Phenotypic and molecular analysis of oleate content in the mutant soybean line M23

Soybean [Glycine max (L.) Merr.] oil with elevated oleate content would be useful for food and industrial applications that require increased oxidative stability. The first objective of this study was to determine if molecular selection for the Fad2-1 deletion associated with the ol allele in the mid-oleate mutant line M23 could be used to identify mid-oleate individuals in a breeding program. The second objective was to determine if modifying genes affect phenotypic expression of oleate content in individuals homozygous for the deletion from a cross between M23 and Archer, a cultivar with normal oleate content. The segregation among 88 F-2 plants from the cross satisfactorily fit a ratio of 1:24 homozygous normal (0101)/heterozygous (Olol)/homozygous (olol) for the Fad2-1 deletion on the basis of Southern analysis. A PCR-based marker Fad2-1-ol identified the same olol individuals as the Southern analysis. The PCR-based marker would be a more rapid and less labor intensive method for molecular selection of olol individuals than Southern analysis. The olol individuals had the highest mean oleate content, the Olol individuals were intermediate, and the olol individuals had the lowest mean oleate content. There was significant variation among the Olol individuals and their distribution overlapped that of the Olol and Olol individuals, which indicated that modifying genes had an important influence on the trait. It would be necessary to test the fatty acid profile of olol individuals to select those with the highest oleate content.