• Korean Journal of Plant Tissue Culture
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• v.24 no.4
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• pp.239-256
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• 1997

Plants belonging to the category of 2n apomixis or agamospermy form embryos and seeds without the processes of normal meiosis and syngamy. Seeds produced in this way have identical genotype of their maternal parent. Three different types of agamospermy are recognized: diplospory, apospory, and adventitious (adventive) embryony. $F_1$ hybrid cultivars cannot be used as seed sources in the next ($F_2$) generation because this generation would be extremely variable as a result of genetic segregation. Hybrid vigor is also reduced in the $F_2$ generation. Therefore, parental stocks for hybrid seed production need to be maintained and cross must be continuously repeated. Agamospermic 2n apomixis would make it possible to fix the genotype of a superior variety so that clonal seeds faithfully representing that genotype could be continuously and cheaply produced independent of pollination. That is, $F_1$ hybrid seeds could be produced for many generations without loss of vigor or genotype alteration. Production of apomictic $F_1$ hybrid seed would be simplified because line isolation would not be necessary to produce seed or to maintain parental lines, and the use of male-sterile lines could be avoided. Overall, apomixis would enable a significant reduction in hybrid seed production costs. Additionally, the production of clonal seed is not only important for seed propagated crops, but also for the propagation of heterozygous fruit trees and timbers. Clonal seed would help avoid costly and time-consuming vegetative propagating methods that are currently used to ensure the large-scale production of these plants. Apomixis is scattered throughout the plant kingdom, but few important agricultural crops possess this trait Therefore, most research to date has centered on introgressing the trait of apomixis into agricultural crops such as wheat, maize, and some forage grasses from wild distant relatives by traditional cross breeding. The classical breeding approach, however is slow and often impeded by many breeding barriers. These problems could be surmounted by taking mutagenesis or molecular approach. Arabidopsis thaliana is a tiny sexually reproducing plant and is convenient in constructing and screening in molecular researches. Male-sterile mutants of Arabidopsis are particularly suitable genetic background for mutagenesis and screening for apomictic mutants. Molecular approaches towards isolating the genes controlling the apomictic process are feasible. Direct isolation of genes conferring apomixis development would greatly facilitate the transfer of this trait to wide variety of crops. Such studies are now in progress.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.574-578
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• 2009

A new red leaf lettuce (Lactuca sativa L.) cultivar, "Gopungjeokchukmyeon" which has late bolting and good red expression leaf color was developed from a cross between "Andongjeokchukmyeon" (red leaf color and late bolting) and "Dukseomjeokchukmyeon" (high yield). The cross and selection for advanced lines had been done by the pedigree method during 2000-2006. The advanced lines were evaluated for yield and adaptability at several locations in Korea (Gangwon, Kyunggi, Chungbuk, Kyungnam, Jeonnam, Jeonbuk, and Jeju) from 2007 to 2008. The "Gopungjeokchukmyeon" has gray seed color and traverse elliptic leaves. Compared to "Dukseomjeokchukmyeon", marketable yield of "Gopungjeokchukmyeon" was higher by 17% (at 330 g per plant) and Gopungjeokchukmyeon has particularly improved expression of red leaf color in high temperature cultivation in the field. The shelf-life of "Gopungjeokchukmyeon" was three weeks longer than "Dukseomjeokchukmyeon" at $4^{\circ}C$. The anthocyanin and sugar contents of "Gopungjeokchukmyeon" were higher than those of "Dukseomjeokchukmyeon" with 29.4 mg/100 g and 4.8 brix, respectively. The content anthocynin of "Gopungjeokchukmyeon" is about 10 times higher than those of "seomjeokchukmyeon". Furthermore, its taste is better, more crispy, and sweeter than those of "Dukseomjeokchukmyeon", This new cultivar "Gopungjeokchukmyeon" can be harvested all year around even summer cultivation.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.616-619
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• 2009

A new standard rose cultivar "Red Charm" was bred from the cross between deep red standard cultivar "First Red" and light red standard cultivar "Cardinal" at the Jeollanamdo Agricultural Research and Extention Services (JARES). The cross was made in 2003 and, "Red Charm" was finally selected in 2008 after investigating characteristics for three times from 2007 to 2008. "Red Charm", a red standard cultivar has good flower shape and velvet flower color. The major characteristics of this cultivar are on average $119.3stems/m^2/year$ in yield, 69.5 cm in length of cut flower, 10.3 cm in flower diameter, 36.9 in petal number, and 9.8 days in vase life. This cultivar can be propagated by both cutting and grafting. The consumer's preference of this cultivar, "Red Charm" is relatively higher than that of control cultivar, "Red Velvet".

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.599-602
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• 2009

A single cross hybrid, Heukjinjuchal, is a black color waxy corn (Zea mays L.) developed by the maize breeding team at NICS in 2008. Heukjinjuchal was produced by crossing two inbred lines, KBW24 as seed parent and KBW2 as pollen parent. Ear length and ear diameter of Heukjinjuchal was 16.0 cm and 4.4 cm, respectively. The ratio of kernel set length/ear length was 89%, similar with that of a check hybrid, Chalok1. It is resistant to Northern corn leaf blight disease and also lodging tolerant. Fresh ear yield of Heukjinjuchal comparable with those of a check hybrid, Chalok1 in regional yield trials for three years. Seed production of this hybrid is relatively easy because of well overlapping period of silking and pollen dispersal between the two parents. This cultivar would be well adaptable to the whole country.

• Korean Journal of Breeding Science
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• v.41 no.3
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• pp.310-313
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• 2009

A single cross, Pyeonganok, is an yellow flint-like maize hybrid (Zea mays L.) developed by the maize breeding team at the National Institute of Crop Science (NICS), RDA in 2008. This hybrid, which has a high yield of dry matter was produced by crossing two inbred lines, KS140 and KS94. KS140 is the seed parent and KS94 is the pollen parent of Pyeonganok. Silking date of Pyeonganok is 3 days later than that of check hybrid, Kwangpyeongok. Stay-green of Pyeonganok is not greatly different with that of Kwangpyeongok. It has resistance to lodging. It has moderately resistance to Bipolaris maydis (southern corn leaf blight), Exserohilum turcicum (northern corn leaf blight), and corn borer but sensitivity to black streaked dwarf virus (BSDV). Pyeonganok was evaluated for the yields of dry matter at four locations from 2006 to 2008. The yields of Pyeonganok in dry matter was 20.84 ton/ha. Seed production of Pyeonganok has gone well due to a good match during crossing between the seed parent, KS140 and the pollen parent, KS94 in Yeongwol.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.556-559
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• 2009

"Hongso" was originated from a cross between "Yoko" and "Hongro" in NIHHS, RDA, in 1989. "Hongso" was preliminarily selected in 2002 for its high fruit quality. After regional adaptability test at five sites from 2003 to 2006 as "Wonkyo Ga-30" it was finally selected in 2006. Optimum harvest time is early September which is similar to that of "Hongro". Fruit shape is globose conical and skin color is light red. Mean fruit weight is 295g and soluble solids content is 14.1oBrix. Fruits acidity is 0.34%, which is higher than that of "Hongro"(0.23%). It has a good taste for harmony of sugar and acidity. Storability is 3 weeks in room temperature. It is apt to russet on fruit skin. It is susceptible to Bitter rot. "Hongso" has a good cross compatibility with major cultivars such as "Fuji", "Hongro" and "Tsugaru". Tree habit is semi-spreading and tree vigor is weak. "Hongso" is high-density cultivation type cultivar, because it has a precocity, spur-type.

• The Korean Journal of Mycology
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• v.49 no.3
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• pp.405-412
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• 2021

Wolfiporia cocos is an important medicinal fungus that has been used in regions of Northeast Asia including Korea, Japan, and China. W. cocos is classified in Korea into two types (red bokryeong and white bokryeong) based on the internal colors (yellow orange-pale pink and white) of the sclerotium. Generally, the W. cocos type cultivated on farms produces white sclerotium. In this study, we endeavored to select strains that form sclerotium in sawdust medium using 2-way cross-breeding among two cultivated strains and three wild strains. Monospores were isolated from the fruiting bodies of cultivated and wild strains on potato dextrose agar. Thirty-nine strains of 338 hybrid strains isolated formed sclerotia with white or yellow colors upon culture for 3 months in Pinus densiflora sawdust medium. Selection for sclerotium forming strains using sawdust culture follows a very simple and easy procedure that is presented for the first time in this paper. We plan to test selected strains in the field to aid in developing new varieties for the future.

• Korean Journal of Breeding Science
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• v.42 no.3
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• pp.226-230
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• 2010

'Gwanghan' (Avena sativa L.), a winter oat for forage use, was developed by the breeding team at the Department of Rice and Winter Cereal Crop, NICS, RDA in 2009. It was derived from a cross between 'Early80' and 'Gwiri23'. A parent, 'Early80', has early heading and high yielding, while Gwiri23 has mid-heading with large-size grain. Subsequent generations followed by the cross were handled in bulk and pedigree selection programs at Suwon and Yeoncheon, respectively. A line, 'SO96016-B-112-YB-12-7', was selected for earliness, cold tolerance, and good agronomic characteristics and designated as a line name of 'Gwiri64'. The line was subsequently evaluated for cold tolerance, earliness, and forage yield in four different locations, Yesan, Iksan, Kimjae, and Jeju, from 2007 to 2009, and finally named as 'Gwanghan'. Over 3 years, the average forage dry matter yield of 'Gwanghan' harvested at milk-ripe stage was $16.4MT\;ha^{-1}$, compared with $15.4MT\;ha^{-1}$ of check cultivar 'Samhan'. 'Gwanghan's' heading date is about 3 days earlier than that of check cultivar, and is adapted primarily for winter cultivation in the mid-southern regions of Korean peninsula.

• Korean Journal of Breeding Science
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• v.42 no.3
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• pp.280-283
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• 2010

A new standard rose cultivar 'Noble Red' was bred by the cross between the pink standard cultivar 'Silba 87' and the red standard cultivar 'Bravo' at the National Institute of Horticultural and Herbal Science. The cross was made in 1999 and 'Noble Red' was finally selected in 2003 after investigating the characteristics such as flower Color, Fragrance, stem length, stem diameter, weight, and number of leaves for three years from 2001 to 2003. 'Noble Red', a red standard cultivar grows vigorously and has good flower shape. The major characteristics of this cultivar are $125stems/m^2/year$ in yield, 71.9 cm in length of cut flower, 6.0cm in flower diameter, 30.8 in petal number, and 9.2 days in vase life. This cultivar can be propagated by both cutting and grafting. The consumer's preference of this cultivar is relatively higher than that of control cultivar, 'Rote Rose'.

• Korean Journal of Breeding Science
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• v.42 no.3
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• pp.231-235
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• 2010

'Jopung' (Avena sativa L.), a winter oat for forage use, was developed by the breeding team at the Department of Rice and Winter Cereal Crop, NICS, RDA in 2009. It was derived from an original cross between the $F_1$ hybrid of 'Early80' and 'PA202-210-S' and 'Walken' in 1999. Subsequent generations followed by the cross were handled in bulk and pedigree selection programs at Suwon and Yeoncheon, respectively. A line, 'SO99006-B-YB-29-Y1', was selected for earliness and good agronomic characteristics and designated as a line name of 'Gwiri65'. The line 'Gwiri65' was subsequently evaluated for earliness and forage yield in four different locations, Yesan, Iksan, Kimjae, and Jeju, from 2007 to 2009 and finally named as 'Jopung'. Over 3 years, the average forage dry matter yield of cultivar 'Jopung' harvested at milk-ripe stage was $17.3MT\;ha^{-1}$, compared with $13.6MT\;ha^{-1}$ of check cultivar 'Swan'. The silage quality of 'Jopung' was superior to the check cultivar 'Swan' in crude protein content, and was similar to the check cultivar in percent total digestible nutrients (TDN). Cultivar 'Jopung' is suitable primarily for winter planting in the southern regions of Korean peninsula.