EMMANUELLE MOUNIER, MARJORIE PERVENT, KARIN LJUNG, ALAIN GOJON and PHILIPPE NACRY
This manuscript deals with the characterisation of the mechanism controlling in Arabidopsis the adaptive developmental response of the roots to the spatial heterogeneity of nitrate availability resulting in a preferential root colonisation of the N-rich patches of the soil
We recently demonstrated that the dual-affinity nitrate transporter NRT1.1 that acts as a nitrate sensor does not transport only nitrate, but also facilitates influx of the phytohormone auxin leading to a modification of its gradients within the root system and then regulating lateral root emergence.
Using a split-root system (low nitrate on one side, high nitrate on the other side), we show that NRT1.1 controls root colonization of nitrate-rich patches by on the one hand, specifically repressing lateral root development in the low nitrate side by lowering auxin levels in priomordia and lateral root tips, and on the other hand stimulating root growth on high nitrate side through a yet uncharacterized mechanism which does not rely on changes in auxin levels.
These results make a clear connection between the original molecular/cellular mechanisms of nutrient sensing we recently identified and the integrated response of the plant to a major environmental constraint in agro-ecosystems and gives a novel view on how plants deals with nitrate patchiness in soil and mixed N nutrition.