Exploring ammonium tolerance in a large panel of Arabidopsis thaliana natural accessions.

ABSTRACT: Plants are dependent on exogenous nitrogen (N) supply. Ammonium (NH?(+)), together with nitrate (NO?(-)), is one of the main nitrogenous compounds available in the soil. Paradoxically, although NH4 (+) assimilation requires less energy than that of NO?(-), many plants display toxicity symptoms when grown with NH?(+) as the sole N source. However, in addition to species-specific ammonium toxicity, intraspecific variability has also been shown. Thus, the aim of this work was to study the intraspecific ammonium tolerance in a large panel of Arabidopsis thaliana natural accessions. Plants were grown with either 1mM NO?(-) or NH?(+) as the N source, and several parameters related to ammonium tolerance and assimilation were determined. Overall, high variability was observed in A. thaliana shoot growth under both forms of N nutrition. From the parameters determined, tissue ammonium content was the one with the highest impact on shoot biomass, and interestingly this was also the case when N was supplied as NO?(-). Enzymes of nitrogen assimilation did not have an impact on A. thaliana biomass variation, but the N source affected their activity. Glutamate dehydrogenase (GDH) aminating activity was, in general, higher in NH4 (+)-fed plants. In contrast, GDH deaminating activity was higher in NO?(-)-fed plants, suggesting a differential role for this enzyme as a function of the N form supplied. Overall, NH4 (+) accumulation seems to be an important player in Arabidopsis natural variability in ammonium tolerance rather than the cell NH?(+) assimilation capacity.

SUBMITTER: Sarasketa A 

PROVIDER: S-EPMC4203136 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature