Differential localization of GFP-ATM1(IQ-tail) in root cells. Serial optic sections (30–70, 0.8 μm apart) of roots were acquired by confocal microscopy. A. Root of 5-day-old seedling. Scale bar: 50 μm. B. Lateral root of 20-day-old seedling. Scale bar: 20 μm. C(1) and C(2). Two images of the same 20-day-old seedling root. C(1) shows the root cap, scale bar: 20 μm, and C(2) shows the upper part. Scale bar: 50 μm. A similar pattern of GFP-ATM1 localization is seen in all roots: diffuse at the root cap, then dots, then more polarized organization along the transverse sides. D. GFP-ATM1 in root hair, scale bar: 10 μm. Arrows show the direction of the root caps.