P-268 - Evaluating resistance to frogeye leaf spot in soybean breeding lines

Tuesday, August 5, 2025

9:30 AM - 10:15 AM HST

Location: Exhibit Hall 3

Author(s)

EC

Elena Cothern

Undergraduate research assistant
Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996
Knoxville, Tennessee, United States
EW

Emily Walker

Research Technitian
Department of Entomology and Plant Pathology, University of Tennessee
Knoxville, Tennessee, United States
HK

Heather Marie Kelly, n/a

Professor
University of Tennessee
Jackson, Tennessee, United States
AM

Alemu Mengistu, PhD

Research Pathologist
USDA ARS
Jackson, Tennessee, United States
VP

Vince Pantalone

Professor
Department of Plant Sciences, University of Tennessee
Knoxville, Tennessee, United States

Presenting Author(s)

GK

Gayan Kanishka Kariyawasam, PhD

Assistant Professor
Department of Entomology and Plant Pathology, University of Tennessee
Knoxville, Tennessee, United States

Abstract Text: Cercospora sojina, the causal agent of frogeye leaf spot (FLS), is one of the most destructive foliar fungal pathogens of soybean, which can cause yield losses of up to 60%. The pathogen is primarily managed by fungicide application and planting genetically resistant varieties. However, the development of QoI-fungicide resistance in C. sojina has increased the importance of planting genetically resistant soybean cultivars. To date, three resistance genes, Rcs1, Rcs2, and Rcs3, have been identified, whereas the pathogen has already overcome the first two. Currently, soybean breeders lack the knowledge of existing FLS resistance genes in their breeding lines. Therefore, this study aimed to evaluate the genetic resistance in soybean breeding lines against various pathogenicity groups (PG) of C. sojina. This study used five C. sojina isolates representing each of the five PGs to evaluate 26 soybean breeding lines from Tennessee, Kansas, Missouri, and Illinois breeding programs. Our results demonstrated that breeding lines TN18-4047, TN11-5140, TN21-5005, S19-19923HOLL, and S17-17644C were resistant to all the PG groups, whereas other lines showed resistance to one or a few PGs. Our findings will be shared with breeding programs to develop C. sojina-resistant soybean cultivars.