• Journal of Plant Biotechnology
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• v.37 no.4
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• pp.343-356
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• 2010

Plant micropropagation techniques include bud cultures using apical or axillary buds, organogenesis through callus culture or adventitious bud induction, and somatic embryogenesis. In Korea Forest Research Institute (KFRI), the first tissue culture trial in woody plant was initiated from the bud culture of hybrid poplars (Populus alba x P. glandulosa) in 1978. Since then several mass propagation techniques have developed from conifer and hardwood species, resulting in allowing practical application to Poplars, Birches and some oak species. In addition, useful micropropagation and genetic resources conservation techniques were established in some rare and endangered tree species including Abeliophyllum distichum. Among various in vitro propagation techniques, somatic embryogenesis is known to be the most efficient plant regeneration system. Since the first somatic embryo induction was reported in Tilia amurensis by KFRI in 1986, various protocols for direct or indirect somatic embryogenesis systems have developed in conifer and hardwood species including Larix leptolepis, Pinus rigida x P. taeda F1, Kalopanax septemlobus and Liliodendron tulipifera, etc. However, most of these technologies have been developed using juvenile tissues, i.e. immature zygotic embryos or mature embryos. Therefore it has been difficult to directly application to tree breeding program due to their unproven genetic background. Recently remarkable progresses and new approaches have been achieved in mature tree somatic embryogenesis. In this article we reviewed several micropropagation techniques, which have been mainly developed by KFRI and recent international progresses.

• Korean Journal of Plant Tissue Culture
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• v.24 no.3
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• pp.129-135
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• 1997

Morphogenetic responses were investigated by culturing embryo and leaf explants of Korean wild type tea plant, Camellia sinensis (L.) O. Kuntze. Induction of direct somatic embryogenesis as well as adventitious and/or axillary shoots was obtained from mature zygotic embryo cultures on Murashige and Skoog (MS) basal medium having 5 to $20\mu\textrm{M}$cytokinin a lone. Morphogenetic response was decreased dramatically by the addition of auxins tested. One hundred percent of induced and isolated shoots formed roots after four weeks of culture on half-strength MS or quarter-strength Schenk and Hildebrandt (SH) media supplemented with $10\mu\textrm{M}$indole-3-butyric acid (IBA). Immature zygotic embryos were shown to be a suitable explant for embryogenic callus formation in the presence of 2, 4-dichlorophenoxyacetic acid(2, 4-D) in basal medium. Mature zygotic embryo originated leaves were used to test their ability for mophogenesis by incorporating plant growth regulators such as IBA, naphthyl-1-acetic acid (NAA), and 6-benzylaminopurine (BAP). Apparently, the morphogenetic responses of the cultured explant sources on the types and/or levels of plant growth regulators tested were observed visually.

• Journal of Ginseng Research
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• v.23 no.3 s.55
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• pp.130-134
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• 1999

Somatic embryos were induced directly from cotyledon explants of Korean ginseng (Panax ginseng C.A. Meyer) on Murashige and Skoog (MS) medium with 2,4-D, BAP, kinetin or lacking growth regulators. When somatic embryos formed on all media grew to cotyledonary stage, the further development of embryos was ceased and remained in white color. By gibberellic acid (over 1.0 mg/1 $GA_3$) treatment, all the somatic embryos turned rapidly to green and germinated within 3 weeks. Chilling treatment also induced the germination of somatic embryos. The effective temperature regime was $-2^{\circ}C$ for over 8 weeks but more higher temperature than $0^{\circ}C$ did not effective for germination of somatic embryos. Ultrastructural observation revealed that the cotyledon cells of somatic embryos without chilling or $GA_3$ treatment contained numerous lipid reserves, dense cytoplasm, proplastids and non-activated mitochondria with poorly differentiated internal structure, but the cotyledon cells of germinating somatic embryos after chilling or $GA_3$ treatment highly vacuolated and contained well-developed chloroplasts and active state of mitochondria enclosing numerous cristae. The above results indicate that in vitro developed somatic embryos of Panax ginseng may be dormant after mature similar to zygotic embryos.

• Korean Journal of Plant Tissue Culture
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• v.24 no.2
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• pp.107-112
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• 1997

This study was carried out to establish a mass production of normal somatic embryos of Oenanthe iavanica (BL.) DC. including examination of nitrogen and sucrose sources, and ABA concentration. Embryogenic cell clumps and embryos were formed on the MS medium devoid of growth regulators. Proliferation of embryogenic cells and clumps was enhanced by 2, 4-D. Meanwhile embryo growth and development occurred on the media containing NAA and IBA. Growth of embryos was generally good in the media containing both 20 mM $KNO_3$ and 20 mM $NH_4NO_3$. The rate of shoot forming embryos was higher on the media containing on1y 20mM $NH_4NO_3$ than on the former. Addition of sucrose at 3-6% enhanced the embryo development, and normal embryos with short hypocotyl was observed on the medium containing $10\mu\textrm{M}$ ABA. Embryogenic cell clumps or globular embryos, when transferred to MS solid media devoid of growth regulators, developed into mature embryos and then into plantlets which had entire primary leaves like zygotic seedlings.

• Korean Journal of Plant Resources
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• v.27 no.3
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• pp.242-248
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• 2014

This study was conducted to establish an efficient transformation system by using somatic embryogenesis in an important Korean native conifer, Korean fir (Abies koreana). Embryogenic masses were induced from mature zygotic embryos of the Korean fir on Schenk and Hildebrandt medium, which was supplemented with thidiazuron. For genetic transformation, the embryogenic masses were co-cultivated with a disarmed Agrobacterium tumefaciens strain C58/pMP90 containing the plasmid vector pBIV10 or LBA4404 containing the plasmid vector MP90. Both vectors contain the kanamycin resistance and beta-glucuronidase (GUS) reporter genes. A total of 48 lines of embryogenic masses were selected on mLV medium containing $50{\mu}g/mL$ of kanamycin after 4 weeks of culture, following 3 days of co-cultivation with A. tumefaciens strain C58/pMP90 carrying pBIV10 (none of the lines was cultivated with strain LBA4404 carrying MP90). Quantitative real-time PCR was performed, and high levels of GUS transcripts were observed in the 48 putative transgenic lines; however, the control (non-transgenic line) showed negative results. Results of histochemical staining showed that the expression of the GUS reporter gene was observed in somatic embryos that developed from the embryogenic masses of all 48 lines. Stably transformed cultures were successfully produced by co-cultivation with A. tumefaciens strain C58/pMP90 carrying pBIV10 in Korean fir. Here, we have reported an Agrobacterium-mediated gene transfer protocol via somatic embryogenesis that may be helpful in developing breeding and conservation strategies for the Korean fir.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.72-79
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• 2014

Adventitious buds were produced from the cultures of mature zygotic embryos of Larix kaempferi with the highest frequency in Quoirin & Lepoivre (LP) medium containing 1.0 mg/L zeatin (76.1%). The effective treatments for inducing adventitious shoots growth above 2 mm were shown in Litvay (LM) medium with 0.5 mg/L zeatin (75.2%) or LP medium with 2.0 mg/L zeatin (70.2%), respectively. In experiment with half strength salts medium for induction of the adventitious buds, the effective treatments were obtained from 1/2LP medium with 1.0 (83.3%) or 2.0 mg/L (81.7%) zeatin, respectively. However, the best adventitious shoot growth more than 2 mm appeared in 1/2LM medium with 1.0 mg/L zeatin (66.7%). In experiment with half strength salts medium for induction of the adventitious buds, the effective treatments were obtained from 1/2LP medium with 1.0 (83.3%) or 2.0 mg/L (81.7%) zeatin, respectively. However, the best adventitious shoot growth more than 2 mm appeared in 1/2LM medium with 1.0 mg/L zeatin (66.7%). In experiment of subsequent treatment with various cytokinins for induction of the adventitious buds, the best one (52.9%) was obtained from 1.0 mg/L zeatin for 2weeks, and then subcultured to the medium with 1.0 mg/L thidiazuron (TDZ). The effect of ethylene synergist or inhibitor on adventitious buds induction was examined. The highest rate (34.6%) of adventitious buds marked from the treatments of 1.0 mg/L zeatin+2.0 mg/L MGBG (methylglyoxal bis-[guanylhydrazone]). And the highest no. of adventitious buds(1.5/explant) was shown in the medium with 1.0 mg/L zeatin+2.0 mg/L $CoCl_2$.

• Korean Journal of Plant Tissue Culture
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• v.26 no.4
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• pp.251-257
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• 1999

Adventitious buds were produced from the cultures of mature zygotic embryos of Larix leptolepis with the highest frequency of 91.7% in SH medium containing 1.0 mg/L zeatin. The most effective cytokinin combination for inducing adventitious buds was 1.0 mg/L zeatin + 1.0 mg/L thidiazuron (40.3%). The highest mean number of adventitious buds induced in 1.0 mg/L zeatin + 1.0 mg/L 2iP or 1.0 mg/L zeatin + 1.0 mg/L kinetin combined treatments. Elongation of the adventitious buds occurred the best on half strength LM salts medium, on which the buds elongated upto 27 mm. Also, the supplement of activated charcoal in medium suppressed the elongation of the adventitious buds. The highest frequency (23.3%) of rooting from elongated shoots was obtained on the medium containing 5.0 mg/L IBA and 0.2 mg/L NAA. The highest number (3.5) of roots was induced on the medium containing 5.0 mg/L IBA alone.