抗苄嘧磺隆雨久花乙酰乳酸合成酶突变的研究

本研究采用cDNA末端快速扩增技术(RACE)结合RT-PCR方法克隆抗苄嘧磺隆雨久花生物型和敏感性雨久花生物型乙酰乳酸合成酶(ALS)基因cDNA序列,并对测序结果进行比对分析。结果表明:与敏感性的雨久花ALS相比,公主岭(GZL)抗性生物型中第197位脯氨酸突变为组氨酸,第556位亮氨酸突变为苯丙氨酸;柳河(LH)抗性生物型中第358位天冬酰胺突变为天冬氨酸;磐石市(PS)抗性生物型中第525位缬氨酸突变为异亮氨酸。分析表明,高度保守区Domain A的第197位氨基酸残基的突变可能是导致公主岭稻区雨久花产生抗药性的主要原因之一,而其他抗性生物型抗性产生的原因有待进一步研究。     

稻田雨久花对苄嘧磺隆的抗药性

性指数达63.4;对德惠抗、感雨久花ALS活力的IC50分别为10 756.2和396.8nmol/L,抗性指数为27.1.表明两地稻田雨久花均对苄嘧磺隆产生了抗药性,而其体内ALS敏感性降低是产生抗药性的原因之一.     

磺酰脲类除草剂与其抗药性的研究进展

本文简述了磺酰脲类除草剂的概况及其抗性和延缓其抗性的研究进展,展望了磺酰脲类除草剂制成混配制剂对延缓抗性发展的前景。     

杂草对乙酰乳酸合成酶抑制剂类除草剂抗药性的研究进展

本文针对杂草对乙酰乳酸合成酶(ALS)抑制剂类除草剂抗药性的产生历史与发展现状、抗药性机理以及抗性基因的利用进行了综述,并讨论了该类除草剂在我国应用过程中应该注意的问题以及今后的发展方向。     

杂草对磺酰脲类除草剂抗性的研究动态

杂草对磺酰脲类除草剂抗性的研究动态刘东卫，闻永星（江苏省农科院杂草研究中心南京２１００１４）（安徽白湖）磺酰脲类除草剂的开发始于７０年代末期。由于其具有极高的活性，杀草谱广，选择性强，标志除草剂新品种的开发进入了“超高效阶段”。正是由于这类除草剂的优...     

除草剂与乙酰乳酸合成酶相互作用的分子机理研究进展

综述了酵母乙酰乳酸合成酶(ScALS)与磺酰脲类除草剂氯嘧磺隆(chlorimuron-ethyl,CE)形成的复合物在0.28 nm分辨率下的晶体结构及拟南芥乙酰乳酸合成酶(AtALS)与磺酰脲类和咪唑啉酮类除草剂复合物的三维结构。除草剂的分子结构与酶、底物并不相似,但它们与酶形成的复合物可阻断底物进入酶活性位点通路而起抑制作用。连接磺酰脲的10个氨基酸残基同样连接咪唑喹啉酸,另有6个残基只与磺酰脲而不与咪唑喹啉酸相连,有2个残基只与咪唑喹啉酸而不与磺酰脲相连,即两种抑制剂占据了特别的重叠位点,但以不同方式连接。抗性杂草的产生是因为突变株ALS的残基位点变异,从而引起除草剂与ALS结合方式的变化。这些研究对进一步理解除草剂与靶分子的作用方式及除草剂的分子药物设计具有重要的指导作用。     

磺酰脲类除草剂新品种

磷酰脲类除草剂是80年代例开发的一类新型超高效除草剂，其作用靶标为ALS。由于该类除草剂选择性强、活性高、用药量极低、对哺乳动物低毒，在日趋重视环境的今天，备受瞩目。该类除草剂的不足之处是：作用粗标单一，连续使用，容易产生抗药性；部分品种（如绿黄隆、甲黄隆）在pH值偏高时，降解较慢，会危及后茬的敏感作物。由于这些缺点，曾被人误认为该类除草剂没有前途，随着科技的发展和应用技术的提高，汗发厂专用的安全利、表面活性剂和～些混配制剂．抗磷酸豚类除q剂的转基网相物也培计成功。这些研究成果都促进广该类除草剂的发展…     

磺酰脲类除草剂与杂草对其抗性的研究进展

1磺酰脲类除草剂的概况1.1磺酰脲类除草剂的发展20世纪70年代末,美国杜邦公司Levitt等首次开发和报道了磺酰脲类除草剂绿磺隆的除草活性[1]。80年代初,这一除草剂开始进行大规模商品化生产,此后,又不断研制和开发了许多磺酰脲类除草剂新品种。此类除草剂问世以后,以其活性高、选择性强、杀草谱广及对动物安全等特性在世界各地得到广泛应用。目前有关磺酰脲类除草剂的专利有400多项,已商品化的有30多种。这类除草剂有很高的除草效率,用量一般为2~100 g/hm2,比传统除草剂的除草效率高100~1 000倍[2]。磺酰脲类除草剂对动物低毒,在非靶标生物…     

磺酰脲类除草剂抗性杂草的出现及其抗性机理

磺酰脲类除草剂抗性杂草的出现及其抗性机理马　勉一、前言磺酰脲类除草剂（以下称为ＳＵ剂）是８０年代初出现的新一类化合物，由于它用量少（每公顷几克至几十克），且对哺乳动物具有高度的安全性，因此为人们所瞩目。现在，ＳＵ剂用于麦类、水稻、大豆、玉米和油菜等主...     

磺酰脲类除草剂开发的新进展

本文对近期开发的磺酰脲类除草剂按用途分类进行了简要的介绍。文中涉及磺酰脲类除草剂的化学结构、生物活性等。     

Transformation a mutant Monochoria vaginalis acetolactate synthase (ALS) gene renders Arabidopsis thaliana resistant to ALS inhibitors

Acetolactate synthase (ALS) genes from Monochoria vaginalis resistant (R) and susceptible (S) biotypes against ALS inhibitors found in Korea revealed a single amino acid substitution of Proline (CCT), at 169th position based on the M. vaginalis ALS sequence numbering, to serine (TCT) in conserved domain A of the gene (equal to the proline 197 in Arabidopsis thaliana ALS gene sequence). A. thaliana plants transformed with the single mutated (Pro₁₆₉ to Ser) M. vaginalis ALS gene (including transit signal peptide) showed cross-resistance patterns to ALS-inhibiting herbicides, like as sulfonylurea-herbicide bensulfuron methyl (R/S factor of 9.5), imidazolinone-herbicide imazapyr (R/S factor of 5.1), and triazolopyrimidine-herbicide flumetsulam (R/S factor of 17.6) when measuring hypocotyls’ length of A. thaliana. The ALS activity from the transgenic A. thaliana plants confirmed the cross-resistance pattern to these herbicides like as R/S factor of 8.3 to bensulfuron methyl, 2.3 to imazapyr, and 13.2 to flumetsulam.     

Cross-resistance pattern and alternative herbicides for Cyperus difformis resistant to sulfonylurea herbicides in Korea

A Cyperus difformis L accession from Chonnam province, Korea was tested for resistance to the sulfonylurea herbicide, imazosulfuron. The accession was confirmed to be resistant (R) and was cross-resistant to other sulfonylurea herbicides, bensulfuron-methyl, cyclosulfamuron and pyrazosulfuron-ethyl, the pyrimidinyl thiobenzoate herbicide, bispyribac-sodium, and the imidazolinone herbicide imazapyr, but not to imazaquin. Multiple resistance was tested using twelve herbicides with target sites other than acetolactate synthase (ALS). The R biotype could be controlled by other herbicides with different modes of action such as butachlor, carfentrazone-ethyl, clomeprop, dithiopyr, esprocarb, mefenacet, oxadiazon, pretilachlor, pyrazolate and thiobencarb, applied to soil at recommended rates. Several sulfonylurea herbicide-based mixtures can control both the R and S biotypes of C difformis, except sulfonylurea plus dimepiperate, molinate or pyriftalid, and pyrazolate plus butachlor. Although mixtures of sulfonylurea herbicides might be more effective, they should be avoided and used only in special cases. In terms of in vitro ALS activity, the R biotype was 1139-, 3583-, 1482-, 416-, 5- and 9-fold more resistant to bensulfuron-methyl, cyclosulfamuron, imazosulfuron, pyrazosulfuron-ethyl, bispyribac-sodium and imazapyr, respectively, than the S biotype. The in vivo ALS activity of the R biotype was also less affected by the sulfonylurea herbicides, imazosulfuron and pyrazosulfuron-ethyl, than the S biotype. Results of in vitro and in vivo ALS assays indicated that the resistance mechanism of C difformis to ALS inhibitor herbicides was primarily due to an alteration in the target enzyme, ALS. Greenhouse experiments showed delayed flowering and reduced seed production of the R biotype, which could possibly result in reduced fitness. This unusual observation needs to be confirmed in field situations.     

Degradation of the sulfonylurea herbicides chlorsulfuron and triasulfuron in a high-organic-matter volcanic soil

The degradation rates of two sulfonylurea herbicides, chlorsulfuron and triasulfuron, were determined at two application rates, 15 and 30 g a.i. ha^–1, in a sandy loam soil of volcanic origin under controlled environment and field conditions. Residues were measured using a modified gas chromatographic (gc) determination method. Both herbicides degraded rapidly in the acidic soil (pH 5.7) with high organic matter levels (7.3% o.m.), generally according to first-order rate kinetics. The respective half-lives ranged from 22 to 38 d for chlorsulfuron and from 31 to 44 d for triasulfuron under five controlled temperature/soil moisture regimens, ranging from 10 to 30 °C and between 40% and 80% maximum water-holding capacity. Half-lives in the field were considerably shorter (13 d for chlorsulfuron and 12–13 d for triasulfuron). The degradation rates of the herbicides were influenced more by soil temperature than by soil moisture content. Bioassays using white mustard ( Sinapis alba L.) and forage sorghum [ Sorghum bicolor (L.) Moench] were also used to determine the persistence of phytotoxic residues of both herbicides in the field, and the results showed that the effects of chlorsulfuron disappeared within 8 weeks. Triasulfuron residues disappeared within 9 and 14 weeks for the 15 and 30 g a.i. ha^–1 rates respectively.     

Mutations in the acetolactate synthase genes of sulfonylurea-resistant biotypes of Lindernia spp.

Acetolactate synthase (ALS) is a key enzyme in the biosynthetic pathway of branched-chain amino acids. A mutation of the ALS gene causing amino acid substitution at the position of proline in Domain A makes ALS less sensitive to sulfonylureas, which are ALS-inhibiting herbicides. We cloned partial ALS genes from four Lindernia plants, L . dubia var. dubia , L . dubia var. major , L . micrantha and L . procumbens , for which biotypes resistant to sulfonylureas have been found in paddy fields. The clones were classified into two groups in each Lindernia plant: Als1 and Als2 . Sequencing of the clones and alignment of deduced amino acid sequences with previously reported ALS of other species suggested that the cloned region contains an intron in both Als1 and Als2 . Comparison of Als1 between resistant and susceptible biotypes showed that the proline of Domain A was replaced by alanine, serine or glutamine in all resistant biotypes of Lindernia plants, while it was conserved in all susceptible biotypes. This amino acid substitution in ALS encoded by Als1 is involved in the resistant mechanism of ALS to sulfonylurea in the four Lindernia plants.     

A molecular assay for the proactive detection of target site-based resistance to herbicides inhibiting acetolactate synthase in Alopecurus myosuroides

Acetolactate synthase (ALS) inhibitors are the most resistance‐prone herbicide group. Rapid resistance diagnosis is thus of importance for their optimal use. We formulate rules to use the derived cleaved amplified polymorphic sequence method to develop molecular tools detecting a change at a given codon, the nature of which is unknown. We applied them to Alopecurus myosuroides (black grass) to develop assays targeting ALS codons A122, P197, A205, W574 and S653 that are crucial for herbicide sensitivity. These assays detected W574L or P197T, or both substitutions, in most plants analysed from a field where ALS inhibitors failed after 3 years of use. Similar assays can easily be set up for any species. Given the rapidity of selection for resistance to ALS inhibitors, these assays should be very useful in proactive herbicide resistance diagnosis.     

Difference in ultraweak photon emissions between sulfonylurea-resistant and sulfonylurea-susceptible biotypes of Scirpus juncoides following the application of a sulfonylurea herbicide

We examined the ultraweak photon emissions from a paddy weed, Scirpus juncoides , to assess the availability of photon emissions for the identification of weed biotypes resistant to sulfonylurea herbicides. The emission intensity from the plant organs increased when treated with a sulfonylurea herbicide in a concentration-dependent manner. The increment in emissions was higher in the sulfonylurea-resistant biotypes than in the sulfonylurea-susceptible biotypes. The difference between the biotypes was greater in the culms than in the roots and remained so through the vegetative growth stage to the flowering stage. This difference was independent of the seed source or mutations in the acetolactate synthase genes of the resistant biotypes. These results suggest that the determination of ultraweak photon emissions can be a useful method for identifying the sulfonylurea-resistant biotypes of S. juncoides.     

Varied occurrence of diverse sulfonylurea‐resistant biotypes of Schoenoplectus juncoides [Roxb.] Palla in Japan,as classified by an acetolactate synthase gene mutation

Suspected sulfonylurea (SU)‐resistant Schoenoplectus juncoides plants were collected from rice paddy fields at 24 sites in Japan in order to discover the occurrence pattern of target‐site substitutions on a nationwide scale and at a local field scale. A genetic analysis of the two acetolactate synthase (ALS) genes, ALS1 and ALS2, of the collected plants confirmed that a single‐nucleotide mutation at the Pro₁₉₇, Asp₃₇₆ or Trp₅₇₄ site of either ALS1 or ALS2 existed in each suspected SU‐resistant plant. On a nationwide scale, it was shown that the ALS1 mutations and the ALS2 mutations occurred at a similar frequency, that the P197S and the P197L substitutions were found most frequently among all the substitutions, and that the W574L substitutions (known as global resistance to any ALS‐inhibiting herbicide) were found at a relatively low frequency but in a geographically wide range. In the local field‐scale survey, which was conducted at two sites in Hyogo Prefecture, it was shown that the substitutions were less diverse, compared to on a nationwide scale, probably because the investigation involved a limited number of local fields, and that several substitutions and a susceptible biotype were found in single fields suggesting that a number of collections is required in order to understand the local SU‐resistant status of S. juncoides. In addition, this study reported new findings, that of the P197R, P197T and D376E substitutions in S. juncoides. This set of diverse substitutions in a weed species can be used for further research purposes.     

Sorption/desorption behaviour of sulfonylurea herbicides as affected by the addition of fresh and composted olive cake to soil

The olive industry generates residues which can be applied as amendments to soils in their original form (olive cake) or after composting or vermicomposting processes. The addition, fresh or incubated, of these amendments to soil and of their different organic fractions was studied in relation to the sorption/desorption of three sulfonylurea herbicides, bensulfuron‐methyl, chlorsulfuron and prosulfuron. Herbicide sorption was low or very low, slightly promoted by the addition of the agricultural by‐products, especially olive cake, and mainly affected by pH of the soil solution, with the organic carbon content having no significant effect on herbicide retention. Desorption was only reduced when fresh olive cake was added. The incubation of soil and amendments for 3 months did not modify herbicide sorption, but made desorption reversible except for olive cake. The transformation of the organic matter of the amendments due to humification and maturity processes are likely to be responsible for this behaviour. Different organic fractions were removed to assess the influence of each fraction on sulfonylurea sorption. Only the removal of all studied organic fractions increased herbicide sorption, revealing the role of humin and mineral fractions in this process. Therefore, the use of organic amendments is not useful for reducing the risk of movement of ionisable molecules in soil.