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 p lants containing elevated levels of the gene product encoding the enzy me catalysing the first committed step in inositol biosynthesis, D-myo -inositol-3-phosphate (Ins3P) synthase. These plants exhibit both an i ncrease in Ins3P synthase activity and an increase in the level of fre e inositol of over four-fold compared to wild-type plants. Despite the se changes, we could detect no significant difference in phenotype in the transgenic plants for a number of characteristics linked with puta tive functions of inositol and inositol-derived metabolites. Our resul ts indicate that the proposed engineering of inositol metabolism to ge nerate specific plant phenotypes (e.g. salt tolerance) may require the manipulation of several genes, and that Ins3P synthase activity can b e manipulated to increase the pool size of free inositol.