Submitted to: Southern Soybean Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 2/11/2007
Publication Date: 2/17/2007
Citation: Wrather, A., Mian, R.M., Shannon, G., Bond, J., Newman, M., Wiebold, B. 2007. Identification of Maturity Group 3 and 4 Soybean Cultivars and Lines Resistant to Cercospora sojina by Field Screening and Molecular Markers. Southern Soybean Conference Proceedings. p.10 Interpretive Summary:
Technical Abstract: Frogeye leaf spot (FLS) of soybean, caused by Cercospora sojina K. Hara, has been a problem in the south US for many years, and some resistant cultivars have been developed. This disease has not been a severe problem in the north US until recently. Unfortunately, few soybean cultivars adapted to the north US have resistance to FLS. The objectives of this project were, 1) to identify maturity group 3 and 4 soybean cultivars and lines (genotypes) with resistance to FLS by field screening at multiple locations and over years, and 2) to determine if the genotypes with field resistance had the Rcs3 gene for resistance to C. sojina. Approximately 520 different genotypes were evaluated in field trials for resistance to C. sojina during each of three years. Thirteen maturity group 3 and 30 maturity group 4 genotypes had no FLS symptoms in field trials. These were subsequently tested for the presence of Rcs3 gene using three SNP markers located within 2 cM of the gene. None of the maturity group 3 soybeans tested had the Rcs3 haplotype of cultivar Davis, the source of the gene. Four of the maturity group 4 genotypes had the Rcs3 haplotype including LN 97-15076, 14 had the haplotype of the universal susceptible cultivar Blackhawk, and the results from 12 genotypes were questionable. The genotypes with Rcs3 haplotype will be screened against a core set of C. sojina isolates to confirm the results of marker assisted selection. The soybean genotypes confirmed to have the Rcs3 gene could be useful in breeding soybean cultivars with broad resistance to FLS and adapted to the north US.