Figure 3.

Auxin Response (GH3:GUS Expression) Is Localized to Dividing Cells during the Early Stages of Nodule and Pseudonodule Development.

(A) Auxin response in a mock-treated wild-type (A17) root.

(B) Auxin response is localized to the root hairs and underlying cortex directly below the root hairs of an A17 root spot-inoculated with E65 at 24 hpi.

(C) Cross section of (B).

(D) Auxin response in the dividing pericycle, endodermal, and cortical cells during early symbiotic stages in an A17 root inoculated with E65 at 48 hpi.

(E) Auxin response in a mock-treated cre1 mutant root.

(F) Auxin response is absent in the root cortex but present in the root hairs of a cre1 mutant root spot-inoculated with E65 at 24 hpi.

(G) Cross section of (F).

(H) In most of cre1 mutant roots, no cell divisions occur in response to E65 inoculation at 48 hpi.

(I) Dividing cells in cre1 mutants are associated with an enhanced auxin response and are observed in <5% of cre1 mutant roots inoculated with E65.

(J) and (K) Auxin response in the dividing cells of A17 (J) and cre1 (K) roots in response to TIBA treatment.

(L) to (O) Auxin response in a cre1 nodule primordium rescued with naringenin (L), isoliquiritigenin (M), kaempferol (N), and quercetin (O).

(P) No enhanced auxin response or cell divisions were observed in hesperetin-treated roots.

Arrowheads indicate nodule primordia. Arrows indicate auxin response in the root hairs and/or the root cortex. At least 30 individual samples were observed for each treatment. Horizontal and vertical scale bars represent 100 µm and 1 mm, respectively. ep, epidermis; c, cortex; en, endodermis; p, pericycle.