• Korean Journal of Breeding Science
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• v.49 no.3
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• pp.250-255
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• 2017

'Hwaweon 7' was developed from a cross between the African upland cultivar, 'Moroberekan' and 'Ilpumbyeo' based on marker-aided backcross selection. The recurrent parent, Ilpumbyeo is a high grain quality cultivar with medium to late maturity. Hwaweon 7 is nearly isogenic to Ilpumbyeo except a small Moroberekan introgressed segment on chromosome 6 harboring genes related with spikelets per panicle and internode diameter. The preliminary and replicated yield trial was conducted at Chungnam National University and Chungcheongnamdo Agricultural Research & Extension (CARES), Yesan in 2010 and 2011. The local adaptability test was carried out by the National Seed Management Office (NSMO) in 2012 and 2013. This cultivar was registered to NSMO with a cultivar designated as "Hwaweon7". This cultivar averaged 80cm in culm length and has a medium growth duration. Milled rice of "Hwaweon7" is translucent and the grain quality traits are comparable to those of the recurrent parent. The average yield potential of Hwaweon 7 in grain was about 6.48 MT/ha at the ordinary fertilizer level for two years about 5.1% higher than that of Ilpumbyeo due to increase in spikelets per panicle. This variety is tolerant to lodging and the tolerance is due to the APO1 gene controlling the base internode diameter on chromosome 6 introgressed from the donor parent, Moroberekan. The Apo1 gene would be useful in enhancing resistance to lodging in rice breeding program.

• Korean Journal of Breeding Science
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• v.43 no.5
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• pp.464-469
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• 2011

Virus diseases often cause serious damage to rice production in Asia. The lack of information on virus resistance genes has been a major obstacle for the breeding of resistant varieties. In order to identify DNA marker associated with resistance against rice stripe virus (RSV), the quantitative trait locus (QTL) was carried out using advanced backcross population developed from a cross between RSV-resistant tongil type cultivar Shinkwang and susceptible japonica cultivar Ilpum. A RSV resistance QTL $qSTV11^{SG}$ explaining 44.2% of the phenotypic variation was identified on chromosome 11 of Tongil type rice cultivar 'Shingwang'. $qSTV11^{SG}$ was tightly linked to DNA marker RM6897. The RM6897 divided as resistance type allele and susceptible type alleles. Twenty seven resistant varieties showed the resistant-type allele and 23 susceptible varieties were susceptible-type allele to the marker of RM6897. This results and the molecular markers presented here may be useful in rice breeding for improving RSV resistance in japonica rice.

• Korean Journal of Breeding Science
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• v.42 no.1
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• pp.100-108
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• 2010

This study was carried out to confirm the chromosome constitution and homoeologous recombination of progenies derived from various cross combination using tetraploid OA interspecific hybrid originated from mitotic chromosome doubling. Based on the chromosome analysis of progenies crossed reciprocally, there were only triploid progenies when crossed with diploid Asiatics as male or female parent. While only tetraploid progenies were produced when crossed tetraploid Asiatics or tetraploid OA hybrid with tetraploid OA hybrid, respectively. However, two types of progenies, that is, diploid and triploid plants, were produced from cross combinations between diploid Oriental hybrid and tetraploid OA hybrid. From the GISH analysis of OA hybrid, it was confirmed that diploid $F_1$ OA hybrid was consisted of 24 chromosomes (12 Oriental and 12 Asiatics) showing authentic OA hybrid. On the other hand, it was notified that triploid plants (3x=36) were consisted of 24 Asiatics lily chromosomes and 12 Oriental lily chromosomes by analysis of backcross progenies derived from either $A{\times}OA$ or $OA{\times}A$ crosses. In cross between tetraploid OA and OA, all the progenies were tetraploid with equal number of chromosomes without any homoeologous recombination, i.e. each 24 chromosomes of Oriental and Asiatics. In 2x-4x ($O{\times}OA$) cross combination, some progenies had 2x=24 chromosomes originated from only Oriental hybrid, and other progenies had 3x=36 chromosomes derived from 24 chromosomes of Oriental hybrid and 12 chromosomes of Asiatic hybrid. Only tetraploid Asiatics chromosomes without any Oriental one were produced in all the progenies from 4x-4x ($AA{\times}OA$) cross combination.

• Korean Journal of Breeding Science
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• v.43 no.6
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• pp.620-624
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• 2011

'Hwaweon 4' was developed from a cross between the African upland cultivar, 'Moroberekan' and 'Ilpumbyeo' based on marker-aided backcross selection. The recurrent parent 'Ilpumbyeo' is a high grain quality cultivar with medium to late maturity. 'Hwaweon 4' is nearly isogenic to 'Ilpumbyeo' except a small Moroberekan introgressed segment on chromosome 4 harboring the resistance gene for blast. The preliminary and replicated yield trial was conducted at Chungnam National University in 2006 and 2007. The local adaptability test was carried out by the National Seed Management Office (NSMO) from 2008 to 2009. This cultivar was registered to NSMO with a cultivar designated as 'Hwaweon 4'. This cultivar averaged 76 cm in culm length and has medium growth duration. Milled rice of 'Hwaweon 4' is translucent and the grain quality traits are comparable to those of the recurrent parent. It has low protein content. The yield potential of 'Hwaweon 4' in grain was about 6.31 MT/ha at the ordinary fertilizer level for two years. This variety showed highly resistance reaction at the blast nursery test at four locations and also at the sequential planting method. This resistance is due to the resistance gene designated as Pi45(t) on chromosome 4 introgressed from the donor parent, 'Moroberekan'. The Pi45(t) gene would be useful inenhancing resistance to blast in rice breeding program.

• Korean Journal of Breeding Science
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• v.42 no.6
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• pp.695-698
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• 2010

The incidence of Anthracnose causing severe damage to the foliage and fruit in watermelon has increased in some major watermelon producing areas in Korea. To develop anthracnose resistant line, 'AU-Producer' having resistant gene to anthracnose was selected from germplasm and crossed with high quality line '920533'. Following the initial cross, backrossing and disease screening were performed to select resistant lines that produced high yields with excellent quality fruit. As a results of these procedure, a mid maturing watermelon line, 'Hangyeol' with resistance to anthracnose (Colletotrichum orbiculare) race 1 and 3 was developed at the National Institute of Horticultural and Herbal Science, Rural Development Administration (RDA). It has red flesh and commonly produces fruit with clear stripes on skin between 5.3 to 10.1 kg. Average soluble solid contents are ranged from 9.8 to 11.8$^{\circ}$Bx. The yield and quality of 'Hangyeol' is comparable to or better than those harvested from the popular commercial cultivars. The achievement of this experiment could contribute to provide the resistant parents in an anthracnose resistance breeding program in watermelon.

• Korean Journal of Breeding Science
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• v.42 no.6
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• pp.699-702
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• 2010

Anthracnose is a major limiting factor of the watermelon production in Korea. A mid-late maturing watermelon line, 'Hanbit' with resistance to anthracnose (Colletotrichum orbiculare) race 1 and 3, was developed by the cross between anthracnose resistant cultivar 'AU-Producer' and high quality inbred line '920533' at the National Institute of Horticultural and Herbal Science, Rural Development Administration (RDA). 'Hanbit' produces 5.4 to 9.5 kg of red flesh fruits with clear stripes on skin. Average soluble solid contents are ranged from 10.4 to 11.2$^{\circ}$Bx. The yield and quality of 'Hanbit' was comparable to or better than those harvested from the popular commercial cultivars. 'Hanbit' can be cultivated in open fields and under the protected green house condition. In addition to the commercial production, it can be used as a resistant material in $F_1$ hybrid breeding program.

• Korean Journal of Breeding Science
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• v.43 no.4
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• pp.304-310
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• 2011

In previous studies, we reported QTLs for grain weight (GW), qGW3 and for spikelets per panicle (SPP), qSPP3 linked to RM60 on chromosome 3 using advanced backcross lines derived from a cross between Oryza sativa ssp. Indica cv. Milyang 23 and O. glaberrima. The O. glaberrima alleles at this locus increased GW and spikelets per panicle in the Milyang 23 background. To further confirm and narrow down the position of the QTLs on chromosome 3, substitution mapping was performed using five lines containing the target O. glaberrima segment on chromosome 3. The size and position of the O. glaberrima segment on chromosome 3 were different in each line. These lines possessed 3-10 non-target O. glaberrima introgressions in the Milyang 23 background. These five lines were evaluated for seven agronomic traits including 1,000 grain weight and spikelets per panicle and also genotyped with seven SSR markers. Four lines were informative in delimiting the position of QTLs, qGW3 and qSPP3. Two lines with the O. glaberrima segment flanked by SSR markers, RM60 and RM523 displayed significantly higher values than Milyang 23 in GW and SPP whereas two lines without that O. glaberrima segment displayed no difference in GW and SPP compared to Milyang 23. The result indicates that two QTL, qGW3 and qSPP3 are located in the interval between RM60 and RM523 which are 1.2-Mb apart. Introgression lines having QTLs, qGW3 and qSPP3 would be useful materials not only to indentify the relationship between these two yield QTLs, but also to develop high yielding variety via marker-aided selection technology.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.5 no.1
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• pp.37-43
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• 1969

A genetrc study was made on plant height of indica rices with a few segregating F2 populations involving three semi-dwarf varieties such as T(N)I, CP231-SLO17, and B569A12. These populations were grown in breeding nursery at the International Rice Research Institute (IRRI) during several seasons. 20 to 25 day old seedlings grown at upland seedbed were transplanted to the paddy in a single plant hill spacing 30 cm ${\times}$ 25cm. Measurements of plant height were made from the juncture between culm and roots to the tip of the longest panicle of a plant pulled out from the paddy when they are matured. The results are summarized as follows: 1. Tall indica varieties originated from the south-east Asian countries could be classified into two groups depending upon their allelism whether they showed monogenic segregating ratio of 3:1 or not when they were crossed to T(N)1. 2. Most of U.S. varieties, especially semi-dwarf breedirg materials such as CP231 ${\times}$ SIO17 and B569A12, did not show monogenic segregating mode of 3:1 ratio when they were crossed to T(N)1 or to other varieties bearing the same genetic allele of T(N)1 such as Peta and Sigadis.

• Korean Journal of Poultry Science
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• v.16 no.2
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• pp.61-71
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• 1989

The purposes of this study were to investigate the genetic variations by backcrossing in commercial chickens. Backcrossing was carried out successively back to parent stock (P.S). Heritabilities and genetic correlation coefficients were estimated to verify the genetic variations. The data obtained from a breeding programme with commercial chickens (I strain) were collected from 1955 to 1987 at Poultry Breeding Farm, Seoul National University. Data came from a total of 1230 female offspring. The results obtained are summarized as follows： 1. The general performance ($Mean\pmStandard deviation$) of each trait was $663.94\pm87.11$g for 8 weeks body weight, $1579.1\pm155.43$g for 20 weeks body weight, $2124.1\pm215.3$g for 40 weeks body weight, $2269.1\pm242.94$g for 60 weeks body weight, $168.43\pm12.94$ day for a9e at sexual maturity (SM), $214.52\pm29.82$ eggs , for total egg number to 60 weeks of age (TEN), $61.45\pm3.48$ g for average weight (AEW), $13180.7\pm1823.22$ g for total egg mass to 60 weeks of age(TEM). All traits, except 10 weeks body weight and AEW, were significant for the degrees of backcross (p＜0.01). 2. The pooled estimates of heritabilities derived from the sire, dam and combined variance components were 0.47~0.52 for age at sexual maturity (SM), 0.07~0.37 for total egg number (TEN), 0.40~0.54 for average egg weight (AEW), 0.18~0.27 for total egg mass (TEM). High heritability estimates were found for SM and AEW. TEN and TEM were estimated to be a lowly heritable traits. Heritability estimates from dam components were higher than those from sire components. These differences might be due to non-additive genetic effect and maternal effect. 3. The estimates of heritabilities and standard errors derived from combined variance components for different degrees of backcross were $0.47\pm0.11$ (BCO), $0.42\pm0.16$ (BC1), $0.51\pm0.29$ (BC2) for TEN, $0.59\pm0.20$ (BCO), $0.43\pm0.17$ (BC1), $0.35\pm0.18$ (BC2) for AEW, $0.28\pm0.12$(BC0), $0.20\pm0.11$(BC1), $0.18\pm0.14$ (BC2) for TEM. Heritability estimates for AEW and TEM were decreased by backcrossing while those for SM and TEN remained constant. Since backcrossing contributes to increased homozygosity, the genetic variation of the traits (AEW and TEM) decreased . 4. The pooled estimates of genetic correlation coefficients were -0.55 between SM and TEN, 0.20 between SM and AEW, -0.29 between TEN and AEW, 0.82 between TEM and TEN, 0.31 between TEM and AEW, -0.42 between TEM and SM. The genetic correlation between TEM and TEN was higher than that between TEM and AEW, and it was suggested that egg mass was strongly affected by egg number. Also, age at sexual maturity(SM) contributes to egg mass(TEM). 5. When backcrossing was carried out successively, the genetic correlation between TEM and TEN increased (BC0：0.79, BC1：0.82, BC2：0.91) but those between TEM and SM decreased (BC0：-0.54, BC1：-0.36, BC2：-0.09) with successive backcrosses.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.314-326
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• 2020

This study was carried out to develop a resistant variety against the K3a race of bacterial blight, Xanthomonas oryzae pv. oryzae, through expansion and pyramiding of resistance genes. To develop an elite bacterial blight-resistant cultivar, the breeding process and bacterial blight resistance reactions in advanced backcross lines (ABLs) were analyzed. ABLs21 which contain Xa3 and Xa21, were developed by double backcrossing japonica cultivar Hwanggeumnuri, which has bacterial blight resistant Xa3 gene, and indica variety IRBB21, which havs Xa21 gene, followed by disease resistance bioassay and marker-assisted selection. The resistance genes of ABLs21 were amplified by PCR with the molecular markers 9643.T4 (Xa3) and U1/I1 (Xa21). Hwanggeumnuri and IRBB3 showed resistance reactions against K1, K2, and K3 races, and a susceptible reaction against K3a, K4, and K5 races. IRBB21 showed resistance reactions against K2, K3, K3a, K4 and K5 races, and a susceptible reaction against K1 race. Hwanggeumnuri showed susceptible reactions at the seedling, tillering and adult stages (all stages), whereas ABL21-1 showed moderate resistance at the tillering stage. ABL21-1 showed stable resistance against 18 isolates of K3a race, and the lesion length was shorter than that of the donor parents. In cluster analysis, the HB4032 isolate showed the highest pathogenicity among the 18 isolates. The molecular marker polymorphisms and average substituted chromosome segment lengths of ABLs21 were 63.2 % and 86.1 cM, respectively. Insertion of the donor chromosomal segments occurred in the predicted region of the Xa21 gene of ABLs21.