Figure 2.

ABA affects PIN distribution and subcellular dynamics. a) The effect of ABA on root basipetal auxin transport. Six‐day‐old seedlings were subjected to 30 × 10⁻⁶ m ABA for 12 h. Basipetal auxin transport in the root was detected using [³H]‐labeled IAA (n = 12 roots). b,c) The effect of ABA on the gravistimulation‐mediated PIN2 gradient. PIN2 immunolocalization was performed in 4‐d‐old seedlings gravistimulated for 4 h in the presence or absence of 30 × 10⁻⁶ m ABA. Relative PIN2 signal intensity in the epidermis at the upper versus lower side of the root was quantified (c; n = 10 roots). Arrows mark PIN2 gradient. Scale bar: 10 µm. d,e) The effect of ABA on BFA‐induced PIN2 internalization. PIN2 immunolocalization was performed in 4‐d‐old seedlings pretreated or not with 30 × 10⁻⁶ m ABA for 3 h and then cotreated with 25 × 10⁻⁶ m BFA for 60 min. Mean surface area (pixels²) of BFA bodies per cell in root epidermis was quantified (e; n ≥ 62 cells). Arrowheads mark PIN2 internalized into BFA compartments. Scale bar: 10 µm. Error bars represent ± SE (a,c,e). (∗) P < 0.05, (∗∗) P < 0.01 (Student's t‐test). Three independent experiments were performed with similar results. Representative images are shown.