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Biochemical and molecular characterization of a mutation that confers a decreased raffinossaccharide and phytic acid phenotype on soybean seed.

Researchers are beginning to understand the complexities of modifying soybean composition. A single, recessive mutation in soybean has been shown to cause increased inorganic phosphate, decreased phytic acid and a decrease in total raffinosaccharides in soybean seed. The research group has shown the mutation is caused by a single amino acid change in the peptide that encodes a seed-expressed myo-inositol 1-phosphate synthase gene. This single amino acid change, replacing lysine with asparagines, causes about 90 percent decrease in the specific activity of the seed-expressed myo-inositol 1-phosphate synthase. Radiotracer studies indicated that the supply of myo-inositol to the reaction that converts UDP-galactose and myo-inositol to galactinol is the controlling factor in the synthesis of raffinosaccharides, myo-inositol hexaphosphate (phytic acid) and the resulting increase in inorganic phosphate. Continued research to isolate the gene and to insert the gene in high-yielding soybean lines could result in soybeans with more available phosphorus and reduced levels of oligosaccharide. Meal produced from these soybeans would have additional feeding value in swine, poultry and aquaculture diets.

Hitz, W.D. and co-workers. 2002. Biochemical and molecular characterization of a mutation that confers a decreased raffinossaccharide and phytic acid phenotype on soybean seed. Plant Physiology 128(2):650-660.