INHERITANCE OF HIGH OLEIC-ACID CONTENT IN THE SEED OIL OF SOYBEAN MUTANT M23

A mutant line, M23, of soybean [Glycine max (L.) Merr.] was found to h ave two fold increases in oleic acid content in the seed oil compared with the original variety, Bay. Our objective was to determine the inh eritance of the high oleic acid content in this mutant. Reciprocal cro sses were made between M23 and Bay. There were no maternal and cytopla smic effects for oleic acid content. The F-1 seeds and F-1 plants were significantly different from either parents or the midparent value, i ndicating partial dominance of oleic acid content in these crosses. Th e oleic acid content segregated in the F-2 seeds and F-2 plants in a t rimodal pattern with normal, intermediate and high classes, satisfacto rily fitting a 1:2:1 ratio. The seeds of a backcross between M23 and F -1 segregated into intermediate and high classes in a ratio of 1:1. Th ese results indicated that oleic acid content was controlled by two al leles at a single locus with a partial dominant effect. Thus, the alle le in M23 was designated ol and the genotypes of M23 and Bay were dete rmined to be olol and OlOl, respectively. The oleic acid contents of t he F-2 seeds and F-2 plants were inversely related with the linoleic a cid content which segregated in a trimodal pattern with normal, interm ediate and low classes in a 1:2:1 ratio. Thus, it was assumed that the low linoleic acid content in M23 was also controlled by the ol allele s. Because a diet with high oleic acid content reduces the content of low density lipoprotein cholesterol in blood plasma, the mutant allele , ol, would be useful in improving soybean cultivars for high oleic ac id content.