Glycoproteins are present in the styles of several self-incompatible species within the Solanaceae which segregate with particular alleles of the S-(self-incompatibility) gene. The amino acid sequences of style glycoproteins corresponding to different S-alleles of N. alata are homologous in some regions and variable in others. Homologous regions include N-terminal sequences as well as most of the glycosylation sites and cysteine residues. The isolated style S-glycoproteins inhibit in vitro growth of pollen tubes of several S-genotypes, with some specificity in the interaction. The isolated S-glycoproteins have ribonuclease activity which may be involved in their action in arrest of growth of incompatible (self) pollen.
Effect on in Vitro Pollen Growth of an Isolated Style Glycoprotein Associated with Self-Incompatibility in Nicotiana alata