Nitrate sensing and signaling in plants

Nitrate (NO3-) is a major nutrient for plants, taken up by their roots from the soil. Plants are able to sense NO3- in their environment, allowing them to quickly respond to the dramatic fluctuations of its availability. Significant advances have been made during the recent period concerning the molecular mechanisms of NO3- sensing and signaling in the model plant Arabidopsis thaliana. The striking action of NO3- as a signal regulating genome expression has been unraveled. Note worthily, NO3- sensing systems have been identified. These correspond to membrane transporters also ensuring the uptake of NO3- into root cells, thus generalizing the nutrient 'transceptor' (transporter/receptor) concept defined in yeast. Furthermore, components of the downstream transduction cascades, such as transcription factors or kinases, have also been isolated. A breakthrough arising from this improved knowledge is a better understanding of the integration of NO3- and hormone signaling pathways, that explains the extraordinary developmental plasticity of plants in response to NO3-. (C) 2012 Elsevier Ltd. All rights reserved.