Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/10/2012
Publication Date: 5/21/2012
Citation: Mengistu, A., Bond, J., Mian, R.M., Nelson, R.L., Shannon, G., Wrather, A. 2012. Resistance to Frogeye Leaf Spot in selected soybean accessions in MG I through MG VI. Plant Health Progress. doi:10.1094/PHP-2012-0521-02-RS. Interpretive Summary: Frogeye leaf spot of soybean has been a problem in the southern USA for many years. Cultivars resistant to the disease have been developed for planting in this area, and resistance in many of these cultivars is conditioned by a resistant gene which provides immunity to all known races of the fungal pathogen. However, frogeye leaf spot has recently become a greater problem in the northern USA, and few cultivars and breeding lines that are adapted to this area have been identified as being resistant to the disease. Thus identification of new sources of resistance to this disease is still needed. Twenty of 260 accessions evaluated for reaction to race 11 in field trials in Missouri and Illinois during 2009 did not develop symptoms of the disease. None of these 20 soybean accessions appeared to contain the gene for resistance to frogeye leaf spot that occurs in soybean cultivar ‘Davis’. These accessions may contain novel genes for frogeye leaf spot resistance and may be used in the development of new soybean cultivars with frogeye leaf spot resistance.
Technical Abstract: Frogeye leaf spot (FLS) caused by Cercospora sojina Hara is a disease of soybean (Glycine max (L.) Merr.) that causes significant seed yield loss in warm, humid environments worldwide. The Rcs3 gene in soybean has been reported to condition resistance to all known races of C. sojina. The objectives of this study were (1) to identify maturity group (MG) I to VI accessions resistant to C. sojina race 11 by field screening at two locations, and (2) to determine if the FLS resistance of the symptomless soybean accessions is likely to be conditioned by the Rcs3 allele. A total of 260 accessions including 11 differentials were evaluated for reaction to race 11 in field trials in Missouri and Illinois during 2009, and 20 accessions did not develop symptoms of FLS. The 20 symptomless accessions were tested for the potential presence of Rcs3 allele using molecular markers; and none was predicted to carry the Rcs3 allele. These accessions may contain novel loci for FLS resistance and may be used to broaden the base for developing soybean cultivars with frogeye leaf spot resistance.