Genetic Analysis of Frogeye Leaf Spot Resistance in PI54610 and Peking Soybean

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From: Crop Science(Vol. 39, Issue 4)
Publisher: Crop Science Society of America
Document Type: Article
Length: 3,986 words

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Abstract :

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 P154610 and Peking and their allelic relationship to [Rcs.sub.3]. `Lee' soybean was used as a susceptible parent for crosses and control in all experiments. Parents and [F.sub.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 P154610 x Lee, and 15:1 in `Davis' x Peking and P154610 x Peking), we found resistance in Peking was determined by a single dominant gene nonallelic to [Rcs.sub.3]. We also found, based on nonsegregation of resistance within the Davis x P154610 population, that P154610 has the same gene as in Davis ([Rcs.sub.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.sub.3] fail.

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Gale Document Number: GALE|A55369498