The G143A Mutation is Responsible for Strobilurin Fungicide Resistance in Cercospora cf. flagellaris, a Leaf Blight and Purple Seed Stain Pathogen of Louisiana Soybean

2016 ◽  
Vol 17 (3) ◽  
pp. 197-197 ◽  
Author(s):  
Sebastian Albu ◽  
Trey Price ◽  
Vinson Doyle ◽  
Boyd Padgett ◽  
Ray Schneider
Keyword(s):  
Cytochrome B ◽  
Mississippi River ◽  
Fungicide Resistance ◽  
Radial Growth ◽  
Leaf Blight ◽  
Cytochrome B Gene ◽  
Pathogen Population ◽  
Lower Mississippi River ◽  
Strobilurin Fungicide ◽  
Purple Seed Stain

Cercospora leaf blight and purple seed stain are economically important diseases of soybean throughout the Lower Mississippi River Valley and Gulf South USA. Fungicide resistance was documented in Louisiana in the pathogen population using radial growth assays. Using some of the same isolates, a portion of the cytochrome b gene was sequenced. The G143A mutation was found in resistant isolates, and results correlated with radial growth assays 97% of the time. Accepted for publication 1 September 2016.

scholarly journals Fungicide Resistance in Cercospora kikuchii, a Soybean Pathogen

Plant Disease ◽  
2015 ◽  
Vol 99 (11) ◽  
pp. 1596-1603 ◽  
Author(s):  
Paul P. Price ◽  
Myra A. Purvis ◽  
Guohong Cai ◽  
Guy B. Padgett ◽  
Clark L. Robertson ◽  
...  
Keyword(s):  
Fungicide Resistance ◽  
Radial Growth ◽  
Management Strategies ◽  
Leaf Blight ◽  
Cross Resistance ◽  
Multiple Resistance ◽  
Cercospora Kikuchii ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Purple Seed Stain

Isolates of Cercospora kikuchii, a soybean (Glycine max) pathogen causing Cercospora leaf blight and purple seed stain, were tested to determine baseline sensitivities (n = 50) to selected quinone outside inhibitor (QoI) fungicides by conducting radial growth assays on fungicide-amended media. Baseline effective fungicide concentration to inhibit 50% of fungal radial growth (EC50) values were compared with EC50 values for isolates collected in 2011 (n = 50), 2012 (n = 50), and 2013 (n = 36) throughout soybean-producing areas in Louisiana. Median EC50 values for isolates subjected to QoI fungicides were significantly (P = 0.05) higher across all 3 years. Cross-resistance to QoI fungicides was observed in resistant isolates collected in 2011 to 2013. Discriminatory doses were developed for QoI fungicides to distinguish between sensitive and resistant isolates. On average, 89% of all isolates screened in 2011 to 2013 were resistant to QoI fungicides. At a discriminatory dose of thiophanate methyl (TM), a methyl benzimidazole carbamate (MBC) fungicide, at 5 μg/ml, resistance was detected in the 2000, 2011, 2012, and 2013 collections at 23, 38, 29, and 36%, respectively. Isolates exhibiting multiple resistance to QoI fungicides and TM also were detected in 2011, 2012, and 2013 at frequencies of 34, 26, and 31%, respectively. Based on these results, Cercospora leaf blight management strategies in Louisiana using solo applications of QoI or MBC fungicides in soybean should be reconsidered.

scholarly journals Characterization of Quinone Outside Inhibitor Fungicide Resistance in Cercospora sojina and Development of Diagnostic Tools for its Identification

Plant Disease ◽  
2015 ◽  
Vol 99 (4) ◽  
pp. 544-550 ◽  
Author(s):  
F. Zeng ◽  
E. Arnao ◽  
G. Zhang ◽  
G. Olaya ◽  
J. Wullschleger ◽  
...  
Keyword(s):  
Cytochrome B ◽  
Leaf Spot ◽  
Fungicide Resistance ◽  
Cytochrome B Gene ◽  
Diagnostic Tools ◽  
Polymerase Chain Reaction Primer ◽  
Cercospora Sojina ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Frogeye Leaf Spot

Frogeye leaf spot of soybean, caused by the fungus Cercospora sojina, reduces soybean yields in most of the top-producing countries around the world. Control strategies for frogeye leaf spot can rely heavily on quinone outside inhibitor (QoI) fungicides. In 2010, QoI fungicide-resistant C. sojina isolates were identified in Tennessee for the first time. As the target of QoI fungicides, the cytochrome b gene present in fungal mitochondria has played a key role in the development of resistance to this fungicide class. The cytochrome b genes from three QoI-sensitive and three QoI-resistant C. sojina isolates were cloned and sequenced. The complete coding sequence of the cytochrome b gene was identified and found to encode 396 amino acids. The QoI-resistant C. sojina isolates contained the G143A mutation in the cytochrome b gene, a guanidine to cytosine transversion at the second position in codon 143 that causes an amino acid substitution of alanine for glycine. C. sojina-specific polymerase chain reaction primer sets and TaqMan probes were developed to efficiently discriminate QoI-resistant and -sensitive isolates. The molecular basis of QoI fungicide resistance in field isolates of C. sojina was identified as the G143A mutation, and specific molecular approaches were developed to discriminate and to track QoI-resistant and -sensitive isolates of C. sojina.

scholarly journals Fungicide resistance in Cercospora species causing cercospora leaf blight and purple seed stain of soybean in Argentina

2020 ◽  
Vol 69 (9) ◽  
pp. 1678-1694 ◽  
Author(s):  
Francisco J. Sautua ◽  
Vinson P. Doyle ◽  
Paul P. Price ◽  
Alejandro Porfiri ◽  
Paula Fernandez ◽  
...  
Keyword(s):  
Fungicide Resistance ◽  
Leaf Blight ◽  
Purple Seed Stain
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