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1.
经过药剂驯化10代后,从对苯醚菌酯(ZJ0712)敏感的小麦白粉病菌Blumeria graminis f.sp.tritici 3个菌株中获得3个抗药突变体,突变体的抗性指数均大于80,且其抗性能够通过无性繁殖稳定遗传。室内接种试验发现,突变体的致病力与亲本菌株无明显差异。细胞色素b (cyt b)基因片段序列分析发现,突变体cyt b基因的第143位密码子均由敏感菌株的GGT(丙氨酸)突变成了GCT(甘氨酸)。研究结果表明,小麦白粉病菌对苯醚菌酯存在较高的抗性风险,该药剂在使用过程中需注意采取相应的抗性治理措施,以延缓抗性发生。  相似文献   

2.
为评估引起小麦茎基腐病的病原菌假禾谷镰孢Fusarium pseudograminearum对氰烯菌酯的抗性风险,对5株敏感菌株进行了室内药剂驯化,获得33株抗性突变体,突变频率为16.5%,其对氰烯菌酯的抗性水平范围为7.39～1 665.76倍,3株表现低抗,4株表现中抗,26株表现高抗;发现在myosin-5基因上存在11种抗性突变类型,其中217位的丝氨酸突变为亮氨酸(S217L)、420位的谷氨酸突变为赖氨酸(E420K)和135位的丙氨酸突变为苏氨酸(A135T)为主要突变类型,其比例分别为45.5%、15.2%和9.1%。S217L型抗性突变体的产孢量显著下降,菌丝生长速率和致病力与亲本菌株无显著差异。E420K型抗性突变体的菌丝生长速率和致病力显著下降,产孢量与亲本菌株无显著差异。A135T型抗性突变体的菌丝生长速率和产孢量与亲本菌株无显著差异。研究结果表明假禾谷镰孢在药剂选择压力下易形成氰烯菌酯的抗性群体,对氰烯菌酯存在中到高等的潜在抗性风险,其myosin-5的点突变与其对氰烯菌酯的抗性相关。  相似文献   

3.
为评价玉米穗腐病主要致病菌拟轮枝镰孢Fusarium verticillioides对多菌灵的敏感性,采用菌丝生长速率法测定了采自山东、河北、河南、四川、甘肃、辽宁及宁夏7省(自治区)的168株玉米穗腐病拟轮枝镰孢对多菌灵的敏感性,并对经药剂驯化获得的拟轮枝镰孢抗多菌灵菌株主要生物学性状和交互抗性进行了研究。结果表明:多菌灵抑制拟轮枝镰孢菌丝生长的EC50值在0.013 2~0.774 0 mg/L之间,平均EC50值为(0.220 8 ± 0.143 7) mg/L。敏感性频率分布显示,供试病原菌群体中已出现对多菌灵敏感性下降的亚群体,但其中仍有35.71%的菌株对多菌灵的敏感性频率呈正态分布,因此可将此部分菌株的平均EC50值 (0.081 4 ± 0.028 9) mg/L作为拟轮枝镰孢对多菌灵的相对敏感基线。药剂驯化共获得6株抗性菌株,抗性倍数在5.05~12.22之间。抗性菌株的菌丝生长速率及菌丝干重均低于亲本菌株,表明其抗性菌株的生物适合度有所降低,同时发现其抗药性均不能稳定遗传。室内交互抗性测定结果表明,拟轮枝镰孢对多菌灵的抗性与咪鲜胺、戊唑醇、三唑酮及吡唑醚菌酯之间均不存在交互抗性关系。  相似文献   

4.
为了解甘肃省裸仁美洲南瓜白粉菌对己唑醇敏感性及抗性产生情况,采用小株喷雾法对采自兰州、武威、景泰等地的20个南瓜白粉菌菌株对己唑醇的敏感性进行了测定,利用紫外诱导、药剂驯化、先紫外后药剂驯化三种方法对敏感菌株进行了抗药性诱导,并对抗性突变菌株的生物学性状及其对丙环唑、氟硅唑、腈菌唑和戊唑醇的交互抗性进行了研究。结果表明20个南瓜白粉菌菌株对己唑醇的敏感性存在一定差异,EC50值在17.77~285.54μg/mL范围内;与其他两种诱导方法相比药剂驯化方法获得的抗性突变菌株的抗性倍数最高,为8.94倍。敏感菌株和抗性突变菌株孢子萌发的最佳时间分别为36h和48h;抗性突变菌株产孢量和致病力明显高于敏感菌株;适合度测定表明抗性突变菌株与敏感菌株之间存在竞争力,孢子萌发率、芽管个数之间差异显著,菌丝分支数、产孢量之间差异不显著;抗性突变菌株在抗性突变菌株和敏感菌株混合比例为80∶20的群体中,存在频率比较稳定,连续培养7代后仍占85.69%;己唑醇抗性突变菌株对丙环唑、氟硅唑、腈菌唑和戊唑醇4种药剂未表现出交互抗性。研究结果可为甘肃省防治南瓜白粉病提供理论依据。  相似文献   

5.
为明确灰葡萄孢对氟唑菌酰羟胺不同敏感型菌株的生物学特性差异,将9个不同敏感型菌株在无药PDA平板上继代培养10代后,测定其对氟唑菌酰羟胺的敏感性。采用菌丝生长速率法分别在PDA平板和离体叶片上测定了其菌丝生长速率、产孢量、孢子萌发率和致病性,以及其对温度、pH值和葡萄糖的敏感性,并对其编码琥珀酸脱氢酶的SdhA、SdhB、SdhC和SdhD 4个亚基基因进行了克隆与测序。结果显示:从田间获得的2个低抗菌株、2个中抗菌株和2个高抗菌株对氟唑菌酰羟胺的敏感性变异指数在0.60~1.15之间,而通过室内药剂驯化获得的高抗菌株BLH5F对氟唑菌酰羟胺的敏感性变异指数为0.23;除低抗菌株WP8的菌丝生长速率显著低于2个敏感菌株,以及中抗菌株WP6和高抗菌株WPE9的产孢量显著低于2个敏感菌株外,其余各抗性菌株在菌丝生长速率、产孢量、孢子萌发率和致病性方面均无显著差异。整体而言,7个抗性菌株在对温度、pH值和葡萄糖的敏感性方面与敏感菌株无显著差异。基因克隆及测序结果表明,室内药剂驯化获得的高抗菌株BLH5F SdhB基因的272位由组氨酸变为了精氨酸 (H272R),田间获得的低抗、中抗和高抗各2个菌株均为SdhB基因的225位由脯氨酸变为了亮氨酸 (P225L)。综合分析表明,灰葡萄孢对氟唑菌酰羟胺不同敏感型菌株具有相似的适合度。因此,推测在药剂的选择压下,抗氟唑菌酰羟胺的灰葡萄孢菌株在田间容易形成优势种群。  相似文献   

6.
由灰葡萄孢(Botrytis cinerea Pers.)引起的草莓灰霉病是严重危害草莓的病害之一。为了解草莓灰霉病菌对杀菌剂嘧菌酯的抗性情况,本研究针对2012年从国内10省市采集和分离的134株草莓灰霉病菌菌株,利用特异性引物BcAR-F/BcAR-R扩增其cytb基因的部分序列,进行了嘧菌酯抗性的分子检测;对检测出的抗性菌株在嘧菌酯浓度分别为22.4、112和224μg·mL~(-1)的含药培养基上进行抗性验证;此外,还比较了抗性菌株与敏感菌株主要生物学性状的差异。结果表明,有54个菌株对嘧菌酯表现抗性,均属于中等抗性水平,占检测总数的40.3%,分布于北京市、湖北、江苏、河北、辽宁和四川各省;对15个抗性菌株cytb基因的序列分析表明,其第143位发生突变,由甘氨酸变为丙氨酸;对随机选取的4株抗性菌株和2株敏感菌株的适合度测定结果发现,抗性菌株和敏感菌株在最适生长温度、菌落生长速度、孢子萌发率方面没有表现出规律性差异,但抗性菌株的产孢量和致病力均显著低于敏感菌株。  相似文献   

7.
草莓枯萎病菌对多菌灵的抗性及其抗性菌株生物学特性   总被引：5，自引：1，他引：4  
为评价草莓枯萎病菌对多菌灵的抗性风险,从山东有代表性的草莓种植区,采集、分离了4个草莓枯萎病菌菌株,分别在含多菌灵的PDA平板培养基上进行继代培养,诱导获得抗性菌株。采用菌落生长速率法测定抗性菌株ZY-D的抗性稳定性及其对其它杀菌剂的交互抗性,比较了抗性菌株ZY-D与敏感菌株ZY的生物学特性差异。结果显示:选育至45代,抗性菌株ZY-D对多菌灵的抗性达53.91倍,抗性能够在无药条件下稳定遗传,4个抗性菌株与敏感菌株ZY具有同样的致病力;抗多菌灵菌株ZY-D对甲基硫菌灵等7种药剂表现出了不同程度的交互抗性;抗性菌株ZY-D与敏感菌株ZY的适宜生长温度均为25℃,适宜pH均为9;在不同的碳、氮源条件下,ZY-D与ZY的菌落直径和产孢量存在差异。  相似文献   

8.
为评价烟草赤星病致病菌链格孢Alternaria alternata对嘧菌酯的抗性风险,以敏感菌株J6为试材,通过菌丝药剂驯化和分生孢子紫外诱变诱导抗性突变体,并对抗性突变体的生物学特性进行了研究,同时对抗性突变体与敏感菌株线粒体的细胞色素b基因 (cyt b) cDNA序列全长进行了测序分析。结果表明:经药剂驯化未获得抗性突变体,而紫外诱变共获得7株抗性突变体,突变频率约为0.007%,抗性水平分别为5.27、8.28、25.28、12.82、6.14、9.28和52.91倍。适合度研究表明,抗性突变体与敏感菌株的分生孢子萌发能力及致病力相当,但分生孢子产生量均高于敏感菌株,菌丝生长速率除突变体6-1外均快于敏感菌株。cyt b基因cDNA序列分析表明:有4株抗性突变体在不同位点上发生了核苷酸突变,其中突变体6-7 cyt b的249位和871位碱基由T突变为C,但其编码的氨基酸未发生突变;突变体6-8 cyt b的734位碱基由T突变为C,引起所编码的245位丙氨酸突变为缬氨酸 (V245A);突变体6-9 cyt b的510位碱基由T突变为A,所编码的170位由精氨酸替代了丝氨酸 (S170R);突变体6-11 cyt b的732位碱基由T突变为A,所编码的244位由苯丙氨酸替代了亮氨酸 (L244F),其776位碱基由T突变为C,所编码的259位由丙氨酸替代了缬氨酸（V259A）,其1 156位碱基由A突变为G,所编码的氨基酸未发生变化。研究结果初步表明,烟草赤星病菌对嘧菌酯存在潜在的抗药性风险,其cyt b基因的点突变与其对嘧菌酯的抗药性有关。  相似文献   

9.
为了解连续施药对番茄灰葡萄孢对咯菌腈敏感性的影响,在温室条件下,从灰霉病发生初期开始,按推荐剂量(有效成分67.5 g/hm2)定期向番茄苗喷施咯菌腈,通过菌丝生长速率法检测灰葡萄孢对咯菌腈的敏感性。结果表明,在番茄1个生长季节中连续施药7次后,病菌对咯菌腈仍表现敏感,其EC50值在0.004 7～0.046 2 μg/mL之间。在含咯菌腈的PDA培养基上对30个灰葡萄孢敏感菌株进行药剂驯化7代后,共产生2个抗药性突变体(Rg-12和Rdz-28),其中Rg-12对咯菌腈的EC50值是其亲本菌株g-12的46倍,Rdz-28的EC50值大于500 μg/mL,2个抗性突变体在菌丝生长速率、产孢量和产菌核能力方面均显著低于其亲本菌株。推测灰葡萄孢可能不易对咯菌腈产生抗性,咯菌腈可作为防治番茄灰霉病的理想候选药剂。  相似文献   

10.
浙江省果蔬灰葡萄孢对啶酰菌胺的抗性   总被引：1，自引：0，他引：1  
以2004—2006年从浙江、江苏等地采集的灰葡萄孢对啶酰菌胺的敏感性基线[EC50 = (1.07 ± 0.11) mg/L]为依据,采用菌丝生长速率法连续监测了浙江省果蔬灰葡萄孢群体对啶酰菌胺的敏感性变化。结果表明:浙江省果蔬灰葡萄孢对啶酰菌胺的抗性发展迅速,2012—2013年和2017—2018年的平均EC50值分别为 (5.23 ± 7.79) 和 (24.30 ± 49.33) mg/L。其中,2012—2013年的抗药性菌株频率为15.3%,且均为低水平抗性 (LR) 菌株;而2017—2018年的抗药性频率上升至53.2%,并出现了7.5%的中等水平抗性 (MR) 菌株和1.3%的高水平抗性 (HR) 菌株。啶酰菌胺抗性菌株的菌丝生长速率、产孢量、产菌核数和致病力与敏感菌株相比均无显著差异。抗药性分子机制研究表明:啶酰菌胺抗性菌株的琥珀酸脱氢酶B亚基 (SDH B) 均发生了点突变,共包括H272R、P225F和N230I 3种类型,其中H272R型突变占88.5%;其SDH A和SDH D均未发生点突变;而SDH C的突变 (G85A + I93V + M158V + V168I) 与对药剂敏感性之间无明显联系。  相似文献   

11.
Mutants of Phytophthora infestans with high resistance to the amidocarbamates iprovalicarb and benthiavalicarb and to the cyanoimidazole cyazofamid were isolated after UV-mutagenesis and selection on media containing one of the above fungicides. In vitro fungitoxicity tests showed that all resistant strains presented a highly reduced sensitivity to both cyazofamid and to the amidocarbamates. Cross-resistance studies with other oomycete fungicides from different chemical groups showed that the mutation(s) for resistance to iprovalicarb (IPV), benthiavalicarb (BVC) and cyazofamid (CZF) also greatly reduced the sensitivity of mutant strains to the phenylamide metalaxyl, acetamide cymoxanil, morpholine dimethomorph, benzamide zoxamide and to chlorothalonil. A lower reduction of sensitivity of mutant strains to the strobilurins azoxystrobin, kresoxim-methyl, pyraclostrobin and trifloxystrobin, azolones famoxadone and fenamidone and to antimycin A was observed. A resistance correlation was not apparent for the dithiocarbamate propineb and phenylpyridinamine fluazinam. Studies of fitness parameters in the wild-type and mutant strains of P. infestans showed that most resistant isolates had significantly reduced sporulation and sporangial germination, but not in the differentiation of sporangia into zoospores. Pathogenicity tests on tomato seedlings showed that most resistant isolates were significantly less pathogenic compared to the wild-type parent strain. However, experiments on the stability of the resistant phenotypes did not show a reduction in resistance when the mutants were grown for more than eleven generations on inhibitor-free medium. This is believed to be the first report of high level multi-drug resistance in fungal pathogens to chemically unrelated fungicides inhibiting different sites of cellular pathway.  相似文献   

12.
Cucurbit powdery mildew caused by Podosphaera fusca limits crop production in Spain. Since its management is strongly dependent on chemicals, the rational design of control programmes requires a good understanding of the fungicide resistance phenomenon in field populations. Fifty single-spore isolates of P. fusca were tested for sensitivity to three quinone-outside inhibiting (QoI) fungicides: azoxystrobin, kresoxim-methyl and trifloxystrobin. Minimum inhibitory concentration (MIC) values for QoI-sensitive isolates were found to range from 0.25 to 10 μg ml−1 for azoxystrobin to 5–25 μg ml−1 for kresoxim-methyl, using a leaf disc-based bioassay. High levels of cross-resistance to QoI fungicides were found. Eleven isolates showed resistance to the three QoI fungicides tested with MIC and EC50 values >500 μg ml−1 resulting in RF values as high as >715 and >1000 for trifloxystrobin and azoxystrobin, respectively. A survey of P. fusca QoI resistance was carried out in different provinces located in the south central area of Spain during the cucurbit growing seasons in 2002, 2003 and 2004. Examination of a collection of 250 isolates for QoI resistance revealed that 32% were resistant to the three fungicides tested; the provinces of Ciudad Real, Córdoba and Murcia being the locations with the highest frequencies of resistance (44–74%). By contrast, no resistance was found in Badajoz, and relatively low frequencies were observed in Almería and Valencia (10–13%). Nearly 50% of resistant isolates were collected from melon plants. Based on these data, recommendations about the use of QoI fungicides for cucurbit powdery mildew management in the sampled areas are made.  相似文献   

13.
A total of 108 isolates of cucurbit powdery mildew (CPM) fungi, 78Golovinomyces cichoracearum (Gc) and 30Podosphaera xanthii (Px), originating from nine Czech regions and 22 districts of the Czech Republic were collected in the years 2001–2004. These isolates were screened for tolerance and/or resistance to the three frequently used fungicides (fenarimol, dinocap, benomyl). Fungicide sensitivity was determined by a modified leaf-disc bioassay with five concentrations. Fungicide efficacy differed significantly: fenarimol was the most effective and all isolates of both CPM were controlled by the recommended concentration (36μg a.i. ml−1). Some isolates expressed resistance (profuse sporulation) or tolerance (limited sporulation) to lower concentrations (9.6 and 18μg a.i. ml−1). Specific temporal variation in tolerance/resistance was observed, with some isolates ofGc from 2002 evincing tolerant or resistant reactions to these low fenarimol concentrations, but isolates with similar reactions were not detected during the years 2003–2004. Dinocap showed decreasing efficacy during all 3 years. A shift to more tolerant reactions in the CPM populations was detected forGc in 2001–2002, and forPx in 2001 and 2004. Benomyl was found to be ineffective, because the majority of screened isolates (88%Gc and 97%Px) belonged to the highly resistant strains, with resistant reaction on the recommended concentration (250μg a.i. ml−1) and tolerance or resistance on higher concentrations (500 and 1000μg a.i. ml−1). Sensitivity differed between the CPM species. Whereas practically allPx isolates (except one from 2003) were resistant, 12% ofGc isolates from the years 2001–2003 showed sensitive and/or tolerant reactions. In 2004, only benomyl-resistantGc strains were detected. Variation in tolerance/resistance was detected to all screened fungicides during the course of this study at some repeatedly sampled locations. http://www.phytoparasitica.org posting June 12, 2008.  相似文献   

14.
Tomato and strawberry are the most important protected crops in Lebanon and are seriously affected by grey mould disease, caused by Botrytis cinerea. In the present study, the fungicide sensitivity assays revealed medium to high frequencies of B. cinerea isolates resistant to benzimidazoles, dicarboximides, and anilinopyrimidines on tomato and strawberry. Fludioxonil- and boscalid-resistant mutants were uncommonly found at generally low frequency on both crops. Resistance to fenhexamid was detected in only one site on tomato but in most sites on strawberry with high frequencies, and the occurrence of resistance to QoI fungicides was ascertained on both crops. The majority of the tested isolates (>90%) exhibited multiple fungicide resistance, and isolates resistant to the seven antibotrydial fungicide classes were detected on strawberry in three locations. A high level of resistance was shown by B. cinerea mutants resistant to boscalid, fenhexamid, and QoI fungicides, while two levels of moderate and high resistance to anilinopyrimidines were identified. Genetic analysis revealed point mutations in the target genes commonly associated with resistance in B. cinerea isolates, with all mutants resistant to dicarboximides, fenhexamid, boscalid, and QoI fungicides carrying single-nucleotide polymorphims in BcOS1 (I365S/N, Q369P, and N373S), Erg27 (F412V/I), SdhB (H272R/Y), and cytb (G143A) genes, respectively. The general incorrect use of fungicides has caused the development and spread of fungicide resistance as a widespread phenomenon on protected tomato and strawberry in Lebanon. The implementation of appropriate antiresistance strategies is highly recommended.  相似文献   

15.
Mutants of Botrytis cinerea and Ustilago maydis highly resistant to fludioxonil were isolated at a high frequency, after nitrosoguanidine or UV mutagenesis, respectively, and selection on media containing fludioxonil. Tests on the response of mutant strains to high osmotic pressure resulted in the identification of two fludioxonil-resistant phenotypes (FLDosm/s and FLDosm/r), regarding the sensitivity to high osmolarity. Approximately 95% of fludioxonil-resistant mutants were found to be more sensitive to high osmotic pressure than the wild-type parent strains. Genetic analysis of phenylpyrrole-resistance in the phytopathogenic basidiomycete U. maydis, showed that fludioxonil-resistance was coded by three unlinked chromosomal loci (U/fld-1, U/fld-2 and U/fld-3), from which only the U/fld-1 mutation coded an osmotic sensitivity similar to that of the wild-types. Cross-resistance studies with fungicides from other chemical groups showed that the mutations for resistance to phenylpyrroles affect the sensitivity of mutant strains to the aromatic hydrocarbon and dicarboximide fungicides, but not to the benzimidazoles, anilinopyrimidines, phenylpyridinamines, hydroxyanilides or the sterol biosynthesis inhibiting fungicides. A study of fitness parameters in the wild-type and fludioxonil-resistant mutants of B. cinerea, showed that all osmotic sensitive (B/FLDosm/s) isolates had significant reductions in the characteristics determining saprophytic fitness such as mycelial growth, sporulation, conidial germination and sclerotial production. Contrary to that, with the exception of mycelial growth, the fitness parameters were unaffected or only slightly affected in most of the osmotic resistant (B/FLDosm/r) isolates. Tests on cucumber seedlings showed that the osmotic-sensitive strains were significantly less pathogenic compared with the wild-type and B/FLDosm/r strains of B. cinerea. Preventative applications of the commercial products Saphire 50 WP (fludioxonil) and Rovral 50 WP (iprodione) were effective against lesion development on cotyledons by the wild-type and the mutant strains of B. cinerea that were resistant to the anilinopyrimidine cyprodinil (B/CPL-27) and to the hydroxyanilide fenhexamid (B/FNH-21), but ineffective, even at high concentrations, against disease caused by the fludioxonil-resistant isolates (B/FLD) and a mutant strain resistant to the dicarboximide iprodione (B/IPR-1). Experiments on the stability of the fludioxonil-resistant phenotype showed a reduction of resistance, mainly in osmotic-sensitive isolates, when the mutants were grown on inhibitor-free medium. A rapid recovery of the high resistance was observed after mutants were returned to the selection medium. Studies on the competitive ability of mutant isolates against the wild-type parent strain of B. cinerea, by applications of a mixed conidial population, showed that, in vitro, all mutants were less competitive than the wild-type strain. However, the competitive ability of osmotic-resistant mutants was higher than the osmotic-sensitive ones. Furthermore, competition tests, in planta, showed a significant reduction of the frequency of both phenylpyrrole-resistant phenotypes, with a respective increase in the population of the wild-type strain of the pathogen.  相似文献   

16.
为明确山东省主要烟草产区烟草赤星病菌Alternaria alternata对苯醚甲环唑和氟环唑的敏感性,采用菌丝生长速率法检测苯醚甲环唑和氟环唑对86株烟草赤星病菌菌株的EC_(50),用Spearman’s秩相关系数法分析供试菌株对2种杀菌剂敏感性的相关性,并评价其对烟草赤星病的田间防效。结果表明,苯醚甲环唑对烟草赤星病菌菌丝生长EC_(50)值介于5.3883～8.0316 mg/L之间,平均值为6.9594 mg/L,敏感性频率分布呈连续性偏正态分布,田间烟草赤星病菌对苯醚甲环唑仍然较为敏感,可建立田间烟草赤星病菌对苯醚甲环唑的敏感基线。氟环唑对烟草赤星病菌菌丝生长的EC_(50)值介于0.1253～0.2517 mg/L,平均值为0.1773 mg/L,敏感性频率分布呈连续性偏正态分布,可建立田间烟草赤星病菌对氟环唑的敏感基线。相关性分析结果表明,烟草赤星病菌对苯醚甲环唑和氟环唑敏感性之间不存在明显的相关性。田间试验结果表明,30%苯醚甲环唑悬浮剂对烟草赤星病具有较好的防效,其有效成分150 g/hm~2处理的防效最高,为73.99%;12.5%氟环唑悬浮剂对烟草赤星病的最高防效为70.57%。表明2种三唑类杀菌剂对烟草赤星病防效较好。  相似文献   

17.
为评估番茄灰霉病菌Botrytis cinerea对咯菌腈的抗性风险,就室内经紫外照射获得抗药突变体的方法及抗性突变体的生物学性状进行了研究。结果表明:番茄灰霉病菌分生孢子的紫外照射亚致死时间为90~120 s;经亚致死时间紫外照射后,4个亲本菌株中有2个菌株共产生了6个抗咯菌腈的突变体,其EC50值是亲本菌株的310倍以上,抗性突变频率为3.13×10-7;经紫外照射诱变获得的所有抗性突变体在菌丝生长速率、产孢量、产菌核能力及其在番茄果实上的致病性方面均比其亲本菌株明显降低。相关分析显示,所得抗咯菌腈突变体对氟啶胺、啶菌唑、啶酰菌胺和嘧霉胺无交互抗性。表明番茄灰霉病菌对咯菌腈的抗药性风险较低。  相似文献   

18.
BACKGROUND: Botrytis cinerea Pers.: Fr. is a high‐risk pathogen for fungicide resistance development that has caused resistance problems on many crops throughout the world. This study investigated the fungicide sensitivity profile of isolates from kiwifruits originating from three Greek locations with different fungicide use histories. Sensitivity was measured by in vitro fungitoxicity tests on artificial nutrient media. RESULTS: Seventy‐six single‐spore isolates were tested for sensitivity to the SDHI fungicide boscalid, the QoI pyraclostrobin, the anilinopyrimidine cyprodinil, the hydroxyanilide fenhexamid, the phenylpyrrole fludioxonil, the dicarboxamide iprodione and the benzimidazole carbendazim. All isolates from Thessaloniki showed resistance to both boscalid and pyraclostrobin, while in the other two locations the fungal population was sensitive to these two fungicides. Sensitive isolates showed EC50 values to boscalid and pyraclostrobin ranging from 0.9 to 5.2 and from 0.04 to 0.14 mg L?1 respectively, while the resistant isolates showed EC50 values higher than 50 mg L?1 for boscalid and from 16 to > 50 mg L?1 for pyraclostrobin. All QoI‐resistant isolates carried the G143A mutation in cytb. Sensitivity determinations to the remaining fungicides revealed in total eight resistance phenotypes. No isolates were resistant to the fungicides fenhexamid and fludioxonil. CONCLUSION: This is the first report of B. cinerea field isolates with resistance to both boscalid and pyraclostrobin, and it strongly suggests that there may be a major problem in controlling this important pathogen on kiwifruit. Copyright © 2010 Society of Chemical Industry  相似文献   

19.
BACKGROUND: Didymella bryoniae has a history of developing resistance to single‐site fungicides. A recent example is with the succinate‐dehydrogenase‐inhibiting fungicide (SDHI) boscalid. In laboratory assays, out of 103 isolates of this fungus, 82 and seven were found to be very highly resistant (BVHR) and highly resistant (BHR) to boscalid respectively. Cross‐resistance studies with the new SDHI penthiopyrad showed that the BVHR isolates were only highly resistant to penthiopyrad (BVHR‐PHR), while the BHR isolates appeared sensitive to penthiopyrad (BHR‐PS). In this study, the molecular mechanism of resistance in these two phenotypes (BVHR‐PHR and BHR‐PS) was elucidated, and their sensitivity to the new SDHI fluopyram was assessed. RESULTS: A 456 bp cDNA amplified fragment of the succinate dehydrogenase iron sulfur gene (DbSDHB) was initially cloned and sequenced from two sensitive (BS‐PS), two BVHR‐PHR and one BHR‐PS isolate of D. bryoniae. Comparative analysis of the DbSDHB protein revealed that a highly conserved histidine residue involved in the binding of SDHIs and present in wild‐type isolates was replaced by tyrosine (H277Y) or arginine (H277R) in the BVHR‐PHR and BHR‐PS variants respectively. Further examination of the role and extent of these alterations showed that the H/Y and H/R substitutions were present in the remaining BVHR‐PHR and BHR‐PS variants respectively. Analysis of the sensitivity to fluopyram of representative isolates showed that both SDHB mutants were sensitive to this fungicide as the wild‐type isolates. CONCLUSION: The genotype‐specific cross‐resistance relationships between the SDHIs boscalid and penthiopyrad and the lack of cross‐resistance between these fungicides and fluopyram should be taken into account when selecting SDHIs for gummy stem blight management. Copyright © 2011 Society of Chemical Industry  相似文献   

20.
Isolates of Cercospora beticola resistant to fungicides that inhibit sterol demethylation (DMIs) were collected from sugar beet fields in Northern Greece. Fitness of these isolates was compared to that of DMI-sensitive isolates. The parameters measured were competitive ability both under growth chamber and field conditions, mycelial growth, spore germination, germ tube length, incubation period, virulence and spore production. The competitive ability under growth chamber conditions was measured for 4 pairs of one resistant and one sensitive isolate. Results showed that after 4 disease cycles, in 2 out of 4 pairs tested, the resistant isolates competed well with the sensitive isolates, but in the remaining two pairs the frequency of the resistant isolate decreased significantly. The competition experiment in the field was carried out by inoculating field plots with a conidial suspension consisting of a spore mixture from all the resistant and all the sensitive isolates used in this study. Results showed that at the end of the growing period the frequency of the resistant isolates had slightly decreased (P < 0.05). The measurements of fitness components of individual isolates showed that the resistant isolates had significantly lower (P < 0.05) virulence and spore production than the sensitive isolates, while no significant differences (P > 0.05) to the remaining 4 fitness components, were detected. With correlation analysis it was determined whether there is a relationship between values of each fitness component and the level of sensitivity to flutriafol of individual isolates. The correlation coefficients for virulence (r = 0.45) and spore production (r = 0.41) were significantly different from 0 (P > 0.05), indicating that resistance to DMIs affected, to some degree, the fitness of the resistant isolates.  相似文献   

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