Figure 4.

Concentration-dependent and temporal expression of Pi transporters. A, Arabidopsis plants grown in liquid culture for 7 d were transferred to medium containing indicated amounts (μm) of Pi. Five days after the treatment, plants were harvested and stored at −70°C. Total RNA extracted from the plants was subjected to northern analysis with AtPT1 and AtPT2 cDNAs as probes. The ethidium bromide-stained gel below shows uniform loading of RNA samples. B, Seven-day-old Arabidopsis plants grown in liquid culture were subject to Pi starvation for indicated time. Total RNA was extracted and subjected to northern analysis with labeled AtPT1 and AtPT2 cDNAs as probes