• Korean Journal of Ecology and Environment
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• v.36 no.4 s.105
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• pp.427-433
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• 2003

We provided diagnostic characters of the adult and larval stages of two co-inhabiting species of ephemerid burrowing mayflies, Ephemera orientalis and E. sachalinensis (new record to South Korea) (Ephemeroptera: Ephemeridae), in Korean streams. E. sachalinensis (mean${\pm}$sd body length male adult 18.44${\pm}$0.70 mm, female adult 21.46${\pm}$0.45 mm) is larger in body length than E. orientalis (male adult 13.92${\pm}$0.04 mm, female adult 15.27 ${\pm}$ 0.48 mm), and can be distinguished by male genitalia, forewing markings, and stripes on the abdominal terga Vl-lX. The mature larvae of E. sachalinensis differ from those of E. orientalis in having a deeper and more divergent head frontal process. Their body size distributions and additional ecolegical findings are discussed.

• Horticultural Science & Technology
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• v.19 no.1
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• pp.48-53
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• 2001

The study was conducted to examine the storage potential of recently developed oriental pears, 'Kamchun' and 'Chuhwang'. The content of soluble solids of 'Kamchun' pears was above 13.2% but the acidity was below 0.082% at three harvest dates. Although skin browning disorder did not occur in 'Kamchun', about 40% of fruits were affected by core breakdown especially when harvested after middle of October. In contrast, flesh browning was also observed in early harvested fruit. Flesh firmness of 'Chuhwang' was higher than that of 'Kamchun' at harvest as well as after storage. The acidity of 'Chuhwang' was constantly higher than that of 'Kamchun'. Severe skin browning (approximately 80%) occurred in 'Chuhwang' pears regardless of harvest dates. Also, more flesh browning disorder was found in fruit harvested early in the season. Further research is required to determine the optimum harvest date of both cultivars and postharvest managements to inhibit the physiological disorders.

• Journal of Bio-Environment Control
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• v.26 no.1
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• pp.19-26
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• 2017

We evaluated the fruit quality and the incidence of physiological disorders in Asian pear (Pyrus pyrifolia Nakai) cultivar 'Jinhwang' treated with 1-methylcyclopropene (1-MCP, $1.0{\mu}L{\cdot}L^{-1}$) under different temperature conditions to determine appropriate shelf-life period. The postharvest application of 1-MCP in 'Jinhwang' pears showed positive effects at all storage temperature (18, 25 or $30^{\circ}C$) with regard to flesh firmness, marketable fruits (>20N) only attainted with 1-MCP treated fruit after 21 days of shelf-life. A high incidences of physiological disorders and of fruit decay rates were obvious in the fruits distributed at $30^{\circ}C$ and low incidence of physiological disorders including core browning and mealiness were attained at the fruits treated with 1-MCP when we compared with untreated control. The production of ethylene and respiration rates increase coincide with elevated distribution temperature. High respiration rates were obvious in the control fruits, it reached approximately two times higher than the that of 1-MCP treated one regardless of market temperature. These results demonstrated that the application of 1-MCP, especially at high temperature market condition, represented as an effective postharvest technique for newly developed Asian pear 'Jinhwang'.

• 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 Breeding Science
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• v.41 no.3
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• pp.354-357
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• 2009

"Wonkyo Na-heukseong 2" was selected from a cross between "Kiyomaro", late season European cultivar with highly resistance and "Mansoo", late season Asian cultivar with long storability, large size and low susceptibility to pear scab made in 1997 at the National Institute of Horticultural & Herbal Science of Rural Development Administration in Korea. "Kiyomaro", released cross between "Taiheiyo" and "Bartlett" with scab resistance caused by Venturia nashicola in Japan, with no visual symptoms on any leaves was used as scab resistant source after field investigation and artificial inoculation test during 1997~1999. "Wonkyo Na-heukseong 2" blooms 1 day earlier than "Mansoo" and 3 days later than "Kiyomaro" in 2008. It is strong in tree vigor and upright-spreading in tree habit. It is classified as highly resistant to pear scab as "Kiyomaro" and "Bartlett", and cross-compatible with parental variety and Korean major pear varieties such as "Niitaka" and "Wonwhang". The average optimum harvest time of "Wonkyo Na-heukseong 2" was approximately 180 days after full bloom and it matured about 20 days shorter than parental varieties. The fruit is spindle in shape and yellowish greenish brown in skin color. Average fruit weight was 484 g and soluble solids content was $13.2^{\circ}Brix$. The flesh had medium to high juice and negligible grit. Its fruit was crisp like Asian pear.

• Journal of Bio-Environment Control
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• v.23 no.3
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• pp.212-220
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• 2014

This study was conducted to investigate the effect of 1-methylcyclopropene (1-MCP), a known ethylene action inhibitor, on fruit quality and incidence of physiological disorders during simulated marketing period in Asian pears (Pyrus pyrifolia Nakai) of early-season cultivar 'Hanareum' and mid-season cultivar 'Manpungbae'. Flesh firmness was decreased abruptly at 15 days after shelf-life in untreated fruit of early-season cultivar 'Hanareum' which showed less than 19N, although those of 1-MCP-treated fruits were kept high value (>28N) during 15 days of shelf-life. However, there were no distinct firmness changes during 30 days of shelf-life in mid-season cultivar 'Manpungbae' pear. Two pear cultivars did not show any considerable differences in quality indices such as soluble solids content, titratable acidity and skin color during the shelf-life regardless of 1-MCP treatment. The reduction of ethylene production level by 1-MCP treatment did not appeared in 'Hanareum' pear. Meanwhile, 1-MCP treated 'Hanareum' pears showed significantly low respiration rate during shelf-life. On the other hand, the inhibitory effect of 1-MCP was not remarkable in mid-season 'Manpungbae' pears. 1-MCP treatment completely blocked the incidence of physiological disorders including core browning and mealiness symptom during shelf-life only in early-season 'Hanareum' pears, and reduced considerably the pithiness disorder regardless of 1-MCP concentration. Consequently, we concluded that the treatment efficacy of 1-MCP is largely cultivar-dependent and the use of $1{\mu}L{\cdot}L^{-1}$ 1-MCP was recommended for the keeping quality and the prevention of physiological disorders only in early-season Asian pear 'Hanareum'.

• Korean Journal of Agricultural Science
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• v.16 no.2
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• pp.225-238
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• 1989

These studies were conducted to investigate the extraction, purification and characterization of oriental pear (Niitaka. Pyrus pyrifolia Nak.) protease, and the results obtained were as follows: 1. Oriental pear protease was effectively extracted by the method of homogenizing pear pulp with 0.7 volume of 0.1M-sodium phosphate buffer, pH 6.5 containing 5mM-cysteine, 40mM-2-mercaptoethanol and 2mM-EDTA at 10,000 rpm for 5 min. 2. The protease was purified by ammonium sulfate fractionation, Sephadex G-100 filtration and DEAE-Sephadex A-50 column chromatography, and the purified enzyme gave a single protein band on polyacrylamide gel electrophoresis. 3. The specific activity of purified enzyme was 29.65 unit/mg protein and the yield was 7.22%. 4. The moecular weight of the protease was estimated to be about 51,000 by SDS-polyacrylamide gel electrophoresis, and the enzyme had Km value of 54.5 mg/ml for casein. 5. The purified enzyme had a maximum activity at pH 6.0 and $50^{\circ}C$, and was stable from pH 5.5-6.5 and at temperatures below $50^{\circ}C$ 6. Casein was a better substrate for this protease compared to hemoglobin. 7. The enzyme activity was markedly inhibited by p-chloromercuribenzoic acid and heavy metal salts such as $HgCl_2$ and $MnSO_4$ also considerably inhibited the enzyme activity.

• Journal of Plant Biotechnology
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• v.43 no.4
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• pp.466-472
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• 2016

This study analyzed the genetic diversity of 115 pear germplasms using 15 SSR markers. Three to forty-one SSR alleles were detected for each locus with an average of 16 alleles per locus. The average availability of markers was 0.966. The average observed heterozygosity ($H_{obs}$) was 0.603 (range: 0.140 to 0.929). The average expected heterozygosity ($H_{exp}$) was 0.718 (range: 0.463 to 0.904). The average polymorphism information content (PIC) was 0.692 (range: 0.403 to 0.897). The genetic relationships of pear germplasms were classified into two major groups by geographic origins and genetic characteristics according to genetic distance. The first group was composed of European pear belonging to Pyrus communis. The second group consisted of P. pyrifolia, P. ussuriensis, P. bretschneideri, P. betulaefolia, P. calleryana, interspecific hybrids, and unclear germplasms. The results of this study suggest that genotype analysis of pear germplasms using SSR markers can identify the genetic diversity of germplasms, and can be used to provide basic information for pear breeding.

• Food Science and Preservation
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• v.16 no.3
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• pp.317-320
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• 2009

'Niitaka' (Pyrus pyriforia) has been the major cultivar of the Asian pear since the 1970s, and yielded about 70% of pear production in South Korea in 2002. When Chuseok (Korean Thanksgiving Day) is earlier than the fruit maturation period, farmers seek to advance the harvesting date to keep pace with the increase in consumer demand caused by the holiday. However, unripened fruit is of suboptimal marketable value because the flesh has a low soluble solid content, the fruit color is not attractive, and stone volume is high. Compost treatment can enhance soil microbial activity and affect soil chemistry, which may accelerate fruit maturation and allow an earlier harvesting date. Therefore, we examined the effect of 2 years of compost application on the fruit quality of Asian pear trees grown under conventional management conditions. The Hunter "L" and "a" values were higher in compost-treated fruit, which also showed greater sweetness and lower acidity than did conventional fruit. The stone volume was reduced and fruit calcium concentration was increased by compost treatment. Therefore, compost treatment may advance fruit harvesting owing to the increased marketability afforded by attractive skin color, sweetness, and reduced stone volume.

• Korean Journal of Food Science and Technology
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• v.45 no.2
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• pp.174-179
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• 2013

Three low-molecular compounds were isolated from methanol extracts of pear (Pyrus pyrifolia N. cv. Chuhwangbae) fruit peels using solvent fractionation, various types of column chromatogrphy (Diaion HP-20, Sephadex LH-20, and silica gel), and high performance liquid chromatography with an assay guided by 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity. The isolated compounds were identified as 2-carboxyl-4(1H)-quinolinone (kynurenic acid, 1) from butanol fraction, cis-p-coumaric acid (2) from ethyl acetate-acidic fraction, and vanillin (3) from the ethyl acetate-phenolic fraction, respectively. These isolated compounds were confirmed on the basis of the spectroscopic data of electrospray ionization mass spectrometry and nuclear magnetic resonance. This is the first time that compounds 1-3 were isolated and identified in pear.