Pulsating ion fluxes and growth at the pollen tube tip.

Reproduction in higher plants requires the directed growth of pollen tubes in order to transmit sperm cells to the ovules at the base of the style. Many signaling processes have been implicated in polarized pollen tube growth. Here, changes in the concentration of calcium, potassium, hydrogen (pH), and chloride are discussed, as they may all contribute to the process of oscillatory growth and guidance observed in pollen tubes.