• Biomolecules & Therapeutics
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• 제30권5호
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• pp.391-398
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• 2022

Polyploidization is a process by which cells are induced to possess more than two sets of chromosomes. Although polyploidization is not frequent in mammals, it is closely associated with development and differentiation of specific tissues and organs. The liver is one of the mammalian organs that displays ploidy dynamics in physiological homeostasis during its development. The ratio of polyploid hepatocytes increases significantly in response to hepatic injury from aging, viral infection, iron overload, surgical resection, or metabolic overload, such as that from non-alcoholic fatty liver diseases (NAFLDs). One of the unique features of NAFLD is the marked heterogeneity of hepatocyte nuclear size, which is strongly associated with an adverse liver-related outcome, such as hepatocellular carcinoma, liver transplantation, and liver-related death. Thus, hepatic polyploidization has been suggested as a potential driver in the progression of NAFLDs that are involved in the control of the multiple pathogenicity of the diseases. However, the importance of polyploidy in diverse pathophysiological contexts remains elusive. Recently, several studies reported successful improvement of symptoms of NAFLDs by reducing pathological polyploidy or by controlling cell cycle progression in animal models, suggesting that better understanding the mechanisms of pathological hepatic polyploidy may provide insights into the treatment of hepatic disorders.

• 식물분류학회지
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• 제48권4호
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• pp.278-288
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• 2018

Polyploidization plays an important role in generating the current high diversity of plants. Studies of the distributional patterns of diploid and derivative polyploid races have provided important insights into the evolutionary process and cryptic speciation by polyploidization within and between closely related taxa defined on the basis of their morphology. Allium thunbergii and A. sacculiferum, occurring throughout eastern Russia, eastern China, Korea, and Japan, are examples of closely related species with unsolved taxonomic relationships. A total of 97 and 65 individuals from 26 and 13 populations of A. thunbergii (including var. thunbergii, var. deltoids, and var. teretifolium) and A. sacculiferum, respectively, were studied to determine their ploidy. The geographic structure and habitat differentiation of the cytotypes were also analyzed. The main cytotype of A. thunbergii was diploid (92.3% in total; the rest were tetraploids). In contrast, the majority of A. sacculiferum plants were tetraploids (69.2% of the total; the rest were diploids). No populations of the studied taxa harbored both cytotypes. Allium thunbergii was more often found at higher elevations than A. sacculiferum, and it tended to occur more frequently on rocky slopes and below forests in mountainous areas. On the other hand, A. sacculiferum occurred at forest margins and in lowland pastures. The cytotypes differed with respect to the elevation; diploids were found more frequently at higher elevations than tetraploids. The results of this study and additional biosystematics data indicate that the morphological characteristics of A. thunbergii and A. sacculiferum may be influenced by polyploidization and by their adaptation to various habitat conditions and that A. thunbergii and A. sacculiferum do not clearly fulfill the requirements of any species concept. Consequently, we propose that A. sacculiferum be considered as an additional synonym of A. thunbergii. Additionally, Allium thunbergii var. deltoides is unified into A. thunbergii var. thunbergii.

• 한국작물학회지
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• 제65권4호
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• pp.447-456
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• 2020

Peanut is an allotetraploid derived from a single recent polyploidization. Polyploidization has been reported to have caused significant loss in genetic diversity during the domestication of cultivated peanuts. Single nucleotide polymorphism (SNP)-based markers such as cleaved amplified polymorphic sequences (CAPS) derived from next-generation sequencing (NGS) have been developed and widely applied for breeding and genetic research in peanuts. This study aimed to identify the genetic diversity and population structure using 30 CAPS markers and 96 peanut accessions from five different origins. High genetic dissimilarities were detected between the accessions from Korea and those from the other three South American origins generally regarded as the origin of peanuts, while the accessions from Brazil and Argentina presented the lowest genetic dissimilarity. Based on the results of the present study, accessions from Korea have unique genetic variation compared to those from other countries, while accessions from the other four origins are closely related. Our study identified the genetic differentiation in 96 peanut accessions from five different origins, and this study also showed the successful application of SNP information derived from re-sequencing based on NGS technology.

• 한국육종학회지
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• 제41권3호
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• pp.213-219
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• 2009

본 연구는 나리의 종간잡종 육성체계를 확립하는데 필요한 기초자료를 얻기 위하여 OA hybrid 중 자발적으로 생식세포 염색체가 배수화된 계통을 이용하여 후대 획득과 후대검정에 필요한 실험을 수행하여 얻은 결과를 요약하면 다음과 같다. 2n 화분을 생산하는 OA hybrid의 경우 화분의 채취시기에 따른 생존율과 발아율은 10월에 비해 6월이, 생존율은 n성 화분이, 발아율은 2n성 화분이 높았다. 2n 화분을 생산하는 2배체 OA hybrid와 2배체 또는 4배체 Asiatic 또는 Oriental hybrid간 교배시 모본과 부본을 달리함에 따라 후대 획득 수에 차이가 있었는데 OA hybrid를 부본으로 이용했을 때, 상대친을 Asiatic hybrid로 교배했을 때 후대획득이 용이하였다. 즉 A$\times$OA교배에서 후대 획득률이 0.64개체로 O$\times$OA교배에서의 후대 획득률 0.42개체보다 높았으며, OA$\times$A간 교배에서 후대 획득률이 0.40개체인 반면 OA$\times$O교배에서는 전혀 후대획득이 불가능하거나 극히 낮아 후대획득이 어려웠으며, 아울러 2n 화분을 생산하는 OA hybrid의 후대생산을 위한 상대친으로 4배체보다는 2배체가 효과적이었다. 2n 화분을 생산하는 OA hybrid와 Asiatic 또는 Oriental hybrid간 정역교배 결과, OA hybrid를 부본으로 교배했을 때, 상대친으로 Asiatic hybrid을 교배했을 때 후대획득이 용이하였다. 자발적인 2n 화분을 생산하는 2배체 OA hybrid의 여교잡 후대의 ploidy level의 측정결과, OA$\times$A교배에서는 3배체, AA$\times$OA, OO$\times$OA교배에서는 4배체임을 확인할 수 있었으나, O$\times$OA교배에서는 2배체, A$\times$OA교배에서는 2배체 또는 3배체로 확인되었다.

• BMB Reports
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• 제48권12호
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• pp.691-695
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• 2015

We report that phytosphingosine, a sphingolipid found in many organisms and implicated in cellular signaling, promotes megakaryocytic differentiation of myeloid leukemia cells. Specifically, phytosphingosine induced several hallmark changes associated with megakaryopoiesis from K562 and HEL cells including cell cycle arrest, cell size increase and polyploidization. We also confirmed that cell type specific markers of megakaryocytes, CD41a and CD42b are induced by phytosphingosine. Phospholipids with highly similar structures were unable to induce similar changes, indicating that the activity of phytosphingosine is highly specific. Although phytosphingosine is known to activate p38 mitogen-activated protein kinase (MAPK)-mediated apoptosis, the signaling mechanisms involved in megakaryopoiesis appear to be distinct. In sum, we present another model for dissecting molecular details of megakaryocytic differentiation which in large part remains obscure.

• Journal of Plant Biotechnology
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• 제37권4호
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• pp.357-369
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• 2010

Cymbidium is horticulturally important and has been one of the most commercially successful orchid plants as well as cut flowers around the world including Korea. Up to now, a huge number of elite Cymbidium cultivars have been released on the commercial market via cross-hybridization, mutation and polyploidization breeding techniques. To investigate on breeding system in Cymbidium, we inquired the brief history and techniques of breeding and the current status on Cymbidium breeding in Korea. Also, the general propagation process of elite Cymbidium lines via tissue culture should be presented. However, the slow process of conventional breeding and the lack of useful genes in Cymbidium species delays the introduction of new cultivars to the commercial market. To solve these limitations, efficient regeneration and genetic transformation systems should be established in the improvement of Cymbidium breeding program. During the last several decades, some progress has been made in tissue culture and genetic transformation in Cymbidium species. We review the recent status of tissue culture and genetic transformation systems in Cymbidium plants.

• 식물분류학회지
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• 제52권3호
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• pp.127-143
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• 2022

This study was conducted to clarify the phylogenetic position and relationships of Korean Poaceae taxa. A total of 438 taxa including 155 accessions of Korean Poaceae (representing 92% and 72% of Korean Poaceous genera and species, respectively) were employed for phylogeny reconstruction. Sequence data of eight chloroplast DNA markers were used for molecular phylogenetic analyses. The resulted phylogeny was mostly concordant with previous phylogenetic hypotheses, especially in terms of subfamilial and tribal relationships. Several taxa-specific indels were detected in the molecular phylogeny, including a 45 bp deletion in rps3 (PACMAD [Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae, Danthonioideae] clade), a 15 bp deletion in ndhF (Oryzeae + Phyllorachideae), a 6 bp deletion in trnLF (Poeae s.l.), and two (17 bp and 378 bp) deletions in atpF-H (Pooideae). The Korean Poaceae members were classified into 23 tribes, representing eight subfamilies. The subfamilial and tribal classifications of the Korean taxa were generally congruent with a recently published system, whereas some subtribes and genera were found to be non-monophyletic. The taxa included in the PACMAD clade (especially Andropogoneae) showed very weak and uncertain phylogenetic relationships, presumably to be due to evolutionary radiation and polyploidization. The reconstructed phylogeny can be utilized to update the taxonomic positions of the newly examined grass accessions.

• 한국자원식물학회지
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• 제25권6호
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• pp.745-752
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• 2012

Compared to wide ranges of genetic variation of natural populations, very limited Miscanthus cultivar has been released. This study was the first report on the development of Miscanthus cultivar by means of radiation breeding. Seeds of M. sinensis were initially exposed to gamma rays of 250 Gy for 24 h, generated from a $^{60}Co$ gamma-irradiator. The irradiated seeds were sown and then the highly tiller-producing mutants were selected for this study. Biomass-related parameters including tiller number, plant height, stem diameter, and leaf number were measured. Ploidy level and internal transcribed spacer (ITS) were investigated to characterize the mutants compared to wild type (WT) Miscanthus. Plant height and tiller number were negatively related, where multi-tillering mutants were relatively short after 4 month growth. However stem diameter and leaf number were greater in mutants. All the materials used in this study were diploid, implying that the mutants with greater tiller numbers and stem diameter were not likely related to polyploidization. Based on the sequence of ITS regions, the mutants demonstrated base changes from the gamma irradiation where G+C content (%) was decreased in the ITS1, but increased in ITS2 when compared to WT sequence. ITS2 region was more variable than in ITS1 in the mutants, which collectively allows identification of the mutants from WT. Those mutants having enhanced tillers and allelic variations might be used as breeding materials for enhanced biomass-producing Miscanthus cultivars.

• 한국초지조사료학회지
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• 제17권1호
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• pp.1-10
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• 1997

Unreduced (2n) gametes are meiotic products (pollen or egg) having a sporophytic (somatic) chromosome number, resulting from abnormalities during either microsporogenesis or megasporogenesis. They occur naturally at a low frequency in many plant species. Unreduced (2n) gametes in plants can be identified for four possible ways as follow i) pollen size and/or shape differences between haploid (n) and diploid (2n) pollen, ii) ploidy analysis (chromosome number) of progeny or meiotic analysis (presence of dyads andlor triads at the microspore stage), iii) progeny performance and fertility and iv) dosage of isozyme and DNA markers. Unreduced (2n) gametes can be an effective breeding tool in synthesizing new cultivars, providing a unique method to maximizing heterozygosity, i.e., transferring a large proportion of the non-additive genetic effects (intra- and inter- locus interactions) h m parent to offspring and can also be used to overcome infertility of interploidy crosses. Sexual polyploidization through 2n gametes has been a major route to the formation of naturally occurring polyploids. The three mechanisms of 2n pollen formation in potato have been discovered as follow: i) parallel spindles (ps) or tripolar spindles (ts), ii) premature cytokinesis (pc-I, pc-2) and iii) synaptic mutants (sy-2, sy-3, sy-4). Genetic analysis indicated that the mechanisms of 2n gamete formation were controlled by single recessive gene in potato, alfalfa, red clover, etc., and by two recessive genes in wheat. The use of 2n gametes which can efficiently transfer germplasm fiom wild relatives to cultivated species, especially fiom diploid to tetraploid could make a contribution to the improvement of germplasm base in breeding programs.

• 식물분류학회지
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• 제35권2호
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• pp.99-114
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• 2005

한국산 땅비싸리속 식물의 종분화를 연구하기위해 염색체수, 형태적변이 및 RAPD분석을 실시하였다. 땅비싸리(2n=16) 와 좀땅비싸리(2n=32)의 염색체수는 기존의 보고와 일치하였다. 본 연구에서 큰꽃땅비싸리의 4배체(2n=32)와 6배체(2n=48)집단이 새로 조사되었다. 큰꽃땅비싸리는 가야산 부근에서 땅비싸리와 좀땅비싸리와 함께 자라고 있었다. 큰꽃땅비싸리는 이들 두 종에 비해 식물체 높이, 잎 및 꽃이 더 크며, 땅비싸리 근연종에서 중요한 분류형질인 잎과 꽃의 털에서 땅비싸리와 좀땅비싸리의 중간 형태를 보이고 있다. RAPD분석에서 큰꽃땅비싸리는 좀땅비싸리와 더 유사하였으나, 4배체와 6배체 간에 차이를 보였다. 이러한 결과는 한반도 고유종인 큰꽃땅비싸리가 공동분포지인 가야산 지역에서 땅비싸리와 좀땅비싸리 사이의 잡종현상과 함께 배수체현상에 의해 기원된 것으로 사료된다.