• Korean Journal of Breeding Science
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• v.50 no.4
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• pp.434-441
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• 2018

High-density genetic linkage mapping is critical for undertaking marker-assisted selection and confirming quantitative trait loci, as well as helping to build pseudomolecules of genomes. We constructed a genetic map using 94 $F_1$ populations generated from the interspecific cross between Korean cultivar "Wonwhang" (Pyrus pyrifolia, NCBI BioSample SAMN05196235) and European cultivar "Bartlett" (Pyrus communis). We designed a total of 24,267 SSR markers based on the genome sequences of "Wonwhang" for this. To select the markers that are linked to the traits important in pear breeding programs, SSR-containing genomic sequences were subjected to nucleotide sequence homology searches, which resulted in 510 SSR markers with high similarity to genes encoding proteins with putative functions such as transcription factors, resistance proteins, flowering time, and regulatory genes. Of these, 70 markers showed polymorphisms in parents and segregating populations and were used to construct a genetic linkage map, together with the unpublished 579 SNPs obtained from genotyping by sequencing analysis. The genetic linkage map covered 3,784.2 cM and the average distance between adjacent markers was 5.8 cM. Seventy SSR markers were distributed across 17 chromosomes with more than one locus.

• Plant Resources
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• v.1 no.2
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• pp.81-91
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• 1998

Fifty-nine Korean soybean (Glycine max L. Merr.) landrace accessions were tested for genotype fingerprinting, differentiation and association between morphological traits and SSR profile. Using 8 SSR loci, 59 varieties were divided into 55 groups, and only 4 pairs of varieties were not uniquely identified. The resolving power of SSR for soybean genotyping was much higher than that of the morphological traits that were studied. Identification efficiency also differed among SSR loci. Those loci with higher numbers of alleles distinguished varieties more effectively. Genetic differentiation values of the soybean landraces varied from 0.57 to 0.82 with a mean of 0.68. The number of alleles detected by the 8 loci ranged from 3 to 8. and the effective number of alleles ranged from 2.3 to 5.1. In a study of the association of SSR alleles with morphological traits, some alleles seemed to be related with some specific morphological traits. Comparison of two kinds of dendrograms which were derived from SSR markers and quantitative traits indicated that the dendrograms were not consistent. Considering the correlation between single SSR locus and qualitative traits governed by major genes, the data suggest that alleles of microsatellite loci be more closely related to some traits determined by major genes than those determined by minor genes.

• Journal of the Korean Geosynthetics Society
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• v.8 no.1
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• pp.11-18
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• 2009

This paper presents a comparative study of reinforced soil slope by using LEM and SSR-FEM. Current analysis methods for reinforced soil wall are based on LEM. SSR-FEM assumes a reduction of soil strength by a factor to reach a critical state prior to failure based on continuum mechanics. In this study the comparisons are concerned with the factor of safety and the potential failure surface in reinforced soil wall. We investigated the stability of the reinforced soil wall with a slope of $60^{\circ}$ by LEM and SSR-FEM. The comparisons indicated good performance of the SSR-FEM on stability analysis of reinforce soil wall.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.2
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• pp.46-53
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• 2022

This paper presents the design and manufacture of a Solid State Relay (SSR) life prediction device that can predict the lifetime of an SSR, which is a key component of a glass forming machine. The lifetime of an SSR is over when the current supplied to the relay is overcurrent (20 A or higher), and the operating time is 100,000 h or longer. Therefore, the life prediction device for the SSR was designed using DSP to accurately read the current and temperature values from the current and temperature sensors, respectively. The characteristic test of the manufactured non-contact relay life prediction device confirmed that the current and temperature were safely measured. Thus, the SSR lifetime prediction device developed in this study can be used to predict the lifetime of an SSR attached to a glass forming machine.

• Journal of Plant Biotechnology
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• v.33 no.4
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• pp.289-295
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• 2006

This study was carried out to evaluate the suitability of simple sequence repeat (SSR) markers for varietal identification and genetic diversity in 28 commercial tomato varieties. The relationship between marker genotypes and 28 varieties was analyzed. Of the 219 pairs of SSR primers screened against ten tomato varieties, 18 pairs were highly polymorphic with polymorphism information content (PIC) ranging from 0.467 to 0.800. Among the polymorphic loci, two to nine SSR alleles were detected for each locus with an average of 3.3 alleles per locus. Genetic distances were estimated according to Jaccard's methods based on the probability that the amplified fragment from one genotype would be present in another genotype. These varieties were categorized into cherry and classic fruit groups corresponding to varietal types and genetic distance of cluster ranging from 0.35 to 0.97. The phonogram discriminated all varieties by marker genotypes. The SSR markers proved to be useful variety identification and genetic resource analysis of tomato.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.4
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• pp.334-340
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• 2001

Two different types of molecular markers, simple sequence repeat (SSR) and single nucleotide polymorphism (SNP), were used to measure genetic diversity among five Korean, eight Thai, and three wild soybeans. For SSR analysis, a total of 20 markers were surveyed to detect polymorphisms. For SNP analysis, four primers were designed from consensus sequence regions on disease resistance protein homolog genes, and used to amplify the genomic region. The PCR products were sequenced. A number of polymorphic SSR and SNP bands were scored on all genotypes and their genetic similarity was measured. Clustering analysis was performed independently on both types of markers. Clustering based on SSR markers separated the genotypes into three main groups originated from Korea, Thailand, and wild soybeans. On the other hand, two main groups were classified using SNP analysis. It seemed that SSR was more informative than SNP in this study. This may be due to the fact that SNP was surveyed on the smaller genomic region than SSR. Grouping based on the combined data of both markers revealed similar results to that of SNP rather than that of SSR. This might be due to the fact that more loci from SNP were considered to measure genetic relatedness than those from the SSR.

• Journal of Life Science
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• v.21 no.3
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• pp.468-472
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• 2011

DNA marker is a powerful tool for plant genetics and breeding. In this study, 995 SSR markers were employed with chilling resistant cucumber, known as 'NC76', and chilling susceptible cucumber, known as 'GY14'. Using 2% agarose gel electrophoresis, 145 SSR markers were identified as length variation markers between 'NC76' and 'GY14'. The SSR markers that showed no length polymorphism were then screened using high resolution melting analysis technique and additional 30 polymorphic SSR markers were identified. As a preliminary evaluation for mapping, 20 markers among these 175 markers were employed to a $F_2$ population of 'NC76' x 'GY14' cross. Linkage analysis revealed 13 markers that joined into six linkage groups and seven markers that remained unlinked. This result indicates that these 175 markers could be used for construction of a genetic map using a cross between 'NC76' and 'GY14' for further investigation in developing markers related to resistance to chilling in cucumbers.

• Journal of Korean Society of Forest Science
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• v.89 no.4
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• pp.536-542
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• 2000

A linkage map for Japanese red pine (Pinus densiflora) was constructed on the basis of two DNA marker systems of random amplified polymorphic DNAs (RAPDs) and inter-simple sequence repeats (I-SSR). Haploid genomic DNAs were extracted from megagametophyte tissues of 96 individual seeds in a single tree. A total of 98 DNA markers including 52 RAPD markers amplified by 25 primers and 46 I-SSR markers amplified by 18 primers were verified as Mendelian loci showing 1 : 1 segregation in 96 megagametophytes which were ${\chi}^2$-tested at 5% significance level. Of them, 63 segregating loci turned out to be linked into 20 linkage groups by the two-point analysis. However, 35 loci (17 RAPD and 18 I-SSR) of the 98 segregating loci did not coalesced into any linkage groups at a LOD of 3.0. The linked 63 loci were separated by an average distance of about 25.5 cM, which were spanned 1097.8 cM as a whole. The minimum and maximum map distances of the linkage groups were 4.3 cM and 54.9 cM, respectively. Incorporation of I-SSR loi into linkage map of RAPD loci resulted in extended and partially more saturated linkage blocks.

• Journal of Mushroom
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• v.15 no.2
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• pp.78-83
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• 2017

Microsatellite SSR markers were developed and utilized to reveal the genetic diversity of 32 strains of Flammulina velutipes collected in Korea, China, and Japan. From the SSR-enriched library, 490 white colonies were randomly selected and sequenced. Among the 490 sequenced clones, 85 (17.35%) were redundant. Among the remaining 405 unique clones, 201 (49.6%) contained microsatellite sequences. We used 12 primer pairs that produced reproducible polymorphic bands for four diverse strains, and these selected markers were further characterized in 32 Flammulina velutipes strains. A total of 34 alleles were detected using the 12 markers, with an average of 3.42 alleles, and the number of alleles ranged from two to seven per locus. The major allele frequency ranged from 0.42 (GB-FV-127) to 0.98 (GB-FV-166), and values for observed ($H_O$) and expected ($H_E$) heterozygosity ranged from 0.00 to 0.94 (mean = 0.18) and from 0.03 to 0.67 (mean = 0.32), respectively. SSR loci amplified with GB-FV-127 markers gave the highest polymorphism information content (PIC) of 0.61 and mean allele number of five, whereas for loci amplified with GB-FV-166 markers these values were the lowest, namely 0.03 and two. The mean PIC value (0.29) observed in the present study with average number of alleles (3.42). The genetic relationships among the 32 Flammulina velutipes strains on the basis of SSR data were investigated by UPGMA cluster analysis. In conclusion, we succeeded in developing 12 polymorphic SSRs markers from an SSR-enriched library of Flammulina velutipes. These SSRs are presently being used for phylogenetic analysis and evaluation of genetic variations. In future, these SSR markers will be used in clarifying taxonomic relationships among the Flammulina velutipes.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.7
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• pp.658-668
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• 2006

The objective of this study was to develop a technique for the cultivar discrimination using SSR markers in soybean. A total of 91 soybean cultivars developed from 1913 to 2002 in Korea were evaluated by five polymorphic SSR markers (Sat_043, Sat_036, Sat_022, Sat_088 and Satt045). Five SSR markers generated a total of 64 alleles and the number of alleles for each SSR marker ranged from 10 to 15 with average of 12.8. Polymorphic information contents (PIC) by five markers of 91 cultivars were ranged from 0.790 to 0.905 with average of 0.857. A total of 82 cultivars (90%) among 91 soybean cultivars could be individually discriminated by combination of five SSR markers through five step analysis. A cultivar, Buseok, by Sat_043 at the first step, 34 cultivars including Hojangkong by Sat_036 at the second step, 29 cultivars including Dankyeongkong by Sat_022 at the third step, 12 cultivars including Sinpaldalkong 2 by Sat_088 at the fourth step, and 6 cultivars including Saebyeolkong by Satt045 at the fifth step were discriminated. Soybean cultivars which were not discriminated by SSR markers could be discriminated by morphological characteristics.