Figure 2.

LBD18 Binds the E2Fa Promoter and Is Induced upon Lateral Root Initiation.

(A) and (B) Interaction of LBD18 with the E2Fa promoter in yeast (A) and in planta (B) as shown by yeast one-hybrid assay and ChIP, respectively. No association was observed with promoters of the closely related genes E2Fb, E2Fc, and DEL1. Interaction of LBD18 was truly positive when both HIS3 (growth on 3-aminotriazole [+ 3-AT] medium) and LacZ (β-galactosidase [X-gal] positive) expression were induced.

(C) Confocal microscope images of ProLBD18:NLS-GFP counterstained with PI during lateral root initiation. Time of NAA treatment (5 μM) is indicated in the top left corner. Bar = 50 μm (all photomicrographs are at the same magnification).

(D) ProLBD18:GUS expression during different lateral root development stages: before asymmetric division (left), at stage I (middle), and at stage IV (right) . Bar = 50 μm (all photomicrographs are at the same magnification).

(E) Root cross section showing GUS staining in XPP cells. Bar = 50 μm.

(F) LBD18 transcript accumulation upon synchronized lateral root initiation. Data are mean ± se (n = 3).