• Journal of Plant Biology
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• v.38 no.1
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• pp.95-105
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• 1995

Complete microsporogenesis of Hibiscus syriacus L. were carried out employing LM, TEM, and SEM to investigate the pollen ontogeny that undergoes considerable structural differentiation. The process first began with several cell diYisions in the anther primordium that produces 3 different tissues of epidennal, archesporial, and connective tissues. Only archesporial tissue involved further differentiation into the tapetum and formation of reproductive cells, pollen mother cells (PMC). The tapetum and PMC were closely associated with each other structurally and metabolically by exhibiting numerous plasmodesmata, mitochondria, and many small vacuoles in their dense cytoplasm. A callosic wall began to surround the PMC while meiosis took place in the PMC to produce 4 microspores. When thick callose encircled each microspore as a frame, the sporodenn development initiated from the plasma membrane of a pollen grain in a tetrad. The first fonned sporoderm layer was bacules and tectum of sexine that originated from the plasma membrane. After the dissolution of a callose, further development Qf sporoderm continued in the order of nexine 1, nexine 2, and intine layer. The nexine layer was thicker (ca. $2-3.5\;\mu\textrm{m}$) than the intine layer whose thickness was about $0.9-1.5\;\mu\textrm{m}$. Upon completion of the sporoderm development, that is after intine formation, spines and apertures of pollen surface ornamentation initiated from the tectum. Spines were dimorphic, about $4-9\;\mu\textrm{m}\;an;15-20\;\mu\textrm{m}$ in length, and no basal cushion was detected. The mature pollen grains ranged $100-200\;\mu\textrm{m}$ in diameter, but their average was about $170\;\mu\textrm{m}$. About 120 spines were observed over the spheroidal pollen surface. Apertures were simple punctures of $2-3\;\mu\textrm{m}$ in diameter and about 50 apertures were arranged somewhat helically over the surface. Comparing such features of form and size of the pollen, sporodenn sculpture and structure, and aperture and spine conditions with known evolutionary trends in the genus Hibiscus, Hibiscus syriacus seemed to possess many advanced features in the sporodenn differentiation.iation.

• Journal of Plant Biotechnology
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• v.45 no.4
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• pp.400-408
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• 2018

Biodiversity has continued to degrade in the $21^{st}$ century due to global warming occasioned by destruction of the environment around the world.. The Nagoya protocol places Korea in a unique position to effectively develop and protect its domestic genetic resources. Microalgae under study in this research contains large amount of antioxidant substances such as beta carotene and astaxanthin, that can be used as biological resource owing to the large amounts of biomass that can be secured through photosynthesis. However, it is difficult to preserve it since cryopreservation method used for long-term preservation is yet to be developed. A basic study for long term cryopreservation was carried out on Nizschia frustulum and Nitzschia amabilis which belong to marine diatoms. As cryoprotectants (CPAs), glycerol, DMSO, and methanol which penetrate into cells were prepared at 5%, 10%, and 15% concentrations each, in case of methanol, it was tested at concentrations of 5%, 10% and 12% by its nature. Two kinds of microalgae, N. frustulum and N. amabilis, were diluted with $10^2$, $10^3$ and $10^4cells\;ml^{-1}$, respectively. The highest survival rate was shown at12% concentration of methanol, and the figures were $6.94{\pm}0.31%$ in N. frustulum and $8.85{\pm}0.16%$ in N. amabilis. As a result of 3 weeks cultivation of thawed microalgae after freezing, the result is shows that N. frustulum increased about 10 times faster and N. amabilis increased about 12 times the original concentration.

• Applied Microscopy
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• v.36 no.1
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• pp.35-45
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• 2006

Plants of Vitex negundo are known to develop numerous trichomes throughout their body, where certain trichome types have been believed to be one of the plausible structures for the unique scents. In the current study. structural aspects of the trichomes have been examined in leaves and stems of Vitex negundo using TEM and SEM. Trichome types as well as structural changes that occurred in certain trichomes during secretion have been mainly focused. Three type of glandular trichomes and two types of non-glandular trichomes were developed in the epidermis of young and mature Vitex negundo plants. The glandular trichomes included the peltate type (Type 1), the capitate type (Type 2), and degraded capitate type (Type 3), whereas the non-glandular warty trichomes contained the multicellular (Types 4) and unicellular type (Type 5). Type 1 and 2 consisted of head and stalk cells, but their number and size were different. One secretory cavity was formed from the four head cells in the former, but only two head cells were involved in the latter. The cytoplasmic density in the head cell was quite high and in particular, sER and Golgi bodies were well developed. At initiation of their development, the cuticle layer of the head cells separated from the outer tangential wall to form a secretory cavity. Subsequently the cavity expanded acropetally and a large number of secretory vesicles continuously produced from the head cells until they filled the entire cavity. The cavity contained materials that would be soon discharged into intercellular spaces and/or into the air. The cavity began to decrease the volume by contracting at initial secretion but degrade rapidly within short time. It has been suggested that the mode of secretion in V. negundo is probably the eccrine secretion, since no break or rupture of the cavity has been observed during examination. Contrastingly Type 3 exhibited deterioration of the head cell at early stage. Type 4 was about $110{\sim}190{\mu}m$ long, consisting of $2{\sim}3$ cells, and distributed more in the adaxial epidermis compared to the abaxial surface. However, $20{\sim}30{\mu}m$ long Type 5 was extremely dense in both epidermis. Among several trichome types, Type 1 and 2 probably play an important role in discharging unique aromatic scents in plants of V. negundo.

• Korean journal of applied entomology
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• v.24 no.2 s.63
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• pp.51-60
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• 1985

This paper was performed to study the nature of varietal resistance of some Korean-new rice cultivars to the brown planthopper (BPH), Nilaparvata lugens ($ST{\AA}L$). The rice cultivars tested were Cheongcheong, Gaya, Hangangchal, Samgang, Nampoong and Yeongpoong which have been reported as having resistant genes for the BPH. The check varieties were Jinheung, Sangpoong and Chucheong for susceptible and IR-36 for resistant. The factors studied were referred to the seedling responses, preference in feeding and oviposition of BPH, antibiosis (nymphal development, adult emergence and sex ratio, adult body weight, population build-up, feeding amount and amylase activity), and chemical composition (inorganic components, chlorophyll contents, cell wall components, amino acids and esterase isozymes) of leaf- sheath and/or roots of rice plants. In conclusion, the natures of varietal resistance of rice cultivars to the BPH were not only correlated with the resistant reaction of rice plant, but also they were related with the non preference in feeding and oviposition and those resistant cultivars had the antibiotic effects to the insects. Their antibiotic effects of rice cultivars to the BPH would be related with some of the chemical components of rice plants, such as the contents of magnesium oxide (MgO), and chlorophyll and the different esterase isozymes.

• The Korean Journal of Mycology
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• v.22 no.1
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• pp.50-61
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• 1994

From soil samples, 380 antagonistic microorgnisms were isolated. Among the isolates, 42 strains had mycelia growing inhibition ability against Fusariun solani, ginseng root rot causing pathogen. Isolates CHA 1 and S-PFHR 6 were proposed as antagonists for this study and they were identified as Promicromonospora sp. and Pseudomonas pseudoalcaligenes respectively. As an antagonism against hyphae of F. solani in dual culture test, CHA 1 and S-PFHR 6 inhibited linear growing, caused abnormal branching, and the membrane projection which formed by cell wall destruction. The secondary metabolites contained in the culture filtrates which prepared from PD broth and Nutrient broth inhibited the spore germination to 14.3%. The culture filtrate of S-PFHR 6 which prepared by a little amount of soil extract addition to nutrient rich medium had more strongly. inhibited the spore germination and spore germination decreased to less than 4.0% in it. The soil used in this study had fungistasis and the germination rate of macroconidia and chlamydospore of F.solani was 19.4% and 17.7% respectively. The steam sterilized soil lost fungistasis and germination rate of conidia increased to more than 97.9%. The soils amended with the propagule of CHA 1 and S-PFHR 6 increased fungistasis and the germination rate of macroconidia decreased to 14.7% and 11.7% respectively in each treatments. But the soil ammended with glucose and asparagine annulled fungistatic ability and the germination rate of macroconidia increased to more than 48.0%. As an antagonistic activity of the secondary metabolites of two antagonistic isolates in soil, the germination rate of macroconidia of F. solani was 9.3% in the soil amended with the culture filtrate of CHA 1 but the culture filtrate of S-PFHR 6 had no such activity. In the soil which treated with antagonist propagule or culture filtrate, the chlamydospore germination rate was lower than that in natural soil. The addition of glucose and asparagine to antagonist propagule treated soil did not enhanced the chlamydospore germination.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.301-309
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• 1985

This experiment was conducted to know a substantial body of information about the differences of the important forage characteristics; green fodder yield, dry matter yield, TDN%, TDN yield and so forth of the seven cultivars selected as the forage crops (Rye, Triticale, Wheat and Barley) depending on the specific times of cutting stage, on the Wheat and Barley Research Institute from October, 1983 to June, 1984, and the results summarized as follows. Green fodder yield & dry matter weight, when clipped at 20, 30 April and 10 May, of varieties Homil #2 showed the most yielding capacity, but when clipped at 20 May, Suweon#8 (triticale) showed the most green fodder yield whereas Homil #1 the most significant dry matter weight. Plant height, in the cases of Paldanghomil, Homil #1 & Homil #2, showed distinctly longer than that of Bunong, Suweon #8 & Suweon #9 and continued to grow even after the heading date. Dry matter ratio increased with time (Dry matter yield/green fodder yield x100). TDN % decreased but TDN yield increased with time but Homil #1, Homil #2 and Paldanghomil showed relatively the higher values. In the elements of nutrient of cell wall, Suweon #8 & Bungong among 7 cultivars have good quality. The reasonable clipping date of wheat &barley as green fodder crops are 10 May to 20 May, but if clipped before 10 May and 20 May, Homil #2 and Suweon #8 became the promising forage crops, respectively.