Cloning and characterization of a differentially expressed cDNA encoding myo-inositol-1-phosphate synthase involved in response to abiotic stress in Jatropha curcas.

D-myo-inositol-3-phosphate synthase (MIPS) catalyzes the reaction from d-glucose 6-phosphate to D-myo-inositol 3-phosphate (MIP), which is the first and rate-limiting step in myo-inositol biosynthesis. In this study, Jatropha curcas MIPS cDNA (JcMIPS) (GenBank accession no. EF 185781) has been isolated using mRNA differential display technology (DDRT) and the rapid amplification of cDNA ends (RACE). The cDNA clone of JcMIPS is comprised of 1,957 bp, encoding 509 amino acids, with a predicted molecular weight of 56.4 kDa. The JcMIPS protein is highly homologous to those from other plant species, ranging from 88.4 to 91.18% homology at the amino acid levels. Real-time quantification polymerase chain reaction (PCR) analysis has revealed that JcMIPS transcripts are highly present in seed and leaf tissues, but are at low levels in stem and flower tissues. Furthermore, the transcription of JcMIPS in leaves is up-regulated by abscisic acid (ABA) (100 μM), drought (30% PEG-6000), NaCl (200 mM), and low-temperature (4°C) treatments. The observed increase of JcMIPS enzyme activity is also detected following treatments with ABA, drought, and NaCl. Interestingly, JcMIPS enzyme activity is only slightly changed following low-temperature treatment. [ABSTRACT FROM AUTHOR]