Determination of S-Genotypes of Pear (Pyrus pyrifolia) Cultivars by S-RNase Sequencing and PCR-RFLP Analyses

摘要

The pear (pyrus pyrifolia) has gametophytic selfincompatibility (GSI). To elucidate the S-genotypes of Korean-bred p[ear cultivars, whose parents are heterozygotes, the PCR amplification using S-RNase primers that are specific for each S-genotype was carried out in 15 Korean-bred pear cultivars and 5 Japanese-bred pear cultivars. The difference of the fragment length was shown in the following order: S_6(355 bp) < S_7(375 bp) < S_1(375 bp) < S_4(376 bp) < S_3 and S_5(384 bp) < S_8(442 bp) < S_9 (1, 323 bp) < S_2 (1, 355 bp). We analyzed the sequence of the S-RNase gene, which had introns of various sizes in the hypervariable (HV) region between the adjacent exons with a fairly high homology. The sizes of the introns were as follows: S_1 = 167 bp, S_2 = 1, 153 bp, S_3 = 179 bp, S_4 = 168 bp, S_5 = 179 bp, S_6 =147 bp, S_7 = 152 bp, S_8 = 234 bp, S_9 = 1, 115 bp. There were five conservative and five hypervariable regions in the introns of S_1, S_3, S_4, S_5, S_6 and S_7-RNases. A pairwise comparison of these introns of S-RNases revealed homologies as follows: 93.7% between S_1-and S_4-RNases, 93.3% between S_3- and S_5-RNases and 78.9% between S_6- and S_7-RNases. PCR-RFLP and S-RNases sequencing determined the S-genotypes of the pear cultivars. The S-genotypes were S_4S_9 for Shinkou, S_3S_9 for Niitaka, S_3S_5 for Housui, S_1S_5 for Kimizuka-wase, S_1S_8 for Ichiharawase, S_3S_5 for Mansoo, S_3S_4 for Shinil, S_3S_4 for Whangkeumbae, S_3S_? for Chengsilri, S_3S_5 for Gamro, S_3S_4 for Yeongsanbae, S_3S_4 for Wonhwang, S_3S_5 for Gamcheonbae, S_3S_5 for Danbae, S_3S_4 for Manpoong, S_3S_4 for Soowhangbae and S_4S_6 for Chuwhangbae. The information on the S-genotypes of pear cultivars will be used for the pollinizer selection and breeding program.