The pollen tube: A model system for cell and molecular biology studies

Abstract

Pollen tubes, the active male gametophytes of seed plants, are the vectors carrying the male sperm cells to the egg cell of the female gametophyte in the ovules of seed plants. Unlike most plant cells in which growth occurs by modification of the existing wall and the insertion of new material throughout its surface, pollen tubes extend strictly at their apex, undergoing a specialized type of growth called tip growth. Consequently, these cells exhibit a highly asymmetric functional behaviour in processes such as ion fluxes, secretion, wall assembly and cytoskeletal arrangements. This spatial segregation is very attractive for cell biology studies. But the pollen tube can also be regarded as a single haploid cell carrying the sperm cells and thus of great interest for genetical and molecular studies. Last, but not least, pollen is easy to germinate under in vitro conditions, where tubes can grow extremely rapid, making it accessible to application of a wide range of technologies. Therefore, it stands as an ideal system for cell and molecular studies. Here I review some of the basic concepts of pollen tube growth (which are thoroughly discussed in subsequent chapters), address current paradigms and how these are likely to be challenged by recent data that stress how dynamic these cells are. © Springer-Verlag Berlin Heidelberg 2006.