Figure 2. Summary of potential roles played by phloem nitrate in signaling for growth regulation . This figure is a simplification and does not mention transporters involved in nitrate transport and sensing (see text for further details). Pathways are sub-divided into xylem (green) and phloem (red) mediated signaling. Abbreviations: CaPK, calcium-dependent protein kinases; CEP, C-terminally encoded peptide; CEPD, CEP downstream; NLP, NIN-like proteins; ROS, reactive oxygen species.