• 한국식물학회:학술대회논문집
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• 한국식물학회 1999년도 제13회 식물생명공학심포지움 New Approaches to Understand Gene Function in Plants and Application to Plant Biotechnology
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• pp.85-89
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• 1999

Somatic embryogendesis is one of good examples of the basic research for plant embryo development as well as an important technique for plant biotechnology. This paper describes the direct somatic embryogenesis from zygotic embryos of Panax ginseng is reversely related to normal axis growth of zygotic embryos by the experiment of various chemical treatments. Under the normal growth condition, the apical tips of embryo axis produced an agar-diffusible substance, which suppressed somatic embryo development from cotyledons. Although the cells of zygotic embryos were released from the restraint of embryo axis, various factors were still involved for somatic embryo development. Electron microscopic observation revealed that the ultrastructure of cells of cotyledon epidermis markedly changed before initiation of embryonic cell division, probably indicating reprogramming events into the cells embryogenically determined state. Polar accumulation of endogenous auxin or cell-cell isolation by plasmolysis pre-treatment is the strong inducer for the somatic embryo development. The cells for the process of somatic embryogenesis might be determined by the physiological conditions fo explants and medium compositions. Direct somatic embryos from cotyledons fo ginseng were originated eithrer from single or multiple cells. The different cellular origin of somatic embryos was originated either from single or multiple cell. The different cellular origin of somatic embryos was depended on various developmental stages of cotyledons. Immature meristematic cotyledons produced multiple cell-derived somatic embryos, which developed into multiple embryos. While fully mature cotyledons produced single cell-derived single embryos with independent state. Plasmolysis pretreatment of cotyledons strongly enhanced single cell-derived somatic embryogenesis. Single embryos were converted into normal plantlets with shoot and roots, while multiple embryos were converted into only multiple shoots. GA3 or a chilling treatment was prerequisite for germination and plant conversion. Low concentration of ammonium ion in medium was necessary for balanced growth of root and shoot of plantlets. Therefore, using above procedures, successful plant regeneration of ginseng was accomplished through direct single embryogenesis, which makes it possible to produce genetically transformed ginseng efficently.

• Journal of Plant Biotechnology
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• 제50권
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• pp.89-95
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• 2023

In order to investigate the effect of carbon sources on somatic embryogenesis and cotyledon number variations in carrot, embryogenic callus were cultured in the medium supplemented with various concentrations of sucroseor glucose, and with combination of 2% sucrose and various concentrations of mannitol or sorbitol. The maximum number of somatic embryos formed per flask (1,555.70) was obtained in the medium supplemented with 2% sucrose rather than glucose alone or a combination of mannitol or sorbitol and 2% sucrose, and the number of somatic embryos was decreased with the increasing of mannitol or sorbitol concentration. The frequencies of somatic embryos with two cotyledons were 35.14% for sucrose, 19.88% for glucose, 32.55% for mannitol + 2% sucrose, and 38.59% for sorbitol + 2% sucrose, respectively, and the frequencies of abnormal somatic embryos having 3 or more cotyledons were 64.86% for sucrose, 80.12% for glucose, 67.44% for mannitol + 2% sucrose, and 61.41% for sorbitol + 2% sucrose, respectively. Particularly, the frequency of somatic embryos with two cotyledons (59.16%) was the highest in the 2% sucrose medium compared to the frequency of abnormal somatic embryogenesis with three or more cotyledons, and the frequency gradually decreased with increasing concentration of glucose, mannitol or sorbitol. According to these results, it was found that the ratio of abnormal somatic embryo was higher than the normal somatic embryo in carrot, and was shown that somatic embryogenesis and the cotyledon number was affected by the concentrations of sucrose, glucose as carbon source, and mannitol and sorbitol as osmotic agents in culture medium.

• Plant Biotechnology Reports
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• 제2권3호
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• pp.179-189
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• 2008

We established an efficient plant regeneration system for Catharanthus roseus L. (G.) Don through somatic embryogenesis. Embryogenic callus was induced from hypocotyl of seed germinated in vitro. Somatic embryogenesis in Catharanthus has been categorized into three distinct stages: (1) initiation and proliferation of embryo; (2) maturation, and; (3) germination or plantlet conversion. Beside plant growth regulators, various stages of embryogenesis were screened for their response to a wide variety of factors (pH, gelrite, light, sugar alcohols, polyethyleneglycol and amino acids), which affect embryogenesis. All of the tested factors had a small to marked influence on embryogeny and eventual conversion to plantlets. The plantlets were acclimatized successfully in a greenhouse. To our knowledge, this is the first report describing a detailed study of various cultural factors which regulate embryogenesis in C. roseus. The results discussed in this paper may be used in mass propagation to produce medicinal raw material, and the embryo precursor cells could be used in genetic modification programmes that aim to improve the alkaloid yield as well.

• 식물조직배양학회지
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• 제27권4호
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• pp.245-258
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• 2000

Somatic embryogenesis has become a major tool in the study of plant embryology, as it is possible in culture to manipulate cells of many plant species to produce somatic embryos in a process that is remarkably similar to zygotic embryogenesis. Traditionally, the process has been studied by an examination of the ex vitro factors which influence embryo formation. Later structural, physiological and biochemical approaches have been applied. Host recently, molecular tools are being used. Together, these various approaches are giving valuable information on the process. This article gives an overview of somatic embryogenesis by reviewing information on the morphogenesis, physiology, biochemistry and molecular biology of the process. Topics covered include a brief description of the factors involved in the production of embryogenic cells. Carrot cell suspension is most commonly used, and the development of a high frequency and synchronous system is outlined. At the physiological and biochemical lev-els various topics, including the reactivation of the cell cycle, changes in endogenous growth regulators, amino acid, polyamine, DNA, RNA and protein metabolism, and embryogenic factors in conditioned medium are all discussed. Lastly, recent information on genes and molecular markers of the embryogenic process are outlined. Somatic embryogenesis, the best example of totipotency in plant cells, is not only an important tool in studies in basic biology, but is potentially of equal significance in the micropropagation of economically important plants.

• Plant Biotechnology Reports
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• 제4권1호
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• pp.23-27
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• 2010

Quantitative trait loci (QTLs) controlling ability of somatic embryogenesis were identified in soybean. A frame map with 204-point markers was developed using an RI population consisting of 117 $F_{11}$ lines derived from a cross between cultivar 'Keburi' and a weedy soybean 'Masshokutou Kou 502'. The parents differed greatly in their abilities of somatic embryogenesis using immature cotyledons as explants. The ability of somatic embryogenesis was evaluated in five different experiments: the $F_{11}$ (evaluated in 1998) and $F_{15}$ (2002) generations cultured on basal media supplemented with $40\;mg\;l^{-1}$ 2,4-D (2,4-D1998 and 2,4-D2002), $F_{14}$ (2001) generation on medium with $40\;mg\;l^{-1}$ 2,4-D and high sucrose concentration [2,4-D2001 ($30\;g\;l^{-1}$ sucrose)], and the $F_{11}$ (1998) and $F_{12}$ (1999) generations on medium with $10\;mg\;l^{-1}$ NAA (NAA1998 and NAA1999). The RILs showed wide and continuous variations in each of the five experiments. In the composite interval mapping analysis, 2 QTLs were found in group 8 (D1b + W, LOD = 5.42, $r^2$ = 37.5) in the experiment of 2,4-D1998 and in group 6 (C2, LOD = 6.03, $r^2$ = 26.0) in the experiment of 2,4-D2001 (high concentration sucrose). In both QTLs, alleles of 'Masshokutou Kou 502' with high ability of somatic embryogenesis contributed to the QTLs. For the other three experiments, no QTL was detected in the criteria of LOD >3.0, suggesting the presence of minor genes.

• Journal of Plant Biotechnology
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• 제6권2호
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• pp.87-90
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• 2004

An efficient plant regeneration system in alfalfa (Medicago sativa L.) through somatic embryogenesis was established. Embryogenic callus was obtained by culture of hypocotyl segments on MS medium with 0.02mg $L^{-1}$ IAA and 1.0mg $L^{-1}$ zeatin after 45 days of culture. Embryogenic calli were converted to the somatic embryos when transferred to either MS medium without plant growth regulators (PGRs) or MS medium containing various cytokinin (BA, kinetin and zeatin). Most of the somatic embryos were developed into plantlets on MS medium supplemented with 0.1 mg $L^{-1}$ kinetin. Also, secondary embryos appeared on the surface of primary embryo but they showed abnormal growth. Regenerated plantlets were transplanted to pots containing vermiculite and perlite for further analysis.

• Plant Biotechnology Reports
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• 제2권4호
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• pp.259-265
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• 2008

Picea koraiensis, called Korean spruce, is an evergreen tree and found mostly in northeast Asia. In this study, plant regeneration via somatic embryogenesis from open-pollinated immature zygotic embryos of nine geno-types of elite trees was established. Immature zygotic embryos were cultured onto RJW medium modified from 505 medium with $21.48{\mu}M$ NAA, $2.22{\mu}M$ BA, and $2.32{\mu}M$ KT. The average frequency for all nine genotypes was 74.2%. Embryogenic calluses of the nine genotypes of elite trees were subcultured on RJW basal medium containing $8.06{\mu}M$ NAA, $1.11{\mu}M$ BA, and $1.16{\mu}M$ kinetin. The calluses of three lines, $3^{\sharp}$, $9^{\sharp}$, and $2^{\sharp}$, were actively proliferated but others were not. Somatic embryogenesis was induced from the embryogenic callus in genotypes of $3^{\sharp}$, $9^{\sharp}$, and $2^{\sharp}$ on RJW medium with ABA and $60g\;l^{-1}$ sucrose. Cotyledonary somatic embryos were subjected to a drying process. The drying of embryos by uncapping the culture bottle for 5 days on a clean bench resulted in a high frequency of germination of somatic embryos (87% in RJW medium). However, plantlet conversion from germinated embryos was greatly reduced and the optimal medium for plant conversion was 1/2 WPM or 1/2 BMI medium. In conclusion, we have, for the first time, established a plant regeneration system via somatic embryogenesis in the Korean spruce, which can be applied for rapid micropropagation of elite trees.

• 식물조직배양학회지
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• 제22권3호
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• pp.157-164
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• 1995

온전한 접합자배 또는 자엽절편을 오옥신(2,4-D, IAA)과 사이토카이닌(BA, kinetin)이 첨가된 배지에 배양하였다. 접합자배를 온전한 상태로 배양했을 경우, 오옥신은 발아를 억제하였으나 사이토카이닌은 억제하지 않았고, 체세포배의 발생은 발아되지 못하는 배에서만 유도되었다. 자엽절편을 배양한 경우, 기본배지에서 체세포배발생률이 가장 높았다. 오옥신을 첨가한 배지에서는 체세포배가 자엽의 표면에서 산재하여 발생되었는데 비해서 기본배지에서는 자엽의 기부에서만 발생되었다. 2,4-D를 첨가한 배지에서는 체세포배가 자엽의 표피 및 하표피를 포함한 다수의 세포로부터 기원되어 다배로 발생되었다. 이 체세포배를 같은 배지에 배양했을 때 일차배의 표면으로부터 이차배가 발생되었는데 이들의 경우는 주로 표피 또는 하표피의 단세포로부터 유래되었음을 조직학적으로 밝혔다.

• Journal of Plant Biotechnology
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• 제4권2호
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• pp.71-76
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• 2002

In order to achieve repetitive somatic embryogenesis in cacao (Theobroma cacao L.), callus derived from floral tissues were continuously cultured in a medium containing 2,4-D. In 5% of the explants, repetitive somatic embryogenesis was observed after 8 weeks and maintained in a globular stage for several weeks. This is the first report showing repetitive somatic embryogenesis in cacao. The calli were bombarded with a plasmid containing $\beta$-glucuronidase (gus) as reporter gene. Two week old calli showed the high average number of cells expressing the us gene. The effect of osmotic agents (mannitol, sorbitol and sucrose) on gene expression was evaluated. Pre-treatment during 16 h with 0.25 M mannitol revealed an improvement in gene expression. The potential utilization of the repetitive embryogenesis, combined with osmotic treatment, is discussed as an alternative to achieve stable transgenic cacao plants.

• 식물조직배양학회지
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• 제27권4호
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• pp.299-307
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• 2000

A large amount of information is currently available for somatic embryogenesis of plants. However, one common problem related to somatic embryos is that the conversion rate can be low for some species. Apical meristems are responsible for post-embryonic growth of the embryo. The low percentage observed is most likely a result of poor apical meristem development or defects in the meristem organization during somatic embryogenesis. In flowering plants, apical meristems are well developed by the late heart stage of zygotic embryo development. In conifers, such as white spruce, apical meristems are formed at the pre-cotyledon stage. Thus, apical meristem development occurs very early, prior to the maturation stage of embryo development. Once formed, meristems are stably determined. In the somatic embryo, as exemplified by white spruce, since embryo development is not synchronous, tissue differentiation including apical meristem formation occurs throughout the“maturation”stage. Different apical meristem organizations can be found among different individuals within a population. In contrast to their zygotic counterparts, the apical meristems appear not to be stably determined as their organization, as the shoot apical meristem especially, can be easily modified or disrupted. Precocious germination seldom results in functional plantlets. All these observations suggest that the conditions for somatic embryo maturation have not been optimized or are not suitable for meristem formation and development. The following strategies could improve meristem development and hence conversion: 1. Simulate in ouuio conditions to promote meristem development prior to the“maturation”treatment.2. Prevent deterioration of apical meristem organization during somatic embryo maturation.3. Promote further meristem development during embryo germination.