Effect on in Vitro Pollen Growth of an Isolated Style Glycoprotein Associated with Self-Incompatibility in Nicotiana alata

The effect on in vitro pollen tube growth of an isolated style glycoprotein (S(2)-glycoprotein) associated with self-incompatibility in Nicotiana alata was investigated. Tube growth of pollen bearing the S(2)-allele was inhibited, but tube growth of pollen bearing other alleles was not affected. Inhibition showed a dose response effect. The percentage of pollen grains that germinated was not significantly affected by the S(2)-glycoprotein. Growth of S(2)-pollen in the presence of the S(2)-glycoprotein resulted in increased binding to the pollen of monoclonal antibody (PCBC3) which has a primary specificity for alpha-l-arabinofuranosyl residues. Growth of pollen bearing other alleles in the presence of the glycoprotein resulted in no increased binding of the antibody.