title: Biochemical and molecular characterization of a mutation that confers a decreased raffinosaccharide and phytic acid phenotype on soybean seeds.
abstract: A single, recessive mutation in soybean (Glycine max L. Merr.), which confers a seed phenotype of increased inorganic phosphate, decreased phytic acid, and a decrease in total raffinosaccharides, has been previously disclosed (S.A. Sebastian, P.S. Kerr, R.W. Pearlstein, W.D. Hitz [2000] Soy in Animal Nutrition, pp 56-74). The genetic lesion causing the multiple changes in seed phenotype is a single base change in the third base of the codon for what is amino acid residue 396 of the mature peptide encoding a seed-expressed myo-inositol 1-phospate synthase gene. The base change causes residue 396 to change from lysine to asparagine. That amino acid change decreases the specific activity of the seed-expressed myo-inositol 1-phosphate synthase by about 90%. Radio tracer experiments indicate that the supply of myo-inositol to the reaction, which converts UDP-galactose and myo-inositol to galactinol is a controlling factor in the conversion of total carbohydrate into the raffinosaccharides in both wild-type and mutant lines. That same decrease in myo-inositol 1-phosphate synthetic capacity leads to a decreased capacity for the synthesis of myo-inositol hexaphosphate (phytic acid) and a concomitant increase in inorganic phosphate.
authors.affiliation: DuPont Crop Genetics, P.O. Box 80402, Wilmington, DE 19880-0402, USA. william.d.hitz@usa.dupont.com
authors.forename: William D
authors.initials: WD
authors.lastname: Hitz
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Carlson
authors.forename: Phil S
authors.initials: PS
authors.lastname: Kerr
authors.forename: Scott A
authors.initials: SA
authors.lastname: Sebastian
mesh_terms: D000595:Amino Acid Sequence; D004187:Disaccharides / Q000096:biosynthesis; D005700:Galactosyltransferases / Q000378:metabolism; D007294:Inositol / Q000378:metabolism; D009154:Mutation; D007296:Myo-Inositol-1-Phosphate Synthase / Q000235:genetics* / Q000378:metabolism; D009844:Oligosaccharides / Q000096:biosynthesis; D010641:Phenotype; D010710:Phosphates / Q000378:metabolism; D010833:Phytic Acid / Q000096:biosynthesis*; D011887:Raffinose / Q000096:biosynthesis*; D012639:Seeds / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013025:Glycine max / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism
chemical_list: D004187:Disaccharides; D009844:Oligosaccharides; D010710:Phosphates; C005695:stachyose; C013536:6 beta-galactinol; D007294:Inositol; D013395:Sucrose; D010833:Phytic Acid; D005700:Galactosyltransferases; C096645:inositol 1-alpha-galactosyltransferase; C113913:galactinol -raffinose galactosyltransferase; D007296:Myo-Inositol-1-Phosphate Synthase; D011887:Raffinose