out of 116 cases in the period from 1986 to 2022 refer to resistant barnyardgrass (E. crus-galli var. crus-galli, E. crus-galli var. formosensis and E. crus-galli var. zelayensis) in 16 countries. Barnyardgrass has been found resistant to acetolactate synthase (ALS) inhibitors (34 cases), acetyl-CoA carboxylase (ACCase) inhibitors (23 cases), photosystem-II inhibitors (11 cases), auxin mimics/cellulose biosynthesis inhibitors (9 cases), very long chain fatty acid inhibitors (6 cases), and microtubule assembly inhibitors (1 case). The majority of all resistance cases reported to the active ingredients penoxsulam, bispyribac-sodium, and imazamox (ALS inhibitors), cyhalofop-butyl and fenoxaprop-ethyl (ACCase inhibitors), propanil (photosystem-II inhibitors), and quinclorac (auxin mimics/cellulose biosynthesis inhibitors). Although target-site resistance with specific mutations has been identified, non-target site resistance mainly through herbicide detoxification is also of great concern increasing the chance of multiple herbicide resistance evolution. Rotation of herbicides should be adopted concerning the modes of action used as well as the application methods to mitigate resistance evolution of this weed in rice paddies.     

乙酰辅酶A羧化酶抑制剂的构效关系和抗性研究进展

乙酰辅酶A羧化酶(ACCase)抑制剂是以乙酰辅酶A羧化酶为作用靶标的一类除草剂.这类除草剂通过抑制真核型乙酰辅酶A生成丙二酰辅酶A的羧化反应,进而抑制植物脂肪酸的合成,多用于苗后有选择性地防除一年生禾本科杂草.本文综述了该类除草剂的作用机理、构效关系及在应用中的抗性研究进展.     

高剂量性信息素环境对草地贪夜蛾求偶和交配行为的影响

本文在风洞中模拟形成高浓度性信息素Z7-12:Ac、Z9-14:Ac和 Z11-16:Ac 环境,研究草地贪夜蛾Spodoptera frugiperda (Smith)的求偶和交配行为,为进一步开发交配干扰技术提供技术参数和依据。研究结果表明,在高剂量性信息素环境下,草地贪夜蛾雄蛾的暗期活动时间延后,而雌蛾的活动节律则没有变化,雌雄蛾之间产生了活动节律的时间差。同时,雌雄交配率和交配持续时间显著下降,交配日龄则显著延迟2 d。由于交配日龄延迟,产卵量及其孵化率也相应降低。性信息素喷射时间间隔对草地贪夜蛾性信息素释放滴度有显著影响,当间隔时间为5、10、20 min时,雌蛾释放的性信息素滴度显著下降,以5 min为最低。因此,高剂量性信息素环境不仅影响雄蛾对性信息素的定向,对雌雄蛾间化学通讯和交配也有显著影响。     

大面积应用性信息素诱捕甘蓝斜纹夜蛾及田间控害效果

2006年应用性信息素大量诱捕法对秋甘蓝斜纹夜蛾开展了大面积诱杀试验,并就配套应用技术及其田间控害效果进行了评估。性信息素防治区内,在外围、中围和内围以及上风口、下风口等不同点位上的斜纹夜蛾雄成虫的单瓶诱集量差异明显,上风口的诱集量大于下风口,且增加幅度从外围往中心依次递减;在不同点位上的斜纹夜蛾雄成虫的诱集量差异跟田间虫口发生量呈正相关,虫口密度越大,外围成虫诱集量比中内围的增幅也越大。性信息素防治区在减少药剂防治2次的情况下,斜纹夜蛾落卵量比化防区和空白对照区分别减少27.5%和65.3%,田间累计幼虫发生量分别下降70.9%和94.3%。本试验结果表明,性信息素大面积诱捕能有效控制甘蓝斜纹夜蛾的危害,可为蔬菜的可持续生产提供技术支持。     

Pheromone Research and Development in Israel 1975–2015

The review describes the history of pheromone research in Israel in 1975–2015. The research focused on sex pheromones of moths that were important agricultural pests. Identification, synthesis and field application of sex pheromones was performed. Synthetic procedures of several known sex pheromones were developed. Monitoring and control of key pest moths was evaluated. The interactions of pheromone components of closely related species were studied in field and laboratory experiments. The sex pheromones of three scale insects, two mealybug species and Matsucoccus josephi were studied. New syntheses were developed and the pheromones were implemented in pest management. Structure activity relationship of the pheromonal and kairomonal of the M. josephi pheromone was investigated. Different pherotypes of P. ficus were identified and evaluated. The aggregation pheromone of sap beetles in combination with food baits was evaluated. The aggregation pheromone of the almond bark beetle was identified and a stereospecific synthesis of its enantiomers was developed. Monitoring the pest in stone fruit orchards was implemented. The activity of the pheromone biosynthesis activating neuropeptide (PBAN) was studied in Helicoverpa armigera and Heliothis peltigera. The ligation technique was used to assess the effect of PBAN on the production of female and male pheromones. A structure-activity relationship study of PBAN indicated that shorter peptides display activity as the full length PBAN. A series of linear and cyclic peptide analogs was prepared, resulting in the discovery of a lead antagonist. The research and development activity facilitated the intensive integration of pheromones in the pest management regimes in Israeli agriculture.     

靶标酶在除草剂研究与开发中的作用

大多数除草剂都是通过特殊酶的抑制而产生杀草作用的。根据作用靶标对除草剂进行分类,了解靶标酶的作用机理及特性,对于新型除草剂的设计和杂草抗性的防治能够起到很大的帮助。本文介绍了谷胱甘肽转移酶(GST)、细胞色素P450酶、乙酰乳酸合成酶(ALS)、乙酞辅酶A羧化酶(ACCace)的研究进展。并分别从酶的生理功能、酶学特征、抑制剂作用机理、抑制剂的研究、抗性等方面进行了不同程度的阐述。     

河南省多花黑麦草对ACCase和ALS抑制剂的抗性及其靶标基因突变分析

为明确河南省部分地区的多花黑麦草Lolium multiflorum种群对乙酰辅酶A羧化酶（acetylCoA carboxylase,ACCase）和乙酰乳酸合成酶（acetolactate synthase,ALS）抑制剂类除草剂的抗性水平和抗性机理,采用整株生物测定法测定采自新乡市和驻马店市的多花黑麦草种群对ACCase抑制剂类除草剂精噁唑禾草灵、炔草酯、唑啉草酯和ALS抑制剂类除草剂甲基二磺隆、氟唑磺隆、啶磺草胺的抗性水平,并对多花黑麦草ACCase和ALS靶标酶编码基因进行克隆及氨基酸序列比对,分析其靶标抗性机理。结果显示,与多花黑麦草敏感种群HNXX01相比,HNZMD04和HNXX05种群对6种除草剂均产生了抗性,HNZMD04种群对精噁唑禾草灵和啶磺草胺的相对抗性倍数分别为44.65和40.31,对炔草酯和氟唑磺隆的相对抗性倍数分别为11.91和11.93;HNXX05种群对精噁唑禾草灵和氟唑磺隆的相对抗性倍数分别为27.70和25.67。HNZMD04和HNXX05抗性种群的ACCase基因均发生了D2078G突变,2个种群的突变率分别为55%和70%;HNZMD04...     

乙酰乳酸合成酶及其抑制剂研究新进展

乙酰乳酸合成酶(AHAS)是支链氨基酸生物合成途径中的一个关键酶,是绿色除草剂的重要作用靶标。由于此生物合成过程只存在于植物和微生物体内,因此该类抑制剂对哺乳动物具有生物安全性。近年来,随着AHAS三维结构的阐明,人们不仅深入了解了已有抑制剂的作用机制,并且依此设计开发了一些新型的抑制剂,拓展了其在抑菌活性方面的生物学功能。文章对近年来AHAS及其抑制剂的最新研究进展进行了综述,重点就AHAS的酶学特征、结构特征及结合方式,以AHAS为靶标的新颖除草活性化合物的设计开发以及AHAS抑制剂的抗菌生物活性研究进展等问题详细进行了总结,以期为设计开发靶向AHAS的新型除草剂或抗菌药物提供参考。