The distribution of microtubules was investigated in Nicotiana tabacum
pollen tubes at different stages of tube growth by immunofluorescence
microscopy. Using specific antibodies, the presence of microtubules c
onsisting of different tubulin isoforms was tested. alpha-, beta- and
tyrosinated alpha-tubulin were present within the tube, whereas the ac
etylated form was lacking. The presence of tubulin subunits in pollen
tube extracts was also investigated by immunoblotting analyses. The us
e of a confocal laser scanning microscope integrated with computer-ass
isted imaging, allowed a detailed visualization of the microtubule dis
tribution and organization. Cytoplasmic microtubules organized as shor
t bundles with various orientations were detected at the apex of long
tubes.