Myosin associated with the surfaces of organelles, vegetative nuclei and generative cells in angiosperm pollen grains and tubes

Myosin, detected by immunofluorescence using an antibody to bovine skeletal and smooth muscle myosin, has been localised on individual identifiable organelles from the grasses Alopecurus praten-sis and Secale cereale, and on the surfaces of vegetative nuclei and generative cells from pollen and pollen tubes of Hyacinthus orientalis and Hel-leborus foetidus. Taken in conjunction with recent evidence showing that the growing pollen tube contains an actin cytoskeleton consisting of numerous mainly longitudinally oriented microfilament bundles, and that isolated pollen-tube organelles show ATP-dependent movement along the actin bundles of the giant cells of the characeous algae, this finding suggests that an actomyosin motility system is present in pollen tubes, and indicates that the movements of the different classes of inclusions are driven by interaction of the surface myosin with the actin fibrils at the zones of contact.