Figure 11.

Distribution of callose in Spm-treated pear pollen tubes. (A) A control pollen tube showing absence of callose in the tip. (B) In balloon-shaped pollen tubes, callose accumulates in the neck region (arrows). (C) In snake-shaped pollen tubes, callose still accumulates in the neck region and it is still absent from the tip. (D) In shovel-shaped pollen tubes, callose showed a consistent accumulation around 20–30 μm, as also shown by the relative fluorescence intensity (E). The square bracket in (D) corresponds to the region indicated by the square bracket in the graph of (E). Bars: 10 μm. Data are representative of three independent experiments.