Figure 1.

Cell-marker expression in wild-type and nov-1 root tips. (A and F) Expression of the columella initials marker J2341. In wild-type roots (A), J2341 is expressed strongly in the first tier of columella cells and very weakly in the quiescent center and other initials. In nov-1 roots (F), J2341 expression encompasses the first to third tiers of columella cells, the quiescent center and cortex/endodermis initial cells. (B, C, G and H) Expression of the ground-tissue marker J0571. In wild-type roots (B and C), J0571 is expressed in the cortex and endodermis and weakly in the quiescent center and cortex/endodermis initials. In nov-1 roots (G and H), J0571 expression is disrupted in the cortex and occasionally perturbed in the endodermis. (D, E, I and J) Expression of Q2500. In wild-type roots (D and E), Q2500 is expressed mainly in the endodermis, weakly in the pericycle and in the epidermis and cortex closer to the root stem-cell niche. In nov-1 roots (I and J), Q2500 expression is also disrupted in the epidermis and cortex. Seedlings used were vertically grown on the surface of 1.5% agar plates for 5 (B, C, G and H) and 7 (A, D–F, I and J) days. The reporter GFP expression (green) is shown with (magenta; A, B, D, F, G and I) and without (C, E, H and J) propidium iodide staining for cell boundary. Arrows in (A) and (F) indicate positions of the first tiers of columella cells. Asterisks in (B–E) and (G–J) mark positions of the cortex cell files. Scale bars = 20 µm [equal scale in (A and B) and in (B–E and G–J), respectively].