Figure 3.

Effect of water stress on distribution of acidification along root elongation zones. A, Color bar based on images of indicator gel with buffers at indicated pH. B, Images of root tips from control seedlings 0 and 5 min after contact with agar gel containing bromocresol purple pH indicator at pH 6.3. Yellow zones indicate acidification. b, Digital posterization of original root tip images reveals regions of intense acidification. C and c, Equivalent images before and after posterization for root tips of seedlings after 2-d water-deficit treatment. Vertical scale bar in c represents 1 mm. D, Color bar shows the range of pixel ratios in relationship to pH as determined by confocal laser scanning microscopy. E1, E2, and E3 show pseudo color images of pH distribution in epidermal cell walls of control plants at 2 to 3, 4 to 5, and 7 to 8 mm from the root tips. F1, F2, and F3 represent equivalent images from roots after water deficit for 2 d. Horizontal bar in F3 = 10 μm.