Characterization and sensitivity of Botrytis cinerea to benzimidazole and succinate dehydrogenase inhibitors fungicides, and illustration of the resistance profile

Author(s):  
Muhammad Imran ◽  
Esmat F. Ali ◽  
Sabry Hassan ◽  
Kamal A. M. Abo-Elyousr ◽  
Nashwa MA. Sallam ◽  
...  
2020 ◽  
Vol 110 (2) ◽  
pp. 327-335
Author(s):  
Achour Amiri ◽  
Adrian I. Zuniga ◽  
Natalia A. Peres

Succinate dehydrogenase inhibitors (SDHIs) are an essential group of fungicides for managing gray mold, caused by Botrytis cinerea, in numerous crops. Resistance to boscalid, an early-generation SDHI, is widespread worldwide and was linked to mutations in the iron-sulfur protein encoding the SdhB subunit of the SDH complex. Herein, we report on four simultaneous dependent mutations at codons 85 (G85A), 93 (I93V), 158 (M158V), and 168 (V168I) of the membrane-anchored SdhC subunit of B. cinerea. Isolates without and with mutations in SdhC were referred to as C− and C+ genotypes, respectively. The C+ genotype was found in all the five surveyed hosts from different U.S. regions but its frequency was higher, 25 to 40%, in the tree fruit isolates compared with 12 to 25% in the small fruit populations. The four SdhC mutations were found in isolates without mutations in SdhB or with mutations known to confer resistance to the SDHIs in SdhB. However, the frequency of C+ isolates was significantly higher in the SdhB wild-type isolates, which suggests that SDHI sprays may have played a role in selecting for the C− over the C+ genotype. Field C+ isolates exhibited reduced sensitivity to fluopyram and increased sensitivity to boscalid and penthiopyrad in vitro and on detached fruit. Homology modeling confirmed the positioning of the four mutations in the ubiquinone-binding pocket. The SdhCG85A is found in the proximal ubiquinone binding site and SdhCM158V is positioned in the iron sulfur protein interface next to the [3Fe-4S] cluster, whereas SdhCI93V is positioned next to the heme b with vital functions in the SDH enzyme. Beside the differential sensitivity to the SDHIs, these mutations caused a significant fitness cost in the C+ isolates including sporulation and increased sensitivity to reactive oxygen species. The presence of Botrytis populations differentially sensitive to the SDHIs suggests increased risks for resistance development but also opens up new perspective for future gray mold management using different SDHI fungicides.


2021 ◽  
Vol 69 (13) ◽  
pp. 3965-3971
Author(s):  
Ge Wei ◽  
Ming-Wei Huang ◽  
Wen-Jie Wang ◽  
Yuan Wu ◽  
Shu-Fen Mei ◽  
...  

Author(s):  
Thomas Assinger ◽  
Stefano F. F. Torriani ◽  
Salvatore Accardo ◽  
James Fountaine ◽  
Siegrid Steinkellner

AbstractRamularia collo-cygni B. Sutton and J.M. Waller is a major disease in Austrian barley-growing regions. To date, fungicide application is the most effective method to manage the disease; however, fungicide resistance to demethylation and succinate dehydrogenase inhibitors has developed over the last few years. In the growing seasons 2016/2017 and 2017/2018, field trials were carried out to analyze the efficiency of fungicide strategies based on different fungicide classes. Disease development, growth parameters and monitoring of CYP51 and sdh mutations were determined. Fungicide treatments resulted in higher disease control, green leaf area and grain yield. In Austrian R. collo-cygni field populations, the frequency of the mutations CYP51-I325T and CYP51-I328L was low to moderate. Frequency of mutations sdhC-H146R and sdhC-H153R was low. Frequencies of CYP51-I325T and -I328L were similar and increased following DMI application. Frequency of sdhC-H146R was higher compared to sdhC-H153R. The SDHI benzovindiflupyr showed a higher selection rate for sdh mutations compared to bixafen. These sdh mutations were not selected if chlorothalonil was used as mixing partner, leading to a stable composition of sdh resistance alleles over the last two years. Chlorothalonil was proven to be an effective tool for anti-resistance strategies. Currently, SDHIs and DMIs are the backbone of Ramularia leaf spot control in Austria; however, the level of resistance is likely to increase in absence of suitable anti-resistance strategies and following the ban of chlorothalonil.


Plant Disease ◽  
2015 ◽  
Vol 99 (2) ◽  
pp. 240-248 ◽  
Author(s):  
Sotirios Konstantinou ◽  
Thomas Veloukas ◽  
Michaela Leroch ◽  
George Menexes ◽  
Matthias Hahn ◽  
...  

Botrytis cinerea is a pathogen with high genetic variability that has also shown high risk for fungicide resistance development. In total, 1,169 isolates obtained from strawberry (n = 297) and tomato (n = 872) in five geographic regions of Greece were tested for their sensitivity to several botryticides. A high frequency of isolates with multiple resistance to carbendazim, cyprodinil, pyraclostrobin, and boscalid was found in isolates from strawberry. In the isolates from tomato, the predominant phenotype was that of dual resistance to carbendazim and cyprodinil in the Crete island, of single resistance to carbendazim in the region of Preveza, and of sensitive isolates in the region of Kyparissia. None of the tested isolates was found to be fludioxonil resistant. High frequencies of boscalid-resistant phenotypes were observed in the strawberry isolates, while boscalid-resistance frequency in the tomato isolates was lower. H272R was the predominant sdhB mutation, associated with resistance to boscalid, in all the sampled isolates, while other sdhB mutations were found at low frequencies. B. cinerea group S, identified by the presence of a 21-bp insertion in the transcription factor mrr1 gene, was predominant within the tomato isolates obtained from all three sampled regions, with frequencies ranging from 62 to 75% of the isolates; whereas, within strawberry isolates, B. cinerea was predominant, with frequencies of 75 to 95%. Correlations of isolate genotype and fungicide resistance profile showed that B. cinerea sensu stricto isolates were more prone to the development of resistance to boscalid compared with the Botrytis group S isolates, which may explain the observed predominance of B. cinerea sensu stricto in strawberry fields.


Author(s):  
Daniel Stierli ◽  
Hans Ulrich Haas ◽  
Ramya Rajan ◽  
Dave Bartlett ◽  
Helge Sierotzki ◽  
...  

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