Fig. 4.

Analysis of pH distribution in pollen tubes grown for 5 h in sucrose- and glycerol-based media. (A) The pH in pollen tubes grown under standard conditions is relatively low (acid) at the apex but increases (becomes more basic) in the subapex and shank of pollen tubes. (B) In pollen tubes grown in glycerol-based medium, the pH is relatively constant along the tube. (C) Measurement of the fluorescence signal from the apex along the axis of pollen tubes. The graph illustrates the differences in pH distribution in pollen tubes grown in different growth media. Values were normalized against the background and referred to the highest value, which was set as 100 %. Scale bars = 10 μm.