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ARS Home » Research » Publications at this Location » Publication #259369
Title: Identification of soybean accessions resistant to Cercospora sojina by field screening, molecular markers and phenotyping

Author
item Mengistu, Alemu
item BOND, JASON - Southern Illinois University
item Mian, Rouf
item Nelson, Randall
item SHANNON, GROVER - University Of Missouri
item WRATHER, ALLEN - University Of Missouri

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/25/2010
Publication Date: 6/1/2011
Citation: Mengistu, A., Bond, J., Mian, R.M., Nelson, R.L., Shannon, G., Wrather, A. 2011. Identification of soybean accessions resistant to Cercospora sojina by field screening, molecular markers and phenotyping. Plant Disease. 51:1101-1109.

Interpretive Summary: Frogeye leaf spot (FLS) of soybean, caused by a fungus Cercospora sojina, has been a problem in the southern USA for many years. Cultivars resistant to FLS have been developed for planting in this area, and resistance in many of these cultivars is conditioned by the Rcs3 allel which provides immunity to all known races of the pathogen. Frog eye leaf spot has recently become a greater problem in the northern U.S.A., and few C. sojina resistant cultivars and breeding lines adapted to this area have been identified, however, identification of new sources are still needed. Out of the total 521 accessions that were evaluated for reaction to race 11 in field trials in Missouri and Illinois during 2006, 2007 and to natural innoculum in Tennessee in 2008, 67 did not develop symptoms of FLS. These were subsequently tested for the possible presence of Rcs3 using five molecular markers, and, only PI437726, PI 438302B, and PI494851 had the similar resistance as the Rcs3 derived from cultivar Davis. Such soybean genotypes with the Rcs3 gene and other genotypes with no FLS symptoms in field trials may be useful in developing soybean cultivars with resistance to FLS and adapted to the northern U.S.A.

Technical Abstract: Frogeye leaf spot (FLS) of soybean, caused by Cercospora sojina K. Hara, has been a problem in the southern U.S.A. for many years. Cultivars resistant to FLS have been developed for planting in this area, and resistance in many of these cultivars is conditioned by the Rcs3 allel which provides immunity to all known races of the pathogen. It has recently become a greater problem in the northern U.S.A., and few C. sojina resistant cultivars and breeding lines adapted to this area have been identified. The objectives of this study were (1) to identify maturity group (MG) 00 to VII accessions resistant to C. sojina race 11 by field screening at multiple locations over years, and (2) to determine if FLS resistance in these accessions is likely to be conditioned by the Rcs3 allele. A total of 521 accessions were evaluated for reaction to race 11 in field trials in Missouri and Illinois during 2006 and 2007, and 75 did not develop symptoms of FLS. These were field screened for reaction to natural inoculum in Tennessee during 2008, and 8 were susceptible. The remaining 67 were subsequently tested for the possible presence of Rcs3 using five molecular markers located within 2 centimorgan (cM) of the gene. Of these 67 accessions, only PI437726, PI 438302B, and PI494851 had the Rcs3 haplotype of cultivar Davis, the source of Rcs3. This is the first report of the possible presence of the Rcs3 allele in these accessions. The soybean genotypes predicted to have the Rcs3 gene and other genotypes with no FLS symptoms in field trials may be useful in developing soybean cultivars with resistance to FLS and adapted to the northern U.S.A.