S-specific proteins in styles of self-incompatible Nicotiana alata

A comparison of the stigma protein patterns of individual plants of the inbred- and cross-progenies in Nicotiana alata by isoelectric focusing revealed the presence of S-specific proteins. The S allele-protein relationship was found for three different S alleles. The S-specific proteins occurred in both stigma and stylar parts of the pistil whereas they were absent in leaves. In clone OWL the concentration of S-specific proteins in the stigma increased gradually during floral development. The shift from compatibility to incompatibility was not accompanied by an abrupt increase in concentration of the S-proteins.