Enzymatic and Metabolic Diagnostic of Nitrogen Deficiency in Arabidopsis thaliana Wassileskija Accession
Résumé
Adaptation to steady-state low-nutrient availability was investigated by comparing the Wassileskija (WS) accession of Arabidopsis thaliana grown on 2 or 10 mM nitrate. Low nitrogen conditions led to a limited rosette biomass and seed yield. The latter was mainly due to reduced seed number, while seed weight was less affected. However, harvest index was lower in high nitrate compared with limited nitrate conditions. Under nitrogen-limiting conditions, nitrate reductase activity was decreased while glutamine synthetase activity was increased due to a higher accumulation of the cytosolic enzyme. The level of nitrogen remobilization to the seeds was higher under low nitrogen, and the vegetative parts of the plants remaining after seed production stored very low residual nitrogen. Through promoting nitrogen remobilization and recycling pathways, nitrogen limitation modified plant and seed compositions. Rosette leaves contained more sugars and less free amino acids when grown under nitrogen-limiting conditions. Compared with high nitrogen, the levels of proline, asparagine and glutamine were decreased. The seed amino acid composition reflected that of the rosette leaves, thus suggesting that phloem loading for seed filling was poorly selective. The major finding of this report was that together with decreasing biomass and yield, nitrogen limitation triggers large modifications in vegetative products and seed quality.
Mots clés
nitrogen remobilization efficiency
%P
partitioning
RSA
Nitrogen limitation nitrogen remobilisation glutamine synthetase nitrate reductase amino acid seed composition asparagine glutamine
Nitrogen limitation
nitrogen remobilisation
amino acid
seed composition
asparagine
glutamine
Asparagine -Glutamine synthetase -Nitrate reductase -Nitrogen limitation -Nitrogen remobilization -Seed composition DAS
days after sowing GABA
g-aminobutyric acid GS
glutamine synthetase HN
high nitrogen nutrition LN
low nitrogen nutrition NHI
nitrgen harvest index NR
nitrate reductase NRE
nitrogen remobilization efficiency %P
partitioning RSA
relative specific allocation
days after sowing
GABA
g-aminobutyric acid
GS
glutamine synthetase
HN
high nitrogen nutrition
LN
low nitrogen nutrition
NHI
nitrgen harvest index
NR
nitrate reductase
NRE
Domaines
Sciences du Vivant [q-bio]
Origine : Fichiers produits par l'(les) auteur(s)