scholarly journals Detection and Molecular Characterization of Resistance to the Dicarboximide and Benzamide Fungicides in Botrytis cinerea From Tomato in Hubei Province, China

Plant Disease ◽  
2018 ◽  
Vol 102 (7) ◽  
pp. 1299-1306 ◽  
Author(s):  
M. Adnan ◽  
M. S. Hamada ◽  
G. Q. Li ◽  
C. X. Luo
Keyword(s):  
Botrytis Cinerea ◽  
Management Strategies ◽  
Resistance Management ◽  
Point Mutations ◽  
Hubei Province ◽  
Cross Resistance ◽  
Resistance Development ◽  
Fitness Parameters ◽  
The Mean

Altogether, 192 Botrytis cinerea isolates collected from tomato greenhouses at different locations in Hubei Province were evaluated for their sensitivity to fungicides procymidone and zoxamide. The mean effective concentration to cause 50% growth inhibition (EC50) values of procymidone for sensitive and resistant isolates were 0.25 and 3.60 μg/ml, respectively. The frequency of procymidone-resistant (ProR) isolates was 18%, and the highest frequency was recorded in Jingmen. Positive cross-resistance was observed for ProR isolates to other dicarboximide fungicides but not to phenylpyrroles. Significant differences were observed for fitness parameters (i.e., mycelial growth, osmotic sensitivity, and virulence between sensitive and resistant isolates). Amino acid sequence of the Bos1 gene revealed that ProR isolates carried either point mutations at codon 365 (I365S) or a pair of point mutations at codons 369 (Q369P) and 373 (N373S). For zoxamide, the mean EC50 values for sensitive and resistant isolates were 0.22 and 5.32 μg/ml, respectively. Approximately 14% of the isolates were found to be resistant to zoxamide, and the highest frequency of resistance was also observed in Jingmen. There was positive cross-resistance for zoxamide-resistant (ZoxR) isolates to carbendazim. No significant differences were observed for fitness parameters between zoxamide-sensitive and ZoxR isolates. Sequence analysis of the β-tubulin gene of Botrytis cinerea revealed two previously reported point mutations (E198A and E198K) and one new point mutation (T351I). This new mutation was detected in only those isolates which possessed the E198K but not E198A substitution. This study allows for a better understanding of the resistance development profile in Hubei Province. Results will be useful for the improvement of fungicide resistance management strategies.

scholarly journals Point Mutations in the β-Tubulin of Phytophthora sojae Confer Resistance to Ethaboxam

2019 ◽  
Vol 109 (12) ◽  
pp. 2096-2106 ◽  
Author(s):  
Qin Peng ◽  
Zhiwen Wang ◽  
Yuan Fang ◽  
Weizhen Wang ◽  
Xingkai Cheng ◽  
...  
Keyword(s):  
Fungicide Resistance ◽  
Germination Rate ◽  
Management Strategies ◽  
Resistance Management ◽  
Point Mutations ◽  
Phytophthora Sojae ◽  
Cross Resistance ◽  
Baseline Sensitivity ◽  
Resistant Mutants ◽  
Β Tubulin

Ethaboxam is a β-tubulin inhibitor registered for the control of oomycete pathogens. The current study was established to determine the ethaboxam sensitivity of the plant pathogen Phytophthora sojae and investigate the potential for the emergence of fungicide resistance. The effective concentration for 50% inhibition (EC50) of 112 Phytophthora sojae isolates exhibited a unimodal distribution with a mean EC50 for ethaboxam of 0.033 µg/ml. Establishing this baseline sensitivity provided critical data for monitoring changes in ethaboxam-sensitivity in field populations. The potential for fungicide resistance was investigated using adaptation on ethaboxam-amended V8 agar, which resulted in the isolation of 20 resistant mutants. An assessment of the biological characteristics of the mutants including mycelial growth, sporulation, germination rate and pathogenicity indicated that the resistance risk in Phytophthora sojae was low to medium with no cross-resistance between ethaboxam and cymoxanil, metalaxyl, flumorph, and oxathiapiprolin being detected. However, positive cross-resistance was found between ethaboxam and zoxamide for Q8L and I258V but negative cross-resistance for C165Y. Further investigation revealed that the ethaboxam-resistant mutants had point mutations at amino acids Q8L, C165Y, or I258V of their β-tubulin protein sequences. CRISPR/Cas9-mediated transformation experiments confirmed that the Q8L, C165Y, or I258V mutations could confer ethaboxam resistance in Phytophthora sojae and that the C165Y mutation induces high levels of resistance. Taken together, the results of the study provide essential data for monitoring the emergence of resistance and resistance management strategies for ethaboxam, as well as for improving the design of novel β-tubulin inhibitors for future development.

Sensitivity of C. fructicola and C. siamense of peach in China to multiple classes of fungicides and characterization of pyraclostrobin-resistant isolates

Plant Disease ◽  
2021 ◽  
Author(s):  
Hafiz Muhammad Usman ◽  
Qin Tan ◽  
Mohammad Mazharul Karim ◽  
Muhammad Adnan ◽  
Weixiao Yin ◽  
...  
Keyword(s):  
High Resistance ◽  
Mycelial Growth ◽  
Management Strategies ◽  
Cross Resistance ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Dmi Fungicides ◽  
Colletotrichum Gloeosporioides Species Complex ◽  
Cyt B Gene

Anthracnose, mainly caused by Colletotrichum gloeosporioides species complex including C. fructicola and C. siamense, is a devastating disease of peach. The chemical control has been widely used for years and management failures have increased towards commonly used fungicides. Therefore, screening of sensitivity of Colletotrichum spp. to fungicides with different modes of action is needed to make proper management strategies for peach anthracnose. In this study, sensitivity of 80 isolates of C. fructicola and C. siamense was screened for pyraclostrobin, procymidone, prochloraz and fludioxonil based on mycelial growth inhibition at discriminatory doses. Results showed that C. fructicola and C. siamense isolates were highly resistant to procymidone and fludioxonil with 100% resistance frequencies to both fungicides, but sensitive to prochloraz, i.e., no resistant isolates were found. For pyraclostrobin, 74% of C. fructicola isolates showed high resistance and 26 % were low resistant, all of the C. siamense isolates were low resistant. No positive cross-resistance was observed between pyraclostrobin and azoxystrobin, even they are members of the same quinone outside inhibitor (QoI) fungicide group, and between pyraclostrobin and non-QoIs. Resistant isolates to QoI fungicides were evaluated for the fitness penalty. Results showed that no significant differences except for mycelial growth rates were detected between highly resistant and low-resistant isolates of C. fructicola. Molecular characterization of Cyt b gene revealed that the G143A point mutation was the determinant of the high resistance in C. fructicola. This study demonstrated the current resistance status of C. fructicola and C. siamense to different fungicides and their future perspectives. Demethylation inhibitor (DMI) fungicides are the best option among different chemicals to control peach anthracnose in China.

scholarly journals Fungicide resistance characterised across seven chemical classes in a Botrytis cinerea population isolated from Australian vineyards

2021 ◽  
Author(s):  
Lincoln A. Harper ◽  
Scott Paton ◽  
Barbara Hall ◽  
Suzanne McKay ◽  
Richard P. Oliver ◽  
...  
Keyword(s):  
Adverse Effect ◽  
Botrytis Cinerea ◽  
Fungicide Resistance ◽  
Chemical Control ◽  
Management Strategies ◽  
Resistance Management ◽  
Gray Mold ◽  
Chemical Groups ◽  
Important Disease ◽  
Selection Of

AbstractGray mold, caused by Botrytis cinerea, is an economically important disease of grapes in Australia and across grape growing regions worldwide. Control of this disease relies heavily on canopy management and the application of single site fungicides. Fungicide application can lead to the selection of fungicide resistant B. cinerea populations, which has an adverse effect on the chemical control of the disease. Characterising the distribution and severity of resistant B. cinerea populations is needed to inform resistance management strategies. In this study, 725 isolates were sampled from 75 Australian vineyards during 2013 – 2016 and were screened against seven fungicides with different MOAs. The resistance frequencies for azoxystrobin, boscalid, fenhexamid, fludioxonil, iprodione, pyrimethanil and tebuconazole were 5, 2.8, 2.1, 6.2, 11.6, 7.7 and 2.9% respectively. Nearly half of the resistant isolates (43.7%) were resistant to more than one of the fungicides tested. The frequency of vineyards with at least one isolate simultaneously resistant to 1, 2, 3, 4 or 5 fungicides was 19.5, 7.8, 6.5, 10.4 and 2.6%.Resistance was associated with previously published genotypes in CytB (G143A), SdhB (H272R/Y), Erg27 (F412S), Mrr1 (D354Y), Os1 (I365S, N373S + Q369P, I365S + D757N) and Pos5 (P319A, L412F). Expression analysis was used to characterise fludioxonil resistant isolates exhibiting overexpression (6.3 - 9.6-fold) of the ABC transporter encoded by AtrB (MDR1 phenotype). Novel genotypes were also described in Mrr1 (S611N, D616G) and Cyp51 (P357S). Resistance frequencies were lower when compared to most previously published surveys of both grape and non-grape B. cinerea resistance. Nonetheless, continued monitoring of critical chemical groups used in Australian vineyards is recommended.

scholarly journals Resistance to Fluopyram, Fluxapyroxad, and Penthiopyrad in Botrytis cinerea from Strawberry

Plant Disease ◽  
2014 ◽  
Vol 98 (4) ◽  
pp. 532-539 ◽  
Author(s):  
Achour Amiri ◽  
Stacy M. Heath ◽  
Natalia A. Peres
Keyword(s):  
Succinate Dehydrogenase ◽  
Botrytis Cinerea ◽  
High Resistance ◽  
Gray Mold ◽  
Cross Resistance ◽  
The Novel ◽  
Resistance Development ◽  
Dehydrogenase Gene ◽  
Resistance Patterns ◽  
Subunit B

Succinate dehydrogenase inhibitors (SDHIs) constitute a mainstay in management of gray mold caused by Botrytis cinerea in strawberry and several other crops. In this study, we investigated the risks of resistance development to three newer SDHIs (i.e., fluopyram, fluxapyroxad, and penthiopyrad) and their cross-resistance with the previously registered boscalid. We investigated the mutations in the SdhB subunit and evaluated their impact on microbial fitness in field populations of B. cinerea. Amino acid substitutions associated with resistance to SDHIs were detected at three codons of the SdhB subunit (BH272R/Y/L, BP225F, and BN230I) in the succinate dehydrogenase gene of field isolates from Florida. The BH272R, BH272Y, BH272L, BP225F, and BN230I mutations were detected at frequencies of 51.5, 28.0, 0.5, 2.5, and 4%, respectively. Strong cross-resistance patterns were evident between boscalid and fluxapyroxad and penthiopyrad but not with fluopyram, except in BH272L, BP225F, and BN230I mutants. All five mutations conferred moderate to very high resistance to boscalid whereas the BH272Y conferred resistance to fluxapyroxad and penthiopyrad. The BH272L, BN230I, and BP225F mutations conferred high resistance to all four SDHIs tested. Resistance monitoring following the first use of penthiopyrad in strawberry fields in Florida in 2013 suggests potential for quick selection for highly resistant populations and warrants careful use of the newer SDHIs. No evidence of major fitness costs due to the mutations in the SdhB subunit was found, which indicates the potential ability of the mutants to survive and compete with wild-type isolates. Our study suggests high risks for rapid widespread occurrence of B. cinerea populations resistant to the novel SDHIs unless appropriate rotation strategies are implemented immediately upon registration.

Resistance to boscalid in Botrytis cinerea from greenhouse grown tomato

Plant Disease ◽  
2020 ◽  
Author(s):  
Shengming Liu ◽  
Liuyuan Fu ◽  
Huanhuan Tan ◽  
Jia Jiang ◽  
Zhiping Che ◽  
...  
Keyword(s):  
Succinate Dehydrogenase ◽  
Botrytis Cinerea ◽  
Mycelial Growth ◽  
Point Mutations ◽  
Dry Weight ◽  
Henan Province ◽  
Cross Resistance ◽  
Tomato Production ◽  
Grey Mold ◽  
Moderately Resistant

Grey mold, caused by the fungus Botrytis cinerea Pers ex Fr., is one of the most destructive spoilage diseases, severely affecting tomato production in Henan Province, China. Spraying fungicides from the flowering to the harvest stage is a necessary measure to reduce losses associated with B. cinerea infection. However, B. cinerea has developed resistance to fungicides in many countries. Boscalid is a succinate dehydrogenase inhibitor (SDHI) fungicide, and was registered for the control of grey mold. In this study, a total of 269 B. cinerea isolates were collected from tomato in commercial greenhouses in different locations of Henan Province, in 2014 and 2015. The sensitivity and resistance of B. cinerea field isolates were determined based on mycelial growth. The effective concentration 50 (EC50) ranged from 0.11 to 15.92 μg ml−1 and 0.16 to 8.54 μg ml−1, in 2014 and 2015, respectively. The frequency of low resistance to boscalid was 12.6% and 7.6%, and moderate resistance were 2.7% and 1.3%, in 2014 and 2015, respectively. No high-resistant isolates were found in Henan Province, China. Mycelial growth, mycelial dry weight, spore production, and pathogenicity were not significantly different between resistant and sensitive phenotypes of the B. cinerea isolates. The results of cross-resistance test showed no correlation between boscalid and carbendazim, procymidone, pyrimethanil, fluazinam or fluopyram. In this study, the succinate dehydrogenase gene B (sdhB), C (sdhC), and D (sdhD) were analyzed and compared in sensitive, low and moderately resistant B. cinerea isolates to boscalid. Results showed point mutations occurred simultaneously at sdhC amino acid positions 85 (G85A), 93 (I93V), 158 (M158V), and 168 (V168I) in 4 out of 10 sensitive isolates, 23 out of 26 low and 5 out of 5 moderately resistant B. cinerea isolates to boscalid. No point mutations were found in the sdhB and sdhD genes of all isolates. Furthermore, no point mutations were found in sdhB, sdhC and sdhD genes in 3 out of 26 low resistant B. cinerea isolates to boscalid. Therefore, we speculate the simultaneous point mutations in the sdhC gene may not be related to the resistance of B. cinerea to boscalid. These results suggested that there might be a substitution mechanism for the resistance of B. cinerea to the SDHI fungicide boscalid.

scholarly journals Extent of Variation of the Bacillus thuringiensis Toxin Reservoir: the Case of the Geranium Bronze, Cacyreus marshalli Butler (Lepidoptera: Lycaenidae)

2002 ◽  
Vol 68 (8) ◽  
pp. 4090-4094 ◽  
Author(s):  
Salvador Herrero ◽  
Marisé Borja ◽  
Juan Ferré
Keyword(s):  
Bacillus Thuringiensis ◽  
Binding Site ◽  
Management Strategies ◽  
Resistance Management ◽  
Cross Resistance ◽  
Binding Studies ◽  
Cry Proteins ◽  
Combined Use ◽  
The Common

ABSTRACT Despite the fact that around 200 cry genes from Bacillus thuringiensis have already been cloned, only a few Cry proteins are toxic towards a given pest. A crucial step in the mode of action of Cry proteins is binding to specific sites in the midgut of susceptible insects. Binding studies in insects that have developed cross-resistance discourage the combined use of Cry proteins sharing the same binding site. If resistance management strategies are to be implemented, the arsenal of Cry proteins suitable to control a given pest may be not so vast as it might seem at first. The present study evaluates the potential of B. thuringiensis for the control of a new pest, the geranium bronze (Cacyreus marshalli Butler), a butterfly that is threatening the popularity of geraniums in Spain. Eleven of the most common Cry proteins from the three lepidopteran-active Cry families (Cry1, Cry2, and Cry9) were tested against the geranium bronze for their toxicity and binding site relationships. Using 125I-labeled Cry1A proteins we found that, of the seven most active Cry proteins, six competed for binding to the same site. For the long-term control of the geranium bronze with B. thuringiensis-based insecticides it would be advisable to combine any of the Cry proteins sharing the binding site (preferably Cry1Ab, since it is the most toxic) with those not competing for the same site. Cry1Ba would be the best choice of these proteins, since it is significantly more toxic than the others not binding to the common site.

scholarly journals Bacillus thuringiensis Vip3Aa Toxin Resistance in Heliothis virescens (Lepidoptera: Noctuidae)

2017 ◽  
Vol 83 (9) ◽  
Author(s):  
Brian R. Pickett ◽  
Asim Gulzar ◽  
Juan Ferré ◽  
Denis J. Wright
Keyword(s):  
Bacillus Thuringiensis ◽  
Heliothis Virescens ◽  
Insect Pests ◽  
Management Strategies ◽  
Resistance Management ◽  
Cross Resistance ◽  
Inheritance Of Resistance ◽  
Resistant Parent ◽  
Bt Crops ◽  
Content Type

ABSTRACT Laboratory selection with Vip3Aa of a field-derived population of Heliothis virescens produced >2,040-fold resistance in 12 generations of selection. The Vip3Aa-selected (Vip-Sel)-resistant population showed little cross-resistance to Cry1Ab and no cross-resistance to Cry1Ac. Resistance was unstable after 15 generations without exposure to the toxin. F1 reciprocal crosses between Vip3Aa-unselected (Vip-Unsel) and Vip-Sel insects indicated a strong paternal influence on the inheritance of resistance. Resistance ranged from almost completely recessive (mean degree of dominance [h] = 0.04 if the resistant parent was female) to incompletely dominant (mean h = 0.53 if the resistant parent was male). Results from bioassays on the offspring from backcrosses of the F1 progeny with Vip-Sel insects indicated that resistance was due to more than one locus. The results described in this article provide useful information for the insecticide resistance management strategies designed to overcome the evolution of resistance to Vip3Aa in insect pests. IMPORTANCE Heliothis virescens is an important pest that has the ability to feed on many plant species. The extensive use of Bacillus thuringiensis (Bt) crops or spray has already led to the evolution of insect resistance in the field for some species of Lepidoptera and Coleoptera. The development of resistance in insect pests is the main threat to Bt crops. The effective resistance management strategies are very important to prolong the life of Bt plants. Lab selection is the key step to test the assumption and predictions of management strategies prior to field evaluation. Resistant insects offer useful information to determine the inheritance of resistance and the frequency of resistance alleles and to study the mechanism of resistance to insecticides.

scholarly journals Multiple Fungicide Resistance in Botrytis cinerea from Greenhouse Strawberries in Hubei Province, China

Plant Disease ◽  
2017 ◽  
Vol 101 (4) ◽  
pp. 601-606 ◽  
Author(s):  
F. Fan ◽  
M. S. Hamada ◽  
N. Li ◽  
G. Q. Li ◽  
C. X. Luo
Keyword(s):  
Botrytis Cinerea ◽  
Management Strategies ◽  
Hubei Province ◽  
Early Summer ◽  
Initial Generation ◽  
Succinate Dehydrogenase Subunit B ◽  
The Stability ◽  
First Time

Two hundred and forty isolates of Botrytis cinerea were collected during the early summer of 2012 and 2013 from strawberry greenhouses in 10 locations in Hubei Province and examined for sensitivity to five fungicides, most of which were commonly used to control this fungus. High frequency of resistance to carbendazim (Car, 63.63%) and cyprodinil (Cyp, 42.42%) was detected. Boscalid-resistant (BosR) isolates were detected for the first time in China, whereas no fludioxonil-resistant isolates were identified. Dual resistance to carbendazim and diethofencarb (Die) was also detected. There were six phenotypes of resistance profile (i.e., CarRDieSBosSCypS, CarRDieRBosSCypS, CarRDieSBosSCypR, CarRDieSBosRCypS, CarRDieRBosSCypR, and CarRDieSBosRCypR). CarRDieSBosSCypS and CarRDieSBosSCypR were the most common phenotypes, occurring at eight and seven locations, respectively. After 10 successive transfers on fungicide-free potato dextrose agar, tested resistant isolates retained levels of resistance similar to or comparative with the initial generation, indicating the stability of these resistances. Fitness evaluations based on investigation of mycelial growth, osmotic sensitivity, sporulation in vitro and in vivo, and virulence revealed the uncompromising fitness in resistant isolates, except that decreased virulence was observed in BosR isolates. The molecular basis of carbendazim, diethofencarb, and boscalid resistance was investigated. Results showed that all 13 sequenced carbendazim-resistant isolates harbored the mutation E198V or E198A in the β-tubulin gene and the five isolates with dual resistance to carbendazim and diethofencarb showed the mutation E198K in the same gene. BosR isolates possessed the H272R mutation in succinate dehydrogenase subunit B gene. The results achieved in this study challenge the current management strategies for B. cinerea, which largely depend on applications of these fungicides.

scholarly journals Baseline Sensitivity and Toxic Action of the Sterol Demethylation Inhibitor Flusilazole Against Botrytis cinerea

Plant Disease ◽  
2020 ◽  
Vol 104 (11) ◽  
pp. 2986-2993
Author(s):  
Yong Wang ◽  
Miaomaio Wang ◽  
Letian Xu ◽  
Yang Sun ◽  
Juntao Feng
Keyword(s):  
Botrytis Cinerea ◽  
Plant Pathogens ◽  
Resistance Mechanism ◽  
Point Mutations ◽  
Gray Mold ◽  
Shaanxi Province ◽  
Cross Resistance ◽  
Baseline Sensitivity ◽  
Single Spore ◽  
Demethylation Inhibitor

In the present study, a total of 95 Botrytis cinerea single-spore strains collected from different hosts in Shaanxi Province of China were characterized for their sensitivity to the sterol demethylation inhibitor fungicide flusilazole. The effective concentration for 50% inhibition of mycelial growth (EC50) of flusilazole ranged from 0.021 to 0.372 µg/ml, with an average value of 0.093 µg/ml. Cross-resistance between flusilazole and commonly used fungicides was not detected, and no flusilazole-resistant mutants were induced. Both on detached strawberry leaves and in greenhouse experiments, flusilazole was more effective than the commonly used fungicide carbendazim at reducing gray mold. After culture on PDA plates or detached strawberry leaves, no difference in sclerotia production or pathogenicity was detected between two strains, WG12 (most sensitive to flusilazole) and MX18 (least sensitive to flusilazole). After treatment with flusilazole, however, the two strains lost the ability to produce sclerotia, and oxalic acid and ergosterol contents in mycelium decreased. Interestingly, the inhibition rate of ergosterol content in MX18 was significantly lower than that in WG12. Expression of Cyp51, BcatrD, and Bcmfs1 genes all increased after treatment with flusilazole, especially the Cyp51 and BcatrD genes. However, the expression of Cyp51 gene or BcatrD gene in WG12 and MX18 were significantly different from each other after treatment with flusilazole. In addition, no point mutations in Cyp51 gene were found in MX18. These data suggest flusilazole is a promising fungicide for resistance management of gray mold and also provided novel insights into understanding the resistance mechanism of flusilazole against plant pathogens.

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