Phenotypic and molecular characterization of the resistance to azoxystrobin and pyraclostrobin in Fusarium graminearum populations from Brazil

Phenotypic and molecular characterization of the resistance to azoxystrobin and pyraclostrobin in Fusarium graminearum populations from Brazil

Wheat farmers rely on fungicides to protect fields against several foliar and flowering diseases, including Fusarium head blight (FHB). A range of active ingredients is used in isolation or in dual premixes that include a dimethylation inhibitor (DMI) or a quinone outside inhibitor (QoI) fungicide....

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Bibliographic Details
Published in:Plant pathology Vol. 71; no. 5; pp. 1152 - 1163
Main Authors: Andrade, Sheila M. P., Augusti, Guilherme R., Paiva, Gabriel F., Feksa, Heraldo R., Tessmann, Dauri J., Machado, Franklin J., Mizubuti, Eduardo S. G., Del Ponte, Emerson M.
Format: Journal Article
Language:English
Published: Oxford Wiley Subscription Services, Inc 01-06-2022
Subjects:
Azoxystrobin
Blight
Flowering
Fungicides
Fusarium graminearum
Fusarium head blight
Germination
Gibberella zeae
Inhibitors
Methylation
Mutation
Point mutation
Population
Quinones
strobilurin
Triticum aestivum
Brazil
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Summary:Wheat farmers rely on fungicides to protect fields against several foliar and flowering diseases, including Fusarium head blight (FHB). A range of active ingredients is used in isolation or in dual premixes that include a dimethylation inhibitor (DMI) or a quinone outside inhibitor (QoI) fungicide. Comprehensive information about fungicide resistance in F. graminearum is available for DMIs, while for QoIs the data are scarce. We characterized 225 strains obtained from two states in southern Brazil, Rio Grande do Sul (RS) and Paraná (PR), in relation to their response to two QoIs. The median EC50 (effective concentration leading to 50% inhibition of conidial germination) value for azoxystrobin (n = 25 isolates) was 2.20 μg/ml in the PR population and 4.04 μg/ml in the RS population. For pyraclostrobin (n = 50), the median EC50 was 0.28 μg/ml in the PR population and 0.24 μg/ml in the RS population. Evidence of cross‐resistance could not be detected. Screening using a discriminatory dose (DD) for azoxystrobin in a larger number of isolates from PR (n = 75) and RS (n = 100) states allowed the detection of 50% and 28% sensitive strains, respectively. Using the DD for pyraclostrobin, 33% and 18.8% were classified as less sensitive in the PR and RS isolates, respectively. In RS, the frequency of less‐sensitive isolates increased over time (2007–2011). No point mutation at any of the target spots (F129L, G137R, G143A) was detected. Our results represent an important step towards the establishment of a sensitivity profile for two of the most commonly used QoIs in commercial premixes targeting FHB control. This is the first establishment of a sensitivity profile for two most commonly used QoIs in commercial premixes targeting FHB control. No point mutation at any of the known target spots was detected.
ISSN:0032-0862
1365-3059
DOI:10.1111/ppa.13535