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Suigen, South Korea

Kim Y.K.,Pear Experiment Station | Kang S.S.,Pear Experiment Station | Cho K.S.,Pear Experiment Station | Hwang H.S.,Pear Experiment Station | And 2 more authors.
Acta Horticulturae | Year: 2011

Pear rootstocks affect the environmental adaptability as well as the nutritional status of the scion. In this research, we investigated the response of pear rootstocks to drought stress using polyethylene glycol (PEG) treatment to pear cultivars in vitro. Materials were obtained from the cultivars 'Chuhwangbae', 'Hwangkeumbae' (Pyrus pyrifolia Nakai), a Pyrus betulaefolia × Pyrus calleryana hybrid (PBPC), and open pollinated Oregon Pear Rootstock 195 (P. calleryana) (OPR195 OP) by shoot tip culture on MS medium supplemented with BA 1.0 mg/L and subjected to several concentrations of polyethylene glycol (PEG). In this experiment, PEG (0, 10, 15, 20, 25%, MW 6,000) inhibited shoot fresh weight and the total chlorophyll content of PBPC to the greatest extent at PEG 20% concentrations. Proline contents of PBPC and OPR195 OP were increased from 2.9 to 6.1 mg g -1 FW and from 6.2 to 10.8 mg g -1 FW, respectively, as PEG concentration increased. However, 'Chuhwangbae' and 'Hwangkeumbae' exhibited no increase in concentrations above 10 and 5%, respectively. Source


Kim Y.K.,South Korean National Institute of Animal Science | Won K.H.,South Korean National Institute of Animal Science | Lee U.Y.,South Korean National Institute of Animal Science | Yim S.H.,South Korean National Institute of Animal Science | And 4 more authors.
Acta Horticulturae | Year: 2015

Twenty-six European pears (P. amygdaliformis, P. communis, P. elaeagrifolia, P. nivalis), 18 Asian pears (P. pyrifolia, P. serotina), and 4 hybrids (P. communis × P. pyrifolia) were classified and identified using seven simple sequenced repeats (SSR) markers. Seven markers in this study displayed informative polymorphisms, of which six were obtained from 'Whangkeumbae' (P. pyrifolia) using fosmid library sequences. Pair-wise genetic distances based of the F statistics of Nei and Li revealed an average distance of 34.4% among European pear cultivars and 44.2% among Asian pear cultivars. Unweighed pair-group method of arithmetic averages cluster analysis results were classified into two main groups. The first group included Asian pear (P. pyrifolia) including P. serotina and some hybrids. The second group contained European pear (P. communis) and also P. nivalis. P. amygdaliformis was on the outside of it. The genetic distance of P. elaeagrifolia was closer to P. communis. Four hybrid cultivars were divided in two groups. 'Oharabenni' and 'Kiyomaru' were clustered with P. communis and 'Greensis', 'OH × Nijisseiki' were P. pyrifolia. In conclusion, genetic analysis using these 7 SSR markers seemed to be make it possible to distinguish European and Asian pear (P. pyrifolia). Source


Kim Y.K.,South Korean National Institute of Animal Science | Lee U.Y.,South Korean National Institute of Animal Science | Won K.H.,South Korean National Institute of Animal Science | Choi J.H.,South Korean National Institute of Animal Science | And 3 more authors.
Acta Horticulturae | Year: 2015

The National Institute of Horticultural and Herbal Science (NIHHS) has released about 30 pear cultivars since systematic pear breeding programs began in 1954. One of the main goals of NIHHS's breeding program is to improve fruit quality. Until now, fruit characteristics between landraces and newly bred cultivars showed a significant difference in fruit size, acidity, sugar content, flesh firmness and core ratio. Soluble solids contents have been improved from 11.7 to 13.4 °Brix, and fruit flesh firmness decreased from 4.8 to 2.9 kg/8 mmφ. Core ratio, which indicates how much of the whole fruit is inedible, has decreased from 40.5 to 35.2% and acidity was from 4.8 to 2.9%. These results illustrate the success of our pear breeding goal to improve fruit quality. Also, It appears to be worthwhile to continue further to investigate the relationship between flesh physical structure and firmness. Source

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