• Journal of Genetic Medicine
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• v.20 no.1
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• pp.15-24
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• 2023

Monogenic disorders are traditionally attributed to the presence of mutations in a single gene. However, recent advancements in genomics have revealed instances where the phenotypic expression of apparently monogenic disorders cannot be fully explained by mutations in a single gene alone. This review article aims to explore the emerging concept of digenic or oligogenic inheritance in seemingly monogenic disorders. We discuss the underlying mechanisms, clinical implications, and the challenges associated with deciphering the contribution of multiple genes in the development and manifestation of such disorders. We present relevant studies and highlight the importance of adopting a broader genetic approach in understanding the complex genetic architecture of these conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.4
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• pp.35-37
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• 1979

To investigate the genetic system in resistance to powdery mildew winter wheat cultivar Diplomat which has stable field resistance was crossed with high yielding susceptible winter type Caribo and Hayman's generation mean analysis technique was employed. Mildewing rate on flag-leaf at both heading-flowering and ripe stages were recorded according to lame's quantitative scale. The result indicated that additive gene effect was more important and significant role in the inheritance of resistance while dominant gene effect was minimum, and digenic interations were absent. Narrow sense heritability of resistance at ripe stage was higher than that of heading-flowering stage.

• Journal of Plant Biotechnology
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• v.7 no.1
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• pp.27-35
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• 2005

Eighty-five different cultivars of Brassica rapa, B. juncea, B. nap us, B. carinata, B. oleracea and hexaploid Brassica collected from Bangladesh, Japan, China and Denmark were analyzed by SDS-PAGE for seed and leaf protein variations, using esterase, acid phosphatase and peroxidase isozyme analysis. Ten polymorphic bands were identified from seed protein however no identifiable polymorphic band was found in the leaf protein. Polymorphic markers clearly distinguished the different Brassica species as well as yellow sarson (YS) and brown seeded (BS) cultivars of B. rapa. The $F_1$ cross between YS and brown seeded cultivars showed the existance of all poly-morphic bands of the respective parents. The Bangla-deshi and Japanese cultivars of B. rapa differed in the amount of seed protein. In the case of isozyme analysis, esterase showed the highest number of polymorphic bands (13) followed by acid phosphatase (9) and peroxidase (5). These polymorphic markers were very effec-tive for classification of all the species studied in this experiment. In parentage tests using isozymes, the hybridity of intra-and-interspecific crosses of almost all the seedlings could be identified from their respective cross combinations. Esterase polymorphism showed a clear differentiation between YS and BS types of B. rapa. In addition, two esterase polymorphic markers were iden ified to differentiate some cultivars of B. juncea. Segregation patterns in these two esterase bands showed a simple Mendelian monohybrid ratio of 3:1 in $F_2$, 1:1 in test cross and 1:0 in back cross progenies. No polymorphic band was identified to distinguish different cultivars of the same species by acid phosphatase or peroxidase. Polymerase Chain Reaction (PCR) was carried out with seed coat color specific marker of B. juncea. The yellow seeded cultivars produced a strong band at 0.5 kb and weak band 1.2 kb. In the addition of these two specific bands, Japanese yellow-seeded cultivars expressed two more weak bands at 1.0 kb and 1.1 kb. Where the brown seeded cultivars generated a single strong band at 1.1 kb. In segregating population, the yellow seed coat color marker segregated at a ratio 15 (brown) : 1 (yellow), indicating the digenic inheritance pattern of the trait.

• Journal of the Korean Society of Tobacco Science
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• v.10 no.2
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• pp.117-122
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• 1988

This experiment was conducted to study the nature of gene effects for the leaf characters in flue-cured tobacco. The genetic populations were derived from crosses between NC 2326 and Mc Nair 373, and NC 628 and DG-72. The generation means experiment Included the Pl, P2. Fl, F2, Bl and B2, which were frown at Taegu Experiment Station, Korea Ginseng & Tobacco Research Institute in 1984. Seedlings were transplanted to the field in a randomized block design with 3 replications. In each block, parental and Fl Plots contained 15 plants in a single row, F2, Bl and B2 plots being composed of 75 plant, in 5 rows. Leaf characters were measured of largest (middle leaf) and 5th leaf(top leaf) from the top after topping. Measurements of the length and width of leaf were obtained from the fresh the middle and top leaves, and weight of leaf, weight and width of midrib were from the satrap leaf after curing. Estimates of additive and dominance genetic variance were analyzed according to Gamble's biometrical model. The results obtained are as follows: 1. The additive gene effects were significant and larger than the dominance gene effects for all leaf and midrib characters in both stalk positions. 2. The dominance gene effects were significant for the length and width of leaf, and weight of midrib in the middle leaves. 3. The digenic epistatic effects were significant for the length and width of leaf in both stalk positions. 4. The additive gene effects were larger in the top than in the middle leaves and midrib characters.

• Molecules and Cells
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• v.24 no.1
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• pp.16-26
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• 2007

Wild progenitor species provide potential gene sources for complex traits such as yield and multiple resistances to biotic and abiotic stresses, and thus are expected to contribute to sustainable food supplies. An introgression line 'IR71033-121-15' was derived from a wild species Oryza minuta (2n = 48, BBCC, Acc No. 101141) at IRRI. Introgression analysis using 530 SSR and STS markers revealed that at least 14 chromosomal segments distributed over 12 chromosomes had been introgressed from O. minuta. An $F_{2:3}$ population from the cross between IR71033 and Junambyeo (a Korean japonica cultivar) consisting of 146 lines was used for quantitative trait loci (QTL) analysis of 16 agronomic traits. A total of 36 single-locus QTLs (S-QTLs) and 45 digenic epistasis (E-QTLs) were identified. In spite of it's inferiority of O. minuta for most of the traits studied, its alleles contributed positively to 57% of the QTLs. The other QTLs originated from either parent, IR71033 or Junambyeo. QTLs for phenotypically correlated traits were mostly detected on introgressed segments. Fourteen QTLs corresponded to QTLs reported earlier, indicating that these QTLs are stable across genetic backgrounds. Twenty-two QTLs controlling yield and its components had not been detected in previous QTL studies. Of these, thirteen consisted of potentially novel alleles from O. minuta. QTLs from O. minuta introgression could be new sources of natural variation for the genetic improvement of rice.

• Molecules and Cells
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• v.24 no.1
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• pp.83-94
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• 2007

During monocarpic senescence in higher plants, functional stay-green delays leaf yellowing, maintaining photosynthetic competence, whereas nonfunctional stay-green retains leaf greenness without sustaining photosynthetic activity. Thus, functional stay-green is considered a beneficial trait that can increase grain yield in cereal crops. A stay-green japonica rice 'SNU-SG1' had a good seed-setting rate and grain yield, indicating the presence of a functional stay-green genotype. SNU-SG1 was crossed with two regular cultivars to determine the inheritance mode and identify major QTLs conferring stay-green in SNU-SG1. For QTL analysis, linkage maps with 100 and 116 DNA marker loci were constructed using selective genotyping with $F_2$ and RIL (recombinant inbred line) populations, respectively. Molecular marker-based QTL analyses with both populations revealed that the functional stay-green phenotype of SNU-SG1 is regulated by several major QTLs accounting for a large portion of the genetic variation. Three main-effect QTLs located on chromosomes 7 and 9 were detected in both populations and a number of epistatic-effect QTLs were also found. The amount of variation explained by several digenic interactions was larger than that explained by main-effect QTLs. Two main-effect QTLs on chromosome 9 can be considered the target loci that most influence the functional stay-green in SNU-SG1. The functional stay-green QTLs may help develop low-input high-yielding rice cultivars by QTL-marker-assisted breeding with SNU-SG1.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.1
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• pp.55-61
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• 1984

A Korean local maize line, MET, which has multi-ears and tillers has been proved as a potential source for silage production. However, no fundamental genetic nature for the line has been investigated. Therefore, this study was done to find genetic information on the multi-earing and -tillering habits of MET line. MET line and a hybrid. (Mo 17 ${\times}$ B68), with monoculm and single ear per plant were used for production of F$_1$(F$\_$1-12/ and F$\_$1-21/), F$\_$2-12/, F$\_$2-21/, BC$\_$1-12/ and BC$\_$1-21/ generations. From the comparison of reciprocal crosses, it was found that the tillering and earing habits of the MET line are controlled by cytoplasmic factors. The tiller and ear numbers, and barren ears were all characters associated with the MET cytoplasm. The cytoplasmic effect of MET on tiller and ear numb en was not evident in F$_1$ generation, probably because of suppressing effect of heterosis on appearance of tillers or ears. Genetic parameters for the gene action for both tiller and ear number also indicated a lack of mono- or digenic-chromosomal gene effects. The heritability (broad) was very low for both characters. Therefore, it is strongly concluded that the tillering and earing characters of MET line are due to cytoplasmic reasons.

• Molecules and Cells
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• v.25 no.3
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• pp.417-427
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• 2008

Comparison of maps and QTLs between populations may provide us with a better understanding of molecular maps and the inheritance of traits. We developed and used two reciprocal $BC_1F_1$ populations, IP/DS//IP and IP/DS//DS, for QTL analysis. DS (Dasanbyeo) is a Korean tongil-type cultivar (derived from an indica x japonica cross and similar to indica in its genetic make-up) and IP (Ilpumbyeo) is a Korean japonica cultivar. We constructed two molecular linkage maps corresponding to each backcross population using 196 markers for each map. The length of each chromosome was longer in the IP/DS//IP population than in the IP/DS//DS population, indicating that more recombinants were produced in the IP/DS//IP population. Distorted segregation was observed for 44 and 19 marker loci for the IP/DS//IP and IP/DS//DS populations, respectively; these were mostly skewed in favor of the indica alleles. A total of 36 main effect QTLs (M-QTLs) and 15 digenic epistatic interactions (E-QTLs) were detected for the seven traits investigated. The phenotypic variation explained (PVE) by M-QTLs ranged from 3.4% to 88.2%. Total PVE of the M-QTLs for each trait was significantly higher than that of the E-QTLs. The total number of M-QTLs identified in the IP/DS//IP population was higher than in the IP/DS//DS population. However, the total PVE by the M-QTLs and E-QTLs together for each trait was similar in the two populations, suggesting that the two $BC_1F_1$ populations are equally useful for QTL analysis. Maps and QTLs in the two populations were compared. Eleven new QTLs were identified for SN, SF, GL, and GW in this study, and they will be valuable in marker-assisted selection, particularly for improving grain traits in tongil-type varieties.