Figure 3.

Auxin response in the maize root visualized by DR5::RFP. (a) Longitudinal section through the root tip. (b–e) Subsequent transverse sections through the apical 5 mm of the root tip. (b) Signal appears first in the precursors of the late meta-xylem. (d) Signal appears in the proto- and early meta-xylem. (d) An auxin response maximum is formed at the phloem poles. Inset shows that RFP is visible in the cells between the proto-phloem (*) and the (future) phloem (Ph). No signal in the pericycle (Pc). (e) At 5 mm from the tip, signal at the phloem poles still remains. (f–h) Auxin response during lateral root formation. (f) In early stages, signal is found in dividing pericycle and endodermis cells. (g) An auxin response maximum is formed at the tip of the growing primordium. (h) Auxin response maxima at the level of vascular connection with the parent root. Scale bars: (a,e) 200 µm; (b–d, f–h) 100 µm.