Fig. 7. gnom^R5 defects in lateral root formation correlate with an inability to establish transport-dependent auxin-response gradients. (A-H) Different stages of wild-type lateral root development. (A-D) PIN1 signals, (E-H) DR5::GUS signals. (A,E) stage I, (B,F) stages III-IV, (C,G) stage VI, (D,H) emerged lateral root. Arrows indicate borders of peripheral cells without PIN1. Staging according to Malamy and Benfey (Malamy and Benfey, 1997). (I-L) Wild-type treated with 0.1 µM 2,4-D. (I,J) PIN1 signals, (K,L) DR5::GUS signals. (I,K) One- or two-layered dividing pericycle, (J,L) multi-layered division zone. (M-P) gnom^R5 treated with 0.1 µM NAA. (M,N) PIN1 signals, (O,P) DR5::GUS signals. (M,O) One- or two-layered dividing pericycle, (N,P) multi-layered division zone.