| Research Abstract |
Relationships between self-incompatibility genotypes and stylar proteins were investigated by isoelectricfocusing polyacrylamide gel electrophoresis (IEF-PAGE) in Japanese pear (Pyrs serotina Rehad. bar. culta). A series of style-specific proteins corresponding to self-incompatibility genotypes(S-protein), S1-S5, were identified just at the cathodic end of the gel containing ph 3.5-9.5 ampholines. Thus, the pIs of these proteins seemed to be higher than 9.5, and each protein band was arranged from a cathodic end as follows ; S1, S4, S5, S2 and S3. Similar basic proteins were also present in the styles of P.communis, P.ussuriensis and Prunus, and thus similar mechamisms of self-incompatibility were suggested in order species of Rosaceae. These protein bands showed RNase activity, but the relation of the enzyme activity to self-incompatibility mechanisms was not clarified. Meanwhile, by inspecting banding patterns in S-genotype unidentified cultivars, we could assume the genotypes of 'Choju', 'Chikusui', 'Hohsui' and 'Kisui' to be S1S5, S3S4, S3S3 and S4S5, respectively. The S1-, S5- and S3-bands separated by IEF-PAGE, however, consisted of 3, 4 and 4 spots respectively when subjected to two-dimensional electrophoresis, suggesting that the protein either possesses several subunits or is a complex of several protein bands with exactly close pIs.
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