Fig. 1.

Schematic summary of the P signalling and homeostasis pathway in plants. Upon Pi deficiency, expression of the miRNA miR399 is induced in the shoot. miR399 moves downwards, inactivating PHO2 in the roots. Regulation of PHO2 prevents the degradation of the Pi transporters PHO1 and PHT1, which increase Pi uptake and translocation. Pi deficiency also induces the expression of IPS1, which binds miR399, modulating this response. Based on Puga et al. (2017). (This figure is available in colour at JXB online.)