Identification of an Arabidopsis thaliana mutant accumulating threonine resulting from mutation in a new dihydrodipicolinate synthase gene

A novel Arabidopsis DHDPS gene named DHDPS2 was found through identificatio n of a mutant by promoter trapping. The mutation promotes a reduction of gr owth resulting from combination of a defect in lysine biosynthesis and accu mulation of a toxic level of threonine or derived products. The mutant also modifies the amino acid composition issuing from the pyruvate and aspartat e pathways, affecting mainly the root compartment These data are in accorda nce with the expression of DHDPS2 in the root apex as visualized by express ion of the GUS reporter gene. This suggests that a large proportion of the amino acids derived from pyruvate and aspartate are synthesized in this org an.