Figure 4.

Compartment specific ascorbate labeling density after long term light stress. Graphs show the amounts of gold particles bound to ascorbate per μm² in mesophyll cells of Arabidopsis thaliana Col-0 plants (black squares) and the Arabidopsis mutants pad2-1 (black circles) and vtc2-1 (black triangles) after the exposure to different light intensities for 14 d. n > 20 for peroxisomes and vacuoles and n > 60 for other cell structures. Data are means with standard errors. Significant differences were calculated within one line of plants between control conditions (exposure to 150 μmol m^-2 s^-1) and the same line exposed to the other light intensities by using the Mann Whitney U-test; *, ** and ***, respectively, indicate significance at the 0.05, 0.01 and 0.001 levels of confidence.