• The Korean Journal of Ecology
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• v.19 no.1
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• pp.71-80
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• 1996

The effects of simulated acid rain on the growth and interspecific competition of Echinochloa crus-galli and Digitaria sanguinalis were studied. Changes of growth in height and dry weight were examined and competition between the two species was investigated using the experimental model proposed by de Wit (1960). The experiments were carried out in the greenhouse, and test plants were germinated and grown for 4 weeks and then sprayed with simulated acid rain of pH 5.6, 4.2 and 2.8 for another 8 weeks. In de Wit replacement experiments, the variation of density and the treatment of simulated acid rain showed little effect on the interspecific competition between E. Crus-galli and D.sanguinalis. The ratio diagram, another method to reveal the interrelations between two competing species, always showed the predominance of E. crus-galli in competition, regardless of density and pH. The interspecific competition of the two species, represented by relative yield total (RYT), revealed that intraspecific competition was stronger than interspecific competition in both species.The treatment of simulated acid rain showed little effect on the growth of E. Crus-galli and D. sanguinalis. Height growth of both species did not differ from that of control (pH 5.6), but root/shoot ratio increased with the decrease in pH of simulated acid rain. Growth of tatal dry weight of E. crus-galli and D. sanguinalis was not influenced by the change of pH, except that D.sanguinalis showed a decrease in the total dry weight at pH 2.8 along with a visible sign of white spots on leaves. Physical environmental conditions can exert an effect on the interrelationships between the two species, but this experiment did not show the reversion of competition, and showed that E.crus-gilli was competitively dominant under any environmental conditions given in this study.

• The Korean Journal of Malacology
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• v.21 no.2 s.34
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• pp.147-161
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• 2005

To elucidate the phylogenetic relation of the superfamily Veneroidea, we obtained partial 28S rRNA sequences of 14 heterodonts and three pteriomorphs which were collected from Korea and the sequence data of related taxa from GenBank, and analyzed maximum parsimony with PAUP program 750 of the nucleotide positions were variable, 560 of which were informative under conditions of parsimony. Total tree length was 2,765, and consistency index, homoplasy index (HI), and Retention index was 0.4843, 0.5157, and 0.6291, respectively. Intraspecific variation of 28 rRNA of Corbicula fluminea and Sinonovacula constricta was 3.1% and 1.3%, respectively. Pitarinae-Cyclininae-Meretrinae group had a clade and Samaranginae, Chioninae, and Dorsininae were clustered.

• Korean Journal of Plant Taxonomy
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• v.46 no.3
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• pp.273-282
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• 2016

The establishment of a DNA barcode database at the regional scale and assessments of the utility of DNA barcodes are crucial for conservation biology and for the sustainable utilization of biological resources. Schisandraceae is a small family consisting of ca. 45 species. It contains many economically important species, such as Schisandra chinensis, which is widely used as a source in tonic beverages and in oriental medicine. In Korea, three species, S. chinensis, S. repanda, and Kadsura japonica, are distributed. We evaluated the level of variation of the DNA sequences of rbcL, matK, and the ITS regions from 13 accessions representing the distributional range of the three species. The three DNA barcode regions were easily amplified and sequenced. The minimum values of the interspecific genetic distances among S. chinensis, S. repanda, and K. japonica either separately or in combination are 4- to 23-fold higher than the maximum value of the intraspecific distance, showing that there is a clear DNA barcoding gap in the regions for Korean Schisandraceae. Phylogenetic analyses of the three DNA barcode regions, separately and simultaneously, indicate that all of the DNA barcode regions are useful for identifying a species of Schisandraceae in Korea. The distinctiveness of the three species of Schisandraceae was also supported at the species level when Chinese and Japanese populations were added. The results of this study indicate that three concatenated regions constitute the best option for DNA barcoding in Schisandraceae in Korea.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.31-31
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• 2017

Understanding the mechanism(s) to overcome or prevent seed ageing deterioration during storage is of fundamental interest to seed physiologists. Vitamin E (tocols) is known as a key metabolite to efficiently scavenge lipid peroxy radicals which cause membrane breakdown resulting in seed ageing. However, in rice research this hypothesis has been tested for very few lines only without considering intraspecific variation in genomic structure. Here, we present a correlation study between tocols and seed longevity using a diverse rice panel. Seeds of 20 rice accessions held in the International Rice Genebank at the International Rice Research Institute, representing aus, indica, temperate japonica and tropical japonica subpopulations, were used for tocols analysis (quantification of ${\alpha}$-, ${\beta}$-, ${\gamma}$-, ${\delta}$-tocopherol/tocotrienol by ultra performance liquid chromatography) and storage experiments at $45^{\circ}C$ and 10.9% seed moisture content (sample taken for germination testing every 3 days up to 60 days). To examine interactions between DNA sequences and phenotype, the 700k high-density single-nucleotide polymorphism marker data-set was utilized. Both seed longevity (time for viability to fall to 50%; $p_{50}$) and tocols content varied across subpopulations due to heterogeneity in the genetic architecture. Among eight types of tocol homologues, ${\alpha}$-tocopherol and ${\gamma}$-tocotrienol were significantly correlated with $p_{50}$ (negatively and positively, respectively). While temperate japonica varieties were most abundant in ${\alpha}$-tocopherol, indica varieties recorded 1.3 to 1.7-fold higher ${\gamma}$-tocotrienol than those of other subpopulations. It was highlighted that specific ratio of tocol homologues rather than total tocols content plays an important role in the seed longevity mechanism.

• Journal of Ecology and Environment
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• v.36 no.3
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• pp.159-166
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• 2013

Oryzias latipes and Oryzias sinensis are indigenous species found in Japan, China, and other East Asian countries, including Korea. Based on morphological differences, the species have been classified distinctly. However, the range of morphological characters such as the number of gill rakers, vertebrae, and spots on the lateral body overlaps and is too vague for clear identification, so their classification based on their morphological characteristics remains uncertain. In this study, the mitochondrial cytochrome oxidase subunit I (COI) gene, which is used for DNA barcoding, was applied to clarify interspecific variation of O. latipes and O. sinensis. Intraspecific genetic diversity was calculated to identify correlations with geographic distributions. We studied two species collected from 55 locations in Korea. All individuals carried a 679-base pair gene without deletion or insertion. Between species, 525 base pairs of the gene were shared. The Kimura two parameter (K2P) distance of O. latipes and O. sinensis was 0.41% and 1.39%, respectively. Mean divergence within genera was 23.5%. Therefore, the species were clearly different. The distance between O. latipes and O. sinensis was 14.0%, which is the closest within genera. Interestingly O. latipes from the Japanese and Korean group represented 16.5% distant. These results were derived from geohistorical and anthropogenic environmental factors. The O. latipes haplotypes were joined in only one group, but O. sinensis was divided into two groups, one is found in the Han River and upper Geum River watershed; the other is found in the remaining South Korean watersheds. Further studies will address the causes for geographic speciation of O. sinensis haplotypes.

• Journal of Species Research
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• v.1 no.1
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• pp.4-34
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• 2012

Parastenocaris koreana sp. nov. is described based on examination of numerous adult specimens of both sexes from several localities in Korea. Scanning electron micrographs are used to examine intra- and interpopulation variability of micro-characters, in addition to light microscopy. The new species is most closely related to the Japanese P. biwae Miura, 1969, which we redescribe based on newly collected material from the Lake Biwa drainage area. The two species differ in size, relative length of the caudal rami, shape of the anal operculum, shape of the genital double somite, relative length of the inner distal process on the female fifth leg, as well as relative length of the apical setae on the second, third, and fourth legs exopods in both sexes. Detailed examinations of three disjunct populations of P. koreana reveal also some geographical variation, especially in the surface ornamentation of somites, which may indicate some population structuring or even cryptic speciation. Lack of intraspecific variability in the number and position of sensilla on somites, as well as their potential phylogenetic significance, is a novel discovery. Both species examined here belong to the brevipes group, which we redefine to include 20 species from India (including Sri Lanka), Australia, East Asia, Northern Europe, and North America. A key to species of this group is also provided. In order to test the monophyly of the redefined brevipes group with highly disjunct distribution, as well as relationship between different species, a cladistics analysis is performed based on 39 morphological characters and with help of three outgroup taxa. Six equally parsimonious cladograms are generated, all of which show that the ingroup is well defined by at least three synapomorphies. Reconstructed phylogeny questions the previously suggested hypothesis about the origin of this group in South East Asia, with one Australian species showing the most basal position. We speculate that the present distribution of this group may be a combination of ancient vicariance and subsequent dispersal, with a possible origin in the Gondwanaland, in the rift valley between Australia and India.

• Korean Journal of Weed Science
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• v.18 no.1
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• pp.76-83
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• 1998

Echinochloa species maintained by selling for more than 10 years were classified using random amplified polymorphic DNAs(RAPDs) analysis. Seventy-four decamer of randomly sequence markers were used to classify intraspecific variation irt Echinochloa species. The number of amplification products increased with increasing GC content of the primer in the range between 60% and 70% GC. Single-base substitutions of a primer altered amplification, providing new polymorphisms. The size of amplified DNA was mostly between 0.40kbp and 1.4kbp with the most common bands at 1.1kbp. Echinochloa species were detected with 6 primers which generated 26 polymorphic amplified DNAs. By hierarchical cluster analysis, Echinochloa species collected in Korea were divided into three groups. These results revealed that RAPD markers are useful tools for the determination of genetic variations in Echinochloa species.

• The Korean Journal of Zoology
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• v.37 no.1
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• pp.49-57
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• 1994

In the course of an investigation on the morphological variation of Korean striped bittering, Acheilognathus vamatsutae Mori, two kinds of morrholoflical types were found. Some morphological characters were compared between them and multivariate analysis was conducted. Since the difference of the barbel length between them was very significant (p < 0.01,1-test), they should be designated as L-and 5-type Hshes: fishes with long barbels and those with should barbels, respectively. Lateral line scales, snout length and prepectoral length showed a tendency that the observation could be distinguished from each other (p < 0.05, Duncan's multiple range tests. There were no individuals over 70 mm BL in S-type and so S-type fishes were somewhat dwarf than L-type fishes. The two types were also clearly distinguished by multivariate analyses using cluster and discriminant analyses. According to the observation on the four populations of the Naktong River, the blue-green stripe on the body side and the white band on the margin of anal fin in males of S-type fishes were well developed through the year but those of males of L-type fishes completely disappeared or became slender during nonbreedins season as that of females. Of the seven localities surveved, there were no places that the two types cohabit. S-type fishes are limited only in the Kumho and Wichon River of the Naktong River system but L-type fishes are distributed more widely In the Hongchon, Mangvons, Somjin, Mirang and Panbyon River.

• Parasites, Hosts and Diseases
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• v.38 no.3
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• pp.151-158
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• 2000

Pneumocystis carinii is a major opportunistic pathogen which has been found in the lungs of a wide variety of mammalian host species, and the fact suggests the possibility of intraspecific variation. Until now, P. carinii from different mammalian species are differentiated as subspecies, and the rats are known to be infected by two subspecies. The present study investigated genetic heterogeneity of P. carinii isolates from two strains of rats in Korea and China by molecular karyotyping, RFLP and sequencing analysis. Karyotypes of P. carinii were grouped into three, two from two strains of rats In Korea and one from rats in China. However RFLP of PCR product of ribosomal and MSG gene of the P. carinii isolates showed same pattern. The sequence homology rates of ${\alpha}-tubulin$ DNA of the P. carinii isolates were 96% in Seoul Wistar rats, 93% in Seoul Sprague-Dawley rats, and 85% in Chinese Sprague-Dawley rats. The present finding confirmed that P. carinii from rats in Korea are grouped into two karyotype strains which are different from that of P. carinii from rats in China. The Chinese isolate shows a little different sequences of ${\alpha}-tubulin$ DNA.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.575-582
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• 2018

Bacterial fruit blotch (BFB) caused by Acidovorax citrulli is a devastating disease found in many cucurbits cultivation fields. The genetic diversity for 29 strains of A. citrulli collected from various cucurbits in South Korea was determined by DNA fingerprinting with a pathogenicity test, multi locus analysis, Rep-PCR (repetitive sequence polymerase chain reaction), and URP (universal rice primers) PCR bands. Two distinct groups (Korean Clonal Complex, KCC1 and KCC2) in the population were identified based on group specific genetic variation in the multi locus phylogeny using six conserved loci and showed a very high similarity with DNA sequences for representative foreign groups [the group I (CC1-1 type) and the group II (CC2-5 type)] widely distributed worldwide, respectively. Additionally, in the case of phaC, a new genotype was found within each Korean group. The KCC1 was more heterogeneous compared to the KCC2. The KCC1 recovered mainly from melons and watermelons (ratio of 6 : 3) and 15 of the 20 KCC2 strains recovered from watermelons were dominant in the pathogen population. Accordingly, this study found that two distinct groups of differentiated A. citrulli exist in South Korea, genetically very similar to representative foreign groups, with a new genotype in each group resulting in their genetic diversity.