High-Resolution Imaging of Arabidopsis Root Tips

5 DAG Arabidopsis seedling root tips were cut and high-pressure freezing/frozen by the high-pressure freezer (EM PACT2, Leica, Germany) prior to subsequent freeze substitution in acetone containing 0.4% uranyl acetate at −85 °C in an AFS freeze-substitution unit (Leica, Wetzlar, Germany). After gradient infiltration with increasing concentration of HM20, samples were embedded and ultraviolet polymerized for ultra-thin sectioning^{48 (link),78 (link)}. TEM analysis was performed by observing the ultra-thin section on the grids under the 80 kV Hitachi H-7650 transmission electron microscope (Hitachi High-Technologies Corporation, Japan) with a charge-coupled device (CCD) camera.