The glutamine formed as a result of primary assimilation of ammonia is funneled into purine biosynthesis pathway which is considered to be induced on commencement of nitrogen fixation. Purines are then transported to the uninfected cells of nodules where they are oxidized. The latter occurs inside peroxisomes that are proliferated in the uninfected cells of nodules. We are interested in understanding the regulation of purine biosynthesis and biogenesis of peroxisomes with the aim to eventually clone the genes involved in peroxisome assembly. We are also interested in osmosensing and osmoregulation in plants.
Many plants accumulate proline in response to water stress.
Our laboratory has isolated all the genes involved in proline synthesis and we have recently introduced a gene encoding a bifunctional enzyme, P5C synthetase, into plants under a constitutive promoter. The transgenic plants are able to produce high amounts of proline which conferred osmotic tolerance. Current emphasis of research in this project is to understand induction of genes of proline pathway and osmosensing in plants with the eventual aim, by metabolic engineering, to produce proline betaine, a well known osmoprotectant. Gu X. and D. P. S. Verma. Verma D. P. S. and X. Gu. 1996.