Functional genomic characterization of ammonium assimilation into asparagine and nitrogen translocation in Arabidopsis thaliana

When the plants accumulate ammonium in excess, a large part of ammonium is assimilated into asparagine. Asparagine synthetase (AS, EC. 6.3.5.4) catalyses the assimilation of ammonium into asparagine. One of the principal functions of asparagine is to preserve and transport nitrogen during plant development, ie: (i) seed germination (nitrogen mobilization), (ii) photorespiration and biotic and abiotic stress (nitrogen recycling) and (iii) senescence of organs and seed development (nitrogen re-mobilization). AS is coded by three genes (ASN1, ASN2 and ASN3) in Arabidopsis thaliana, and it is essential to distinguish the role of each member of genes during plant development. Expression of ASN3 is associated with imbibition of seeds during germination. The over-expression of ASN3 is related to the phenotype of higher biomass during the vegetative stage, whereas the physiological role of gene ASN3 remains largely unknown. Doctoral work aims at demonstrating regulation and function of gene ASN3 as well as ASN1 and ASN2 in the assimilation and the translocation of nitrogen, and in the quality and yield of seeds in Arabidopsis thaliana.

PhD subject IJPB 2010 from research group Functional genomic of nitrogen recycling in plants