Inheritance of low linolenic acid content of the seed oil of a mutant in Glycine max.

Linolenic acid content of the oil from F1, F2, and F3 seeds was compared with the parental values from a cross between a soybean cultivar with high (7.0%) and a mutant line with low (3.4%) linolenate (18∶3). Linolenic acid content of F1 seeds was intermediate to that of selfed seeds from the two parents and values from reciprocal crosses were essentially the same. This demonstrated that in this cross, linolenic acid content of the oil was controlled by the embryo rather than by the maternal parent. The distribution of linolenic acid in F2 seeds from F1 plants was trimodal and extended across the range of parental values. High and low linolenate F2 plants bred true for 18∶3 content and the F3 distribution of seeds from F2 plants with intermediate levels of 18∶3 was similar to the F2 distribution. The data were consistent with a model for two alleles with additive effects at a single locus controlling percent linolenic acid in these progenies. The simply-inherited alleles for low linolenate could be readily transferred to agronomically superior soybean cultivars, which would improve the fatty acid composition of the oil.