‘Jinhyang’ is a fragrant pear bred in 2019. Field crossings to breed fragrant pears were conducted in 1984 at the Pear Research Center of the National Institute of Horticultural and Herbal Science. The maternal and paternal parents were ‘Okusankichi’ (IT254489) and ‘Hori’ (IT226291), respectively. The 84-16-5 line, which had a good fragrance, was first selected in 2007, and regional adaptation tests were conducted from 2011 to 2019 in five regions (Suwon, Chuncheon, Jinju, Yecheon, and Naju). The morphological characteristics of ‘Jinhyang’ include vigorous spreading tree form, brown-colored one-year-old shoot, elliptical leaf blade, round leaf tip, and white-colored flowers. The full bloom date was April 11, and the harvest date was in late September. The fruit of ‘Jinhyang’ weighs 439.9 g and has a soluble solid content of 13.0 °Brix, with a good sugar-acid balance and abundant juice. Analysis of the fragrance components of ‘Jinhyang’ revealed the presence of a large amount of fragrant volatile compounds compared to that of the standard cultivar ‘Niitaka’. In particular, ‘Jinhyang’ contains ethyl hexanoate and ethyl butanoate, which are known volatile compounds generated by pineapple and mango. Because of its strong uprightness, cultivation management, such as shoot bending, is necessary to maintain flower buds (Registration No. 9387).

“CenSall” is a cultivar that can be easily consumed due to its thin fruit skin and small core. “Whangkeumbae” and “Minibae” were crossed in 1999 to breed this pear cultivar. After the first selection in 2010, regional adaptation tests were conducted in five regions (Suwon, Chuncheon, Jinju, Yecheon, and Naju) from 2011 to 2017. The selected tree exhibited a vigorous spreading form and white flowers. “CenSall” contains 165 mg of pollen per 100 flowers; therefore, it can be used as a pollinator. However, it is sensitive to scabs, and thus, cultivation management to control scab is necessary. “CenSall,” harvested in early August, had a fruit weight of 336.3 g and soluble solid contents of 10.2 °Brix, hardness of 2.4 kg⋅8 mmØ^-1, and the fruit skin color was yellowish green. The fruit has many edible portions, accounting for 94.5% of the entire flesh. Notably, only 22.7% of the seeds developed normally but fruited stably. The thickness of the hypodermis was 62.57 μm, which was half the thickness of the main cultivar “Niitaka” (113.49 μm). The cuticle developed without a cork layer, fruit skin was smooth, and it could be eaten with the peel (Registration No. 8046).

Pear (Pyrus spp.) is an economically important fruit tree that grows extensively worldwide. To facilitate the identification of agronomically important traits and provide new information for genetic and genomic research concerning this fruit tree, a high-density genetic linkage map of pear was constructed using 178 F₁ populations derived from a cross between ‘Manpungbae’ and ‘Oharabeni’. Single nucleotide polymorphisms (SNPs) detected by genotyping-by-sequencing (GBS) and simple sequence repeats (SSRs) developed from pears were analyzed to construct a genetic linkage map. SSR markers were used to locate the corresponding chromosome number for each linkage group (LG). A total of 1,807 GBS-SNPs and 41 SSRs were anchored to the integrated genetic linkage map. Seventeen LGs were identified, covering a genetic distance of 1,519.4 cM with an average marker density of 0.87 cM. The lengths of the LGs ranged from 70.9 cM (LG 14) to 160.4 cM (LG 15). Each LG had SSR markers from 1 to 5, except for LGs 7, 8, and 9. Our integrated genetic map of pear could be used as a basic frame map for comparative analysis of genomic structure between different pear research groups.

Interspecific hybridization is a valuable approach to generate genetic variation and to introgress desirable genes. The
objective
of the current study was to estimate the heritability and correlation coefficient of several fruit traits for three years (from 2016 to 2018) using a set of 178 interspecific F₁ populations developed from a cross between ‘Manpungbae’ (Pyrus pyrifolia) and ‘Oharabeni’ (P. pyrifolia×P. communis). For ‘Manpungbae’, the average values of fruit weight, length, diameter, fruit shape index, and soluble sugar content for the three years were 967.8 g, 109.0 mm, 125.7 mm, 0.87, and 13.4 °Brix, respectively. The average values for ‘Oharabeni’ were 268.2 g, 75.2 mm, 81.4 mm, 0.93, and 9.9 °Brix, respectively. The average values and heritability for three years in F₁ progenies were 222.0 g and 85.55%, 67.3 mm and 84.14%, 75.4 mm and 81.18%, 0.89 and 79.33%, and 10.7 °Brix and 77.75%, respectively. Among the five fruit traits we surveyed, the Pearson’s correlation coefficients between three traits (weight, length, and diameter) were highly significantly positive (over 0.8) for the three years.

High-density genetic linkage mapping is critical for undertaking marker-assisted selection and confirming quantitative trait loci, as well as helping to build pseudomolecules of genomes. We constructed a genetic map using 94 F₁ populations generated from the interspecific cross between Korean cultivar “Wonwhang” (Pyrus pyrifolia, NCBI BioSample SAMN05196235) and European cultivar “Bartlett” (Pyrus communis). We designed a total of 24,267 SSR markers based on the genome sequences of “Wonwhang” for this. To select the markers that are linked to the traits important in pear breeding programs, SSR-containing genomic sequences were subjected to nucleotide sequence homology searches, which resulted in 510 SSR markers with high similarity to genes encoding proteins with putative functions such as transcription factors, resistance proteins, flowering time, and regulatory genes. Of these, 70 markers showed polymorphisms in parents and segregating populations and were used to construct a genetic linkage map, together with the unpublished 579 SNPs obtained from genotyping by sequencing analysis. The genetic linkage map covered 3,784.2 cM and the average distance between adjacent markers was 5.8 cM. Seventy SSR markers were distributed across 17 chromosomes with more than one locus.

Apple (Malus × domestica Borkh.) has gametophytic self-incompatibility (S) controlled by the multi-allelic S-locus. In the present study, S-genotypes of 24 apple cultivars including newly released Korean cultivars and seven crabapple cultivars were identified using S-allele specific polymerase chain reaction analysis. Twelve different S-alleles (S₁, S₂, S₃, S₅, S₇, S₉, S₁₀, S₁₆, S₂₁, S₂₃, S₂₆, and S₂₉) from 31 apple and crabapple cultivars were identified using 23 S-allele specific primers. Among them, S₁ (41.7%), S₃ (58.3%), S₇ (29.2%), and S₉ (54.2%) S-alleles were found to be common in 24 apple cultivars. The newly released Korean cultivars ‘Arisoo’ and ‘Hwangok’ were genetyped as S3S7 and S3S9, respectively. S-genotypes information obtained from the present study will be useful to select proper pollinzers for stable production of apple fruit and to design cross of breeding programs.