Fig. 4.

Pi-starvation responsiveness of EZ2, an enhancer element present in the PLDZ2 promoter. (A) Structure of a chimeric promoter composed of a PLDZ2 Pi-responsive enhancer inserted upstream of the –46 35S minimal promoter to direct expression of GUS (EZ2::GUS). (B) Arabidopsis seedlings of a representative line harbouring PLDZ2::GUS and EZ2::GUS constructs grown for 10 days in media supplemented with 1 mM (P+) or 0 mM (P–), subjected to histochemical GUS assays, and photographed using Nomarsky optics. The name of each construct is indicated at the top of each set of three images, which show the expression pattern for cotyledons, lateral roots, and root apical meristems from top to bottom, respectively. Bars, 100 μm. (This figure is available in colour at JXB online.)