• Proceedings of the Korean Society of Crop Science Conference
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• 1989.10a
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• pp.3-4
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• 1989

• Korean Journal of Plant Resources
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• v.29 no.6
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• pp.658-669
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• 2016

Rice blast, caused by a fungus Magnaporthe oryzae, is one of the most devastating diseases of rice worldwide. Analyzing the valuable genetic resources is important in making progress towards blast resistance. Molecular screening of major rice blast resistance (R) genes was determined in 2,509 accessions of rice germplasm from different geographic regions of Asia and Europe using PCR based markers which showed linkage to twelve major blast R genes, Pik-p, Pi39, Pit, Pik-m, Pi-d(t)2, Pii, Pib, Pik, Pita, Pita/Pita-2, Pi5, and Piz-t. Out of 2,509 accessions, only two accessions had maximum nine blast resistance genes followed by eighteen accessions each with eight R genes. The polygenic combination of three genes was possessed by maximum number of accessions (824), while among others 48 accessions possessed seven genes, 119 accessions had six genes, 267 accessions had five genes, 487 accessions had four genes, 646 accessions had two genes, and 98 accessions had single R gene. The Pik-p gene appeared to be omnipresent and was detected in all germplasm. Furthermore, principal component analysis (PCA) indicated that Pita, Pita/Pita-2, Pi-d(t)2, Pib and Pit were the major genes responsible for resistance in the germplasm. The present investigation revealed that a set of 68 elite germplasm accessions would have a competitive edge over the current resistance donors being utilized in the breeding programs. Overall, these results might be useful to identify and incorporate the resistance genes from germplasm into elite cultivars through marker assisted selection in rice breeding.

• Horticultural Science & Technology
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• v.35 no.4
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• pp.465-479
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• 2017

Chili pepper (Capsicum annuum L.) is an economically important horticultural crop in Korea; however, various diseases, including Phytophthora root rot, anthracnose, powdery mildew, Cucumber mosaic virus (CMV), Pepper mild mottle virus (PMMoV), and Pepper mottle virus (PepMoV), severely affect their productivity and quality. Therefore, pepper varieties with resistance to multiple diseases are highly desired. In this study, we developed 20 SNP type assays for three pepper populations using Fluidigm nanofluidic dynamic arrays. A total of 4,608 data points can be produced with a 192.24 dynamic array consisting of 192 samples and 24 SNP markers. The assays were converted from previously developed sequence-tagged-site (STS) markers and included markers for resistance to Phytophthora root rot (M3-2 and M3-3), anthracnose (CcR9, CA09g12180, CA09g19170, CA12g17210, and CA12g19240), powdery mildew (Ltr4.1-40344, Ltr4.2-56301, and Ltr4.2-585119), bacterial spot (Bs2), CMV (Cmr1-2), PMMoV (L4), and PepMoV (pvr1 and pvr2-123457), as well as for capsaicinoids content (qcap3.1-40134, qcap6.1-299931, qcap6.1-589160, qdhc2.1-1335057, and qdhc2.2-43829). In addition, 11 assays were validated through a comparison with the corresponding data of the STS markers. Furthermore, we successfully applied the assays to commercial $F_1$ cultivars and to our breeding lines. These 20 SNP type assays will be very useful for developing new superior pepper varieties with resistance to multiple diseases and a higher content of capsaicinoids for increased pungency.

• Current Research on Agriculture and Life Sciences
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• v.28
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• pp.39-46
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• 2010

Selection procedures for breeding lines resistant to both bacterial wilt caused by Ralstonia solanacearum and Phytophthora blight caused by P. capsici were executed to generations from $F_2$ and $BC_1F_1$ to $F_4$ and $BC_1F_3$ of crosses between a Phytophthora resistant breed, 'Chilbok No. 1' and bacterial wilt resistant accessions introduced from Vietnam during 2009 and 2010. The breeding populations or lines were tested for resistance to P. capsici and resistant plants were selected. The resistant selections were inoculated with R. solanacearum to discard susceptible plants. Resistance to P. capsici was conspicuously improved by selection from $F_2$ and $BC_1F_1$ and the final selections showed a similar level of resistance to P. capsici as a commercial Phytophthora resistant cultivar, Muhanjilju. A few $BC_1F_2$ selections were crossed to a cytoplasmic male sterile line, Chilbok-A, to identify their nuclear genotype interacting with male sterile cytoplasm. Majority of them was fixed to maintainer (Nrfrf) and only two resulted segregating into male sterile and male fertile plants indicating that the pollen parents were heterozygous in the fertility-restoring gene.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.281-285
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• 2005

Pod dehiscence (PD), defined as the opening of pods along both the dorsal and ventral sutures, causes the seed to shatter in the field before harvesting and results in loss of seed yields. However, breeding for resistance to PD is difficult due to the complicated genetic behavior and environmental interaction. The objective of the present research was to analyze the genetic behavior of PD for improving the breeding efficiency of resistance to PD in soybean. PD after oven-drying the sampled pod at $40^{\circ}C$ for 24 hours was the most reliable to predict the degree of PD tested in the field. Keunolkong, a dehiscent parent, was crossed with non-dehiscent parents, Sinpaldalkong and Iksan 10. Using their $F_1\;and\;F_2$ seeds, PD was measured after oven drying the pod at $40^{\circ}C$ for 24 hours. The gene conferring PD behaved in different manners depending on the genetic populations. In the Keunolkong$\times$Sinpaldalkong population, PD seemed to be governed by single major recessive gene and minor genes, while several genes were probably involved in the resistance to pod dehiscence in the Keunolkong$\times$Iksan 10 population. Heritability for PD estimated in F2 population showed over $90\%$ in the two populations. High heritability of PD indicated that selection for resistance to PD should be effective in a breeding program. In addition, genetic mapping of quantitative locus (QTL) for PD in both populations may reveal that genes conferring PD are population-specific.

• The Plant Pathology Journal
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• v.30 no.1
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• pp.75-81
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• 2014

In total, 170 carrot lines developed in Korea were screened for resistance to Meloidogyne incognita race 1 to select parental genetic resources useful for the development of nematode-resistant carrot cultivars. Using the gall index (GI), gall formation was examined on carrot roots inoculated with approximately 1,000 second-stage juveniles of the nematode 7 weeks after inoculation. Sixty-one carrot lines were resistant (GI ${\leq}1.0$), while the other 109 were susceptible (GI > 1.0) with coefficient of variance (CV) of GI for total carrot lines 0.68, indicating low-variation of GI within the lines examined. The histopathological responses of two carrot plants from resistant and susceptible lines were examined after nematode infection. In susceptible carrots, giant cells formed with no discernible necrosis around the infecting nematodes. In the resistant carrot line, however, no giant cells formed, although modified cells were observed with extensive formation of necrotic layers through their middle lamella and around the infecting nematodes. This suggested that these structural modifications were related to hypersensitive responses governed by the expression of true resistance genes. Therefore, the Korean carrot lines resistant to the nematode infection are potential genetic resources for the development of quality carrot cultivars resistant to M. incognita race 1.

• Horticultural Science & Technology
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• v.33 no.5
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• pp.730-736
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• 2015

Tomato spotted wilt virus (TSWV) causes one of the most destructive viral diseases that threatens global tomato production. Sw-5b was reported as the resistance gene effective against TSWV. The objective of this research was to develop a single-nucleotide polymorphism (SNP) marker to distinguish tomato cultivars resistant to TSWV from susceptible cultivars for marker-assisted breeding. First, we determined genotypes for TSWV resistance in 32 commercial tomato cultivars using the previously reported Sw-5b gene-based marker. Then, DNA sequences of Sw-5b alleles in tomato cultivars showing resistant or susceptible genotypes were analyzed; a single SNP was found to distinguish tomato cultivars resistant to TSWV from susceptible cultivars. Based on the confirmed SNP, a SNP primer pair was designed. Using this new SNP sequence and high-resolution melting analysis, the same 32 tomato cultivars were screened. The results were perfectly correlated with those from screening with the Sw-5b gene-based marker. These results indicate that the SNP maker developed in this study will be useful for better tracking of resistance to TSWV in tomato breeding.

• BMB Reports
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• v.51 no.2
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• pp.55-56
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• 2018

Long terminal repeat retrotransposons (LTR-Rs) are major elements creating new genome structure for expansion of plant genomes. However, in addition to the genome expansion, the role of LTR-Rs has been unexplored. In this study, we constructed new reference genome sequences of two pepper species (Capsicum baccatum and C. chinense), and updated the reference genome of C. annuum. We focused on the study for speciation of Capsicum spp. and its driving forces. We found that chromosomal translocation, unequal amplification of LTR-Rs, and recent gene duplications in the pepper genomes as major evolutionary forces for diversification of Capsicum spp. Specifically, our analyses revealed that the nucleotide-binding and leucine-rich-repeat proteins (NLRs) were massively created by LTR-R-driven retroduplication. These retoduplicated NLRs were abundant in higher plants, and most of them were lineage-specific. The retroduplication was a main process for creation of functional disease-resistance genes in Solanaceae plants. In addition, 4-10% of whole genes including highly amplified families such as MADS-box and cytochrome P450 emerged by the retroduplication in the plants. Our study provides new insight into creation of disease-resistance genes and high-copy number gene families by retroduplication in plants.

• Journal of Plant Biotechnology
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• v.45 no.3
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• pp.228-235
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• 2018

In this study, two pepper varieties, PRH1 (powdery mildew resistance line) and Saengryeg (powdery mildew resistance line), were resequenced using next generation sequencing technology in order to develop InDel markers. The genome-wide discovery of InDel variation was performed by comparing the whole-genome resequencing data of two pepper varieties to the Capsicum annuum cv. CM334 reference genome. A total of 334,236 and 318,256 InDels were identified in PRH1 and Saengryeg, respectively. The greatest number of homozygous InDels were discovered on chromosome 1 in PRH1 (24,954) and on chromosome 10 (29,552) in Saengryeg. Among these homozygous InDels, 19,094 and 4,885 InDels were distributed in the genic regions of PRH1 and Saengryeg, respectively, and 198,570 and 183,468 InDels were distributed in the intergenic regions. We have identified 197,821 polymorphic InDels between PRH1 and Saengryeg. A total of 11,697 primers sets were generated, resulting in the discovery of four polymorphic InDel markers. These new markers will be utilized in order to identify disease resistance genotypes in breeding populations. Therefore, our results will make a one-step advancement in whole genome resequencing and add genetic resource datasets in pepper breeding research.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.1
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• pp.97-107
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• 1990

The epidemiology of plant disease deals with the dynamic processes of host-pathogen interactions, which determine the prevalence and severity of the disease. Epidemic processes for most foliar diseases of plants follow a series of steps: arrival of pathogens on plant surfaces, initial infection, incubation period, latent period, sporulation, dissemination of secondary inoculum, and infectious period. These complex biological processes are influenced by the environment-Man also often interfers with these processes by altering the host and pathogen populations and the environment. Slowing or halting any of the epidemic processes can delay the development of the epidemic, so that serious losses in yield due to disease do not occur. It is generally recognized that the most effective and efficient method of minimizing disease damage is through the use of resistant cultivars, particularly when other methods such as fungicide applications are not economically feasible-Populations of plant pathogens are not genetically uniform nor are they necessarily stable. Cultivars bred for resistance to current populations of a pathogen may not be resistant in the future due to selection pressures placed on the pathogen populations. Understanding population development and genetic variability in the pathogen, and knowledge of the genetics of resistance in the plant should help in developing breeding strategies that wi1l provide effective and stable disease control through genetic resistance. In the United States, soybeans have ranked first in value of crops sold off the farm in recent years. Soybeans have been the leading U. S.