• Animal cells and systems
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• v.9 no.1
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• pp.27-35
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• 2005

Bupleurum euphorbioides is isolated and restricted to high mountains in Korea northeastern China. Its conservation depends on whether it is threatened by inbreeding or a loss of genetic diversity. We compared the genetic variability in B. euphorbioides with B. longiradiatum, a widespread congener, to understand how they differ in their population genetic structure. Although B. euphorbioides showed a little lower genetic variability than B. longiradiatum, $F_{IS}$ statistics for most loci were strongly positive in both B. euphorbioides (0.445) and B. longiradiatum (0.553). In addition, B. euphorbioides showed higher mean $F_{ST}$ value than B. longiradiatum (0.297 vs 0.194). It might be due to the polycarpic nature of B. longiradiatum, which holds higher genetic potentials effectively in homogeneous environment than the monocarpic B. euphorbioides. The results suggested that B. euphorbioides is a genetically viable species, and that they are threatened primarily by environmental factor.

• Journal of Crop Science and Biotechnology
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• v.11 no.1
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• pp.75-82
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• 2008

Functional stay-green is a beneficial trait that may increase grain yield through the sustained photosynthetic competence during monocarpic senescence in cereal crops. The temporal changes of photosynthesis and related characteristics throughout the grain filling period of a stay-green japonica rice "SNU-SG1" was compared in growth chamber conditions with three high-yielding cultivars(HYVs) and their $F_1$ hybrids with SNU-SG1. SNU-SG1 exhibited a typical characteristic of functional stay-green in terms of chlorophyll degradation and photosynthetic competence during grain filling. According to the photosynthesis-light response curve measured at 10 and 35 d after heading for the flag leaf, SNU-SG1 exhibited higher initial light conversion efficiency and thus higher gross photosynthetic rate at light saturation compared to HYVs. Light saturation point was not different among genotypes, ranging from 1000 to 1500 ${\mu}mol$ photon $m^{-2}s^{-1}$. Net photosynthetic rate at light saturation($P_{max}$) of the upper four leaves in SNU-SG1 was much higher and sustained longer throughout grain-filling than HYVs and $F_1$ hybrids. The sustained high photosynthetic competence of SNU-SG1 during grain filling was ascribed to the longer maintenance of high mesophyll conductance that resulted from not only high chlorophyll content and its delayed degradation but also the slow degeneration of photosystem II(PS II) as judged by chlorophyll fluorescence($F_v/F_m$) of flag leaves. $F_1$ hybrids showed slow degeneration of photosystem II similar to the male parent SNU-SG1 while chlorophyll degradation pattern close to female parents, thus exhibiting a little higher $P_{max}$ than female parents. These results suggest that SNU-SG1 has a typical functional stay-green trait that can be utilized for increasing rice yield potential through the improved dry matter production during grain filling.

• Korean Journal of Medicinal Crop Science
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• v.14 no.4
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• pp.239-243
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• 2006

Orostachys japonicus, a monocarpic plant, is artificially grown in greenhouses. The study was carried out to examine the effect of shading (0, 35, 55, 75, 95%) on growth, morphological characters, and flowering. The treatments were done on August 25 and afterward samples were taken every 2 weeks until October 20, in which growth, morphological and flowering related characters were measured. With severer shading plant height, inflorescence length, number of leaves including bracts and stem diameter were decreased although severely declined in 95% shading treatment. Leaves and bracts, stem, root, shoot and total dry weights increasingly declined with severer shading. Florets formed on the inflorescence showed similar response to the shading treatment as plant height did. Flowering of the florets was not observed throughout all the sampling period, meaning that different light intensities by shading did not affect their flowering.

• Journal of Ecology and Environment
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• v.42 no.4
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• pp.308-316
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• 2018

Background: Genus Sasa, dwarf bamboos, are considered to be species that lower biodiversity in the temperate forests of East Asia. Although they have a long interval, they, the monocarpic species, have a unique characteristic of large-scale synchronized flowering. Therefore, once they have flowered and then declined, it may be an opportunity for suppressed surrounding species. A previous study reported that Sasa borealis showed specialized flowering nationwide with a peak in 2015. However, this was based on data from a social network service and field survey at Mt. Jeombong. Therefore, we investigated S. borealis in the forests of five national parks in order to determine whether this rare synchronized flowering occurred nationwide, as well as its spatial distribution. Results: We found a total of 436 patches under the closed canopy of Quercus mongolica-dominated deciduous forests in the surveyed transects from the five national parks. Of these patches, 75% occupied a whole slope area, resulting in an enormous area. The patch area tended to be larger in the southern parks. Half (219 patches) of the patches flowered massively. Among them, 76% bloomed in 2015, which was consistent with the results of the previous report. The flowering rate varied from park to park with that of Mt. Seorak being the highest. The culms of the flowering patches were significantly taller (F = 93.640, p < 0.000) and thicker (F = 61.172, p < 0.000). Following the event, the culms of the flowering patches declined, providing a good opportunity for the suppressed plant species. The concurrent massive flowering of the mature patches was believed to be triggered by some stress such as a spring drought. Conclusion: We confirmed that the rare synchronized flowering of S. borealis occurred with a peak in 2015 nationwide. In addition, we explored that S. borealis not only monopolized an enormous area, but also dominated the floors of the late-successional Q. mongolica-dominated deciduous forests. This presents a major problem for Korean forests. As it declined simultaneously after flowering, there are both possibilities of forest regeneration or resettlement of S. borealis by massively produced seeds.

• Korean Journal of Medicinal Crop Science
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• v.14 no.3
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• pp.153-157
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• 2006

Floret flowering of Orostachys japonicus, a monocarpic and short day plant, should be controlled to continue cultivating. The study was done to examine the effect of transplanted seedling size (large, 18 leaves; medium, 13 leaves; small, 8 leaves) on growth, morphological characters, and flowering. Night-break treatment of 2 hours at midnight were done on August 25 and afterward samples were taken every 2 weeks. Growth, morphological and flowering related characters were measured from each sample. With larger seedling transplanted, plant height, inflorescence length, number of leaves including bracts and stem diameter were increased. Leaves and bracts, stem, root, shoot and total dry weights were increased as transplanted seedlings became larger. Although formed florets were inclined with larger transplanted seedling, they were not flowered because of the night-break treatment, meaning that the larger transplanted seedlings, the more economic yield.

• Korean Journal of Medicinal Crop Science
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• v.15 no.4
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• pp.251-255
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• 2007

Floret flowering of a monocarpic plant Orostachys japonicus should be controlled to change its harvest time. The study was done to clarify the effect of pinching time of inflorescence with many florets (Aug. 25, Sept. 8 and 22, Oct. 4) on its growth, morphological characters, and flowering. Night-break treatment of 2 hours at midnight were done since Aug. 25 when afterward samples were taken every 2 weeks to Nov. 4. Growth, morphological and flowering related characters were measured from each sample. Plant height, inflorescence length and number of leaves including bracts showed significant difference between the treatments because they were sharply increased until each pinching time. Stem diameter did nearly same. Leaf and bract, floret, shoot and total dry weights had similar response to the plant height, but stem and root dry ones did similar response to the stem diameter. Most florets were removed by the pinching treatments after formed ones were increased until each pinching time. Few florets were left after the treatment, meaning that night-break treatment after that could be skipped.

• Korean Journal of Medicinal Crop Science
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• v.15 no.4
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• pp.256-260
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• 2007

Year-round cultivation of a monocarpic plant Orostachys japonicus should be possible in case to controlling floret flowering. To give some information on its year-round cultivation, this study was carried out to examine the effect of night-break treatment time (June 10, Aug. 25) on its growth, morphological characters, and flowering. Night-break treatment of 2 hours at midnight were done since Aug. 25 and heating were made under $20^{\circ}C$ Samples were taken every 4 weeks from Aug. 25. Growth, morphological and flowering related characters were measured from each sample until March 9. Plant height, inflorescence length, number of leaves including bracts and stem diameter were greater in the earlier treatment than in the later one. Leaves and bracts, floret, stem, root, shoot and total dry weights showed the same response as plant height did to the night-break treatment time. Florets were more formed in the earlier treatment than in the later treatment in which they were flowered only on March 9, meaning that its year-round cultivation should be possible under night-break treatment before bolting and heating during winter season.

• Korean Journal of Medicinal Crop Science
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• v.16 no.1
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• pp.16-19
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• 2008

Shoot parts of a monocarpic and short day plant Orostachys japonicus have been used as a herbal medicine. The study was carried out to examine the effect of transplanting time (May 30, June 30, July 30) of its seedlings on its growth, morphological characters, and flowering. Two hours night-break treatment at midnight was done since Aug. 25 when samples were taken afterward every 4 weeks. Growth, morphological and flowering related characters were measured from each sample. Plant height and inflorescence length became longer with delayed transplanting time. Number of leaves including bracts and stem diameter were more and thicker when transplanted on June 30 than two other treatments. Leaves and bracts, stem, root, shoot and total dry weights showed nearly the same result to the number of leaves although floret dry weight were increased as transplanting time was delayed. Although florets were most formed when transplanted on June 30, they were not flowered because of the night-break treatment, meaning that the transplanting time had little effect on its growth and anthesis of the florets.

• 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.