Study of nitrite tranport in Arabidopsis thaliana

Nitrate is the major nitrogen form up taken by plants and its assimilation consists of several enzymatic steps producing successively nitrite, ammonium and amino acids in different cellular compartments. The transport and the storage of the different nitrogen compounds is submitted to fine regulations. Nitrogen assimilation needs also to be tightly coordinated with the carbon metabolism pathway which furnishes the reducing power and the carbon skeletons used to synthesise the organic nitrogen molecules. Using reverse genetic, biomolecular and biochemical approaches, this thesis project will consist in the characterisation of 1) the molecular actors involved in nitrite transport and homeostasis and 2) the regulation of this transport and its physiological role. In Arabidopsis, a transporter (AtNitr) and a channel (AtClce) have already been associated with nitrite transport and accumulation. The PII protein (AtGlB1) is a regulating protein involved in the regulation of nitrite accumulation inside the chloroplast. The physiological role of these transporters and ion channel will be studied as well as their potential direct or indirect interaction-regulation by the PII protein. NO2- as a new signalling molecule in the nitrogen assimilation will also be analysed.

PhD subject IJPB 2010 from research group Plant response to nitrogen availability: transport, signaling and natural variation