A STYLE-SPECIFIC 120-KDA GLYCOPROTEIN ENTERS POLLEN TUBES OF NICOTIANA-ALATA IN-VIVO

Pistils of Nicotiana alata (Link et Otto) contain an abundant, style-s pecific glycoprotein (120 kDa) that is rich in hydroxyproline and has both extensin-like and arabinogalactan-protein-like carbohydrate subst ituents. An antibody specific for the protein backbone of the glycopro tein was used to localise the glycoprotein in both unpollinated and po llinated pistils. The glycoprotein is evenly distributed in the extrac ellular matrix of the style transmitting tract of unpollinated pistils and, despite the presence of extensin-like carbohydrate substituents, is not associated with the walls of the transmitting tract cells. In pollinated pistils the 120-kDa glycoprotein is concentrated in the ext racellular matrix adjacent to pollen tubes, and is also present in the cytoplasm and the cell walls of pollen tubes. Pollen tubes grown in v itro do not contain the 120-kDa glycoprotein unless it is added to the growth medium, suggesting that the 120-kDa glycoprotein located in pi stil-grown pollen tubes is derived from the extracellular matrix of th e transmitting tract.