Figure 2.

Effect of P availability on both primordia number and meristematic activity. A, Histochemical GUS staining of transgenic (CycB1::GUS) Arabidopsis plants that were cultivated on high (1 mm) or low (3 μm) P medium on vertically oriented agar plates. Meristematic activity was estimated according to staining intensity; plain boxes correspond to emerged LRs, black dots represent intensely stained primordia, and white dots correspond to weakly stained primordia. Bar = 1 cm. B and C, Schematic representation of individual entire PRs (B) of plants grown on high or low P medium for 9 d or apical part of the PR (C) of a 14-d-old plant that had developed after d 9. Bars = 1 cm.