Figure 9

Expression of the ANN2::green fluorescent protein (GFP) fusion in root tips of wild type (WT) and pin 2 mutant background seedlings. Longitudinal opitical sections through root tips of 6-day old WT (a-d) and pin 2 (e-h) seedlings subjected to the horizontal clinorotation(H) or hypergravity (G) condition in comparison with its controls under 1 g stationary control (S) or the vertical clinorotation (V) conditions. a, b and c, Representative images of WT root tips depicting a meristematic columella initial cell (M), and three stories of derived columella cells (nos. 1,2 and 3). Most of the GFP signal was confined to the lateral root cap (LRC) cells and to a lesser extent to the columella cell region in plants grown under the S, V and H conditions, respectively. d, Representative images of ANN2::GFP expression in wild-type roots exposed to 7 g hypergravity treatment. Note that a strong GFP signal is seen both in columella cells and lateral root cap cells. e and f, Representative images of ANN2::GFP expression in pin2 roots under the control conditions (S and V). g and h, Representative images of pin2 root tips under H and G condition, respectively. Note the increase in GFP signal in the first and the second tier columella cells. Arrows indicate direction of gravity. Bars = 20 μm.