• Journal of Plant Biotechnology
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• v.41 no.4
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• pp.180-193
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• 2014

In plants, a shoot apex has a small region known as the shoot apical meristem (SAM) having a group of dividing (initiating) cells. The SAM gives rise to all the groundabove structures of plants throughout their lifetime, and thus it plays important role in growth and development of plants. This review describes theories to explain the SAM organization and function developed over the last 250 years. Since in 1759 German botanist C. F. Wolff has described firstly the SAM, in 1858 Swiss botanist C. N${\ddot{a}}$geli proposed the apical cell theory from the observation of a large single apical cell in the SAM of seedless vascular plants: however, this view was recognized to be unsuitable to seed plants. In 1868, German botanist J. Hanstein suggested the histogen theory: this concept subdividing the SAM into dermatogen, periblem, and plerome was unable to generally apply to seed plants. In 1924, German botanist A. Schmidt proposed the tunica-corpus theory from the examination of angiosperm SAM in which two parts show different planes of cell division: this theory was proved to be not suitable to gymnosperm SAM, not have stable surface tunica layer. In 1938, American botanist A. Foster described zones in gymnosperm SAM based on the cytohistologic differentiation and thus called it a cytohistological zonation theory. With works by E. Gifford, in 1954, this zonation pattern was demonstrated to be also applicable to angiosperm SAM. As another theory, in 1952 French botanist R. Buvat proposed the m${\acute{e}}$rist${\grave{e}}$me d'attente (waiting meristem) theory: however, this concept was confuted because of its negation of function during vegetative growth phase to central initial cells. Rescent studies with Arabidopsis thaliana have found that formation and maintenance of the SAM are under the control of selected genes: SHOOTMERISTEMLESS (STM) gene forms the SAM, and WUSCHEL (WUS) and CLAVATA (CLV) genes function in maintaining the SAM; signaling between WUS and CLV genes act through a negative feedback loop.

• Journal of Life Science
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• v.16 no.7 s.80
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• pp.1141-1147
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• 2006

This study was carried out to establish a reproducible culture system for callus formation and adventitious shoot development from young stem segments of Vigna radinta, and histological work for orgin of callus tissue and adventitious shoot. Induction of callus from young stem explants of Vigna radiata was very effective on MS inorganic salts supplemented with 0.5 mg/L 2,4-D and 1.0 mg/L kinetin. For the adventitious shoot regeneration from the callus tissues, the hormone combination of 0.75 mg/L NAA, 1.5 mg/L kinetin and MS salts resulted in about 21% efficiency. Histological examination showed that callus tissues originated from out-growths by callus cambium rings with do novo meristematic activities, which were localized at the outside of the vascular cambium. Adventitious shoots were developed from shoot apical meristem originated from the surface of callus masses. The shoot apical meristem produced leaf primordium, which then became leaf.

• Korean Journal of Plant Taxonomy
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• v.38 no.1
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• pp.51-61
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• 2008

Leaves are indeterminate organs and possess a lot of genes which is involved in establishing leaf polarities. These polarities are regulated relatively early during leaf development and defined relative to the factors intrinsic to the primordia and interactions with the shoot apical meristem (SAM). Recently, several genes that control the polarity of lateral organs have been identified. Our genetic study of deformed root and leaf1 (drl1) mutant, which produces narrow, filament‐like leaves and defective meristems, revealed that DRL1 is involved in the regulation of SAM activity and leaf polarity. The DRL1 gene was found to encode a novel protein showing homology to Elongator‐associate protein (EAP) of yeast KTI12. The amino acid sequence of DRL1 is universally conserved in prokaryotes and eukaryotes. DRL1 and the plant DRL1 homologs clearly formed a monophyletic clade, suggesting the evolutionary conservation of DRL1 homologs was maintained in the genomes of all land plants.

• Korean Journal of Plant Tissue Culture
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• v.26 no.2
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• pp.85-91
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• 1999

In sweet potato cultivars 'Mokpo #29' and 'Sanchunza', shoots from extplants were formed 100% on the MS medium with 0.1 ㎎/L NAA and 2.0 ㎎/L BA after 30 days of culture and roots produced from the base of stem at frequencies of 66.7% ('Mokpo #29') and 69.2% ('Sanchunza'), respectively, The media with 0.5∼4.0 ㎎/L BA were produced the greatest frequency of multiple shoot and the most of shoots developed rapidly into normal plantlets with rooting within 60 days of culture. Whereas the cultivar 'Keumsi' failed to produce normal shoot multiplication on the medium with cytokinins alone because of callusing of adventitious shoots. When single shoots with 1 to 2 nodes were excised from the multiple shoot or shoots covered with callus devoid of root and transferred to MS medium with 4.0 ㎎/L BA or kinetin. Host divided shoots showed the callus induction at the stem base and it was enable to obtain regenerated plantlets with shoot and root normally.

• Korean Journal of Plant Resources
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• v.17 no.1
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• pp.1-6
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• 2004

Apical meristems tissue were cultured on LS medium with different zeatin and NAA concentrations to compare their potential to regenerate shoots, roots and bulblet formation. Shoot regeneration from apical meristem was effective on LS medium added with zeatin 0.1, 0.5, 1.0 mg/L alone treatment or zeatin 0.5 mg/L and NAA 1.0 mg/L combination treatment. A high frequency of root regeneration was obtained on LS medium supplemented with zeatin 0.5 mg/ and NAA 1.0 combination treatment. Linsmaier and Skoog(LS) medium with NAA 3.0 mg/L and zeatin 1.0 mg/L combination treatment gave the best results for normal bulblet formation#KW=Allium wakegi ; plant regeneration ; bulblet formation

• Korean Journal of Plant Resources
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• v.17 no.3
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• pp.331-338
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• 2004

This study was conducted to obtain the virus free plants through meristem culture of carnation (Dianthus caryophillus). Four cultivars (Roland, Desio, Casha, Giant Gipsy) were collected for materials. The apical meristem 0.3-0.5mm in size was cultured on MS medium containing 3% sucrose, 0.9% agar at pH 5.8 with various plant growth regulators for 7 weeks. Among the cultivars, Giant Gipsy had a better response than other cultivars in shoot formation and reduced vitrification. Callus induction and shoot formation from the meristem culture were influenced by the various kinds of cytokine. Kinetin supplement was the most effective for shoot formation and NAA addition was good for callus induction among the treatments. Total 115 plantlets derived from apical meristem culture were checked for CarMV and CarRSV infection by ELISA test. Among them, 40 plantlets (34.8%) were infected with CarMV but not detected for CarRSV.

• Korean Journal of Plant Tissue Culture
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• v.21 no.4
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• pp.247-252
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• 1994

The effects of explant sources, plant growth regulators on callus induction and plantlet differentiation from leaf blade, petiole, and meristem tissue of Pelalgonium citrosa were investigated under illumination or in dark condition Leaf blade explants cultured on Murashige and Skoog's medium containing 2,4-D and kinetin did not form callus or organ. But those cultured on medium with NAA and BA produced callcus and shoots. Dark condition was more effective than light condition to callus induction and showed that some of shoot were differentiated directly from leaf blade explane. Callus proliferated vigorously on meristem tissue after 7 days of culture, and multiple shoots were obtained Sum callus on medium with 0.5 mg/L NAA and BA. Roots formed readily from about 80% of the shoots cultured on medium with 1.0 mg/L NAA. Regenerated plantlets regenerated had phenotypically normal leaves and roots.

• Journal of Plant Biotechnology
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• v.29 no.1
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• pp.37-40
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• 2002

Sweet potato is a crop vegetatively propagated by vine cuttings, an ineffective method for maintaining pathogene-free stock plants. As an alternative method, single-node cultures of virus-free plantlets derived from apical meristem in sweet potato (cv. Yulmi) was examined. Effective pH range, sugar concentration and nodal order were investigated to establish an in vitro mass propagation system with high quality virus-free stock plantlets to farmhouse. Although the plantlets grew at wide range of pH, the most effective pH of the medium was 4.8 in single-node cultures. High sugar concentration of 60∼80 g/L resulted in increased growth response in shoot length, root length, number of node, leaf area and fresh and dry weight of shoot and root, whereas reducing sugar contents below 6% was showed reduced growth response. The first node including meristem tip was the best for the rapid growth of plantlets and the other nodes also showed a very similar growth response. Uniform plantlet can be obtained massively at the same time by culture of single node except for the first node including meristem tip. In conclusion, the most effective pH range and sugar concentration of medium for the growth of plantlets via single-node cultures was 4.8, 60∼80 g/L respectively. The first node was the best for the rapid propagation of plantlets in nodal order.

• Korean Journal of Plant Resources
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• v.16 no.1
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• pp.34-39
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• 2003

Corm apical meristem cultures of thirteen glasshouse freesia cultivars were tested to investigate the possibility of micropropagation using MS basal medium supplemented with 2,4-D, NAA(0.1, 0.5, 1.0mg/L, respectively) and BA (0.5∼2.0mg/L). The majority of the tested cultivars could be induced callus and shoot buds in all culture condition. The combinations of NAA and BA appeared superior to that of 2,4-D and BA depending on cultivars for callus induction and shoot formation. Among the cultivars, 'Golden Yellow' showed the highest regeneration capacity on MS media with 0.5mg/L NAA and 1.0 mg/L BA. The highest percentage of regeneration and the greatest number of shoot from calli were obtained through successive subculture on MS medium supplimented with 0.5mg/L BA. In that condition, more than 60 ％ shoot regeneration and average of 25.1 shoots per explant was achieved. Transformed shoots on half-strength MS medium without plant growth regulators rooted easily.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.233-236
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• 2006

This study was conducted to investigate somatic embryogenesis capacity using callus derived from bud meristems in sweetpotato. Shoot apical meristem explants $(height:150{\mu}m;base:\;350{\mu}m)$were cultured on MS medium supplemented with 1 mg/L 2/4-D. Embryogenic callus were observed in five cultivars when their shoot apices were cultured on MS medium supplements with 1 mg/L 2,4-D. After 6 weeks of culture, greater than 80% of the survived explants produced embryogenic calli and the calli gave rise to somatic embryos at frequencies of 72% (Yulmi), 60% (Shinhwangmi), 78% (Geonmi), 70% (KoKei 14), 40% (Sinjami). The regenerated plants developed into whole plantlets after they were transferred onto the fresh hormon-free MS medium of 74% (Yulmi), 82% (Shinhwangmi), 86% (Geonmi), 74% (Kokei 14), 41% (Sinjami) respectively.