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Auxin‐mediated nitrate signalling by NRT 1.1 participates in the adaptive response of A rabidopsis root architecture to the spatial heterogeneity of nitrate availability
Author(s) -
MOUNIER EMMANUELLE,
PERVENT MARJORIE,
LJUNG KARIN,
GOJON ALAIN,
NACRY PHILIPPE
Publication year - 2014
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12143
Subject(s) - auxin , nitrate , lateral root , chemistry , meristem , psychological repression , arabidopsis , microbiology and biotechnology , botany , biochemistry , biology , mutant , gene , gene expression , organic chemistry
To optimize their nitrogen nutrition, plants are able to direct root growth in nitrate‐rich patches. This depends in A rabidopsis on the NRT 1.1 nitrate transporter/sensor. NRT 1.1 was shown to display on homogenous medium, an auxin transport activity that lowers auxin accumulation in lateral roots and inhibits their growth at low nitrate. Using a split‐root system, we explored the hypothesis that preferential lateral root growth in the nitrate‐rich side involves the NRT 1.1‐dependent repression of lateral root growth in the low nitrate side. Data show that NRT 1.1 acts locally to modulate both auxin levels and meristematic activity in response to the low nitrate concentration directly experienced by lateral roots leading to a repression of their growth. A stimulatory role of NRT 1.1 in the high nitrate side, which does not rely on changes in auxin levels, is also observed. Altogether, our data suggest that NRT 1.1 allows preferential root colonization of nitrate‐rich patches by both preventing root growth in response to low nitrate, through modulation of auxin traffic, and stimulating root growth in response to high nitrate, through a yet uncharacterized mechanism. In addition, transcriptional regulation of NRT1.1 affects both mechanisms allowing plants to modulate the effect of nitrate on root branching.