Endocytosis and membrane recyling in pollen tubes

In plants, tip-growing cells are an ideal system to investigate signal transduction mechanisms and, among these, pollen tubes are one of the favourite models. Many signalling pathways have been identified during germination and tip growth and, not surprisingly, the apical secretory machinery, essential for tip growth, seems to be an intersection point for all these pathways. Here we review previous data on the pollen tube endocytic machinery and its coupling to the exocytic delivery of new cell wall material. Additionally, we discuss new methodologies and how these are shaping our current working hypothesis to explain endocytosis in pollen tubes.