Abstract: A new self2incompatibility gene, which contains an open reading frame of 681 nucleotides en
coding a 227 amino acid protein, was isolated from Pyrus bretschneideri cultivars of Zaosu by rap id amp lifica
tion of cDNA ends (RACE). DNA sequece analysis revealed that the isolated gene contains the specific se
quences of S-RNase, such as conserved histidines and cysteines, hypervariable region and conserved regions.
It displayed the highest homology of 94% with the embodied S₄-RNase (AB014072). The new S-allele was
named S₃₅-RNase and its accession number wasDQ224344 in GenBank. The northern blot analysis indicated
that this gene only exp ressed in p istil, with a higher exp ression level at the balloon stage than at the stage of 3
days before or after flowering.

Key words: Pyrus bretschneideri, Rapid amplification of cDNA ends, Self2incompatibility, S₃₅-RNase, Northern blot