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        검색결과 59

        41.
        1996.12 KCI 등재 SCOPUS 구독 인증기관·개인회원 무료
        In the present work we introduce a new flare activity indicator, MAD and examine its characteristics by analyzing a set of successive three days' observations of a typical active region, AR2372. The computed MAD is compared with conventional activity indicator such as separator. It is found that. (1) MAD traces very well the separator, (2) it. singles out. local discontinuity of magnetic field lines and (3) it. is a good measure of describing the evolutionary status of active region.
        44.
        2014.07 서비스 종료(열람 제한)
        As one of the most important crop, rice is not only a staple food of half world’s population but a wonderful model plant, which has been leading the evolution and functional genomics study. The next-generation sequencing technology are expediting rice genomic study, by providing a simple but powerful way. In this study, we re-sequenced a core collection of 137 rice accessions from all over the world along with 158 Korean breeding varieties. Finally, 6.3G uniquely mapped reads were obtained, and about 10 million SNPs and ~1.2 million InDels were identified with average sequencing depth of 7.5X. These will help us to maximize our germplasm utilization and assists all the deep research in population dynamics and functional studies. Here, we’d like to show the approaches applied to resequencing data mining and on-going activities.
        46.
        2013.07 서비스 종료(열람 제한)
        We investigated whether sound could alter gene expression in plants. Using a sound-treated subtractive library, a set of sound-responsive genes in plants was demonstrated through mRNA expression analyses. Of them, the rbcS and ald genes, which are light responsive, up-regulated their expression with sound treatment in both light and in dark conditions. This suggested that sound could be used as a gene regulator instead of light. When we analyzed ald gene expression using various single wavelengths, a significant increase in mRNA levels was found at 125 or 250 Hz but decreased at 50 Hz, indicating that the gene responded to sound in a wavelength-specific manner. To determine whether the ald promoter respond to sound, we generated transgenic rice plants harboring the chimeric gene consisting of a 1,506-bp promoter fragment of the ald gene fused to Escherichia coli GUS reporter gene. Analyses of mRNA expressison level of three independent transgenic lines sound-treated with 50 or 250 Hz for 4 h showed that the Gus gene expression in all three transgenic lines was up regulated by 250 Hz, but down regulated by 50 Hz. These results correlated with sound responsive mRNA expression pattern observed for the ald gene in rice plants, indicating that the 1,506-bp ald promoter confers sound-responsiveness on a reporter gene in transgenic rice plants. We also investigated whether sound waves could improve salt tolerance in rice seedling. The rice seedlings were sound treated with 800 Hz for 1hr, and then treated with 0, 75, 150, and 225mM NaCl for 3 days to observe changes in physiological and morphological aspects. Sound treatment seedlings resulted in enhanced salt stress tolerance, mainly demonstrated by the sound treated seedlings exhibiting of increased root relative water contents (RWC), root length and weight, photochemical efficiency (ratio of variable to maximum fluorescence, Fv/Fm), and germination rate under salt stress condition. This demonstrates that a specific sound wave might be used, not only to alter gene expression in plant, but also to improve salt stress tolerance.
        47.
        2013.07 서비스 종료(열람 제한)
        This study was set up to get plants from anther culture of Chrysanthemum (Dendranthema grandiflorum) gardenmum cultivar “Yes Morning’ and potmum cultivar “Peace Pink” for breeding program. The induction of callus was quick and high on MS basal medium supplemented with 1.0 mg/L of 2,4-D + 2.0 mg/L of 6-BA + 4% W/V sucrose. Induction potential was slightly increased by addition of 250 mg/L Casein hydrolysate to the induction medium. Calluses were allowed to differentiate on MS basal medium + 2.0 mg/L of BA + 0.1 mg/L of NAA + 3%W/V sucrose. The rate of callus formation differed little between the cultivars. A pretreatment of anthers at 4℃ for 48h enhanced both the induction and differentiation ratio. Multiple shoots were initiated from most of the calluses and were shifted to MS basal medium + 0.1 mg/L of NAA + 3%W/V sucrose for rooting. Regenerated plantlets were acclimatized and transferred to the soil. Some of the regenerated plants showed slow growth with little morphological difference.
        50.
        2012.07 서비스 종료(열람 제한)
        The plant family chrysanthemum is known for its medicinal, ornamental, and economic purposes. Owing to its economic and biological significance to the difficult identification based on morphological characters, it is useful to develop DNA barcodes. DNA sequence data enable not only the inference of phylogenetic relationships but also provide an efficient method for species-level identifications under terms DNA barcoding or DNA taxonomy. The purpose of this study is to evaluate the utility of DNA barcoding in discriminating Chrysanthemum species. Four cpDNA regions (matK, rpoC, rpoB, trnH-psbA) and one nuclear (ITS) marker have sequenced from 28 specimens of 11 species from 4 genera of Chrysanthemum which were collected from 5 provinces in Korea. Comparisons of within and between species levels of sequence divergence showed that genetic variation between species exceeds variation within species.
        51.
        2012.07 서비스 종료(열람 제한)
        Allele mining in starch synthesis-related genes (SSRGs) has facilitated the discovery of desired natural sequence variations for eating quality in rice. This study investigated the sequence variations from 10 SSRGs, and further evaluated their relationship with the amylose content (AC) and rapid viscosity analysis profiles in a global collection of rice accessions by association mapping (AM). In total, 83 sequence variations were found in 10 sequenced amplicons, including 73 single nucleotide polymorphisms (SNPs), eight insertion-deletions (InDels) and two polymorphic simple sequence repeats (SSRs). Four subpopulations were identified by population structure analysis based on 170 genome-wide SSR genotypes. AM revealed 11 significant associations between three phenotypic indices and three sequence variations. One SNP with a g/c transversion at the 63rd nucleotide downstream of the OsBEIIb gene termination codon on rice chromosome 2 was significantly associated with multiple trait indices in both the general linear and mixed linear models (GLM and MLM), including the final viscosity (p < 0.001, R2 = 23.87%) in both 2009 and 2010, and AC (p < 0.01, R2 = 11.25%) and trough viscosity (p < 0.01, R2 = 20.43) in 2010. This study provides a new perspective of allele mining for breeding strategies based on marker-assisted selection.
        52.
        2011.02 KCI 등재 서비스 종료(열람 제한)
        In this study, 15 simple sequence repeat (SSR) markers were used to analyze the population structure of 55 mungbean accessions (34 from South Asia, 20 from West Asia, 1 sample from East Asia). A total of 56 alleles were detected, with an average of 3.73 per locus. The mean of major allele frequency, expected heterozygosity and polymorphic information content for 15 SSR loci were 0.72, 0.07 and 0.33 respectively. The mean of major allele frequency was 0.79 for South Asia, and 0.74 for West Asia. The mean of genetic diversity and polymorphic information content were almost similar for South Asian and West Asian accessions (genetic diversity 0.35 and polymorphic information content 0.29). Model-based structure analysis revealed the presence of three clusters based on genetic distance. Accessions were clearly assigned to a single cluster in which >70% of their inferred ancestry was derived from one of the model-based populations. 47 accessions (85.56%) showed membership with the clusters and 8 accessions (14.54%) were categorized as admixture. The results could be used to understanding the genetic structure of mungbean cultivars from these regions and to support effective breeding programs to broaden the genetic basis of mungbean varieties.
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