DETECTION AND INHERITANCE OF A STYLAR PROTEIN ASSOCIATED WITH A SELF-INCOMPATIBILITY GENOTYPE OF JAPANESE PEAR

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.