Molecular mechanisms of nitrogen dose signaling in Arabidopsis roots

Nitrogen (N) is often a limiting nutrient in plant growth. Consequently, increasing soil N content – for example through fertilizer use - leads to proportional changes in plant biomass, root architecture, and grain yield. While such nutrient dose responses play a central role in crop agriculture, how plants are able to signal nutrient status quantitatively at the molecular level remains largely unexamined. Here, we assay the Arabidopsis root transcriptome in response to changes in N-dose availability. We find that Arabidopsis N-signaling transcriptomic responses are proportional to the amount of N provided. Through our analysis we identify and characterize HHO5, a transcription factor involved in mediating the amplitude of N-dose responses both at the transcript and phenotypic level.