The Microtubule Cytoskeleton and Pollen Tube Golgi Vesicle

S-RNase is the female determinant of gametophytic self-incompatibility in apple and is usually considered to be the reason for rejection of pollen. In this study, we inves-tigated the role of microtubules (MTs) in internalization of S-RNases by pollen tubes cultured in vitro. The results showed that S-RNase was imported into the pollen tube where it inhibits pollen tube growth, and that S-RNase is co-localized with the Golgi vesicle during the internaliza-tion process. Moreover, MT depolymerization is observed following accumulation of S-RNases in the pollen cytosol. On the other hand, S-RNase was prevented from entering the pollen tube when the pollen was treated with the actin filament (AF) inhibitor latrunculin A (LatA), the MT inhibitor oryzalin, or the MT stabilizer taxol at sub-toxic concentrations. These hindered the construction o