摘要
A new S9-allele was discovered in 6 Japanese pear cultivars, `Shinkou', `Shinsei', `Niitaka', `Amanogawa', `Nangetsu' and `Nansui'. cDNA encoding S9-RNase, a stylar product of S9-allele, was cloned from pistils of `Shinkou' and `Shinsei' by 3' and 5' RACE. The S9-RNase gene had anopen reading frame of 684 nucleotides encoding 228 amino acid residues. S9-RNase had a hypervariable (HV) region different from S1- to S8-RNase and shared higher similarity (95.2%) with apple S3-RNase than with 8 Japanese pear S-RNases (from 61.0% to 70.7%). Genomic PCR with primers `FTQQYQ' and `anti-(I/T) IWPNV' provided S1- to S9-amplicon(product), but could not discriminate the S2 from the S9 of ca. 1.3 kb. The S2 and S9 were distinguished by digestion with AflIIand BstBI, respectively. The digestion with nine S-allele-specific restriction endonucleases, SfcI, AflII, PpuMI, NdeI,AlwNI, HincII, AccII, NruI and BstBI, distinguished S1 to S9, establishing that this PCR-RFLP system is useful for S-genotype assignments in Japanese pear harboring S1- to S9-allele. `Shinkou', `Shinsei', `Nangetsu' and `Nansui' assigned as S4S9 were determined to be cross incompatible.