Figure 3.

Regional sectors of polarity within ordered cortical MT arrays. EB1b-GFP in BY-2 cells and Arabidopsis plants were analyzed microscopically as described in Figure 2. The asterisks mark specific MT comets to illustrate how growth trajectory was assessed (shown by the dotted arrows). The polarity of the cortical MTs in the last image is represented diagrammatically in the last panel. MT polarity bias is concentrated in different parts of the same cell (designated as sectors I and II). The dotted lines show the boundary areas not included in the quantization. Sector I in A shows 70% polarity oriented facing the top-left; whereas sector II shows 82% polarity oriented in the opposite direction. Similarly, sector I in B shows 79% polarity oriented facing the top-right, whereas sector II shows 77% polarity oriented in the opposite direction. Scale bar, 2 μm.