Fungicide modes of action and resistance in downy mildews

Among oomycetes, Plasmopara viticola on grape and Phytophthora infestans on potato are agronomically the most important pathogens requiring control measures to avoid crop losses. Several chemical classes of fungicides are available with different properties in systemicity, specificity, duration of activity and risk of resistance. The major site-specific fungicides are the Quinone outside inhibitors (QoIs; e.g. azoxystrobin), phenylamides (e.g. mefenoxam), carboxylic acid amides (CAAs; e.g. dimethomorph, mandipropamid) and cyano-acetamide oximes (cymoxanil). In addition, multi-site fungicides such as mancozeb, folpet, chlorothalonil and copper formulations are important for disease control especially in mixtures or in alternation with site-specific fungicides. QoIs inhibit mitochondrial respiration, phenylamides the polymerization of r-RNA, whereas the mode of action of the other two site-specific classes is unknown but not multi-site. The use of site-specific fungicides has in many cases selected for resistant pathogen populations. QoIs are known to follow maternal, largely monogenic inheritance of resistance; they bear a high resistance risk for many but not all oomycetes. For phenylamides, inheritance of resistance is based on nuclear, probably monogenic mechanisms involving one or two semi-dominant genes; resistance risk is high for all oomycetes. The molecular mechanism of resistance to QoIs is mostly based on the G143A mutation in the cytochrome b gene; for phenylamides it is largely unknown. Resistance risk for CAA fungicides is considered as low to moderate depending on the pathogen species. Resistance to CAAs is controlled by two nuclear, recessive genes; the molecular mechanism is unknown. For QoIs and CAAs, resistance in field populations of P. viticola may gradually decline when applications are stopped.     

琥珀酸脱氢酶抑制剂类杀菌剂抗性研究进展

作用于琥珀酸脱氢酶复合体的新型杀菌剂-琥珀酸脱氢酶抑制剂(succinate dehydrogenase inhibitors, SDHIs)已逐步成为继Qo位点呼吸抑制剂类(QoIs)和麦角甾醇生物合成抑制剂类(EBIs)杀菌剂之后的世界第3大类杀菌剂。近年来,SDHIs杀菌剂的市场占有份额逐年增加,新品种不断涌现,在植物病害化学防治中发挥着重要作用。然而,由于该类杀菌剂作用位点单一,抗药性已成为制约该类杀菌剂创制发展与科学应用的重要科学问题。本综述归纳了琥珀酸脱氢酶抑制剂类杀菌剂的开发、品种、抗性发生发展、抗性分子机制与应用现状,并结合作者研究团队的最新研究成果对其靶标生物学及应用技术研究进行了总结,以期为更高活性的SDHIs杀菌剂创制和应用提供参考。     

Mutations in the CYP51 gene correlated with changes in sensitivity to sterol 14 alpha-demethylation inhibitors in field isolates of Mycosphaerella graminicola

In France, as in many other European countries, Mycosphaerella graminicola (Fuckel) Schr?ter in Cohn (anamorph Septoria tritici), the causal agent of wheat leaf blotch, is controlled by foliar applications of fungicides. With the recent generalization of resistance to strobilurins (QoIs), reliable control is mainly dependent upon inhibitors of sterol 14 alpha-demethylation (DMIs). To date, strains with reduced sensitivity to DMIs are widespread, but disease control using members of this class of sterol biosynthesis inhibitors has not been compromised. In this study, sensitivity assays based on in vitro effects of fungicides towards germ-tube elongation allowed the characterization of seven DMI-resistant phenotypes. In four of them, cross-resistance was not observed between all tested DMIs; this characteristic concerned prochloraz, triflumizole, fluquinconazole and tebuconazole. Moreover, the highest resistant factors to most DMIs were found only in recent isolates; according to their response towards prochloraz, they were classified into two categories. Molecular studies showed that DMI resistance was associated with mutations in the CYP51 gene encoding the sterol 14 alpha-demethylase. Alterations at codons 459, 460 and 461 were related to low resistance levels, whereas, at position 381, a valine instead of an isoleucine, in combination with the previous changes, determined the highest resistance levels to all DMIs except prochloraz. Mutations in codons 316 and 317 were also found in some isolates exhibiting low resistance factors towards most DMIs.     

Fungicide resistance status in French populations of the wheat eyespot fungi Oculimacula acuformis and Oculimacula yallundae

Eyespot, caused by Oculimacula acuformis and Oculimacula yallundae, is the major foot disease of winter wheat in several European countries, including France. It can be controlled by chemical treatment between tillering and the second node stage. The fungicides used include antimicrotubule toxicants (benzimidazoles), inhibitors of sterol 14α‐demethylation (DMIs) or of succinate dehydrogenase (SDHIs), the anilinopyrimidines cyprodinil and the benzophenone metrafenone. Since the early 1980s, a long‐term survey has been set up in France to monitor changes in the sensitivity of eyespot populations to fungicides. Resistance to benzimidazoles has become generalised since the early 1990s, in spite of the withdrawal of this class of fungicides. In the DMI group, resistance to triazoles is generalised, whereas no resistance to the triazolinethione prothioconazole has yet developed. Resistance to the imidazole prochloraz evolved successively in O. acuformis and O. yallundae and is now well established. Specific resistance to cyprodinil has also been detected, but its frequency has generally remained low. Finally, since the early 2000s, a few strains of O. yallundae displaying multidrug resistance (MDR) have been detected. These strains display low levels of resistance to prothioconazole and SDHIs, such as boscalid. Knowledge of the spatiotemporal distribution in France of O. acuformis and O. yallundae field strains resistant to fungicides allows resistance management strategies for eyespot fungi in winter wheat to be proposed.© 2012 Society of Chemical Industry     

Amino acid substitutions responsible for different QoI and SDHI sensitivity patterns in Puccinia horiana,the causal agent of chrysanthemum white rust

Quinone outside inhibitors (QoIs) and succinate dehydrogenase inhibitors (SDHIs) are major groups of agricultural fungicides. However, resistance to some of these fungicides has been reported in a Japanese population of Puccinia horiana, the causal agent of chrysanthemum white rust disease. Because their mechanisms are not well understood, we investigated the existence of mutations in QoI and SDHI target protein-encoding genes. Eight out of nine isolates from cultivated chrysanthemum carried L275F and L299F amino acid substitutions in cytochrome b, the target protein of QoIs. These isolates showed 23- and 17-fold higher EC₅₀ values for the QoI fungicides azoxystrobin and kresoxim-methyl, respectively, in basidiospore germination inhibitory tests, while they were hypersensitive to another QoI, famoxadone. All nine isolates were resistant to SDHI oxycarboxin and carried the I88F substitution in SdhC. This substitution was orthologous to the SdhC-I86F substitution found in some Brazilian isolates of the soybean rust fungus, Phakopsora pachyrhizi, showing reduced sensitivity to some SDHIs. Although the rarity of wild-type sensitive isolates, the subsequent limited number of comparisons between wild types and mutants, and a difficulty in applying reverse genetic analysis to this obligate parasite, are obstacles in making definitive conclusions, L275F and L299F in cytochrome b and SdhC-I88F are suspected to be responsible for the different patterns of sensitivity to QoI and for oxycarboxin-resistance in P. horiana, respectively.     

Assessment of fungicide resistance and pathogen diversity in Erysiphe necator using quantitative real-time PCR assays

BACKGROUND: Management of grapevine powdery mildew Erysiphe necator Schw. requires fungicide treatments such as sterol demethylation inhibitors (DMIs) or mitochondrial inhibitors (QoIs). Recently, reduction in the efficacy of DMIs or QoIs was reported in Europe and the United States. The aim of the present study was to develop real‐time qPCR tools to detect and quantify several CYP51 gene variants of E. necator: (i) A versus B groups (G37A) and (ii) sensitive versus resistant to sterol demethylase inhibitor fungicides (Y136F). RESULTS: The efficacy of the qPCR tools developed was better than the CAPS method, with a limit of 2 pg for E necator DNA, 0.06 ng for genetic group A and 1.4 ng for the DMI‐resistant allele. The detection limits of qPCR protocols (LOD) ranged from 0.72 to 0.85%, and the quantification limits (LOQ) ranged from 2.4 to 2.85% for the two alleles G47A and Y136F respectively. The application of qPCR to field isolates from French vineyards showed the presence of DMI‐resistant and/or QoI‐resistant alleles in French pathogen populations, linked to genetic group B. CONCLUSION: The real‐time PCR assay developed in this study provides a potentially useful tool for efficient quantification of different alleles of interest for fungicide monitoring and for population structure of E. necator. Copyright © 2010 Society of Chemical Industry     

Impact of fungal drug transporters on fungicide sensitivity, multidrug resistance and virulence

Drug transporters are membrane proteins that provide protection for organisms against natural toxic products and fungicides. In plant pathogens, drug transporters function in baseline sensitivity to fungicides, multidrug resistance (MDR) and virulence on host plants. This paper describes drug transporters of the filamentous fungi Aspergillus nidulans (Eidam) Winter, Botrytis cinerea Pers and Mycosphaerella graminicola (Fückel) Schroter that function in fungicide sensitivity and resistance. The fungi possess ATP-binding cassette (ABC) drug transporters that mediate MDR to fungicides in laboratory mutants. Similar mutants are not pronounced in field resistance to most classes of fungicide but may play a role in resistance to azoles. MDR may also explain historical cases of resistance to aromatic hydrocarbon fungicides and dodine. In clinical situations, MDR development in Candida albicans (Robin) Berkhout mediated by ABC transporters in patients suffering from candidiasis is common after prolonged treatment with azoles. Factors that can explain this striking difference between agricultural and clinical situations are discussed. Attention is also paid to the risk of MDR development in plant pathogens in the future. Finally, the paper describes the impact of fungal drug transporters on drug discovery.     

樱桃褐腐病菌对啶酰菌胺的敏感性及其对4种琥珀酸脱氢酶抑制剂的交互抗性

采用菌丝生长速率法测定了樱桃褐腐病菌Monilinia fructicola对啶酰菌胺的敏感性,同时研究了不同敏感性菌株的生物学性状,探究了琥珀酸脱氢酶B亚基的氨基酸突变与其对啶酰菌胺产生抗性的相关性,并分析了樱桃褐腐病菌对啶酰菌胺与其他3种琥珀酸脱氢酶抑制剂(SDHIs)氯苯醚酰胺、氟唑菌苯胺和氟吡菌酰胺之间的交互抗...     

Biological and molecular characterization of field isolates of <Emphasis Type="Italic">Alternaria alternata</Emphasis> with single or double resistance to respiratory complex II and III inhibitors

Field isolates of Alternaria alternata collected from tomato processors were characterized for sensitivity to respiration inhibitors using in vitro mycelial growth assays. Pyraclostrobin (QoI), boscalid, fluopyram and isopyrazam (SDHIs) mean EC₅₀ values were 0.32, 1.43, 2.21, and 3.53 μg/ml respectively. Of the 42 isolates, 36 were sensitive to all respiration inhibiting fungicides tested whereas three isolates were less sensitive to boscalid, one to pyraclostrobin and two were simultaneously resistant to both inhibitors and isopyrazam. Correlation analysis between fungicide sensitivities revealed a positive cross-resistance between pyraclostrobin and tebuconazole, and between cyprodinil and mancozeb. There was no cross-resistance between QoIs, SHDIs or any other mode of action. Sequencing of the QoI and SDHI targets revealed the G143A cytochrome b resistance mutation in all pyraclostrobin-resistant isolates while analysis of the succinate dehydrogenase coding gene revealed point mutations in two of three of the gene subunits analyzed in boscalid-resistant isolates. Specifically, two isolates carried the H277Y and three the H133Q resistance mutations located in the sdhB and sdhD subunits of the respiration complex II, respectively. Isolates bearing the H277Y mutation also carried the G143A cytochrome b resistance mutation. Boscalid and pyraclostrobin-resistant isolates exhibited greater pathogenicity and sporulation compared to sensitive isolates, respectively. Isolates with cross-resistance exhibited greater pathogenicity and sporulation but slower mycelial growth compared to sensitive isolates. This is the first report of field isolates of A. alternata with single or double resistance to QoIs and SDHIs in Greece and should be considered in planning and implementing effective anti-resistance strategies.     

病原菌对Strobilurin类杀菌剂抗药性机理的研究进展

结合strobilurin类杀菌剂作用机制的特点,通过室内和田间研究的结果总结了病原菌对该类杀菌剂产生抗药性的主导机制。Strobilurin类杀菌剂主要结合于病原菌细胞色素bc1复合物中细胞色素b部分的Qo位点,而细胞色素b由突变率很高的线粒体基因组编码,所以病原菌很容易因该基因的突变而导致抗药性发生。至今已至少有14种寄主植物上的25种病原菌在田间表现出了对strobilurin类杀菌剂的抗药性。抗药性产生的主要机理是病原菌细胞色素b的氨基酸残基发生了单点取代。田间抗性菌株的主要取代位点是G143A、F129L和G143R。一些非靶标生物细胞色素b的143位为丙氨酸,这可能是strobilurin类杀菌剂对其表现安全性的原因之一。由于锈病病菌Puccinia spp.中内含子剪切位点恰好出现在编码G143的GGT之后,G143A的突变会导致突变菌株的死亡,因而它们在田间不会表现出抗药性。此外,Qo抑制剂阻断电子传递后会导致胞内活性氧(ROS)的增加,而ROS可以诱导细胞交替氧化酶(AOX)的表达,进而启动线粒体的旁路氧化途径,使病原菌表现出抗药性。因此,病原菌氨基酸残基的单点取代和交替氧化途径是导致病原菌对strobilurin杀菌剂产生抗药性的主导机制。     

New Cases of Negative Cross-resistance between Fungicides,Including Sterol Biosynthesis Inhibitors

A survey of fungicide resistance in Mycosphaerella graminicola and Tapesia acuformis, two major pathogens of winter wheat in France, respectively responsible for speckled leaf blotch and eyespot, led to the characterization of two types of resistant strains to sterol 14α-demethylation inhibitors (DMIs). Most of the strains of M. graminicola collected in France in 1997–1998 were resistant to all DMIs, and only in a few strains was the resistance to several triazoles associated with increased susceptibility to pyrimidine derivatives (i.e., fenarimol, nuarimol) and triflumizole. On the other hand, in T. acuformis the most prevalent strains were those which exhibited negative-cross resistance between DMIs. In both fungi such a phenomenon could be related to changes in cytochrome P450 sterol 14α-demethylase, the target site of these fungicides. For Botryotinia fuckeliana, the causal agent of grey mould, the extensive monitoring conducted in French vineyards before the marketing of fenhexamid revealed the presence of highly resistant strains to this promising botryticide (only in tests involving mycelial growth measurements). Negative cross-resistance to edifenphos and several sterol biosynthesis inhibitors, such as prochloraz and fenpropimorph, was observed in fenhexamid resistant strains. Synergism of the antifungal action of fenhexamid by cytochrome P450 inhibitors, such as the DMI fungicides, was only recorded in fenhexamid resistant strains. These data and those previously obtained with edifenphos resistant strains of Magnaporthe grisea (rice blast pathogen) suggest that in fenhexamid resistant strains of B. fuckeliana the same cytochrome P450 monooxygenase could be involved in detoxification of fenhexamid and activation of edifenphos. Received 6 September 1999/ Accepted in revised form 13 September 1999     

Sensitivity of Mycosphaerella graminicola (anamorph: Septoria tritici) to DMI fungicides across Europe and impact on field performance

Since the occurrence and spread of resistance to quinone outside inhibitors (QoI) in Mycosphaerella graminicola in the early 2000s in Europe, demethylation inhibitors (DMIs) form the backbone for control of Septoria leaf blotch. European monitoring studies, carried out by various research institutes and DMI manufacturers, have shown a shift of the European M. graminicola population towards increased ED₅₀ values for DMI fungicides. Populations of M. graminicola consist of very heterogeneous isolates within a region, and even within a field, in terms of DMI sensitivity. Sensitivity to DMIs is influenced by the haplotype of CYP51, the target of DMIs. New CYP51‐haplotypes have emerged and the frequency of less sensitive haplotypes in Europe has increased in recent years. Studies with efflux transporter inhibitors showed that not only CYP51, but also enhanced efflux, may play a role in the DMI sensitivity response. Sensitivity studies with 5 DMIs registered for Septoria leaf blotch control indicated that sensitivity of isolates to the 5 DMIs is heterogeneous and the overall correlation of sensitivity to the different DMIs is poor. A key requirement for sustainable control and resistance management of Septoria leaf blotch is therefore the continued availability of different DMIs.     

Distributions of Sensitivities to Three Sterol Demethylation Inhibitor Fungicides Among Populations of Uncinula necator Sensitive and Resistant to Triadimefon

ABSTRACT Single-conidial isolates of Uncinula necator from (i) a population representing two vineyards with no previous exposure to sterol demethylation inhibitor (DMI) fungicides ("unexposed," n = 77) and (ii) a population representing two vineyards in which powdery mildew was poorly controlled by triadimefon after prolonged DMI use ("selected," n = 82) were assayed to determine distributions of sensitivities to the DMI fungicides triadimenol (the active form of triadimefon), myclobutanil, and fenarimol. Median 50% effective dose (ED(50)) values (micrograms per milliliter) in the selected versus unexposed populations were 0.06 versus 1.9 for triadimenol, 0.03 versus 0.23 for myclobutanil, and 0.03 versus 0.07 for fenarimol, respectively. Isolates were grouped into sensitivity classes according to their ED(50) values, and those from the selected population were categorized as resistant if the frequency of their sensitivity class had increased significantly relative to levels found in the unexposed population (ED(50) values exceeding 0.56, 0.18, and 0.18 mug/ml for triadimenol, myclobutanil, and fenarimol, respectively). Of the 76 isolates defined as resistant to triadimenol, 64% were classified as cross-resistant to myclobutanil, 18% were classified as cross-resistant to fenarimol, and 17% were classified as resistant to all three fungicides; 25% of the isolates classified as resistant to myclobutanil also were classified as resistant to fenarimol. Similar cross-resistance relationships were revealed when all isolates were examined by regressing log ED(50) values for each fungicide against those for the remaining two fungicides to determine the correlation coefficients (e.g., r = 0.85 for triadimenol versus myclobutanil and 0.56 for triadimenol versus fenarimol). The restricted levels of cross-resistance indicated by these data, particularly between fenarimol and the other two fungicides, is in sharp contrast to the high levels of cross-resistance among DMIs reported for some other pathogens and has significant implications with respect to programs for managing grapevine powdery mildew and DMI resistance.     

Does agricultural use of azole fungicides contribute to resistance in the human pathogen Aspergillus fumigatus?

Azole resistance in human fungal pathogens has increased over the past twenty years, especially in immunocompromised patients. Similarities between medical and agricultural azoles, and extensive azole (14α‐demethylase inhibitor, DMI) use in crop protection, prompted speculation that resistance in patients with aspergillosis originated in the environment. Aspergillus species, and especially Aspergillus fumigatus, are the largest cause of patient deaths from fungi. Azole levels in soils following crop spraying, and differences in sensitivity between medical and agricultural azoles (DMIs), indicate weaker selection in cropping systems than in patients receiving azole therapy. Most fungi have just one CYP51 paralogue (isozyme CYP51B), but in Aspergillus sp. mutations conferring azole resistance are largely confined to a second paralogue, CYP51A. Binding within the active centre is similar for medical and agricultural azoles but differences elsewhere between the two paralogues may ensure selection depends on the DMI used on crops. Two imidazoles, imazalil and prochloraz, have been widely used since the early 1970s, yet unlike triazoles they have not been linked to resistance in patients. Evidence that DMIs are the origin, or increase the frequency, of azole resistance in human fungal pathogens is lacking. Limiting DMI use would have serious impacts on disease control in many crops, and remove key tools in anti‐resistance strategies. © 2017 Society of Chemical Industry     

Evidence for the Predisposition of Fungicide-Resistant Isolates of Venturia inaequalis to a Preferential Selection for Resistance to Other Fungicides

In the United States, populations of the apple scab pathogen Venturia inaequalis have progressed through three consecutive rounds of fungicide resistance development, first to dodine, then to the benzimidazoles, and most recently to the sterol demethylation inhibitors (DMIs). Analysis of extensive monitoring data have to date provided no indication of detectable cross-resistance or partial cross-resistance of V. inaequalis populations to the three unrelated classes of fungicides prior to the selection of resistant subpopulations. However, in this study, resistance to both benomyl and DMIs developed to significantly higher frequencies within the previously established dodine-resistant population than in the population sensitive to dodine. Accelerated selection of phenotypes double resistant to dodine and the DMI fenarimol was apparent over the course of distinct seasons of apple scab management with either dodine or fenarimol. The data provide evidence for an accelerated speed of resistance development among phenotypes of V. inaequalis already resistant to an unrelated fungicide. This finding represents a departure from the previous model, which assumed entirely independent rounds of resistance developments. The data indicate that phenotypes of V. inaequalis might not only be selected for the trait of fungicide resistance but also for traits allowing a more flexible response to changes in the environment where they compete.     

Mutations in sdh genes in field isolates of Zymoseptoria tritici and impact on the sensitivity to various succinate dehydrogenase inhibitors

Zymoseptoria tritici is the causal agent of septoria tritici blotch (STB), a foliar wheat disease important worldwide. Succinate dehydrogenase inhibitors (SDHIs) have been used in cereals for effective control of STB for several years, but resistance towards SDHIs has been reported in several phytopathogenic fungi. Resistance mechanisms are target‐site mutations in the genes coding for subunits B, C and D of the succinate dehydrogenase (SDH) enzyme. Previous monitoring data in Europe indicated the presence of single isolates of Z. tritici with reduced SDHI sensitivity. These isolates carried mutations leading to amino acid exchanges: C‐T79N, C‐W80S in 2012; C‐N86S in 2013; B‐N225T and C‐T79N in 2014; and C‐V166M, B‐T268I, C‐N86S, C‐T79N and C‐H152R in 2015. The current study provides results from microtitre and greenhouse experiments to give an insight into the impact of different mutations in field isolates on various SDHIs. In microtitre tests, the highest EC₅₀ values for all tested SDHIs were obtained with mutants carrying C‐H152R. Curative greenhouse tests with various SDHIs confirmed the findings of microtitre tests that isolates with C‐H152R are, in general, controlled with lower efficacy than isolates carrying B‐T268I, C‐T79N and C‐N86S. SDHI‐resistant isolates of Z. tritici found in the field were shown to have cross‐resistance towards all SDHIs tested. So far, SDHI‐resistant isolates of Z. tritici have been found in low frequencies in Europe. Therefore, FRAC recommendations for resistance management in cereals, including a limited number of applications, alternation and combination with other MOAs, should be followed to prolong SDHI field efficacy.     

番茄叶霉病菌异菌脲抗药性突变体的诱导与生物学性状

测定了苯并咪唑类杀菌剂敏感-乙霉威抗性(BenS-DieR)、苯并咪唑类杀菌剂抗性-乙霉威敏感(BenR-DieS)和苯并咪唑类杀菌剂抗性-乙霉威抗性(BenR-DieR)3种类型的番茄叶霉病菌Cladosporium fulvum菌株对不同类型药剂的敏感性。结果表明,蕃茄叶霉病菌对供试药剂的敏感性与其对苯并咪唑类杀菌剂及乙霉威的敏感性无关。根据药剂对3类菌株EC50值的平均值, 16种杀菌剂抑制菌丝生长的活性依次为腐霉利＞乙烯菌核利＞异菌脲＞戊唑醇＞百菌清＞嘧霉胺＞醚菌酯＞代森锰锌＞8-羟基喹啉铜＞丙环唑＞苯醚甲环唑＞嘧菌酯＞灭锈胺＞烯酰吗啉＞烟酰胺＞三唑酮;抑制孢子萌发的活性依次为醚菌酯＞腐霉利＞百菌清＞乙烯菌核利＞灭锈胺＞8-羟基喹啉铜＞异菌脲＞代森锰锌＞嘧菌酯＞烟酰胺＞嘧霉胺＞戊唑醇＞丙环唑＞苯醚甲环唑＞三唑酮＞烯酰吗啉。通过紫外诱变共获得17株抗异菌脲突变体,突变频率为4.5×10-7。其中低抗、中抗和高抗菌株分别占 17.65%、70.59%和11.75%。这些突变体对腐霉利和乙烯菌核利表现交互抗性,对苯并咪唑类、脱甲基抑制剂(DMIs)、QoIs等药剂的敏感性与亲本菌株之间没有显著性差异,与亲本菌株在生长、产孢、致病能力等方面也无显著差异,但对渗透胁迫的敏感性要显著高于亲本。     

植物病原真菌对杀菌剂抗性的研究进展

科学施用杀菌剂是植物病害综合治理的重要措施之一, 然而由于杀菌剂的长期使用, 病菌抗药性问题逐渐加重, 严重影响药剂的防治效果和使用寿命。近年来, 随着分子生物学技术的快速发展, 人们对杀菌剂抗性机制有了更深入的理解, 并开发出了病菌抗药基因型快速检测的方法。本文总结了植物病原真菌对苯并咪唑类杀菌剂(BZD)、肌球蛋白合成抑制剂、甾醇脱甲基抑制剂(DMI)、QoI类抑制剂、琥珀酸脱氢酶抑制剂（SDHI）和二甲酰亚胺类杀菌剂(DC)的抗药性现状与抗性机制。在此基础上, 介绍了聚合酶链反应(PCR)、限制性片段长度多态性(RFLP)、等位基因特异性PCR和环介导等温扩增(LAMP)技术在杀菌剂抗性快速检测方面的研究进展。此外, 对抗药性治理对策进行了讨论和展望。     

developed by the Phenylamide Fungicide Resistance Action Committee (PA-FRAC) of GIFAP

Methods are presented for monitoring the sensitivity to phenylamide fungicides of plant pathogenic fungi belonging to the Peronosporales, e.g. Phytophthora infestans, Plasmopara viticola, Peronospora tabacina, Pseudoperonospora cubensis and soil-borne Phytophthora and Pythium species. The methods are intended for practical use in the implementation of anti-resistance strategies. Methods for sterol demethylation inhibitors (DMIs), benzimidazoles and dicarboximides have already been published in Bulletin OEPP/EPPO Bulletin 21, 291–354 (1991)     

Chemical control of plant diseases

As the world population increases, we also need to increase food production. Chemical control has been critical in preventing losses due to plant diseases, especially with the development of numerous specific-action fungicides since the 1960s. In Japan, a host-defense inducer has been used to control rice blast since the 1970s without any problems with resistance development in the pathogen. Leaf blast has been controlled using a labor-saving method such as the one-shot application of a granular mixture of fungicide and insecticide to nursery boxes, which became mainstream in the 2000s. However, the need for many choices of fungicides that have several modes of action was demonstrated by the development of resistance to cytalone dehydratase inhibitors. In Europe, many pathogens have threatened cereals since the great increase in cereal production in 1970s, creating a large market for broad-spectrum fungicides. In Brazil, Phakopsora pachyrhizi was distributed to large soybean acreages during 2000s, and the outbreak of soybean rust resulted in a large increase in fungicide use. While the importance of chemical control is recognized, fungicide resistance is an avoidable problem; published guidelines on countermeasure and manuals on testing sensitivity to fungicides are available. Since chemical regulations have become stricter, new fungicides are less likely to be developed. Our task is to maintain the effectiveness and diversity of the present modes of action for fungicides and implement countermeasures against the development of fungicide resistance.