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The conventional method to identify pear tree cultivars is to evaluate the morphological characteristics of the trunk, leaves, flowers, and fruit. However, it is difficult to distinguish between the closely related pear cultivars using only morphological traits, particularly if the cultivars to be compared share the same pedigree. Thus, we developed more reliable DNA markers to identify 39 pear cultivars bred in Korea and Japan. In total, 147 random amplified polymorphic DNA (RAPD) markers were developed from 40 different random primers. The resulting 51 RAPD fragments were selected, and their sequences were determined to convert them into sequence-characterized amplified region (SCAR) markers. As a result, 19 of 51 RAPD fragments were successfully converted to SCAR markers. A single polymorphic band of the same size as the RAPD fragments or smaller DNA fragments were amplified depending on primer combinations in the 17 SCAR markers, and co-dominant polymorphisms were observed using two of the SCAR markers (named PK10_514 and PK15_616). A combination of eight SCAR markers (P561_331, P561_372, PH02_405, PH15_ 452, PT16_472, PK10_514, P270_593, and PK15_616) provided sufficient polymorphisms to identify 25 Korean pear cultivars among the 39 pear cultivars tested. A combination of nine SCAR markers (P561_331, P561_372, PH02_ 405, PH15_452, PT16_472, PT14_578, P270_593, PK10_514, and PK15_616) could be used to sufficiently distinguish among the 39 pear cultivars examined in this study. These newly developed markers will be useful as a fast and reliable tool to identify Korean pear cultivars.

To prevent self-fertilization, apple has a gametophytic self-incompatibility mechanism, part of a widespread intraspecific system, that is controlled by a multi-allelic locus. This attribute has been exploited in breeding programs for new cultivars. Likewise, many apple orchards depend on artificial pollination. Therefore, molecular analysis and early identification of the self-incompatibility (S) genotype could greatly improve breeding schemes and pollen donors selection. Here, we PCR-amplified the S-RNase PCR fragments from a total of 14 cultivars and parents, using new primers (ASPF3+ASPR3) common to 23 S-alleles in apple. The S-genotypes were determined for the following: ‘Hongro’ (S1S3), ‘Gamhong’ (S1S9), ‘Saenara’ (S1S3), ‘Chukwang’ (S3S9), ‘Hwahong’ (S3S9), ‘Seokwang’ (S3S3), ‘Hwarang’ (S1S9), ‘Sunhong’ (S3S9), ‘S.E.B.’ (S1S19), ‘S.G.D.’ (S2S3), and ‘Mollie’s Delicious’ (S3S7). We also confirmed the characteristics of the S-genotypes for eight Korean apple cultivars by PCR-Southern blot analysis, using seven S-RNases as probes.

The pear cultivar ‘Osa-Nijisseiki’ (S2Ssm 4; sm = stylar-part mutant) has been used as a parent to breed self-compatible cultivars that produce excellent fruits. However, determination of the self-compatibility of ‘Osa-Nijisseiki’ offspring requires a lot of time, 6 years or more, by conventional cross breeding. We have designed a rapid reliable method for the identification of self-compatible varieties of ‘Osa-Nijisseiki’ offspring based on the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) with S-allele specific restriction endonucleases. By using this method, 8 self-compatible varieties were selected among 16 selections resulting from a cross between the self-compatible cultivar ‘Osa-Nijisseiki’ (S2Ssm 4) and the self-incompatible cultivars ‘Niitaka’ (S3S9), ‘Whasan’ (S3S5), ‘Chuwhangbae’ (S4S6). The S-genotypes of 16 ‘Osa-Nijisseiki’ offsprings were also determined.