Figure 3.

Phenotypes of the Wild Type and the txr1 Mutant (Line BF1) Grown in the Presence of Thaxtomin.

(A) to (F) Phenotypes of wild-type and txr1 mutant seedlings after growth on 100 nM thaxtomin for 6 days.

(A) and (D) Aspects of a wild-type seedling (A) and a txr1 mutant seedling (D).

(B) and (E) Bright-field magnification of a wild-type hypocotyl with drastically swollen, unordered cells (B) and a txr1 mutant hypocotyl with normal, straight cell files (E).

(C) and (F) Aspects of shoot apices in the wild type (C) and the txr1 mutant (F). Wild-type shoot apices display drastic cell swelling and severely disturbed organ formation, whereas the shoot apex of txr1 develops normally. Arrowheads in (C) indicate the location where true leaves normally would emerge.

(G) to (I) Phenotypes of dark-grown, 5-day-old wild-type seedlings.

(G) Thaxtomin concentrations of 50 nM (middle) and 100 nM (right) clearly inhibit hypocotyl elongation compared with seedlings that grew in the absence of the phytotoxin (left). Root elongation is unaffected under these conditions.

(H) Etiolated seedlings grown in the absence of thaxtomin have slim hypocotyls and closed cotyledons.

(I) Etiolated seedlings grown with 100 nM thaxtomin show swelling symptoms in the upper part of the hypocotyls and the petioles of the cotyledons, forcing the cotyledons to open.