Utilizing metabolomic approach to study the mode of action of fungicides and corresponding resistance in plant pathogens

Fungicides are an indispensable tool in plant disease control.Various modes of action(MOAs)have been identified in different fungicides to suppress plant pathogens.The combined use of fungicides with distinct MOAs has been recommended to prevent the development of pathogen resistance.In studying MOAs,metabolomics has been proven to be a robust and high-throughput method.Because metabolites are unique and distinct depending on the biological activities of an organism,MOAs can be identified and classified by establishing metabolic fingerprinting and metabolic profiles.Similarly,if fungicide resistance is developed in a pathogen,the metabolome will change,which can be identified.In this review,we have discussed the principles and advanced applications of metabolomics in the study of MOAs and resistance mechanisms of fungicides,and the potential of metabolic data in understanding the interaction between fungicides and pathogens.Challenges are also discussed in the application of metabolomics,improvement of the study on the mechanism of fungicides in their functions against pathogens and advancing the development of novel fungicides.

Comparative Study of Bunt Pathogen Resistance to the Effects of Fungicides in Callus Co-Cultures <i>Triticum aestivum</i>with Tilletia caries

The morphophysiological and molecular-genetic parameters of T. caries isolates collected from various fields of Southern Urals agrocenoses have been analysed. Isolate 1 of wheat callus had a high growth rate in vitro even in the presence of 0.1 mg/l fungicide Baitan. Isolate 2 of wheat callus had a low growth rate whereas 0.1 mg/l Baitan significantly inhibited its growth. Comparison of nucleotide sequences of 18S RNA gene of the two isolates showed high level of homology between them, but a large number of nucleotide substitutions have been found. The most characteristic excision was five nucleotides at position 461 of the isolate 2, compared with the isolate 1. Our results allow to assume that the environmental stress including high pesticide concentration may cause the resistance of T. caries pathogen to fungicides.

A Preliminary Study on the Resistance to Different Fungicides in Phytophthora parasitica var. nicotianae

[Objective] This study aimed to investigate the resistance to different fungicides in Phytophthora parasitica var. nicotianae. [Method] Under indoor incubation conditions, the resistance to dimethomorph, metalaxyl-mancozeb, propamocarb and ovraclostrobin.dimethomorph in P. parasitica strain isolated from Zhenyuan County in Qiandongnan State was analyzed with colony growth measurement method. [Result] P. parasitica exhibited different levels of sensitivity to four fungicides. To be specific, P. parasitica exhibited the highest resistance to dimethomorph, and ECho reached 1.19 μg/ml. [Conclusion] In Zhenyuan tobacco-growing area, long-term single use of dimethomorph possesses certain resistance risk in prevention and control of black shank disease.

Evaluation of host resistance and fungicide application as tools for the management of root rot of field pea caused by Aphanomyces euteiches

Aphanomyces root rot(ARR) of field pea(Pisum sativum), caused by Aphanomyces euteiches, can cause severe root damage, wilting, and large yield losses under wet soil conditions. To identify ways to manage this disease, the effect of A. euteiches inoculum density on field pea was studied under greenhouse and field conditions in 2015 and 2016. Increases in inoculum density reduced seedling emergence, root nodulation, and plant vigor, and resulted in increased root rot severity in both field and greenhouse tests. Seed treatments with the fungicides Apron Advance(thiabendazole + fludioxonil + metalaxyl) + Vibrance(difenoconazole + metalaxylM + sedaxane), INTEGO Solo(ethaboxam), BAS 516F(boscalid + pyraclostrobin), BAS 720F(metalaxyl + pyraclostrobin + fluxapyroxad), and BAS 516F + BAS 720F(3:1) were evaluated for their efficacy against ARR. All seed treatments except Apron Advance + Vibrance reduced root rot severity under controlled conditions. BAS 516F, BAS 720F and INTEGO Solo improved plant vigor and all treatments reduced seedling blight to varying degrees under greenhouse conditions, but not in the field. A collection of 22 pea genotypes was evaluated for resistance to root rot in field plot experiments. Line 00–2067 showed the least severe root rot symptoms,whereas ‘Spring D' showed the lowest reduction in yield. The results suggest that there may be an opportunity to combine partial host resistance and fungicidal seed treatments to adequately manage ARR of field pea.

Study on the Resistance of Pseudoperonospora cubensis to Cymoxanil

[Objective] The paper was to clarify the sensitivity and resistance of Pseudoperonospora cubensis to cymoxanil.[Method] A total of 69 strains were collected from 13 major cucumber producing areas in eight provinces and cities of Guangdong, Hubei, Jiangsu, Shandong, Beijing, Liaoning, Jilin and Heilongjiang from 2012 to 2016, and their sensitivity and resistance to cymoxanil was determined using leaf disc floating method.[Result] The EC50 of cymoxanil to P. cubensis were 0.006 8-0.134 1 μg/mL and the average EC50 was 0.062 4 μg/mL. The sensitivity of P. cubensis to cymoxanil presented a single-peak curve, which was approximately normal distribution, and no strains with decreased sensitivity were found. The average EC50 (0.062 4 μg/mL) could be used as the sensitivity baseline of P. cubensis to cymoxanil. Among the 69 strains, 16 were low-resistance strains, accounting for 23.19% of the total strains;53 were sensitive strains, accounting for 76.81%, which were dominant populations;and no medium-resistance and high resistance strains were found. The resistance of P. cubensis to cymoxanil ranged from 0.11 to 2.15 times, and the average resistant level was 1.00 times.[Conclusion] Cymoxanil showed strong inhibitory effect against P. cubensis.

Activity of the Fungicide JS399-19 Against Fusarium Head Blight of Wheat and the Risk of Resistance

This report reviews the characteristics of JS399-19, a novel cyanoacrylate fungicide. JS399-19 strongly inhibits the mycelial growth of the fungal plant pathogens of the genus Fusarium and exhibits great potential in controlling Fusarium head blight （FHB） on wheat and other cereals. The mode of action of JS399-19 is evidently different from that of benzimidazole （for example, carbendazim） and other sort of fungicides, making it a possible replacement for carbendazim in China to manage carbendazim-resistant subpopulations of Fusarium graminearum and F. asiaticum. JS399-t9 has excellent protective and curative activity against these pathogens. Incorrect use of this fungicide, however, is likely to select for resistance. Among JS399-19-resistant mutants of F. asiaticum induced in the laboratory, the resistant level of mutants was high and the phenotype of resistance against JS399-19 was conferred by a major gene by genetic analysis. The fitness of laboratory-induced JS399-19-resistant mutants of F. asiaticum was nearly equal to that of their parents. JS399-19 lacks cross resistance with other sort fungicides. To control FHB with JS399-19 and to delay the development of the fungicide-resistance, farmers should use tank mixtures containing JS399-19 and carbendazim, metconazole, tebuconazole, or prothioconazole.

Wheat Yield Response to Foliar Fungicide Application against Leaf Rust Caused by Puccinia triticina

A study was conducted on reducing the yield loss of wheat due to leaf rust caused by Puccinia triticina with foliar application of fungicides during the 2014-2015 and 2015-2016 growing seasons at the Wheat Research Institute in Faisalabad, Pakistan. Three fungicides： Folicur （tebuconazole） at 300 mL/ha, Nativo （tebuconazole ＋ trifloxystrobin） at 300 g/ha and Tilt （propiconazole） at 500 mL/ha were applied single or two times to Morocco and Sehar-06 wheat varieties used in the trial. The trial plots were first sprayed at the Zadok＇s scale （ZS） 3 stage and second sprayed between ZS 4.3 and 5.4 stages. The greenness of the trial crop was measured using GreenSeeker. Foliar application of fungicides significantly reduced the loss of grain yield and 1,000-grain weight （TGW） of wheat due to leaf rust in comparison to the control without fungicides application. Of the three fungicides, two times spray of Nativo reduced the grain yield loss of leaf rust susceptible mega wheat variety Sehar-06 by 45%-56% and the loss of TGW by 42%, also giving the highest marginal return in the trial. Single application of Nativo was equally effective as two times spray of Folicur in reducing the loss of wheat grain yield. Two times spray of Folicur was found to be the second choice of fungicide for reducing the yield loss of wheat. The research identified suitable fungicides for reducing the yield loss of wheat due to leaf rust and also generated important scientific knowledge required to manage a sudden outbreak of leaf rust to ensure food security.

致病疫霉(Phytophthora infestans)对杀菌剂抗药性研究进展

综述了致病疫霉 (Phytophthorainfestans)对内吸性杀菌剂甲霜灵、霜脲氰和保护性杀菌剂代森锰锌和百菌清的抗性研究进展 ,总结了当前用于防治晚疫病的药剂种类并提出了抗性治理策略。对于致病疫霉抗性遗传研究和抗性治理及药剂防治都具有一定的参考价值。

棉铃疫病菌(Phytophthora boeh meriae)对甲霜灵的抗性遗传研究

本文在实验室条件下 ,经药物直接诱变 ,筛选获得棉铃疫病菌 (PhytophthoraboehmeriaeSawada)抗甲霜灵突变株 ,研究了其抗药性性状的遗传。结果表明 ,棉铃疫病菌易对甲霜灵产生抗性 ,抗性菌株对甲霜灵的抗性水平可高达其敏感亲本的 5 16 1 3倍以上 ;部分抗性菌株的抗药性性状在无性及有性单孢后代均可稳定遗传 ,另有部分抗性菌株的抗性性状在无性单孢后代出现分离甚至完全丧失。初步认为 。

重庆地区马铃薯晚疫病菌(Phytophthora in festans)对甲霜灵抗性及抗性水平测定

20 0 1年从北碚、云阳、开县、万州、巫溪和忠县等地采集马铃薯晚疫病病叶 ,共分离得 94株致病疫霉。用生长速率法测定其对甲霜灵的抗性和抗性水平 ,结果表明 :2 0 2 %的菌株表现为抗性 ,11 7%的菌株表现为中抗 ,6 8 1%的菌株表现为敏感 ;以菌株PBB 110 2为敏感对照 ,所测定的 2株抗性菌株的抗性水平达 10 6倍以上 ,各地菌株抗性表现与菌株来源地的施药水平密切相关 。

番茄晚疫病菌(Phytophthora infestans)对甲霜灵的抗性测定及治理

2 0 0 0～ 2 0 0 1年连续 3季从壁山、沙坝坝蔬菜基地采集番茄晚疫病病叶和病果 ,共分离得 80株晚疫病菌。用生长速率法测定其对甲霜灵的抗性和抗性水平 ,结果有 75 0 %的菌株表现为抗性 ,13 8%的菌株表现为中抗 ,11 2 %的菌株表现为敏感。以菌株TBS 2 131为敏感对照 ,所测定的 4株抗性菌株的抗性水平达 5× 10 4倍以上。此结果表明当地晚疫病菌抗性菌株已占优势 ,并且抗性水平已很高。同时有针对性地提出了防治番茄晚疫病的用药策略。

Effect of Azoxystrobin on Oxygen Consumption and cyt b Gene Expression of Colletotrichum capsici from Chilli Fruits

Azoxystrobin acts as an inhibitor of electron transport by binding to the Qo center of cytochrome b （cyt b）. Resistance to azoxystrobin was usually caused by the point mutation of cyt b gene or by the induction of alternative respiration. Oxygen consumption test for mycelia of Colletotrichum capsici showed that azoxystrobin inhibited mycelial respiration within 12 h; however, as time went on, the respiration of the mycelia recovered when the mycelia were treated with azoxystrobin and salicylhydroxamic acid （SHAM, a known inhibitor of alternative respiration）, and the oxygen consumption of the mycelia could not be inhibited. Meanwhile, cytochrome b （cyt b） gene expression increased with the recovery of mycelial respiration. The increased cyt b gene expression might play a role in the development of resistance to azoxystrobin in C. capsici.

Sensitivity of Fusarium graminearum to Carbendazim and Prochloraz

[ Objective] The paper was to understand the resistance of Fusarium graminearum to carbendazim and prochloraz in the main wheat producing areas in Hubei Province. [ Method] Totally 350 F. graminearum strains isolated in 2014 were determined to clear their sensitivity to carbendazim and prochloraz. [ Result] ALl isolates were sensitive to carbendazim and procidoraz in Hubei Province, and carbendazim was still valuable in controlling Fusarium head blight. The control effect of prochloraz was better than that of carbendazim, and the combination of prochloraz and carbendazim at the proportion of 1：7 received the best control effect. [ Conclusion ] Combination of chemical agents will occupy a more and more important position in future prevention and control against Fusarium head blight.

Carbendazim resistance and calculation effective concentration of carbendazim for Trichoderma harzianum

There is a method for investigating the transformation of resistance gene of carbendazim into Trichoderma harzianum. In order to introduce the resistance to benzimidazole fungicide into bio-control microorganism Trichoderma harzianum was transformed with the resistance gene. In this study, we investigate resistance level and calculate EC 50 (effective concentration of carbendazim that can survive 50% of Trichoderma harzianum in that concentration) and stability of the resistance for the transformant isolate of Trichoderma harzianum. Results show the transformants can growth on the medium containing more than 1 000 μg/ml carbendazim and the resistance is stabled after 10 times transfer on non-selective medium and have EC 50 average about, 1 200 μg/ml.

Screening of Trichoderma harzianum mutants tolerant to carbendazim and UV-light

After comparison of Trichoderma population density and test of colonization ability in rhizospheres were conducted. Auxotrophic mutants of T. harzianum tolerant to carbendazim and UV-light were obtained by UV-light mutagenesis and carbendazim stress on PDA medium and a basis medium with hot pepper root exudation by adding the fungicide. The results showed: all four different isolates of Trichoderma had certain colonization ability in rhizosphere with the characteristic of growing as roots and distributing many more around root tips. The ability, however, was different for the 4 isolates, showing the wild isolates colonized weakly in rhizosphere. Around 5% spores alive and mutants could be obtained after the isolates were irradiated under a 20W UV-light at 25 cm distance for 5 min. The mutants tolerant to carbendazim were screened out by adding the fungicide into PDA medium, which increased resistance to the fungicide 100 times higher than their original isolates and showed auxotrophic. Three mutants,G7n,G20n and G5n, grew very well on PDA and a basic medium with hot pepper root exudation. Therefore, these mutants could be used as the isolates with good colonization ability for further research.

中国防治果蔬灰霉病的杀菌剂应用及防控关键技术

由葡萄孢属真菌(Botrytis spp.)引起的果蔬灰霉病是一种世界性的植物病害,采收前及采收后均能对果蔬产生危害,造成严重经济损失。介绍了我国果蔬灰霉病的发生与为害、杀菌剂应用现状、防治中存在的问题、防控关键技术,以期为灰霉病的科学防控提供参考。

杨叶枯病病原菌生物学特性、防治药剂筛选及杨树抗病性评价

为防治杨树叶枯病,利用单因素试验,对中荷64杨(P.×euramericana cv.‘N3016’)上分离获得的链格孢菌(Alternaria alternata)进行了生物学特性及室内防治药剂筛选研究,并开展了不同品种杨树抗叶枯病综合评价。结果表明:链格孢菌菌丝生长的适宜培养基为马铃薯蔗糖琼脂培养基,适宜碳源为玉米粉,适宜氮源为酵母提取物,适宜培养温度范围为25~30℃,适宜pH为8,光照条件对菌丝生长影响不大,致死温度为52℃。采用生长速率法进行室内防治药剂筛选,结果显示,选用的5种生物制剂防治效果优于2种化学药剂,各药剂抑制作用排序从大到小依次为哈茨木霉(3亿菌落/g)、枯草芽孢杆菌(100亿芽孢/g)、质量分数为10%的多抗霉素、质量分数为3%的中生菌素、质量分数为2%的宁南霉素、质量分数为50%的多菌灵、质量分数为75%的百菌清,将哈茨木霉(3亿菌落/g)和枯草芽孢杆菌(100亿芽孢/g)作为防治链格孢菌的适宜药剂。选用7个黑杨派品种杨树,利用模糊数学隶属度函数法,开展了杨树抗叶枯病综合评价,确定中荷64杨为高感品种,中辽1号杨和欧美杨177为中感品种,渤丰1号杨、渤丰3号杨、辽育3号杨和欧美杨111为高抗品种。

我国小麦赤霉病流行与化学防控现状及控病降毒关键技术理论创新与应用

概述了我国小麦赤霉病发生危害现状,深入剖析了该病流行危害的原因,回顾了近年来我国小麦赤霉病化学防控历程,综述了化学防控及其抗药性发生的现状,并总结了小麦赤霉病菌抗药性检测技术的发展过程。此外,对小麦赤霉病控病降毒关键技术理论创新与应用成果进行了分析和总结,展望了小麦赤霉病精准防控的科学用药技术方案,并对其可行性和有效性进行了阐释。旨在为小麦赤霉病的精准选药、科学用药提供重要的参考数据,保障我国的粮食生产安全和食品安全,进而推动我国农业实现可持续、高质量发展。

抗抑霉唑葡萄白腐病菌的适合度及与三唑类杀菌剂的交互抗性研究

以对抑霉唑不同敏感性的葡萄白腐病菌菌株为试材,研究抗抑霉唑菌株的适合度及抑霉唑与常用三唑类杀菌剂的交互抗性。结果显示,在菌丝生长速率、产孢量、致病力方面,部分抗性菌株显著高于敏感菌株,但致病力与菌株的EC_(50)值无显著相关性。37个葡萄白腐病菌菌株对抑霉唑、丙环唑、苯醚甲环唑、氟硅唑的平均EC_(50)值分别为16.5339、1.1159、2.2293、1.6481μg·mL^(-1),抑霉唑与丙环唑、苯醚甲环唑、氟硅唑的EC_(50)对数值之间的相关系数分别为0.6572、0.5261、0.5106,表明抑霉唑与丙环唑存在正交互抗性,与苯醚甲环唑、氟硅唑无显著交互抗性。本研究表明,对抑霉唑产生抗性的葡萄白腐病菌菌株具有较强的适合度,存在形成优势群体的潜在性,因此,用抑霉唑防治葡萄白腐病时,应尽量避免与丙环唑混合使用,以延缓其抗药性的发展。

禾谷镰孢复合种对常用杀菌剂抗性研究进展

近年来,受秸秆粗放还田、气候变化等因素影响,由禾谷镰孢复合种(Fusarium graminearum species complex)引起的小麦赤霉病在我国频繁暴发流行,成为长江中下游和黄淮海等小麦主产区的主要病害,严重影响小麦稳产丰收。病菌产生的脱氧雪腐镰刀菌烯醇和玉米赤霉烯酮等真菌毒素也严重威胁小麦质量安全。当前,由于缺乏高抗小麦品种,化学防治仍然是赤霉病防控的重要措施,但随着单一作用方式药剂的长期使用,病菌抗药性问题也逐渐加重。本文综述了禾谷镰孢复合种对苯并咪唑类杀菌剂、甾醇脱甲基抑制剂、肌球蛋白抑制剂、琥珀酸脱氢酶抑制剂等几类常用药剂的抗性现状和抗性机制。在此基础上,探讨禾谷镰孢复合种的抗药性治理对策。