• Asian-Australasian Journal of Animal Sciences
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• v.17 no.9
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• pp.1210-1213
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• 2004

Quantitative trait loci (QTL) mapping can be applied to detect chromosomal locations that control economic traits in farm animals. Teat number has been considered as one of the most important factors to evaluate mothering ability of sow. Especially, teat number is more important when the number is less than the litter size. This study was conducted to identify QTL affecting teat number in the Korean native pig${\times}$Landrace resource family. A total of 240 animals was genotyped for 132 polymorphic microsatellites covering the 18 pig autosomes. Mean and standard deviation of teat number in $F_2$animals is 13.46${\pm}$1.40. QTL was analyzed using F2 QTL Analysis Servlet of QTL express. A QTL for teat number on SSC9 was significant at the 1% chromosome-wide level and three suggestive QTL were detected on SSC3, 7 and 14. All QTL detected in this study had additive effect and Landrace alleles were associated with higher teat number in comparison with Korean native pig for three of four QTL.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.4
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• pp.199-204
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• 1998

This study was conducted to investigate the chromosomal locations and effects of quantitative trait loci (QTL) associated with chemical properties of rice (Oryza sativa L.). One hundred sixty four recombinant inbred lines (MGRILs) of $F_{11}$ were derived from the cross between Milyang 23, Tongil type, and Gihobyeo, japonica type. They were evaluated for 7 traits of chemical property in rice. Transgressive segregation was observed for all traits examined. Eight significant QTLs were detected (LOD$\geq$2.0) for five traits, including two QTLs for amylose content, two QTLs for potassium content, one QTL for ratio of magnesium to potassium, one QTL for fat content and two QTLs for ash content. Phenotypic variation explained by each QTL ranged from 7.2% to 14.4%. However, no significant QTL was detected for magnesium and protein contents. In amylose content and ash content M alleles originated from Milyang 23 were responsible for increasing these traits and J alleles originated from Gihobyeo also responsible for increasing these traits. Pleiotropic effects of single QTLs on different traits are observed.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.12
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• pp.1665-1669
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• 2001

A QTL was localized near S0120 on porcine chromosome 18. The QTL was significant (p<0.05) for average daily gain (ADG) of body weight and backfat thickness (BFT). The estimates of additive and dominance effects for the QTL were 0.0135 kg/day (p<0.001) and 0.0138 kg/day (p>0.5) for ADG and 1.6115 mm (p<0.001) and 0.9281 mm (p>0.05) for BFT. The location of this QTL coincided with a few growth hormone pathway genes. This study suggested that a QTL allele probably resulted from a mutation responsible for physiological lipase deficiency favoring obesity. This QTL might be important to obesity as well as growth in pigs.

• Plant Biotechnology Reports
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• v.4 no.1
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• pp.61-73
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• 2010

Quantitative trait loci (QTL) associated with six physical traits of cooked rice and seven chemical properties of rice grain were identified using a recombinant inbred (RI) population of rice evaluated over 3 years at the National Honam Agricultural Research Institute in Korea. The RI population consisted of 164 lines derived from a cross between Milyang23 and Gihobyeo, and the genetic map consisted of 414 molecular markers. A total of 49 QTL were identified for the 13 physico-chemical properties using composite interval mapping. Of these, 13 QTL were identified for 2 or more years, while 36 were detected in only 1 year. Five QTL were identified over all 3 years and will be useful for marker-assisted improvement of rice grain quality in Korea. The two QTL with the highest LOD scores, adhesiveness1.2 and potassium content7.1, provide a valuable starting point for positional cloning of genes underlying these QTL.

• Journal of Life Science
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• v.14 no.2
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• pp.339-344
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• 2004

Identification of individual quantitative trait loci (QTL) is a prerequisite to application of marker-assisted selection for stern length. Two simple sequence repeat (SSR)-based linkage maps were constructed from recombination inbred line populations between cross of Keunolkong and Shinpaldalkong. Two parents used differed greatly in stem length, which were 30.57 cm and 49.75 cm in Keunolkong and Shinpaldalkong, respectively. Using the constructed maps, regression analysis and interval mapping were performed to identify QTLs conferring stem length. Four QTLs for stem length on linkage groups (LG) F, J, N and O were identified in the Keunolkong ${\times}$ Shinpaldalkong population and they totally explained 37.83% of variation for stem length. In the population, two major QTLs on LG J and O conditioning 14.25% and 10.68% of the phenotypic variation in stem length were determined and two QTLs with minor effect were detected on LG F and N. Identification of QTLs for stem length and mapping individual locus should facilitate to describe genetic mechanisms for stem length in different population. SSR markers tightly linked to QTLs for stem length allow to accelerate the elimination of deleterious genes and selection for desirable recombinants at early stage in crop breeding programs.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.92-92
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• 2017

Bakanae disease is one of the most serious and oldest problems of rice production, which was first described in 1828 in Japan. This disease has also been identified in Asia, Africa, North America, and Italy. Germinating rice seeds in seed boxes for mechanical transplantation has caused many problems associated with diseases, including bakanae disease. Bakanae disease has become a serious problem in the breeding of hybrid rice, which involves the increased use of raising plants in seed beds. The indica rice variety Shingwang was selected as resistant donor to bakanae disease. One hundred sixty nine NILs, YR28297 ($BC_6F_4$) generated by five backcrosses of Shingwang with the genetic background of susceptible japonica variety, Ilpum were used for QTL analysis. Rice bakanae disease pathogen, CF283, was mainly used in this study and inoculation and evaluation of bakanae disease was performed with the method of the large-scale screening method developed by Kim et al. (2014). SSR markers evenly distributed in the entire rice chromosomes were selected from the Gramene database (http://www.gramene.org), and the polymorphic markers were used for frame mapping of a $BC_5F_5$ resistant line. Here, we developed 168 near-isogenic rice lines (NILs, $BC_6F_4$) to locate a QTL for resistance against bakanae disease. The lines were derived from a cross between Shingwang, a highly resistant variety (indica), and Ilpum, a highly susceptible variety (japonica). The 24 markers representing the Shingwang allele in a bakanae disease-resistant NIL, YR24982-9-1 (parental line of the $BC_6F_4$ NILs), were located on chromosome 1, 2, 7, 8, 10, 11, and 12. Single marker analysis using an SSR marker, RM9, showed that a major QTL was located on chromosome 1. The QTL explained 65 % of the total phenotype variation in $BC_6F_4$ NILs. The major QTL designated qBK1 was mapped in 91 kb region between InDel15 and InDel21. The identification of qBK1 and the closely linked SSR marker, InDel18, could be useful for improving rice bakanae disease resistance in marker-assisted breeding.

• Korean Journal of Agricultural Science
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• v.39 no.4
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• pp.477-482
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• 2012

Low-temperature germination is one of the major determinants for stable stand establishment in the rice direct seeding method in temperate regions and at high altitude areas. Quantitative trait loci (QTL) controlling low-temperature germinability in rice were identified using 96 introgression lines (ILs) derived from a cross between Oryza rufipogon and the Korean japonica cultivar, 'Hwaseongbyeo'. The germination rate at $15^{\circ}C$ was measured to represent low-temperature germination and used for QTL analysis. The germination rate at $15^{\circ}C$ for 7 days of Oryza rufipogon and Hwaseongbyeo was 93.3 and 28.7%, respectively, and that of progenies ranged from 0 to 48%. A linkage map was constructed using 135 simple sequence repeat (SSR) markers. Five putative QTLs associated with low-temperature germination were detected on chromosomes 1, 3, 4, 10 and 11. The QTL, qltg10 on chromosome 10 accounted for 19.2% of the total phenotypic variation for low-temperature germinability. Four additional QTL, accounted for 10.4 - 15.1% of the total phenotypic variation. The O. rufipogon alleles in all detected QTLs loci increased the low-temperature germination rate. No QTL associated with low temperature germinability has been detected near the qltg10 QTL in this study suggesting that qltg10 is a new QTL. The locus, qltg10 is of particular interest because of its independence from undesirable height and maturity effects. The DNA markers linked to the QTL for low temperature germinability would be useful in selecting lines with enhanced low temperature germinability in rice breeding program.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.2
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• pp.109-127
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• 2014

Maize is one of the most important food and feed crops in the world including Southeast Asia. In spite of numberous efforts with conventional breeding, the maize productions remain low and the loss of yields by drought and downy mildew are still severe in Asia. Genetic improvement of maize has been performed with molecular marker and genetic engineering. Because maize is one of the most widely studied crop for its own genome and has tremendous diversity and variant, maize is considered as a forefront crop in development and estimation of molecular markers for agricultural useful trait in genetics and breeding. Using QTL (Quantitative Trait Loci) and MAS (Marker Assisted Breeding), molecular breeders are able to accelerate the development of drought tolerance or downy mildew resistance maize genotype. The present paper overviews QTL/MAS approaches towards improvement of maize production against drought and downy mildew. We also discuss here the trends and importance of molecular marker and mapping population in maize breeding.

• Horticultural Science & Technology
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• v.35 no.2
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• pp.149-164
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• 2017

Next generation sequencing (NGS) technologies have led to the rapid accumulation of genome sequences through whole-genome sequencing and re-sequencing of crop species. Genomic resources provide the opportunity for a new revolution in plant breeding by facilitating the dissection of complex traits. Among vegetable crops, reference genomes have been sequenced and assembled for several species in the Solanaceae and Cucurbitaceae families, including tomato, pepper, cucumber, watermelon, and melon. These reference genomes have been leveraged for re-sequencing of diverse germplasm collections to explore genome-wide sequence variations, especially single nucleotide polymorphisms (SNPs). The use of genome-wide SNPs and high-throughput genotyping methods has led to the development of new strategies for dissecting complex quantitative traits, such as genome-wide association study (GWAS). In addition, the use of multi-parent populations, including nested association mapping (NAM) and multiparent advanced generation intercross (MAGIC) populations, has helped increase the accuracy of quantitative trait loci (QTL) detection. Consequently, a number of QTL have been discovered for agronomically important traits, such as disease resistance and fruit traits, with high mapping resolution. The molecular markers for these QTL represent a useful resource for enhancing selection efficiency via marker-assisted selection (MAS) in vegetable breeding programs. In this review, we discuss current genomic resources and marker-trait association analysis to facilitate genome-assisted breeding in vegetable species in the Solanaceae and Cucurbitaceae families.

• Journal of Crop Science and Biotechnology
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• v.11 no.3
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• pp.163-170
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• 2008

The detection, characterization and use of quantitative traits loci, QTL, have significant potential to improve the efficiency of selective breeding of species. Therefore, a population with 59 advanced backcross lines($BC_2F_5$), derived from a cross between IR64 and Tarome molaei, were studied in Tonekabon Rice Research Station of Iran in order to map QTLs for panicle length, number of grain per panicle, and panicle grain sterility in rice. The parental screening wtih 235 SSR markers in agarose and polyacrylamide gels revealed 114 markers with clear polymorphic bands. To search for QTLs associated with panicle length, number of grain per panicle, and panicle grain sterility, we constructed a genetic linkage map using 114 microsatellite markers. Positive and negative transgressive segregations were observed in $BC_2F_5$ lines for all traits. Using multiple interval mapping(MIM), a total of 20 putative QTLs were detected, of which eight were for panicle length, three for number of grains, and nine for panicle grain sterility. The maximum number of QTLs were mapped on chromosomes 1 and 2 with eight QTLs. These QTL markers could possible be utilized for marker-assisted selection.