Detection and inheritance of a stylar protein associated with a self-incompatibility genotype of Japanese pear

Summary Stylar proteins in 6 cultivars of Japanese pear (Pyrus serotina Rehd.) with different self-incompatibility alleles were examined by isoelectricfocusing polyacrylamide gel electrophoresis (IEF-PAGE). Cultivars used involved 1 self-compatible mutant Osa-Nijisseiki obtained from Nijisseiki (S₂S₄). Banding patterns of proteins were almost the same among the 6 cultivars except for 3 bands; one of which associated clearly with self-incompatibility S₂-allele (hereafter the protein referred to as S₂-protein) and was easily detectable because of its large amount and its pI value differed from many other proteins. Two other bands were seemingly associated with S₃- and S₄-alleles, respectively. The S₂-protein was apparently present in the styles of Osa-Nijisseiki.The inheritance of S₂-protein was studied by using 15 selfed plants of Osa-Nijisseiki. Eight out of 15 plants possessed the S₂-protein as a major component of the stylar proteins and 3 plants as a minor component. The remainder 4 plants did not have the protein. This result may support that the S₂-protein is the actual S₂-gene product.Abbreviations IEF-PAGE isoelectrifocusing polyacrylamide gel electrophoresis - CBB Coomassie Brilliant Blue