Genetic analysis of frogeye leaf spot resistance in PI54610 and Peking soybean

• Published in: Crop science 1999-07, Vol.39 (4), p.1021-1025
• Main Authors: Baker, W.A, Weaver, D.B, Qiu, J, Pace, P.F
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; alleles; Biological and medical sciences; Biotechnology industry; Cercospora; Cercospora sojina; Control; cultivars; disease course; disease outbreaks; disease resistance; Diseases and pests; dominance; experimental infections; frogeye leaf spot; Fundamental and applied biological sciences. Psychology; fungal spores; Fungi; Fungi, Pathogenic; Genes; genetic resistance; Genetics; Genetics and breeding of economic plants; germplasm; Glycine max; interactions; leaf spotting; leaves; Pest resistance; Plant genetics; Plant pathogens; segregation; Soybean; Soybeans; symptoms; Varietal selection. Specialized plant breeding, plant breeding aims
• ISSN: 0011-183X; 1435-0653
• DOI: 10.2135/cropsci1999.0011183X003900040010x

Frogeye leaf spot (FLS) of soybean [Glycine max (L.) Merr.] is caused by the fungus Cercospora sojina Hara. The fungus is ubiquitous, but only problematic in hot humid soybean-producing regions such as Brazil, China, Nigeria, and the southern USA. Significant yield losses (10-50%) are commonly associated with FLS epidemics. The quantification of unique alleles for resistance within the southern germplasm pool is an essential step toward developing a more usable set of differential genotypes and thereby clarifying the race situation within the C. sojina-soybean interaction. Our objective was to determine the inheritance of resistance to FLS in PI54610 and Peking and their allelic relationship to Rcs(3). 'Lee' soybean was used as a susceptible parent for crosses and control in all experiments. Parents and F(2) seedlings were inoculated with a C. sojina spore suspension in the greenhouse or field and then rated for disease development 14 to 21 d later. On the basis of segregation ratios (3:1 resistant/susceptible in Peking x Lee and PI54610 x Lee, and 15:1 in 'Davis' x Peking and PI54610 x Peking), we found resistance in Peking was determined by a single dominant gene nonallelic to Rcs(3). We also found, based on nonsegregation of resistance within the Davis x PI54610 population, that PI54610 has the same gene as in Davis (Rcs(3)). Resistance in Peking should be considered unique for the purpose of race differentiation and as a commercial source of resistance to FLS should Rcs(3) fail.