Figure 6.

BRI1 Endocytosis in Arabidopsis Roots.

(A) and (B) Confocal images of root from 7-d-old Pro_BRI1-BRI1-GFP transgenic seedling. BRI1-GFP signal is detected internalized in the cells immediately adjacent to the quiescent center ([A], arrowhead) and in the meristem zone as shown in (B).

(C) A confocal image of root meristem from bak1/serk3 mutant seedlings expressing Pro_BRI1-BRI1-GFP construct.

(D) and (E) Confocal images of wild-type BRI1-GFP expressing roots after BFA application in the presence of CHX (D) followed by 2 h washing out in (E). Note the BFA-induced accumulation of BRI1-GFP indicated by an arrowhead.

(F) to (H) Confocal images of FM4-64–stained root meristem area. BRI1-GFP fluorescence (green) is shown in (F). FM4-64–stained cells (red) are shown in (G). The combined images of (F) and (G) resulted in (H). Arrowheads mark vesicles colabeled by both BRI1-GFP and FM4-64.

(I) to (K) Confocal images of protoplasts derived from 7-d-old Pro_BRI1-BRI1-GFP transgenic seedling.

(I) Root protoplasts expressing BRI1-GFP.

(J) Protoplasts from the aerial part of the seedling expressing BRI1-GFP.

(K) Mixture of root and shoot protoplasts expressing BRI-GFP after BFA application. Note the formation of BFA compartments only in the chlorophyll-free cells (arrowhead). Bar = 10 μM.