TY - JOUR
AU - Gojon, Alain
AB - Regulation of root N uptake by whole‐plant signalling of N status was investigated at the molecular level in Arabidopsis thaliana plants through expression analysis of AtNrt2.1 and AtAmt1.1. These two genes encode starvation‐induced high‐affinity NO3– and NH4+ transporters, respectively. Split‐root experiments indicate that AtNrt2.1 expression is controlled by shoot‐to‐root signals of N demand. Together with 15NO3– influx, the steady‐state transcript level of this gene is increased in NO3–‐fed roots in response to N deprivation of another portion of the root system. Thus AtNrt2.1 is the first identified molecular target of the long‐distance signalling informing the roots of the whole plant's N status. In contrast, AtAmt1.1 expression is predominantly dependent on the local N status of the roots, as it is mostly stimulated in the portion of the root system directly experiencing N starvation. The same behaviour was found for NH4+ influx, suggesting that the NH4+ uptake system is much less efficient than the NO3– uptake system, to compensate for a spatial restriction of N availability. Other major differences were found between the regulations of AtNrt2.1 and AtAmt1.1 expression. AtNrt2.1 is strongly upregulated by moderate level of N limitation, while AtAmt1.1 transcript level is markedly increased only under severe N deficiency. Unlike AtNrt2.1, AtAmt1.1 expression is not stimulated in a nitrate reductase‐deficient mutant after transfer to NO3– as sole N source, indicating that NO3–per se acts as a signal repressing transcription of AtAmt1.1. These results reveal two fundamentally different types of mechanism involved in the feedback regulation of root N acquisition by the N status of the plant.
TI - Differential regulation of the NO3– and NH4+ transporter genes AtNrt2.1 and AtAmt1.1 in Arabidopsis: relation with long‐distance and local controls by N status of the plant
JF - The Plant Journal
DO - 10.1046/j.1365-313x.2001.01016.x
DA - 2001-04-01
UR - https://www.deepdyve.com/lp/wiley/differential-regulation-of-the-no3-and-nh4-transporter-genes-atnrt2-1-ijptwF0rGv
SP - 143
EP - 155
VL - 26
IS - 2
DP - DeepDyve
ER -