Figure 2.

Effect of MONOPTEROS (MP) on lateral root normalization and PIN FORMED1 (PIN1) activation in Arabidopsis.

(a–f) PIN1-GFP in lateral root primordia (LRPs) of 4-to-5d after germination (DAG) seedlings (distal tip to the right). (a–c) Wild type and (d–f) mp nph4 MP-GR^er LRPs (with rainbow spectrum look-up-tables) transferred to 15μM dexamethasone (DEX) at 0min. Ratios of LRPs exhibiting the depicted PIN1-GFP distribution and intensity are shown. LRPs that differed from images depicted in (d–f) did not show an increase in PIN1-GFP expression. Transverse and lateral cell membranes are denoted by white and red arrowheads, respectively.

(g,h) 9DAG seedlings germinated and grown without DEX for 6d, then transferred to 15μM DEX for 3d. When transferred at 6DAG, the primary root tip (arrow) had ceased growth and disorganized lateral outgrowths had initiated. Arrowheads point to emerging lateral roots.

(i) Time course of mp nph4 MP-GR^er lateral root outgrowth transferred to 30μM DEX at 0h. Asterisks denote an emerging lateral root. 24h and 36h pictures are composites of two images (separated by white lines) at different focal planes.

(j) PIN1-GFP expression in mp nph4 MP-GR^er lateral root outgrowths of 8DAG seedlings transferred to 30μM DEX at 0h.

Bars: (a–f) 20μm; (g) 1mm; (h) 0.5mm; (i) 0.2mm; (j) 50μm.