• Journal of Conservation Science
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• v.1 no.1 s.1
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• pp.12-26
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• 1992

Ilsan peat-bed site, newly constructed city area, is located at the northern part of Seoul. This site is situated near the mouth of Han river, which flows through central Korea. Many fossil woods were excavated from this site, and surveyed the wood anatomical features. Totally 90 specimens were identified into 10 species including two roots and five barks which were not identified in detail. Alnus japonica and A. maxmowiczii are the most common and occupied 26. 7%, 34.4% of the total specimen number respectively, and then other species which excavated from Ilsan area are follows : Fraxinus rhynchophylla(18.9%), Lepido-balanus spp.(3.3%), Maackia amurensis(2.2%), Diospyros spp.(2.2%), Juglans mandshrica(1.1%), Prunophora spp.(1.1%), Malus or Pyrus spp.(1.1%), Rhamnus spp.(1.1%). Among the identified species there are fairly some species growing in the central - or northern temperate zone, such as A. maxmowiczii, F. rhynchophylla, Lepidobalanus spp., M. amurnsis, J. mandshurica, Rhumnus spp. Therefore, it can be estimated that the former temperature of Ilsan area was same or slightly cold than today. The species bearing fruit for food as .J, mandshunca, Diospyros spp., Prunophora spp., Mulus or Pyrus spp. were regarded as artificially planting trees, because they do not grow together in the same site.

• Journal of Plant Biotechnology
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• v.42 no.4
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• pp.290-297
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• 2015

Based on the place of its origin, pear tree (Pyrus spp.) is largely divided into European pears (P. communis, cultivated mainly in Europe and the U.S.) and Asian pears (P. pyrifolia, P. bretschneideri, and P. ussuriensis, distributed and grown in East Asian countries including China, Japan, and Korea). Most pear trees have 17 chromosomes (diploidy, 2n=2x=34). Their genetic studies and precise cultivar breeding are highly restricted by conditions such as self-incompatibility controlled by S-locus and juvenility as one major character of fruit crops. Genetic studies on Pyrus have been promoted by the development of various molecular markers. These markers are being utilized actively in various genetic studies, including genetic relationship analysis, genetic mapping, and QTL analysis. In addition, research on pear genetic linkage maps has been extended to studies for the identification of QTL for target traits such as disease resistance and genetic loci of useful traits. NGS technology has radically reduced sequencing expenses based on massive parallel reactions to enable high-capacity and high-efficiency. NGS based genome analyses have been completed for Chinese pear 'Danshansuli' and European pear 'Bartlett'. In Korea, GWAS for agricultural valuable traits such as floral structure, ripening, and total soluble contents have been conducted through resequencing. GBS has been performed for 'Whangkeumbae', 'Cheongsilri', and 'Minibae'.

• Korean Journal of Plant Resources
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• v.35 no.6
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• pp.770-777
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• 2022

The main objective of this study was to identify the most appropriate condition for root formation of in vitro micropropagated pear (Pyrus spp.) plants. In vitro propagation was induced on Murashige and Skoog (MS) medium with 2.0 mg/L of N6-benzyladenine (BA) and 0.2 mg/L of Indole-3-butyric acid (IBA) medium. The short pre-treatment of explants with a high concentration (1 mg/L) of NAA and IBA (R0 medium) in dark for three days, followed by transfer to five different media (R1 to R5) resulted in good rooting responses in the pear 'Oharabani (P. pyrifolia × P. communis)' genotype. For the rooting experiments, the highest rooting percentage (83.3 ± 8.3%), average root length (3.6 ± 1.9 mm), total root number (31 ± 4.0), and average root number per plant (2.6 ± 2.1) were obtained on half strength (1/2) of MS medium supplemented with 30 g/L sucrose without hormones and activated charcoal (AC) (R1 medium). The highest rooting percentage was obtained at 83.3% from explants on R1 and R3 media. The rooting procedure described in this study resulted in good root formation and significantly shorting the root induction time to within 14 days of culture. Further studies are underway to test the suitability of the protocol developed in this study for other pear genotypes.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.35-35
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• 2022

Pears (Pyrus spp.) have been grown worldwide as a kind of important economical fruits. Over 1,500 accessions collected from countries have been preserved in National Institute of Horticultural and Herbal Science, Rural Development Administration in Korea. However, redundancies and misidentification are happening in the germplasm preservation due to same cultivars which have different names in various localities (synonyms) and different cultivars which have same names (homonyms). That can lower germplasm management efficiency. The object of this study is to identify synonyms and homonyms in pear germplasms by analyzing genetic variation with four microsatellite markers: CH03d12, CH03g07, CH02b10, and EMPc117. PCR amplification with above 4 microsatellite markers was done for the 31 pear accessions, and the products were analyzed by agarose gel electrophoresis. As a result, 7 synonyms and 9 homonyms were identified among 31 pear accessions. We'll compare these genotypes with phenotypes of each pear accessions, and reduces the redundancy and misidentification in pear germplasm collection for the reliable management.

• Korean Journal of Plant Resources
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• v.36 no.6
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• pp.571-579
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• 2023

In this study, cryopreservation by droplet-vitrification was applied to pear (Pyrus spp.) germplasm. We focused on the development and assessment of various strategies for the selection of suitable tissue, osmoprotection, and dehydration. We also evaluated post-thaw recovery of cryopreserved explants by droplet-vitrification. Preferentially, we tested the effects of preculture and loading treatments to determine which tissues were more suitable, either the apical shoot tips or the axillary buds. Apical shoot tips showed the better regrowth rate than in vitro axillary buds. The most effective techniques for cryopreservation were as follows. Shoots from in vitro seedlings which had been cultured for about 5-6 weeks were cold-hardened at 4℃ for one week, excised shoot tips were precultured on liquid MS medium including 0.3 M sucrose for 31 hours and 0.7 M sucrose for 17 hours, osmoprotected in loading solution (LS) for 40 min, and then cryoprotected in dehydration solution (PVS3) for 90 min. In addition, we found that regrowth rates of explants on regrowth medium after exposure to liquid nitrogen (LN) were higher than those on MS medium. Results indicated that the highest regrowth percentage was 95.6% for 'Bartlett' cultivar and 68.9% for 'BaeYun No.3' cultivar. Consequently, apical shoot tips of two pear cultivars, 'Bartlett' (P. communis) and 'BaeYun No.3' (P. pyrifolia), were successfully cryopreserved by droplet-vitrification. Results of this study show that the enhanced droplet-vitrification method described in the present study could be used as an effective means for long-term storage of pear genetic resources.

• Journal of Plant Biotechnology
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• v.4 no.2
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• pp.45-52
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• 2002

A lot of SSRs (simple sequence repeats) in peach and pear from enriched genomic libraries and in peach from a cDNA library were developed. These SSRs were applied to other related species, giving phenograms of 52 Prunes and 60 pear accessions. Apple SSRs could also be successfully used in Pyrus spp. Thirteen morphological traits were characterized on the basis of the linkage map obtained from an $F_2$ population of peach. This map was compiled with those morphological markers and 83 DNA markers, including SSR markers used as anchor loci, to compare different peach maps. Molecular markers tightly linked to new root-knot nematode resistance genes were also found. A linkage map including disease related genes, pear scab resistance and black spot susceptibility, in the Japanese pear Kinchaku were constructed using 118 RAPD markers. Another linkage map, of the European pear Bartlett, was also constructed with 226 markers, including 49 SSRs from pear, apple, peach and cherry. Maps of other Japanese pear cultivars, i.e., Kousui and Housui, were also constructed. These maps were the first results of pear species.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.444-450
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• 2009

Amplified fragment length polymorphism (AFLP) marker was utilized for evaluation of genetic diversity of 60 pear germplasms. Twenty selective AFLP primer pairs generated a total of 522 polymorphic amplification products. From UPGMA (unweighted pair-group method arithmetic average) cluster analysis by using polymorphic bands, the pear germplasms were divided into four clusters by similarity index of 0.691. The first cluster (I) included European pears belonging to Pyrus communis and wild species such as P. nivalis and P. cordata. The second cluster (II) included Ussurian pea pears belonging to P. betulaefolia and P. fauriei. The third cluster (III) included pea pears belonging to P. calleryana and P. koehnei. Most of germplasms belonging to P. pyrifolia and P. ussuriensis, and interspecific hybrids were included in the fourth (IV) cluster. Therefore pear germplasms originated from East Asia were closely related to P. pyrifolia and P. ussuriensis. Similarity values among the tested pear germplasms ranged from 0.584 to 0.879, and the average similarity value was 0.686.

• Journal of the Korean Wood Science and Technology
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• v.36 no.1
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• pp.1-11
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• 2008

The purpose of this study is to examine the species of wooden members used in the Youngsanjeon Hall of the Sucknamsa temple in Anseong, Korea. Ninety-five wood samples from pillars, head-penetrating ties, beams, corner rafter, rafter, floor board and other wood members were identified. Seven species identified were hard pine, exotic pine, Zelkova serrata, Ginkgo biloba, Diospyros, Quercus(Cerrus) and Pyrus spp. In the case of pillars, eight were hard pines and the others Zelkova and Pyrus. Species of angle rafter were Ginkgo biloba and Zelkova. and those of beams were one hard pine and one Zelkova. Two purlin samples were Quercus(Cerrus) and rafters were hard pines except one Ginkgo and one exotic pine. Roof-filling timbers were identified as Zelkova and Diospyros spp. The other samples of roof-filling timbers were all identified as hard pines. The use of Ginkgo and several hardwoods in addition to hard pines may indicate supply of local logs near the Sucknamsa temple.

• Korean Journal Plant Pathology
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• v.11 no.3
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• pp.210-216
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• 1995

Alternaria spp.were predominantly isolated from the abnormal leaf spot lesions of pear cultivars Niitaka and Nijiiseiki. Alternaria isolates from the cultivar Niitaka were not pathogenic to both cultivars, but the isolates from the cultivar Nijiiseiki developed typical lesions of black leaf spots and were identified as A. kikuchiana. However, no typical abnormal leaf spot lesions were produced by the Alternaria isolates. Foliar spray of twelve different agrochemicals including lime sulfur, either alone or in combinations, with 7 times applications from April to July failed to reduced the disease development. Application of 17 different pesticides including fungicides, insecticides and herbicides currently used in pear orchards did not cause leaf injury similar to the abnormal leaf spot. Simulated acid rain of as low as pH 3.0 did not incite any leaf lesions alike the abnormal spot lesions. Mineral contents in the leaves of both cultivars did not differ significantly between the healthy leaves and those with abnormal leaf spots. When cuttings of pear tree were obtained in February from newly emerged twigs of the healthy or the diseased trees of Niitaka and planted in sand in the greenhouse, only those from the diseased trees developed typical leaf lesions of the abnormal spot. These results indicate that abnormal leaf spots are caused by unknown systemic agents in pear trees, rather than by Alternaria spp., chemical injury or acid rain.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2002.04a
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• pp.101-109
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• 2002

A lot of SSRs (simple sequence repeats) in peach and pear from enriched genomic libraries and in peach from a cDNA library were developed. These SSRs were applied to other related species, giving phenograms of 52 Prunus and 60 pear accessions. Apple SSRs could also be successfully used in Pyrus spp. Thirteen morphological traits were characterized on the basis of the linkage map obtained from an $F_2$ population of peach. This map was compiled with those morphological markers and 83 DNA markers, including SSR markers used as anchor loci, to compare different peach maps. Molecular markers tightly linked to new root-knot nematode resistance genes were also found. A linkage map including disease-related genes, pear scab resistance and black spot susceptibility, in the Japanese pear Kinchaku were constructed using 118 RAPD markers. Another linkage map, of the European pear Bartlett, was also constructed with 226 markers, including 49 SSRs from pear, apple, peach and chewy. Maps of other Japanese pear cultivars, i.e., Kousui and Housui, were also constructed. These maps were the first results of pear species.