Submitted to: Plant Breeding
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/7/2006
Publication Date: 9/12/2006
Citation: Chappell, A.S., Scaboo, A., Wu, X., Nguyen, H., Pantalone, V., Bilyeu, K.D. 2006. Characterization of the mips gene family in glycine max. Plant Breeding. 125(5):493-500. Interpretive Summary: It is estimated that over 2 billion people, mostly women and children in developing countries, suffer from iron deficiency. These deficiencies are due in part to iron uptake inhibitors found in staple foods, which are often of plant origin in developing countries. Phytic acid, a phosphorous storage molecule found in plant seeds, is considered to be the most important iron uptake inhibitor contributing to iron deficiency. Phytic acid strongly binds iron and other positively charged minerals in the small intestines and prevents their absorption. These antinutritional properties make the development and characterization of low phytic acid soybean lines a high priority in agricultural research. To this end, a low phytic acid line has been identified that contains a mutation in a gene involved in the very first step of phytate biosynthesis. Previous work suggests that this gene is actually a member of a multi-gene family. Here, we describe the characterization of this gene family. All four genes of this family were sequenced and their expression analyzed. These data will aid researchers and breeders who wish to identify additional low phytic acid soybean lines through manipulation of this gene family.
Technical Abstract: Myo-inositol is a precursor to compounds in plants that function in a variety of processes including signal transduction, stress response, cell wall biosynthesis and phosphorus storage. The first step in the de novo synthesis of myo-inositol is catalyzed by the enzyme D-myo-inositol 3-phosphate synthase (MIPS EC 22.214.171.124), which converts glucose 6-phosphate to D-myo-inositol 3-phosphate. MIPS is a highly conserved enzyme that is found in both prokaryotes and eukaryotes. Previous work has revealed that MIPS sequences comprise gene families in several plant species, including Glycine max. At least four MIPS genes have been identified by southern blot in soybean. Here we describe the cloning and characterization of these four MIPS genes. Sequencing of the complete genomic sequence of all four genes revealed a conserved intron/exon structure. Quantitative real-time RT-PCR revealed that only one of the MIPS genes is preferentially expressed in developing seeds. A candidate gene approach was taken to examine whether MIPS genes were responsible for the low phytate phenotype of soybean line CX1834. Complete sequencing of the coding sequence of all four MIPS genes revealed no mutations in the CX1834 line.