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1.
Mesotrione is a new callistemone herbicide that inhibits the HPPD enzyme (p-hydroxyphenylpyruvate dioxygenase) and introduces a new naturally selective tool into weed-management programmes for use in maize. Mesotrione provides control of the major broad-leaved weeds, and it can be used in integrated weed-management programmes depending on the grower's preferred weed-control strategy. At post-emergence rates of 150 g AI ha-1 or less, mesotrione provides naturally selective control of key species that may show triazine resistance (TR), e.g. Chenopodium album L, Amaranthus species, Solanum nigrum L, as well as species of weed that show resistance to acetolactase synthase (ALS) inhibitors e.g. Xanthium strumarium L, Amaranthus spp and Sonchus spp. The data presented show that resistant and susceptible biotypes of these species with resistance to triazine herbicides, such as atrazine, simazine, terbutylazine and metribuzin, or ALS-inhibitor herbicides, such as imazethepyr, remain susceptible to mesotrione. These results confirm that there is no cross-resistance in biotypes with target site resistance to triazine or ALS-inhibiting herbicides. It is important that herbicide choice and rotation becomes an integral part of planning weed management, so as to minimise the risks of crop losses from weed competition, build-up of weed seed in the soil and the further development of weed resistance across a range of herbicide modes of action.  相似文献   

2.
对羟基苯基丙酮酸双氧化酶抑制剂筛选方法研究进展   总被引：1，自引：1，他引：0  
对羟基苯基丙酮酸双氧化酶(HPPD)是植物体正常生长所必需的质体醌和生育酚生物合成路径中的关键酶,已成为当前最重要的除草剂作用靶标之一。发展快速、可靠的HPPD抑制剂筛选方法对研究小分子化合物与HPPD之间的相互作用,以及开展基于靶酶结构的新型HPPD抑制剂设计均具有重要意义。结合HPPD的结构和功能,文章从生物分析的角度分别就高效液相色谱、同位素标记、偶联法、电化学及简易筛选模型等方法在HPPD抑制剂筛选中的运用进行了总结,并对发展HPPD抑制剂的高通量筛选方法进行了展望。  相似文献   

3.
对羟基苯基丙酮酸双加氧酶（HPPD）是一种重要的除草剂作用靶标。为了发现具有高活性和高选择性的新型HPPD抑制型除草剂,对前期合成的23个含咪唑啉酮结构单元的吡唑类衍生物（2A~2W）进行了深入的生物活性评价和构效关系研究,比较了它们对拟南芥HPPD（AtHPPD）和人源HPPD（hHPPD）抑制活性的差异,从酶水平上总结了该类化合物的结构-活性关系和种属选择性规律,从活体植株水平研究了它们的除草活性。结果表明:部分化合物表现出良好的除草活性和作物安全性,其中化合物2E和2G在150 g/hm2剂量下对荠菜、繁缕、小藜和棒头草抑制活性达到80%以上,且其对作物的安全性也明显优于商品化除草剂硝磺草酮。此外,化合物2P在酶水平上的选择性倍数高达93倍,展示出良好的应用潜力。  相似文献   

4.
In aqueous solution, the herbicide pyrazolate [4‐(2,4‐dichlorobenzoyl)‐1,3‐dimethyl‐5‐pyrazolyl p‐toluenesulfonate] is rapidly hydrolyzed to destosyl pyrazolate (DTP), 4‐(2,4‐dichlorobenzoyl)‐1,3‐dimethyl‐5‐hydroxypyrazole, which is an active form of the herbicide. The objective of this study was to examine the effect of pyrazolate and DTP on carotenoids synthesis in susceptible weed, early watergrass (Echinochloa oryzicola Vasing.). Furthermore, their in vitro effect on 4‐hydroxyphenylpyruvate dioxygenase (HPPD) was determined. Roots of the plants at the two‐leaf stage were soaked for 24 h into pyrazolate (5 × 10–5 mol L?1) or norflurazon (10–6 mol L?1) solution containing 0.5% volume of acetone. At the first sampling time (3 days after treatment: 3 DAT), the chlorophyll content in the third leaves of pyrazolate‐treated plants were not different compared with the untreated control, but it was decreased between 3 and 6 DAT. The declining pattern of β‐carotene in the third leaf of early watergrass was very similar to that of chlorophyll. Both herbicides induced greater accumulation of phytoene in the third leaves of early watergrass 3 DAT, and the levels were kept until 9 DAT. However, feeding of homogentisate reduced the phytoene accumulation only in pyrazolate‐treated plants, suggesting the site of action of the herbicide located in the pathway of plastoquinone synthesis. In a HPPD assay, DTP revealed to inhibit the enzyme with an IC50 value of 13 nmol L?1 and that of pyrazolate was 52 nmol L?1. In the pyrazolate solution used in the assay, some of the herbicide possibly has been hydrolyzed to DTP. From the all results obtained, it is strongly suggested that pyrazolate inhibits carotenoids synthesis and causes bleaching on the developing leaves by the similar mechanism with norflurazon, but its action site is not phytoene desaturase and is HPPD.  相似文献   

5.
Protoporphyrinogen oxidase (PPO) is the target enzyme of peroxidizing herbicides. The overexpression of Myxococcus xanthus PPO (Mx PPO) confers a high level of herbicide resistance in rice. Among the peroxidizing herbicides, butafenacil has an efficiency ∼1000-fold that of oxadiazon, as judged by calli susceptibility tests upon herbicide treatment. Butafenacil (0.1 μM) was used to select transgenic rice plants expressing Mx PPO under the control of the constitutive maize ubiquitin promoter. The ectopic expression of the Mx PPO transgene was investigated in the T0 generation by Northern blot and Western blot analysis. The T0 transgenic plants expressing the Mx PPO gene were resistant to butafenacil based on in vitro leaf disk and in vivo foliar spray tests.  相似文献   

6.
对羟基苯丙酮酸双加氧酶 (HPPD) 抑制剂近年来因其高活性和低抗性风险成为了除草剂领域的研究热点。喹唑啉二酮被证明是一类具有潜力的骨架结构,为了继续发挥该骨架的优势,在前期工作的基础上,结合已有的构效关系研究结果,设计并合成了30个新型含喹唑啉二酮结构的吡唑类HPPD抑制剂,其结构均经过了高分辨质谱 (HRMS)、核磁共振氢谱 (1H NMR) 和碳谱 (13C NMR) 的表征。酶水平和活体活性测试结果表明,大部分目标化合物展现出了与对照药剂喹草酮相当甚至更优异的酶抑制活性。温室除草活性测试结果表明,目标化合物对6种供试杂草均有一定的生长抑制作用,特别是化合物 9-28 ,在有效成分150 g/hm2剂量下,对6种杂草的防治效果均在80%以上,其中对稗草和马唐的防治效果达100%。最后,培养了代表性化合物 9-28 与拟南芥HPPD的复合物晶体结构,从分子层面说明了该类抑制剂与靶标的结合模式,也为后续该类抑制剂的开发提供了一定的分子基础和设计思路。  相似文献   

7.
Mechanisms of herbicide resistance include (1) modified target site, (2) enhanced detoxification or delayed activation, and (3) alterations in the uptake, translocation, or compartmentalization of a herbicide. The first two mechanisms have mainly been identified in plants. Herbicide resistance genes were isolated for several herbicides of different modes of action. Genes that coded for herbicide target or detoxification enzymes were transferred into crop plants. The transgenic plants expressing these genes were tolerant of the active ingredients of herbicides. Before commercialization, the transgenic plants were tested in the field for risk assessment. In the case of crops with herbicide detoxification enzymes, including cytochrome-P450-species-metabolizing xenobiotics, the substrate specificity of the enzymes as well as the toxicological properties of the herbicide metabolites and the pattern of secondary metabolites in plants must be evaluated. © 1999 Society of Chemical Industry  相似文献   

8.
Most modern herbicides have low mammalian toxicity. One of the reasons for this safety is that the target site for the herbicides is not often present in mammals. There are approximately 20 mechanisms of action that have been elucidated for herbicides. Of these, some do share common target sites with mammals. The mechanisms include formation of free radicals, protoporphyrinogen oxidase (PROTOX), glutamine synthetase (GS) and 4-hydroxyphenylpyruvate dioxygenase (HPPD). PROTOX, HPPD and GS inhibitors have been shown to inhibit these enzymes in both plants and mammals and there are measurable effects in mammalian systems. However, the consequences of inhibiting a common target site in plants can be quite different than in animals. What may be a lethal event in plants, eg inhibition of HPPD, can have a beneficial effect in mammals, eg treatment for tyrosinemia type I. These chemicals also have low mammalian toxicity due to rapid metabolism and/or excretion of the herbicide from mammalian systems.  相似文献   

9.
农田杂草防治是农作物稳产高产的一个重要环节。化学除草剂以其高效、简便、经济的优势,一跃而成为我国现代农业中杂草治理的重要手段,但与此同时也带来了药害（对作物不安全）和抗药性问题。转基因技术的发展为培育耐除草剂作物品种提供了有力的手段。至今,全世界已培育出大量转基因耐除草剂作物品种。转基因耐除草剂作物的利用为拓宽除草剂的使用范围、减少作物药害带来了新的希望。本文在对国际上转基因耐除草剂作物的研发和商业化应用情况进行概述和分析的基础上,结合我国农作物生产的实际情况和小农户、多种作物混合种植的模式,提出转基因耐除草剂植物在我国开发利用的前景和相应的发展策略,以期为转基因耐除草剂作物的研究、开发和推广管理提供科学依据。  相似文献   

10.
Transgenic tomato plants containing the coat protein (CP) gene of Cucumber mosaic virus (CMV) of subgroup IB were developed through Agrobacterium-mediated transformations. The progenies of transgenic plants showed the presence of transgene, its expression and translation of 26 KDa CP. The T1 and T2 generation plants were evaluated for resistance against challenge inoculations by a homologous strain of CMV. Visual observations of challenged transgenic plants categorized them into resistant, tolerant and susceptible as compared with untransformed control plants. Out of 33 plants of the T1 generation, 36.3% showed resistance and remained symptomless throughout their life, 48.4% showed tolerance which developed delayed symptoms of mild mosaic, and 15.1% showed susceptibility to CMV which developed severe systemic mosaic and leaf distortion symptoms after 30?days of virus challenge. Out of 120 plants of the T2 generation, 60% showed resistance, 26.6% were tolerant and only 13.3% were found susceptible to challenge inoculations of CMV. Resistant transgenic plants also showed less CP accumulation in systemic upper leaves as compared with challenged untransformed plants. In this study, CP of a CMV subgroup IB strain has demonstrated a significant level of resistance in transgenic tomato plants against the CMV strain. The strategy may be applied for better quality and productivity of tomato crops.  相似文献   

11.
为明确广东省稻菜轮作区中牛筋草对10种常用除草剂的抗性水平及抗性分子机制,采用整株生物测定法测定广东省稻菜轮作区内8个牛筋草种群P1～P8对草甘膦、草铵膦和乙酰辅酶A羧化酶(acetyl-CoA carboxylase,ACCase)抑制剂类等10种除草剂的抗性水平,并进一步分析P1和P8种群相关靶标酶基因5-烯醇丙酮酰莽草酸-3-磷酸合酶(5-enolpyruvyl-shikimate-3-phosphate synthase,EPSPS)、谷氨酰胺合成酶(glutamine synthetase,GS)和ACCase的部分功能区序列特征。结果显示,牛筋草P1～P8种群对草甘膦抗性指数为敏感种群的5.9倍～17.7倍,其中P8种群对草甘膦的抗性水平最高;8个种群对草铵膦也产生了不同程度的抗性,抗性指数为敏感种群的2.3倍～14.2倍,其中P1种群抗性最高。牛筋草P1和P8种群均对ACCase抑制剂类除草剂精喹禾灵、氰氟草酯和噁唑酰草胺产生了交互抗性;P1种群ACCase基因在第2 041位氨基酸处发生突变,该突变在牛筋草种群中首次发现;而P8种群ACCase基因则在第2 027位氨基...  相似文献   

12.
转基因棉花的研发现状与发展策略   总被引：6，自引：0，他引：6  
国内外转基因棉花的研发主要集中于抗虫、耐除草剂、抗病、纤维改良、抗旱和耐盐碱等性状,但只有抗虫、耐除草剂棉花注册应用。自1996年商业化种植以来,年种植面积逐年上升,到2010年全世界转基因棉花的种植面积已达2 100万hm2。转基因棉花的大规模种植,对有效控制棉花害虫与杂草的发生为害发挥了重要作用,显著降低了生产成本,提高了棉花产量。本文综述了国内外转基因棉花的研发动态及其商业化进程,并结合我国棉花产业发展需求,提出了我国转基因棉花的发展对策。  相似文献   

13.
为研究宁波沿海地区水稻田稗草发生量及对丙草胺和丁草胺的抗药性,本研究以宁波沿海地区土壤盐碱化、碱化和非盐碱化稻田的稗草及土壤中稗草种子库密度为研究对象,通过连续3年的大田试验及室内抗药性分析,研究稗草草相及土壤中稗草种子库密度变化,并对稗草的抗药性进行了分析。结果表明,在调查周期内,宁波沿海的盐碱化稻田稗草发生密度为16.23株/m2,显著高于土壤碱化和非盐碱化稻田中的11.70株/m2和10.10株/m2。盐碱化稻田稗草种子库密度为19 169.17粒/m2,高于土壤碱化稻田的17 224.83粒/m2,并显著高于非盐碱稻田的15 411.33粒/m2。在庵东镇和大徐镇的盐碱稻田中,稗草对丙草胺和丁草胺的相对抗药性指数(RI)分别从调查初始期的4.51和2.88上升至调查末期的5.52和6.14,达到中抗水平;而在土壤碱化稻田和非盐碱稻田中,稗草对丙草胺和丁草胺的RI均维持在相对较低的水平,调查周期内介于1.00~2.33之间,处于低抗水平。因此,在该地区的水稻生产过程中,应尽量改善土质,以控制稗草种群规模、延缓抗药性的产生。  相似文献   

14.
Protoporphyrinogen oxidase (Protox) of Myxococcus xanthus (Mx Protox) is a 49-kDa membrane protein that catalyzes conversion of protoporphyrinogen IX (Protogen IX) into protoporphyrin IX (Proto IX). Upon heterologous expression in transgenic rice plants, Mx Protox is dually targeted into plastids and mitochondria, increasing resistance against the herbicidal Protox inhibitor oxyfluorfen. Here, we describe the chemical synthesis of the Mx Protox gene by assembling several small synthetic DNA fragments derived by ligation-PCR. Codon usage in the resulting 1416-bp gene was modified to correspond to that of the Arabidopsis Protox gene, a change that resulted in a decrease in G+C content from 71 to 49%. The modified Mx Protox gene was used to generate transgenic rice plants via Agrobacterium-mediated transformation. Integration, expression, and inheritance of the transgenes were demonstrated by Southern, Northern, and Western blot analyses. In plants transformed with the modified, low G+C-content Mx Protox gene, levels of Protox expression and enzyme activity were low compared to the levels observed for plants transformed with the native Mx Protox gene. Nonetheless, like the native gene, the modified gene conferred a high level of resistance to the herbicide oxyfluorfen in a seedling growth test.  相似文献   

15.
Uptake and metabolism of propanil were measured in both susceptible (S) and resistant (R) biotypes of Jungle-rice, Echinochloa colona (L.) link at different growth stages. Results showed that there was no significant difference in uptake between S and R biotypes of E. colona at any given growth stage, but that uptake was significantly reduced at older plant growth stages in all biotypes studied. Metabolism of propanil was more rapid in R biotypes than in S biotypes at all growth stages studied. Specific and total aryl acylamidase activity, responsible for the first stage of propanil metabolism, was higher in R biotypes than in S at all growth stages, but declined to about 50% of the maximum at older growth stages, confirming the importance of this enzyme in conferring resistance to this herbicide. The area of necrosis that developed around a single drop of propanil deposited on the adaxial leaf surface was used to assess the degree of propanil resistance; it was found that resistance increased at older E. colona growth stages in contrast to the rate of propanil metabolism and amidase activity. Treatment of leaves with the amidase inhibitors, carbaryl or piperophos, simultaneously with propanil, caused a decrease in resistance at growth stages where amidase activity was greatest. This treatment was less effective at older growth stages. These results show that, in E. colona, propanil metabolism is important for conferring resistance in younger plants (four-six-leaf stage). It is suggested that restricted uptake confers resistance in older plants.  相似文献   

16.
The gene gdhA from Escherichia coli, that encodes a NADPH‐dependent glutamate dehydrogenase (GDH), directs a novel pathway in transgenic plants that allows an increase in ammonium assimilation. Glufosinate leads to plant death by the irreversible inhibition of glutamate synthetase (GS) leading to a disruption of subsequent GS‐related processes resulting in elevated ammonium and disruption of photorespiration. Therefore, it was speculated that the gdhA‐transformed plants may exhibit a novel mechanism of resistance to glufosinate by altered activity of the GDH‐directed pathway(s) and subsequently related processes. Studies were conducted in the greenhouse to evaluate the resistance of tobacco plants containing the gdhA gene to glufosinate. Five tobacco genotype lines were investigated including a non‐transformed control line, a positive control line and three transformed lines with levels of increasing GDH activity directed by the gdhA gene. Plants transformed with the gdhA gene expressed up to six times increased level of resistance (GR50) to glufosinate compared with the non‐transformed control, which is 100 times less resistant than plants transformed with the bar gene. The GDH activity among lines was highly correlated (r2 = 0.9903) with the level of herbicide resistance. Thus, the use of the E. coli gdhA gene in plant transformations can provide an additional mechanism for resistance to glufosinate.  相似文献   

17.
转基因作物与植物保护   总被引：6，自引：0，他引：6  
黄大昉 《植物保护》2007,33(5):11-14
作为农业生物技术最活跃的研究领域之一,抗病虫、抗除草剂转基因作物的应用已成为病虫害综合治理的新的有效手段。本文综述了国内外这一领域产业化开发的最新进展,提出了实行积极的产业化政策、理性认识转基因生物安全和加强基础和创新性研究等项建议。  相似文献   

18.
BACKGROUND: The acetolactate synthase (ALS)-inhibiting herbicide sulfosulfuron is registered in Australia for the selective control of Hordeum leporinum Link. in wheat crops. This herbicide failed to control H. leporinum on two farms in Western Australia on its first use. This study aimed to determine the level of resistance of three H. leporinum biotypes, identify the biochemical and molecular basis and develop molecular markers for diagnostic analysis of the resistance. RESULTS: Dose-response studies revealed very high level (>340-fold) resistance to the sulfonylurea herbicides sulfosulfuron and sulfometuron. In vitro ALS assays revealed that resistance was due to reduced sensitivity of the ALS enzyme to herbicide inhibition. This altered ALS sensitivity in the resistant biotypes was found to be due to a mutation in the ALS gene resulting in amino acid proline to serine substitution at position 197. In addition, two- to threefold higher ALS activities were consistently found in the resistant biotypes, compared with the known susceptible biotype. Two cleaved amplified polymorphic sequence (CAPS) markers were developed for diagnostic testing of the resistant populations. CONCLUSION: This study established the first documented case of evolved ALS inhibitor resistance in H. leporinum and revealed that the molecular basis of resistance is due to a Pro to Ser mutation in the ALS gene.  相似文献   

19.
Transgenic potato and rice plants were generated by the introduction of human P450 species, CYP1A1, CYP2B6, CYP2C9 and CYP2C19, which metabolized a number of herbicides, insecticides and industrial chemicals. The transgenic potato plant T1977 co-expressing CYP1A1, CYP2B6 and CYP2C19 genes showed remarkable cross-resistance to several herbicides with different structures and modes of action due to metabolism of these herbicides by the P450 species expressed. The transgenic rice plant 2C9-57R2 expressing CYP2C9 gene showed resistance to sulfonylureas, and the transgenic rice plant 2C19-12R1 expressing CYP2C19 gene showed cross-resistance to certain herbicides with different structures and modes of action. These transgenic plants appear to be useful for herbicide resistance as well as phytoremediation of environmental contaminants.  相似文献   

20.
Weeds resistant (R) to herbicides are widespread worldwide. Bidens subalternans is one of the most troublesome weeds in conventional soyabean fields in Brazil, and in a crop rotation system of cotton/soyabean and maize/soyabean some populations had evolved resistance to acetolactate synthase (ALS)-inhibiting herbicides. Bidens subalternans plants suspected of resistance were observed in soyabean fields where the main ALS-inhibiting herbicide sprayed is chlorimuron-ethyl. To confirm and characterise the resistance of B. subalternans to ALS inhibitors, whole-plant bioassays were conducted in 2006 and 2008. ALS in vivo enzyme bioassays were also conducted in 2007. In both bioassays, the R biotype showed cross-resistance to four chemical families of ALS-inhibiting herbicides. According to whole-plant level tests the R biotype showed 498-, 797-, 726- and >877-fold resistance to chlorimuron-ethyl, imazethapyr, cloransulam-methyl and pyrithiobac-sodium herbicides respectively. The R biotype was also 17-, 166-, 436- and 516-fold R to chlorimuron-ethyl, imazethapyr, cloransulam-methyl and pyrithiobac-sodium herbicides, respectively, based on the enzyme assay. Therefore, the herbicide-R B. subalternans can no longer be controlled by any ALS-inhibitor herbicides. Integrated control methods involving alternative herbicide with different modes of action are needed, to avoid yield losses in conventional soyabean fields in Brazil that are infested by ALS-R B. subalternans populations.  相似文献   

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