Figure 2.

Summary of signalling pathways underpinning root system architecture responses to nitrate or phosphate deficiency. Components of signalling pathways discussed in this review are shown as coloured boxes (genes) or circles (proteins). Arrows and bars indicate positive and negative regulation, respectively. Broken lines represent indirect pathways or circumstantial evidence. RSA targets (red boxes) are primary root (PR) growth, lateral root initiation (LR In), emergence (LR Em) and elongation (LR El), as well as root hair elongation (RH El). Cellular localization is indicated as cell wall (CW), plasma membrane (PM) or endoplasmic reticulum (ER). Root tissues and other features are coloured as detailed in the legend.