Overexpression of D-myo-inositol-3-phosphate synthase leads to elevated levels of inositol in Arabidopsis.

In this paper, we report on the generation of transgenic Arabidopsis plants containing elevated levels of the gene product encoding the enzyme catalysing the first committed step in inositol biosynthesis, D-myo-inositol-3-phosphate (Ins3P) synthase. These plants exhibit both an increase in Ins3P synthase activity and an increase in the level of free inositol of over four-fold compared to wild-type plants. Despite these changes, we could detect no significant difference in phenotype in the transgenic plants for a number of characteristics linked with putative functions of inositol and inositol-derived metabolites. Our results indicate that the proposed engineering of inositol metabolism to generate specific plant phenotypes (e.g. salt tolerance) may require the manipulation of several genes, and that Ins3P synthase activity can be manipulated to increase the pool size of free inositol.