植物病原真菌抗药性的基因诊断和分子免疫学的利用

作物栽培中需经常使用农药,对于杀虫剂的抗性问题已为人们所熟知,但对植物病原菌的抗性问题则知之其少。自发现抗性菌以来虽已有30余年,人们希望通过开发新药剂来解决,但植物病原菌仍然相继产生抗性菌,为了控制由于抗性菌所造成的危害,科技人员正积极设法采用基因疗法来快速诊断抗性菌,以期能有效地选择防治药剂     

植物的非寄生抗性

作为病原体的防御组织,动物系由机能分化发达的免疫细胞承担,其通过自然免疫,获得免疫系统,并经逐步进化而得。对于无免疫细胞和循环器官系体的植物而言,其所有细胞均可对病原菌产生各种形式的抗性。被某种病原菌侵染的某种植物,人们称之为寄主。而某种植物的所有品种均对某种病原菌的菌丝均有抗性的话,则此种植物则称为非寄主植物,又称为非寄主抗性。然而某特定病原菌对寄主植物的致病性也并非一致,有的品种易于感病,有的则不易感染。本文仅就非寄主抗性来描述植物体的防卫组织。     

我国植物病原菌抗药性研究进展

从抗药性监测、抗性风险评估、交互抗性、抗性机制和抗性遗传五方面,总结了我国植物病原菌抗药性的研究成果。     

新杀菌剂抗性风险评估及其在市场预测中的作用

杀菌剂抗性风险是指病原菌抗药性发展使杀菌剂防效丧失或药效降低的可能性.一个农药新品种投入市场时,抗性风险评估、抗性检测技术和抗性治理策略也往往同时推出.通过药剂驯化、诱导、化学诱变、紫外线诱变等方法获得抗性菌株,并对抗性菌株的致病力和遗传稳定性进行研究,对新杀菌剂可能产生抗性的风险做出评估.植物病原菌对杀菌剂的抗药性风险的高低,是影响杀菌剂新品种在市场中使用时间长短和销量的关键因素,杀菌剂抗性风险评估是新品种市场预测和应用开发的重要依据.     

杀菌剂抗性鉴别和测量通则

植物病原菌对杀菌剂抗性的发展结果使得药剂防治病害失效,进而引起作物损失,对当地和世界粮食生产造成不利影响。因此尽快鉴别和测量杀菌剂抗性、采取适当措施是极为重要的。虽然鉴别和测量抗性的方法各不相同,但是化合物与生物结合这一通常的原则是一致的。只有与敏感菌株祖比较才能鉴别抗性菌株。因此确定存在问题的某种病原菌对杀菌剂的敏感性基线是十分必要的,可以用被一般认为对杀菌剂是敏感的野生型菌株进行适当的     

番茄灰霉病菌(Botrytis cinerea)对3种杀菌剂的抗性监测及交互抗药性研究

采用菌丝生长速率法,测定了采自江苏和河南的158株番茄灰霉病菌对嘧菌酯、啶酰菌胺、啶菌噁唑等3种药剂的敏感性,并研究了部分抗性菌株的交互抗性情况。结果显示,供试菌株对嘧菌酯、啶酰菌胺、啶菌噁唑的EC50值分别在0.0045~90.5、0.0576~36.8、0.0169~2.64μg/mL,并分别出现了19.0%、11.4%、0.6%的抗性菌株频率。整体上,江苏菌株的抗性水平高于河南地区。番茄灰霉病菌对嘧菌酯、醚菌酯、肟菌酯和吡唑醚菌酯之间存在交互抗性;对啶酰菌胺与萎锈灵和噻呋酰胺之间存在交互抗性;但与氟吡菌酰胺、之间不存在交互抗性。病原菌群体中已存在多药抗性问题,1株病原菌对嘧菌酯、啶酰菌胺、啶菌噁唑等3种药剂同时产生可抗性,17株病菌对嘧菌酯和啶酰菌胺同时产生了抗性。     

种子生物处理防治土传植物病原菌

农业现代化在很大程度上取决于各类农用化学品的发展,其中有些是高度危险的(化学)农药。据世界卫生组织最近的估计,每年因农药中毒致病的约有75万人,致死的约1.4万人(1989年)。除了引起环境污染以外,化学农药对非靶标生物、包括一些有益生物产生不利影响,从而威胁生态平衡。随同化学防治出现的问题还有害虫和病原菌对农药产生的抗性。此外,有些新筛选的农药作用专一,只能提供短期的保护,有时只对某些害物有效。在几种害虫和病原菌同时存在时,如土壤传播的病原菌,它们就无法减少作物的损失。此     

水稻突变体对除草剂苯达松敏感致死的机理研究

水稻苯达松敏感致死突变体在杂交水稻生产中具有广阔的应用前景。分析了两个水稻突变体农林8m和8077S对除草剂苯达松敏感致死的生理和遗传规律，综述了其对苯达松敏感致死的分子机理。普通水稻品种具有对苯达松抗性是由于苯达松在普通水稻品种细胞中被羟基化，并最终被代谢为对植物无毒性的6-OH-葡萄糖苷苯达松和8-OH-葡萄糖苷苯达松。普通水稻品种具有的苯达松抗性基因可能是编码与苯达松羟基化相关的某种P450酶，或者编码某种参于解毒的受体蛋白，而苯达松本身对P450酶和受体蛋白有诱导和激活作用；此外，苯达松抗性基因也可能是一种催化羟基化苯达松与葡萄糖缀合、同淀粉合成酶相似的缀合酶基因，而水稻苯达松敏感致死突变体表现出对苯达松敏感致死是由于γ-射线导致上述与苯达松解毒相关的酶活性丧失所致。     

除草剂多抗性作物的发展

草甘膦抗性作物已经发展10余年,给农业生产中杂草治理带来了革命性变化。目前,作物单纯抗草甘膦一种除草剂已经终止,下一代抗性技术将是对草甘膦抗性与其他除草剂抗性相结合。简要介绍了多抗性作物技术的发展。     

杂草对除草剂的抗性现状、发展与治理

杂草对除草剂的抗性目前已成为农业中的一个重要问题,阐述了当前杂草对除草剂的抗性现状、发展及其治理.     

New Carbapenemase Inhibitors: Clearing the Way for the β-Lactams

Carbapenem resistance is a major global health problem that seriously compromises the treatment of infections caused by nosocomial pathogens. Resistance to carbapenems mainly occurs via the production of carbapenemases, such as VIM, IMP, NDM, KPC and OXA, among others. Preclinical and clinical trials are currently underway to test a new generation of promising inhibitors, together with the recently approved avibactam, relebactam and vaborbactam. This review summarizes the main, most promising carbapenemase inhibitors synthesized to date, as well as their spectrum of activity and current stage of development. We particularly focus on β-lactam/β-lactamase inhibitor combinations that could potentially be used to treat infections caused by carbapenemase-producer pathogens of critical priority. The emergence of these new combinations represents a step forward in the fight against antimicrobial resistance, especially in regard to metallo-β-lactamases and carbapenem-hydrolysing class D β-lactamases, not currently inhibited by any clinically approved inhibitor.     

The Characterization of SaPIN2b,a Plant Trichome-Localized Proteinase Inhibitor from Solanum americanum

Proteinase inhibitors play an important role in plant resistance of insects and pathogens. In this study, we characterized the serine proteinase inhibitor SaPIN2b, which is constitutively expressed in Solanum americanum trichomes and contains two conserved motifs of the proteinase inhibitor II (PIN2) family. The recombinant SaPIN2b (rSaPIN2b), which was expressed in Escherichia coli, was demonstrated to be a potent proteinase inhibitor against a panel of serine proteinases, including subtilisin A, chymotrypsin and trypsin. Moreover, rSaPIN2b also effectively inhibited the proteinase activities of midgut trypsin-like proteinases that were extracted from the devastating pest Helicoverpa armigera. Furthermore, the overexpression of SaPIN2b in transgenic tobacco plants resulted in enhanced resistance against H. armigera. Taken together, our results demonstrated that SaPIN2b is a potent serine proteinase inhibitor that may act as a protective protein in plant defense against insect attacks.     

Antibody-mediated Prevention of Fusarium Mycotoxins in the Field

Fusarium mycotoxins directly accumulated in grains during the infection of wheat and other cereal crops by Fusarium head blight (FHB) pathogens are detrimental to humans and domesticated animals. Prevention of the mycotoxins via the development of FHB-resistant varieties has been a challenge due to the scarcity of natural resistance against FHB pathogens. Various antibodies specific to Fusarium fungi and mycotoxins are widely used in immunoassays and antibody-mediated resistance in planta against Fusarium pathogens has been demonstrated. Antibodies fused to antifungal proteins have been shown to confer a very significantly enhanced Fusarium resistance in transgenic plants. Thus, antibody fusions hold great promise as an effective tool for the prevention of mycotoxin contaminations in cereal grains. This review highlights the utilization of protective antibodies derived from phage display to increase endogenous resistance of wheat to FHB pathogens and consequently to reduce mycotoxins in field. The role played by Fusarium-specific antibody in the resistance is also discussed.     

Disease problems of sunflowers

Sunflower, the second most important oilseed crop in the world, was developed as a crop in eastern Europe, but is a native of North America. The pathogens causing many of its major diseases are also native to North America. Although a profitable crop, sunflowers have fairly low value per hectare. Disease control must, therefore, be inexpensive, by resistant varieties or seed treatment or cultural practices, rather than repeated field application of chemicals. Rust, a limiting factor in many countries, has been successfully controlled everywhere by resistance from wild sunflowers discovered in Canada about 1950. New races are posing problems in Argentina and Australia, but new resistance may be available. Verticillium wilt has been destructive in some areas but resistance is available from wild sunflowers and Russian high-oil varieties. Downy mildew, highly destructive in many countries, has been effectively controlled by two genes from the original rust-resistant material. A new race attacking this resistance was discovered in 1980: resistance to it appears to be available. Sclerotinia stalk rot and head rot, caused by a pathogen with wide host range, is much harder to control by breeding. Leaf spot diseases have long been a limiting factor in some European countries and elsewhere, but were considered minor in North America until recently. Broom rape, a root parasite which almost destroyed the crop in the USSR and elsewhere in eastern Europe, does not attack it in North America. It is controlled by resistant varieties.     

琥珀酸脱氢酶抑制剂类(SDHIs)杀菌剂及其抗性研究进展

琥珀酸脱氢酶抑制剂(SDHIs)是一类作用于病原菌琥珀酸脱氢酶而抑制其呼吸作用的杀菌剂,目前已成功开发的这类杀菌剂至少有15个品种,主要从杀菌作用机制、主要品种、作用特性、抗性发生情况、抗性机制及抗性治理措施等方面对这类杀菌剂进行介绍。     

Acquisition and Spread of Antimicrobial Resistance: A tet(X) Case Study

Understanding the mechanisms leading to the rise and dissemination of antimicrobial resistance (AMR) is crucially important for the preservation of power of antimicrobials and controlling infectious diseases. Measures to monitor and detect AMR, however, have been significantly delayed and introduced much later after the beginning of industrial production and consumption of antimicrobials. However, monitoring and detection of AMR is largely focused on bacterial pathogens, thus missing multiple key events which take place before the emergence and spread of AMR among the pathogens. In this regard, careful analysis of AMR development towards recently introduced antimicrobials may serve as a valuable example for the better understanding of mechanisms driving AMR evolution. Here, the example of evolution of tet(X), which confers resistance to the next-generation tetracyclines, is summarised and discussed. Initial mechanisms of resistance to these antimicrobials among pathogens were mostly via chromosomal mutations leading to the overexpression of efflux pumps. High-level resistance was achieved only after the acquisition of flavin-dependent monooxygenase-encoding genes from the environmental microbiota. These genes confer resistance to all tetracyclines, including the next-generation tetracyclines, and thus were termed tet(X). ISCR2 and IS26, as well as a variety of conjugative and mobilizable plasmids of different incompatibility groups, played an essential role in the acquisition of tet(X) genes from natural reservoirs and in further dissemination among bacterial commensals and pathogens. This process, which took place within the last decade, demonstrates how rapidly AMR evolution may progress, taking away some drugs of last resort from our arsenal.     

现代杀菌剂抗性研究进展

使用现代杀菌剂防治植物病害是保证农作物高产、稳产的重要措施之一，但是现代杀菌剂很容易出现抗性而导致化学防治失败，农业生产蒙受巨大损失。从杀菌剂的抗性发生现状、抗性机制、抗性检测和治理技术等方面概述了甲氧基丙烯酸酯类、脱甲基抑制剂、苯并咪唑类、苯基酰胺类和二甲酰亚胺类杀菌剂的抗性研究进展。     

Development of Quorum-Based Anti-Virulence Therapeutics Targeting Gram-Negative Bacterial Pathogens

Quorum sensing is a cell density-dependent signaling phenomenon used by bacteria for coordination of population-wide phenotypes, such as expression of virulence genes, antibiotic resistance and biofilm formation. Lately, disruption of bacterial communication has emerged as an anti-virulence strategy with enormous therapeutic potential given the increasing incidences of drug resistance in pathogenic bacteria. The quorum quenching therapeutic approach promises a lower risk of resistance development, since interference with virulence generally does not affect the growth and fitness of the bacteria and, hence, does not exert an associated selection pressure for drug-resistant strains. With better understanding of bacterial communication networks and mechanisms, many quorum quenching methods have been developed against various clinically significant bacterial pathogens. In particular, Gram-negative bacteria are an important group of pathogens, because, collectively, they are responsible for the majority of hospital-acquired infections. Here, we discuss the current understanding of existing quorum sensing mechanisms and present important inhibitory strategies that have been developed against this group of pathogenic bacteria.     

"绿生源"高效植物营养液的研制及其应用

通过对蔬菜和花卉的试验表明,“绿生源”高效植物营养液对促进作物生长发育、增强光合作用、提高植株的抗逆性等方面,均有明显作用。