QTL mapping for resistance to Cercospora sojina in Essex Forrest soybean (Glycine max L.) lines

Frogeye leafspot (FLS), caused by Cercospora sojina, is observed as red-brown lesions on leaves that can coalesce and decrease the photosynthetic ability of soybeans. The average yield loss due to Frogeye Leaf Spot is estimated at approximately 40% in established fields, whereas 100% incidence was previously recorded. QoI inhibitor fungicides were considered an effective control method, but the pathogen quickly evolved an ability to thrive post-application. This trait quickly spread across North America. Therefore, genetic host resistance is likely the most effective method to prevent the disease. To achieve this goal, we aimed to screen 91 recombinant inbred lines (RILs) of ‘Essex’ × ‘Forrest’ under greenhouse conditions for FLS resistance and used single nucleotide polymorphism (SNP) markers to identify associated quantitative trait loci (QTL). Two QTL were mapped in this study. One QTL reported on Chr. 13 coincides with the QTL previously reported, and the QTL on Chr. 19 was novel. Overall, this study will help to better understand the underlying mechanisms of soybean resistance to C. sojina as well as to develop soybean varieties with resistance to FLS using marker assisted selection.  \r\n\r\n\tKey words: Cercospora sojina, quantitative trait loci, Frogeye Leaf Spot, Essex × Forrest, disease resistance, genotypic and phenotypic traits.