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1.
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   

2.
The development of resistance to chemical control agents needs continuous monitoring in Botrytis cinerea. 790 isolates from lettuce and other vegetable crops were collected from six widely separated sites in Greece and tested for their sensitivity to 11 fungicides from nine unrelated chemical groups. 44 of the isolates exhibited multiple resistance to fenhexamid (hydroxyanilides), azoxystrobin and pyraclostrobin (QoI’s), boscalid (SDHI’s), cyprodinil and pyrimethanil (anilinopyrimidines), fludioxonil (phenylpyrroles), carbendazim (benzimidazoles) and iprodione (dicarboximides). Thirty per cent of such phenotypes were detected in an experimental glasshouse with lettuce crops, the third year after commencing fungicide applications. The average resistance factor (Rf) for mycelial growth to fenhexamid, pyraclostrobin, boscalid, cyprodinil and fludioxonil, was over 40, 1,000, 100, 700 and 50, respectively. Some strains with high resistance to anilinopyrimidines (14 %) or moderate to fludioxonil (7 %) were detected even in isolates collected from vegetable crops prior to commercial use of these fungicides in Greece. Isolates with fludioxonil moderate resistance and fenhexamid high resistance, were detected for the first time in Greece. The results suggested the high risk in chemical control of grey mould due to development of resistance to most fungicides with site-specific modes of action. Isolates with resistance to fluazinam (phenylpyridinamines) and to chlorothalonil (phthalonitriles) were not found. The inclusion of appropriate multi-site inhibitors like chlorothalonil in fungicide anti-resistance strategies was indispensable.  相似文献   

3.
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   

4.
A novel, high‐resolution melting (HRM) analysis was developed to detect single nucleotide polymorphisms (SNPs) associated with resistance to fenhexamid (hydroxyanilides) and boscalid (succinate dehydrogenase inhibitors) in Botrytis cinerea isolates. Thirty‐six single‐spore isolates arising from 13 phenotypes were selected and tested for fungicide sensitivity. Germ tube elongation assays showed two distinct sensitivity levels for each fungicide. Sequencing revealed that resistance to fenhexamid was due to a nucleotide change in the erg27 gene, resulting in an amino acid replacement of phenylalanine (F) with serine (S) or valine (V) at position 412 of the protein, whereas in isolates resistant to boscalid, a nucleotide change in the sdhB gene resulted in the replacement of histidine (H) with arginine (R) or tyrosine (Y) at position 272 of the respective protein. In each case, melting curve analysis generated three distinct profiles corresponding to the presence of each nucleotide in the targeted areas. HRM analysis successfully detected and differentiated the substitutions associated with resistance to both fungicides. In vitro bioassays, direct sequencing and high‐resolution melting analysis showed a 100% correlation with detection of resistance. The results demonstrate the utility of HRM analysis as a potential molecular tool for routine detection of fungicide resistance using known polymorphic genes of B. cinerea populations.  相似文献   

5.
In a four-year survey of strawberry nursery plants, 340 Botrytis isolates were collected and examined for fungicide resistance. High percentages of isolates with resistance to members of all fungicide classes registered on strawberries in Germany were found, i.e. trifloxystrobin (90.3%), boscalid (53.8%), cyprodinil (41.5%), fludioxonil (28.2%) and fenhexamid (15.6%). Of these isolates, 10.3% possessed multiple resistance to all compounds. At 5.0%, resistance to the recently registered fungicide fluopyram was low. Dutch nursery material harboured significantly higher proportions of isolates with resistance to any or all fungicides than plants produced in Germany. These data point to nursery plants as a possible route of introducing fungicide-resistant Botrytis strains into commercial strawberry fields.  相似文献   

6.
BACKGROUND: Succinate dehydrogenase inhibitors (SDHIs) constitute a fungicide class with increasing relevance in crop protection. These fungicides could play a crucial role in successful management of grey mould disease. In the present study the effect of fluopyram, a novel SDHI fungicide, on several developmental stages of Botrytis cinerea was determined in vitro, and the protective and curative activity against the pathogen was determined on strawberry fruit. Furthermore, fungal baseline sensitivity was determined in a set of 192 pathogen isolates. RESULTS: Inhibition of germ tube elongation was found to be the most sensitive growth stage affected by fluopyram, while mycelial growth was found to be the least sensitive growth stage. Fluopyram provided excellent protective activity against B. cinerea when applied at 100 µg mL?1 96, 48 or 24 h before the artificial inoculation of the strawberry fruit. Similarly, fluopyram showed a high curative activity when it was applied at 100 µg mL?1 24 h post‐inoculation, but, when applications were conducted 48 or 96 h post‐inoculation, disease control efficacy was modest or low. The measurement of baseline sensitivity showed that it was unimodal in all the populations tested. The individual EC50 values for fluopyram ranged from 0.03 to 0.29 µg mL?1. In addition, no correlation was found between sensitivity to fluopyram and sensitivity to other fungicides, including cyprodinil, fenhexamid, fludioxonil, iprodione, boscalid and pyraclostrobin. CONCLUSIONS: The obtained biological activity, baseline sensitivity and cross‐resistance relationship data suggest that fluopyram could play a key role in grey mould management in the near future and encourage its introduction into spray programmes. Copyright © 2011 Society of Chemical Industry  相似文献   

7.
BACKGROUND: Previous studies have shown that resistance of Botrytis cinerea to QoI fungicides has been attributed to the G143A mutation in the cytochrome b (cytb) gene, while, in a part of the fungal population, an intron has been detected at codon 143 of the gene, preventing QoI resistance. During 2005–2009, 304 grey mould isolates were collected from strawberry, tomato, grape, kiwifruit, cucumber and apple in Greece and screened for resistance to pyraclostrobin and for the presence of the cytb intron, using a novel real‐time TaqMan PCR assay developed in the present study. RESULTS: QoI‐resistant phenotypes existed only within the population collected from strawberries. All resistant isolates possessed the G143A mutation. Differences were observed in the genotypic structure of cytb. Individuals possessing the intron were found at high incidence in apple fruit and greenhouse‐grown tomato and cucumber populations, whereas in the strawberry population the intron frequency was lower. Cultivation of QoI‐resistant and QoI‐sensitive isolates for ten culture cycles on artificial nutrient medium in the presence or absence of fungicide selection showed that QoI resistance was stable. CONCLUSIONS: The results of the study suggest that a high risk for selection of QoI‐resistant strains exists in crops heavily treated with QoIs, in spite of the widespread occurrence of the cytb intron in B. cinerea populations. The developed real‐time TaqMan PCR constitutes a powerful tool to streamline detection of the mutation by reducing pre‐ and post‐amplification manipulations, and can be used for rapid screening and quantification of QoI resistance. Copyright © 2011 Society of Chemical Industry  相似文献   

8.

A simple test based on the germination of conidia of Botrytis on agar media augmented with various fungicides has been developed. Average concentrations causing a 50% reduction of germ-tube growth (EC50) of highly sensitive isolates were determined on 1% malt extract agar (thiophanate-methyl 0.090 ppm; iprodione 0.566 ppm; fludioxonil 0.026 ppm; fenhexamid 0.144 ppm), 1% malt extract agar with 100 ppm salicyl hydroxamic acid (QoI fungicides, viz. trifloxystrobin 0.009 ppm; pyraclostrobin 0.013 ppm; azoxystrobin 0.087 ppm), 0.5% yeast extract agar (boscalid 0.069 ppm) and 0.5% sucrose agar (cyprodinil 0.053 ppm). In order to detect different levels of resistance against these various fungicides, two discriminatory concentrations were identified for each compound. A routine assay method was developed in which drops of a conidial suspension harvested directly from diseased plant material or sporulating cultures were incubated on each of 20 different agar media. Because of a very short time-span of 24–48 h between sample collection and evaluation of results, field-specific information on the occurrence, frequency and types of resistance of Botrytis against common botryticides in soft-fruit production may be generated prior to the main fungicide spray season at blossom time.

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9.
Botrytis cinerea is a complex species prone to fungicide resistance and characterized by enormous genetic diversity. During 2013, 220 B. cinerea isolates causing gray mold were collected from greenhouse-grown crops in the regions of Ammochostos, Larnaca, and Limassol (Cyprus). Sensitivities of the sampled populations to seven botryticides with different modes of action were screened in vitro. The results of this in vitro screening highlighted the widespread phenomenon of fungicide resistance in greenhouses, since only 8.6 % of the isolates were sensitive to all botryticides. Resistance to thiophanate-methyl was the most prevalent, with frequencies ranging from 53.8 % to 80 %. Similarly, high resistance frequencies were observed for pyraclostrobin (27.1 to 78.9 %) and boscalid (28.2 to 66.2 %). Multiple fungicide resistant phenotypes were predominant, covering 67.3 % of the population, with frequencies of 80.0, 37.5, 53.8, 83.1, and 60.2 % in cucumber, eggplant, green bean, strawberry, and tomato, respectively. No fludioxonil-resistant isolates were observed. Botrytis cinerea and Botrytis group S genotypes comprised the gray mold population. B. cinerea was predominant within cucumber, eggplant and strawberry, whereas both genotypes were in equilibrium in green bean and tomato. However, Botrytis group S was found in all hosts. B. cinerea was the most prevalent in the majority of fungicide resistance phenotypes from strawberry, while genotype distributions within tomato were generally more balanced. B. pseudocinerea was not detected in the sampled population. Overall, frequency of the mating type allele MAT1–1 was higher to MAT1–2, underlying their unequal distribution in the population. However, cases of 1:1 distribution were apparent within particular subpopulations, suggesting that mating in the field cannot be excluded.  相似文献   

10.
‘Long-canes’ which produce the first fruit crop within three months of being planted in spring are becoming the preferred raspberry nursery material in north-western Europe. However, infections of these canes by grey mould fungi (Botrytis spp.) are common. In a survey of Botrytis infections in 22 batches of long-cane plants from six different nurseries, high proportions of strains with resistance to fenhexamid (45.5 %), trifloxystrobin (87.3 %), boscalid (75.9 %), fludioxonil (35.0 %) and cyprodinil (46.4 %) were found. Further, 29.4 % of all strains harboured multiple resistance to all five of these fungicides. Fungicide-resistant strains increased in frequency during the first cropping season and were shown in one case to spread to an adjacent raspberry field within one season. Contaminated planting material may therefore compromise the long-term productivity of raspberry plantations.  相似文献   

11.
The plant‐pathogenic fungus Sclerotinia sclerotiorum has a broad host range and a worldwide distribution. Boscalid, an inhibitor of succinate dehydrogenase in the electron transport chain of fungi, is highly effective in controlling sclerotinia stem rot caused by S. sclerotiorum. The current study characterized the S. sclerotiorum boscalid‐resistant (BR) mutants obtained by fungicide induction. Among the bioactive fungicides against S. sclerotiorum, cross‐resistance was not detected between boscalid and dimethachlon, fluazinam or carbendazim; positive cross‐resistance was detected between boscalid and carboxin; and negative cross‐resistance was detected between boscalid and kresoxim‐methyl. Compared to their parental isolates, BR mutants had slower radial growth, no ability to produce sclerotia, lower virulence and oxalic acid content but higher mycelial respiration and succinate dehydrogenase (SDH) activity. Moreover, BR mutants had decreased sensitivity to salicylhydroxamic acid (SHAM) but not to oxidative stress. All the results indicated that the risk of resistance to boscalid in S. sclerotiorum is low to moderate. DNA sequence analysis showed that all of the BR mutants had the same point mutation A11V (GCA to GTA) in the iron sulphur protein subunit (SDHB). Interestingly, expression of the cytochrome b (cytb) gene was reduced to different degrees in the BR mutants, and this might be correlated with the negative cross‐resistance between boscalid and kresoxim‐methyl. Such information is vital in the design of resistance management strategies.  相似文献   

12.
Pristine® (pyraclostrobin + boscalid) is a fungicide registered for the control of alternaria late blight in pistachio. A total of 95 isolates of Alternaria alternata collected from orchards with and without a prior history of Pristine® sprays were tested for their sensitivity towards pyraclostrobin, boscalid and Pristine® in conidial germination assays. The EC50 values for 35 isolates from orchards without Pristine® sprays ranged from 0·09 to 3·14 µg mL?1 and < 0·01 to 2·04 µg mL?1 for boscalid and Pristine®, respectively. For pyraclostrobin, 27 isolates had EC50 < 0·01 µg mL?1 and six had low resistance (mean EC50 value = 4·71 µg mL?1). Only one isolate was resistant to all three fungicides tested, with EC50 > 100 µg mL?1. Among 59 isolates from the orchard with a history of Pristine® sprays, 56 were resistant to pyraclostrobin; only two were sensitive (EC50 < 0·01 µg mL?1) and one was weakly resistant (EC50 = 10 µg mL?1). For the majority of these isolates EC50 values ranged from 0·06 to 4·22 µg mL?1 for boscalid and from 0·22 to 7·74 µg mL?1 for Pristine®. However, seven isolates resistant to pyraclostrobin were also highly resistant to boscalid and Pristine® and remained pathogenic on pistachio treated with Pristine®. Whereas strobilurin resistance is a common occurrence in Alternaria of pistachio, this is the first report of resistance to boscalid in field isolates of phytopathogenic fungi. No cross resistance between pyraclostrobin and boscalid was detected, suggesting that Pristine® resistance appears as a case of multiple resistance.  相似文献   

13.
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.  相似文献   

14.
BACKGROUND: Fenhexamid, a sterol biosynthesis inhibitor effective against Botrytis, inhibits the 3‐ketoreductase (Erg27) involved in C‐4 demethylation. Several fenhexamid‐resistant phenotypes have been detected in Botrytis cinerea populations from French vineyards. The field isolates with the highest resistance levels display amino acid changes in Erg27 (F412S, F412I or F412V). RESULTS: Fenhexamid‐resistant mutants were generated by site‐directed mutagenesis of the erg27 gene in a sensitive recipient strain to overcome the impact of different genetic backgrounds. The wild‐type erg27 allele was replaced by the three mutated alleles (erg27F412S/I/V) by homologous recombination. These isogenic strains were shown to be fenhexamid‐resistant and were used to quantify the impact of F412 mutations on fungal fitness. Several parameters, including radial growth, the production of sclerotia and conidia, freezing resistance and aggressiveness, were quantified in laboratory conditions. Analysis of variance demonstrated significant differences between the mutant and parental strains for some characters. In particular, the mutants grew more slowly than the wild‐type strain and displayed variations in the production of sclerotia and conidia with temperature and susceptibility to freezing. CONCLUSIONS: The results highlight a moderate but significant impact of F412 mutations on the survival capacity of B. cinerea strains displaying high levels of resistance to fenhexamid in laboratory conditions, potentially limiting their dispersal and persistence, particularly in terms of overwintering, in field conditions. Copyright © 2011 Society of Chemical Industry  相似文献   

15.
Cercospora species cause cercospora leaf blight (CLB) and purple seed stain (PSS) on soybean. Because there are few resistant soybean varieties available, CLB/PSS management relies heavily upon fungicide applications. Sensitivity of 62 Argentinian Cercospora isolates to demethylation inhibitor (DMI), methyl benzimidazole carbamate (MBC), quinone outside inhibitor (QoI), succinate dehydrogenase inhibitor (SDHI) fungicides, and mancozeb was determined in this study. All isolates were sensitive to difenoconazole, epoxiconazole, prothioconazole, tebuconazole, and cyproconazole (EC50 values ranged from 0.006 to 2.4 µg/ml). In contrast, 51% of the tested isolates were sensitive (EC50 values ranged from 0.003 to 0.2 µg/ml), and 49% were highly resistant (EC50 > 100 µg/ml) to carbendazim. Interestingly, all isolates were completely resistant to azoxystrobin, trifloxystrobin, and pyraclostrobin, and insensitive to boscalid, fluxapyroxad, and pydiflumetofen (EC50 > 100 µg/ml). The G143A mutation was detected in 82% (53) of the QoI-resistant isolates and the E198A mutation in 97% (31) of the carbendazim-resistant isolates. No apparent resistance mutations were detected in the succinate dehydrogenase genes (subunits sdhB, sdhC, and sdhD). Mancozeb completely inhibited mycelial growth of the isolates evaluated at a concentration of 100 µg/ml. All Argentinian Cercospora isolates were sensitive to the DMI fungicides tested, but we report for the first time resistance to QoI and MBC fungicides. Mechanism(s) other than fungicide target-site modification may be responsible for resistance of Cercospora to QoI and MBC fungicides. Moreover, based on our results and on the recent introduction of SDHI fungicides on soybean in Argentina, Cercospora species causing CLB/PSS are insensitive (naturally resistant) to SDHI fungicides. Insensitivity must be confirmed under field conditions.  相似文献   

16.
Botrytis cinerea, which causes grey mould, is a major pathogen of many crops. On strawberry, isolates of Trichoderma spp. can effectively control B. cinerea, but frequent application is necessary. Bees can be used to disseminate biological control agents to the target crop. We tested the ability of honey bees to disseminate Trichoderma harzianum T39 to control B. cinerea in strawberry in the field during the winter in Israel over two consecutive seasons. We used the recently developed ‘Triwaks’ dispenser for loading the bees with the T. harzianum inoculum. During both years, grey mould developed in late January in untreated control plots; at low to medium disease levels it was partially controlled by fungicide treatment, and was best controlled in bee-visited plots. At high disease levels neither chemical nor biological control was effective. To assess the spatial distribution of inoculum by bees, we sampled flowers up to 200 m from the hives and found effective levels of T. harzianum even at 200 m. The approach used in this study provides an effective control of grey mould in strawberry in conditions of low to medium grey mould incidence.  相似文献   

17.
为评价38%唑醚·啶酰菌悬浮剂 (有效成分质量分数:12.8%吡唑醚菌酯,25.2%啶酰菌胺) 在农产品和环境中的安全性,于2015年和2016年在中国北京及山东分别进行了该药剂在草莓及土壤中的残留及消解动态试验,建立了同时测定草莓及土壤中吡唑醚菌酯和啶酰菌胺残留量的高效液相色谱-串联质谱 (HPLC-MS/MS) 检测方法。样品用乙腈提取,经N-丙基乙二胺 (PSA) 净化,电喷雾多反应监测模式HPLC-MS/MS检测,基质匹配标准曲线外标法定量。结果表明:在草莓和土壤中添加0.015~3.0 mg/kg吡唑醚菌酯,平均回收率分别为97%~107%和94%~106%,相对标准偏差 (RSD) 分别为1.8%~3.9%和2.2%~4.1%,定量限 (LOQ) 为0.015 mg/kg;添加0.03~6.0 mg/kg啶酰菌胺,平均回收率分别为90%~101%和92%~97%,RSD为4.6%~13%和2.9%~14%,LOQ为0.03 mg/kg。田间试验结果表明,吡唑醚菌酯和啶酰菌胺在草莓和土壤中的消解动态均符合一级动力学方程,在草莓中的半衰期分别为4.8~6.0 d和5.1~11 d,在土壤中为3.4~10.0和3.4~6.0 d。采用38% 唑醚·啶酰菌悬浮剂,分别按有效成分228和342 g/hm2于草莓幼果期施药,最多施药 4 次,采样时间距离最后一次施药的间隔时间为3、5、7 d。吡唑醚菌酯在草莓中的最大残留量为 0.13 mg/kg,低于欧盟规定的最大残留限量 (MRL)(0.5 mg/kg);啶酰菌胺在草莓中的最大残留量为 0.78 mg/kg,低于中国的 MRL值 (3.0 mg/kg)。建议38%唑醚·啶酰菌悬浮剂在草莓上的安全间隔期为3 d,试验结果为农药在草莓中的安全使用和农产品的食用安全提供了数据支持。  相似文献   

18.
BACKGROUND: Cercospora leaf spot (CLS), caused by the fungus Cercospora beticola, is the most serious foliar disease of sugar beet (Beta vulgaris L.) worldwide. Disease control is mainly achieved by timely fungicide applications. In 2011, CLS control failures were reported in spite of application of quinone outside inhibitor (QoI) fungicide in several counties in Michigan, United States. The purpose of this study was to confirm the resistant phenotype and identify the molecular basis for QoI resistance of Michigan C. beticola isolates. RESULTS: Isolates collected in Michigan in 1998 and 1999 that had no previous exposure to the QoI fungicides trifloxystrobin or pyraclostrobin exhibited QoI EC50 values of ?0.006 µg mL?1. In contrast, all isolates obtained in 2011 exhibited EC50 values of > 0.92 µg mL?1 to both fungicides and harbored a mutation in cytochrome b (cytb) that led to an amino acid exchange from glycine to alanine at position 143 (G143A) compared with baseline QoI‐sensitive isolates. Microsatellite analysis of the isolates suggested that QoI resistance emerged independently in multiple genotypic backgrounds at multiple locations. A real‐time PCR assay utilizing dual‐labeled fluorogenic probes was developed to detect and differentiate QoI‐resistant isolates harboring the G143A mutation from sensitive isolates. CONCLUSION: The G143A mutation in cytb is associated with QoI resistance in C. beticola. Accurate monitoring of this mutation will be essential for fungicide resistance management in this pathosystem. Copyright © 2012 Society of Chemical Industry  相似文献   

19.

Sensitivity and inherent resistance risk of Alternaria solani to fludioxonil, cross-resistance profiles and the potential implications of resistance mutations on fitness parameters were investigated. Fludioxonil was highly effective against a wild type A. solani field strain both in vitro (EC50?=?0.05 μg/mL) and in preventive applications on artificially inoculated tomato fruit. Mutants with low [Resistance factor (Rf): 15 based on EC50], medium (Rf: 150–300) and high (Rf: > 1000) levels of phenylpyrrole resistance were isolated from the wild type strain at high frequencies following mutagenesis with UV irradiation and selection on fludioxonil containing medium. Resistant isolates retained their resistance levels even after 9 subcultures on fungicide-free growth medium while they could express their resistant phenotypes in planta. Investigation of cross-resistance relationships showed that fludioxonil resistance mutations also reduce the sensitivity of mutant strains to the aromatic hydrocarbon fungicide quintozene as well as the dicarboximides iprodione and vinclozolin. No cross-resistance was observed between fludioxonil and fungicides with different modes of action such as the sterol biosynthesis inhibitors (DMIs) imazalil and flusilazole and the carboxamide boscalid. All fludioxonil resistant isolates were more sensitive to the anilinopyrimidine pyrimethanil, while only two isolates were less sensitive to the QoI pyraclostrobin compared to the wild-type strain. Study of fitness determining parameters showed that resistance mutation(s) had no adverse effects on mycelial growth, conidial germination and sensitivity to osmotic stress while they had a pleiotropic effect on virulence and conidia production in resistant mutants. Results of the present study indicate that fludioxonil is a highly effective fungicide against A. solani, while the risk of resistance development to this fungicide is considered to be medium making fludioxonil an ideal alternative to high risk fungicides such as boscalid and pyraclostrobin whose performance against early blight has already been compromised by resistance development.

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20.
Grey mould, caused by Botrytis cinerea, is a disease severely affecting grape production in northern Italy. However, little information is available on the variability of B. cinerea populations associated with grapevine. The mode of reproduction, sensitivity to fungicides, and for the first time in Italy, the genetic structure of B. cinerea populations isolated from grapevine in a northern Italian region are reported. Botrytis cinerea isolates (317) were completely genotyped for six microsatellite loci and characterized for the presence of the transposable elements Boty and Flipper, for the mating type and for resistance to cyprodinil, fludioxonil, boscalid and fenhexamid. All the isolates were found to belong to B. cinerea Group II, indicating the absence of B. pseudocinerea in the investigated areas. The populations possess a high genotypic diversity, different frequencies of transposable elements and a mixed mode of reproduction. At a regional level, B. cinerea populations belong to a large and interconnected pathogen population that includes the major grape‐growing districts. The populations were generally sensitive to fungicides, with a low proportion (8%) of isolates resistant to cyprodinil, fludioxonil and boscalid. A small genetic distance was found between B. cinerea populations. However, the populations geographically isolated from the others by a mountain range showed a small but statistically significant genetic differentiation and a different pattern of fungicide resistance. The results show that northern Italian B. cinerea populations possess a high evolutionary potential and adaptive capacity.  相似文献   

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