Cloning and characterization of MYO- Inositol-1-Phosphate synthase (MIPS1) gene in developing seeds of Glycine Max

Phytic acid (myo-inositol 1, 2, 3, 4, 5, 6 hexakisphosphate) is a phoshphorylated derivative of myoinositol, which functions as a major storage form of phosphorous in plant seeds. MIPS (myo- inositol-1phosphate synthase) catalyzes the first and rate limiting step in phytic acid biosynthesis. In the present study, a genomic sequence of MIPS from soybean (Glycine max var. Pusa16) was amplified using long PCR. Cloning and characterization of the genomic sequence revealed a total length of 2608 bp containing 9 introns interrupting 10 exons. The transcribed sequence of the gene had an expected open reading frame of 1533 bp encompassing MIPS1a variant of the MIPS1 isoform of MIPS gene. Strong homology with the previously reported MIPS gDNA as revealed in the BlastN search also indicated a high degree sequence similarity to Phaseolus vulgaris, Vigna radiata, Cicer arietinum, Lotus japonica and Medicago truncatula. The maximum level of phytate content observed in mature soybean seeds was 1.9%. MIPS expression by RT-PCR and Northern analysis revealed increased transcript levels during early stages of seed development reaching a maximum at 6–8 mm seed size. At least four copies of the MIPS were detected during Southern analysis of the genomic DNA.