Figure 4.

Y898F, Y945F, and Y956F Mutations Impair BRI1 Endocytosis.

(A) and (C) Images of epidermal cells from root meristems of 5-d-old transgenic Arabidopsis seedlings expressing different BRI1 mutants tagged with mCitrine (mCit) pretreated with CHX (50 μM) for 1.5 h (A) or pretreated with CHX (50 μM) for 1 h, followed by a combined treatment with CHX (50 μM) and BFA (50 μM) for 30 min (C). Green fire blue LUT in ImageJ was applied to the images to enhance contrast and highlight the differences between different transgenic lines. Bars = 5 μm.

(B) and (D) Measurements of the relative PM BRI1-mCitrine (BRI1-mCit) fluorescence (B) and BFA body size (D). For each transgenic line, at least 50 cells from five seedlings were measured.

(E) Time of residency in the PM of BRI1-mCitrine (BRI1-mCit). The box plot was based on kymograph analysis of at least 100 tracks from five cells of at least three seedlings.

In (B), (D), and (E), box plots show the first and third quartiles, split by the medians (lines), with whiskers extending 1.5-fold interquartile range beyond the box. P-values (one-way ANOVA and Tukey’s post hoc), *P < 0.05, **P < 0.01 relative to BRI1-mCit;bri1.