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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Genetics Research » Research » Publications at this Location » Publication #336197
Title: Population structure and the rapid increase of QoI fungicide resistance in frogeye leaf spot (Cercospora sojina) from Tennessee

Author
item SHRESTHA, SANDESH - University Of Tennessee
item COCHRAN, ALICIA - University Of Tennessee
item Mengistu, Alemu
item LAMOUR, KURT - University Of Tennessee
item CASTRO-ROCHA, ARTURO - Universidad Autonoma De Chihuahua
item YOUNG-KELLY, HEATHER - University Of Tennessee

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/2017
Publication Date: 5/9/2017
Citation: Shrestha, S., Cochran, A., Mengistu, A., Lamour, K., Castro-Rocha, A., Young-Kelly, H. 2017. Population structure and the rapid increase of QoI fungicide resistance in frogeye leaf spot (Cercospora sojina) from Tennessee. PLoS One. 12(5):e0177220. https://doi.org/10.1371/journal.pone.0177220.
DOI: https://doi.org/10.1371/journal.pone.0177220

Interpretive Summary: Frogeye leaf spot (FLS) is a soybean disease caused by a fungus that causes significant damage to soybean yield in the US. In this study, isolates from FLS disease were collected from Jackson and Milan, TN in 2015 and historical isolates collected before 2015 were included in this study. Fifty novel genetic markers, that included the gene that have resistance to a fungicide, quinone, was included and 186 isolates were examined for their resistance or sensitivity to this fungicide. A total of 35 unique genes clustered into three different groups. Isolates from the FLS fungus collected from two locations in 2015 were dominated by a single group consisting of 130 isolates. The remaining 56 isolates were genetically diverse. Genotyping of fungicide resistant/sensitive in 477 FLS isolates revealed 344 of those isolates were resistant and 133 were sensitive. As was expected, all the historical isolates had sensitive allele. A higher proportion of quinone fungicide resistant isolates were recovered from quinone treated soybean cultivars and more sensitive isolates were recovered from non-treated plants. All isolates in dominant lineage were all quinone resistant. Two genetic mating types were found in Jackson and Milan, TN and also recovered from a single FLS lesion. The implications of this study is that the increased use of quinone fungicide have resulted in the appearance of rapid fungicide resistance FLS isolates and an increased sexual outcrossing that may contribute to the quinone fungicide.

Technical Abstract: Frogeye leaf spot (FLS), caused by Cercospora sojina, causes significant damage to soybean in the US. In this study, C. sojina isolates collected from Jackson and Milan, TN in 2015 and historical isolates collected before 2015 were included. Fifty novel single nucleotide polymorphism (SNP) markers, including the quinone outside inhibitor (QoI) resistant locus, were genotyped in 186 isolates. A total of 35 unique genotypes clustered into three different groups. C. sojina collected from two locations in 2015 were dominated by a single clonal lineage consisting of 130 isolates. The remaining 56 isolates were genetically diverse. Genotyping of 30 QoI resistant/sensitive locus in 477 C. sojina isolates revealed 344 resistant and 133 sensitive isolates. As was expected, all the historical isolates had sensitive allele. A higher proportion of QoI resistant isolates were recovered from QoI treated soybean cultivars and more sensitive isolates were recovered from non-treated plants. All isolates in dominant clonal lineage were QoI resistant. Both mating type alleles (MAT1-1-1 and MAT1-2) were found in Jackson and Milan, TN and also recovered from a single lesion.