Cloning and Molecular Characterization of MIPS and Phytase from Mungbean (Vigna radiata (L.) Wilczek)

Mungbean has claimed its rich source of protein and premium quality of starch; however the disadvantage of antinutritional factor phytic acid in monogastric animals is needed to be decreased. Understanding both upand down-stream of phytic acid biosynthetic pathway will be a great benefit for controlling the appropriate level phytic acid in legumes. Cloning of D-myo-inositol 3-phosphate synthase (MIPS; EC 5.5.1.4) and phytase (EC 3.1.3.26) were conducted. In this study MIPS cDNA from developing mungbean seeds was isolated by reverse transcriptase-PCR using consensus primers designed from highly conserved regions in other plant MIPS sequences. The 1,743 bp cDNA sequence contained a 1,533 bp coding sequence that could encode a protein of 510 amino acids, whereas phytase sequence was isolated by reverse transcriptase-PCR using consensus primers designed from highly conserved regions in other plant phytase sequences. The partial clone of phytase was 862 nucleotides in length and Northern analyses showed no transcript in dry seed. The phytase mRNA accumulated during the first hours of germination, and reached a maximum level after 24 hours, and the expression was diminished in young seedlings. While MIPS transcript was observed in cotyledons at the earliest developmental stages. Strong signals were detected in developing seed after 7 DAF and remained until 13 DAF, after which time it gradually decreased. This research will lead to a fine control of phytic acid by working at both ends to developing a high value-added mungbean in the near future.