Figure 3.

Localization of Al-induced callose in wheat cv Scout 66 using immunogold labeling coupled with transmission electron microscopy. Ultrathin sections of peripheral root cells were incubated with a monoclonal antibody raised against 1→3-β-d-glucan followed by a second antibody conjugated with 15-nm gold particles. All images are from the 1- to 2-mm DFT and show callose particles preferentially at PD regions. Control cells showing few gold particles surrounding PD (A) and increased number of gold particles after Al (3 h, 20 μm) treatments (B), which decreased considerably when the roots received DDG prior to Al treatments (C). Number of arrows correspond to number of gold particles in a single PD (A–C). Representative pair of images from two independent experiments each comprising four to six individual root apices showing similar pattern. D, As a positive control, a single control cell sieve plate showing the antibody specificity. Sieve plates are known to be rich in callose (see also Fig. 2). Sieve cells have P-plastids containing protein crystals (arrows). Note the labeling restricted to defined sieve tubes (arrowheads) and other parts of the cell wall were not labeled. Scale bar represents 0.3 μm.