Abstract: ‘Osa-Nijisseiki’ is a stylar-specific self-compatible (SC) mutant from 'Nijisseiki' which exhibit S-RNase-mediated gametophytic self-incompatibility. The mechanism underlying SC was not clear though many investigations have been carried out. In the present study, the S-RNase genes in ‘Osa-Nijisseiki’and its SC progenies were systematically investigated at genomic, transcriptional and translational level in comparison with its wild type, 'Nijisseiki'. Results showed that both ‘Osa-Nijisseiki’ and ‘Nijisseiki’showed no differences in performances of S2-RNase gene, but the former produced less S₄-RNase gene signals than the latter did. However, S₄-RNase genes were absent in progeny of 'Osa-Nijisseiki'. It could be concluded that S₄-RNase in ‘Osa-Nijisseiki’ gene does present in the genome and express, but could not be transmitted sexually.

Key words: pear, self-incompatibility, S-RNase gene, stylar-part mutant