Inheritance and Interaction of Low Palmitic and Low Linolenic Soybean.

Decreasing the palmitic and linolenic acid content of soybean [Glycine max (L.) Merrill] oil would help improve its nutritional quality and oxidative stability. The altered fatty acid profile in soybean germplasm lines with decreased levels of palmitic and linolenic acid have been developed at the University of Guelph, Canada, by combining different mutant alleles through hybridization. The objectives of this study were to determine the inheritance and interaction of palmitic and linolenic acid levels in RG3 and RG1, and the effects of these altered fatty acid levels on other fatty acids. RG3 and RG1 (low palmitic approximately 45 g kg(-1) and linolenic approximately 40 g kg(-1)) were crossed reciprocally to several soybean lines with altered or normal fatty acid profiles. Analysis of the reciprocal F(2) generations indicated no maternal or cytoplasmic effects for palmitic or linolenic acid content. Chi-square analyses of the F(2) generation demonstrated that RG3 and RG1 contained two alleles, fap1 and fapx, that controlled palmitic acid content. In addition, RG1 had a third allele, fan, which reduced its linolenic acid content. Calculation of gene substitution values indicated additive gene action at the fap1 and fan loci, whereas the fapx locus involved partial dominance. Correlation coefficients indicated no association between palmitic and linolenic acid. Decreases in palmitic and linolenic acid content were associated primarily with increases in linoleic acid content. Since fap1, fapx, and fan were inherited independently of each other and appeared to behave in an additive manner, RG3 and RG1 can be used in breeding programs as additional valuable sources of germplasm with altered fatty acid profiles.

Genotype x Environment Interactions, Stability, and Agronomic Performance of Soybean with Altered Fatty Acid Profiles.

There has been a major effort to produce soybean [Glycine max (L.) Merr.] lines with modified fatty acid profiles in order to improve quality and develop new uses for soybean oil. Utilization of the lines depends on their agronomic traits and stability of the fatty acid profiles in diverse environments. The objectives of this study were to (i) evaluate the influence of years and locations on the fatty acid composition of soybean genotypes with unique fatty acid profiles, (ii) determine which fatty acids and fatty acid profiles are the most stable, and (iii) evaluate agronomic and seed quality traits of mutant soybean lines. Genotypes were evaluated over three years (1996, 1997, and 1998) at four locations in Southern Ontario, Canada. Year effects had the largest impact on all fatty acid levels. Location effects were significant only for oleic and linolenic acids. Genotype x year interaction effect was significant for all fatty acids whereas genotype x location and genotype x year x location interaction effects were significant only for oleic, linoleic, and linolenic acids. Mutants with reduced or elevated palmitic, elevated oleic, or reduced linolenic acid concentrations exhibited average or higher stability than lines with normal levels of these fatty acids. Therefore, these lines may be suitable for growing in a wide range of environments. Maturity, plant height, lodging, seed size, and seed quality were significantly different between mutants and cultivars. Seed yield was significantly reduced in mutants compared to cultivars.