GENETIC-RELATIONSHIPS BETWEEN LOCI CONTROLLING PALMITIC AND LINOLENIC ACIDS IN SOYBEAN

Three mutagen-derived soybean [Glycine max (L.) Merr.] lines have been identified with unique levels of fatty acids. Levels of linolenic acid (18:3) in C1640 and palmitic acid (16:0) in C1726 and C1727 are controlled by alleles with additive effects at three loci. If these loci are independent, soybean strains could be developed with unique and useful combinations of both linolenic and palmitic acids. The primary objective of this study was to determine the genetic relationships between loci controlling levels of palmitic acid and the locus controlling linolenic acid. Additionally, effects of altered levels of linolenic and palmitic acids on total fatty acid composition were determined. Fatty acid composition of F2 seeds from crosses of C1640 (low 18:3) with both C1726 (low 16:0) and C1727 (high 16:0) were determined by gas chromatography. Chi-square analyses of the data demonstrated that the fan locus controlling low 18:3 was inherited independently from both the fap1 and fap2 loci controlling low and high levels of 16:0, respectively. There was no indication of an interaction among alleles at these loci. The decreases in palmitic acid due to fap1 and increases due to fap2 were associated primarily with changes in oleic and linoleic acids. Decreases in linolenic acid due to fan were associated primarily with increases in linoleic acid.