Localization of actin in pollen tubes of Ornithogalum virens L.

The germinating pollen grain (in vivo on the stigma or in vitro in germinat ion medium) forms a pollen tube which transports the vegetative nucleus and generative cell/two sperm cells participating in the process of double fer tilization. The growth of the tube and the transport of organelles and the cells occur due to two major motor systems existing in the pollen tubes of higher plants: the tubuline-dynein/kinesin and the actin-myosin system. In pollen tubes of Ornithogalum vit ens the actin filaments were labelled with TRITC-phalloidin (2 mu g/ml) in the PIPES buffer and the 10% sucrose, with out the fixative and DMSO. Omission of the fixative and permeabilizing agen t (DMSO) allowed better preservation of the structure, and the "fluorescenc e" of actin was observed in living pollen tubes. Observations in CLSM (conf ocal laser scanning microscope) showed that actin is distributed in the vic inity of the cell membrane. This could support the view that actin filament s and the plasmalemma form the pollen tube cortex along which the cytoplasm ic movement of organelles, and cell transport occurs.