Developing Soybean Cultivars with Improved Composition

To develop soybean meal with enhanced compositional traits that are more useful to the nutritionist, several soybean breeding programs are involved in molecular studies designed to speed the development of value-added soybean cultivars. These studies involve determining the heritance of the value-added trait, mapping the gene(s) responsible for the trait, and identifying closely linked molecular markers to the gene(s) or loci on the various soybean chromosomes. Once the gene(s) and molecular markers have been identified, soybean breeders can then use molecular techniques to select germplasm that can be used in developing soybean lines with value-added traits. The following three papers cite scientific achievements in developing soybeans desired by the animal/poultry nutritionist.

Reducing the levels of phytate phosphorus in soybean is an objective of several soybean breeding programs. Researchers reported results of molecular studies with a low phytic acid mutant soybean line (CX1934-1-2). They identified two loci associated with low phytate phenotype of CX1934-1-2; one locus was found on linkage group N that accounted for 41% and a second locus on linkage group L that accounted for another 11% of the observed variation in seed inorganic phosphorus in this mutant line. An interaction between the two linkage groups accounted for another 8-11%. Molecular markers for these two traits have been identified and associated with these two loci. Efforts to develop soybean cultivars with reduced phytic acid will be facilitated knowing the location and contributions of the phytate loci and with DNA markers that can be used in soybean breeding programs.

Walker, D.R. and co-workers. 2006. Genetic mapping of loci associated with seed phytic acid content in CX1834-1-2 soybean. Crop Sci. 46(1): 390-397.