Details

Autor(en) / Beteiligte

• Lejay, Laurence
• Tillard, Pascal
• Lepetit, Marc
• Olive, Francesc Domingo
• Filleur, Sophie
• Daniel‐Vedele, Françoise
• Gojon, Alain

Titel

Molecular and functional regulation of two NO3– uptake systems by N‐ and C‐status of Arabidopsis plants

Ist Teil von

• The Plant journal : for cell and molecular biology, 1999-06, Vol.18 (5), p.509-519

Ort / Verlag

Oxford, UK: Blackwell Science Ltd

Erscheinungsjahr

1999

Link zum Volltext

Quelle

Wiley Online Library Database Model

Beschreibungen/Notizen

• Summary Root NO 3 – uptake and expression of two root NO 3 – transporter genes ( Nrt2;1 and Nrt1) were investigated in response to changes in the N‐ or C‐status of hydroponically grown Arabidopsis thaliana plants. Expression of Nrt2;1 is up‐regulated by NO 3 – starvation in wild‐type plants and by N‐limitation in a nitrate reductase (NR) deficient mutant transferred to NO 3 – as sole N source. These observations show that expression of Nrt2;1 is under feedback repression by N‐metabolites resulting from NO 3 – reduction. Expression of Nrt1 is not subject to such a repression. However, Nrt1 is over‐expressed in the NR mutant even under N‐sufficient conditions (growth on NH 4 NO 3 medium), suggesting that expression of this gene is affected by the presence of active NR, but not by N‐status of the plant. Root 15 NO 3 – influx is markedly increased in the NR mutant as compared to the wild‐type. Nevertheless, both genotypes have similar net 15 NO 3 – uptake rates due to a much larger 14 NO 3 – efflux in the mutant than in the wild‐type. Expressions of Nrt2;1 and Nrt1 are diurnally regulated in photosynthetically active A. thaliana plants. Both increase during the light period and decrease in the first hours of the dark period. Sucrose supply prevents the inhibition of Nrt2;1 and Nrt1 expressions in the dark. In all conditions investigated, Nrt2;1 expression is strongly correlated with root 15 NO 3 – influx at 0.2 m m external concentration. In contrast, changes in the Nrt1 mRNA level are not always associated with similar changes in the activities of high‐ or low‐affinity NO 3 – transport systems.