• Korean Journal of Microbiology
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• v.52 no.4
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• pp.437-443
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• 2016

In this study Streptomyces strains were isolated from soils and their antifungal activities and involved mechanisms were investigated. Among over 400 isolates of actinomycetes, Streptomyces costaricanus HR391 was selected as a potential antagonist to control several plant-pathogenic fungi. S. costaricanus HR391 inhibited mycelial growth of Fusarium oxysporum f. sp. raphani, F. oxysporum f. sp. niveum, F. oxysporum f. sp. lycopersici, and Rhizoctonia solani by 26.5, 26.2, 21.2, and 23.8%, respectively compared to those of uninoculated control after 7-day incubation on PDB medium. S. costaricanus HR391 produced $89{\mu}M$ of siderphore, and showed fungal cell wall-degrading activity including $0.46{\mu}mol/min/mg$ of chitinase and $0.83{\mu}mol/min/mg$ of ${\beta}$-1,3 glucanase. S. costaricanus HR391 secreted 87.49 mg/L of rhamnolipid, and produced 9.49 mg/L and 4.3 mM of lipopeptide, iturin A and surfactin, respectively, all they are membrane-disrupting biosurfactants. It also produced antimicrobial peptide and antibiotics phenazine. In addition to antifungal substances, S. costaricanus HR391 secreted plant growth-promoting phytohormones, zeatin, gibberellins and IAA. These results suggest that S. costaricanus HR391 may be utilized as an environment-friendly biocontrol agent against some important pathogenic fungi.

• Korean Journal of Agricultural Science
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• v.20 no.2
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• pp.133-144
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• 1993

Calli were induced on microtuber disks of potato(S.tuberosum) infected with three binary vectors transconjugated with C58, A281 and LBA 4404 of Agrobacterium tumefaciens and pBI121. The frequency inducing callus was the highest by infection of C121 carrying pC58 and pBI121, and shoots were differentiated on the calli without any hormonal application. Transformed calli were selected by their resistance to kanamycin and identified by GUS activity. The frequency of callus formation by infection of binary vector strain was affected according to the hormonal application.

• Journal of Plant Biotechnology
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• v.34 no.1
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• pp.37-45
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• 2007

The genetic transformation of watermelon by Agrobacterium has been known very difficult and a few successful cases have been reported by obtaining the direct shoot formation. However, since this direct shoot formation is not guaranteed the stable transformation, the stable transformation with reproducibility is required by a different approach such as a callus induced manner. The best conditions for inducing the callus from cotyledon and root explants of watermelon were 2 mg/L zeatin + 0.1 mg/L IAA and 2 mg/L BA + 0.1 mg/L 2,4-D, respectively. The GFP expression in the callus was identified and monitored through fluorescent microscopy after transformation with pmGFP5-ER vector. Paromomycin rather than kanamycin was used for selecting the nptll gene expression because it was more effective to select the watermelon explants. Four different callus types were observed and the solid green callus showed stronger GFP expression. The highest frequency of GFP expression in the callus developed from cotyledon was 9.0% (WM8 inbred line), while the highest frequency from root was 8.3% (WM6 inbred line). The WMV-CP was transformed using the method of GFP transformation and the genetic transformation of WMV-CP was confirmed by PCR and Southern blot analysis. Here we present a system for callus induction of watermelon explant and the callus induced method would facilitate the establishment of stable watermelon transformation.

• Korean Journal of Plant Resources
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• v.31 no.5
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• pp.515-521
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• 2018

This was carried out to develop a chromosome-doubled (12x) persimmon that will be used as a crossing parent to select seedless persimmon cultivars with the change of the consumption trend recently. To obtain a chromosome-doubled (12x) persimmon, colchicine was applied at the meristem of seedlings in vitro derived from cross among hexaploid persimmon (Diopyros kaki Thunb.). These were treated with 0.03%, 0.05% and 0.1% colchicine respectively for doubling chromosome, and it was most effective at the concentration of 0.05% colchicine. After colchicine treatment, we conducted tests to elucidate conditions for inducing shoot and root development. As the result, the shoots grew best when cultivated at 1/2MS media plus 10 and $30{\mu}M$ zeatin respectively, and the roots grew best when cultivated at 1/2MS media after dipping for 5 seconds at 10 mM NAA+5% DMSO. We also compared seedlings that have chromosome (6x) do not doubled and crossing parents (6x) and chromosome-doubled seedlings (12x). As the result, these chromosome-doubled seedlings (12x) showed lower stomatal density and larger stomatal size.

• Korean Journal of Plant Tissue Culture
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• v.22 no.3
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• pp.121-126
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• 1995

Diploid plants were obtained by anther culture of tetraploid poplar(Populus alba L. X P.glandutosa Uyeki). The effect 2,4D on callus formation from anther culture was greater than any other auxins tested. The highest average number of multiple shoots per callus was obtained when zeatin was used at levels of 6-8 ${\mu}$M. Regenerated shoots were excised and transferred to MS basal medium. Rooted plantlets were subsequently transferred to pots containing artificial soil mix. Finally 100 plane were transplanted in nursery located in forest Genetics Research Institute. for the 300 anther clones growing in greenhouse for 6 months after transplanting, 33% were slow-growing, 47% were rapid-growing and 20% had huge leaf size with rapid-growing characteristics. Chromosome study showed a narrow range of variation from diploid to tetraploid. DNA polymorphism studies using various RAPD markers revealed some extend of differences among the anther-clones in their band pattern.

• Korean Journal of Plant Tissue Culture
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• v.22 no.6
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• pp.317-322
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• 1995

As a basic research for breeding new varieties, reciprocal -intergeneric crosses between Citrus junos and P.trifoliata were made. F$_1$ hybrid production using in vitro ovule culture, gametogenesis, and fertilization phenomena were investigated. Frequency of fruit set resulting from crossing of Citrus junos and Poncirus Trifoliata was 16.6% while that of Poncirus Trifoliata and Citrus junos was 11.7%. Callus formation occurred well when ovules at the 6th week after pollination were cultured on MT (Murashige and Tucker) medium supplemented with zeatin 0.5 mg/L and NAA 1.0 or 3.0 mg/L. Immature ovules developed into mature embryos of the MT medium supplemented with 2,4-D 0.1 or 3.0 mg/L. Immature ovules developed into mature embryos of the MT medium supplemented with 2,4 D 0.1 or 0.5 mg/L. The invitro germination rates of 20-week-old ovules set C. junos $\times$ P. Trifoliata and P. Trifoliata $\times$ C. junos were 54.5% and 48.6%, respectively. The emergence ratios of trifoliate hybrids obtained by C. junos $\times$ P. Trifoliata and P. Trifoliata $\times$ C. junos were 56.7% and 100%, respectively. The chromosome number of C. junos and P. Trifoliata was n = 9 or 2n = 18, and the sizes of their pollen grain were 33.75 $\mu$ and 25.0 $\mu$. The length and width of embryo sac in C. junos and P. Trifoliata were 69.38~79.23 $\mu$ and 27.50~38.56 $\mu$, and those of egg cells were 17.50~41.50 $\mu$ and 6.25~8.12$\mu$. Fertilization of C. junos and P. trifoliata terminated 72 h after pollination.

• Journal of Korean Society of Forest Science
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• v.96 no.1
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• pp.83-88
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• 2007

Micropropagation of Ulmus davidiana Planch was established via adventitious shoot formation from the segments of adventitious roots. Adventitious roots were produced directly from root segments of seedlings on a 1/2 SH medium plus various concentrations of IBA. The maximum growth of adventitious roots was observed in the presence of 2.0 mg/L IBA. After the segments of adventitious roots were cultured on various cytokinins (zeatin, 2-iP, BA, kinetin) and cytokinins plus auxin (IBA), formation of adventitious shoot was investigated. Among cytokinin treated, kinetin was the most effective on both adventitious shoot induction and number of shoots. Especially, 2.0 mg/L kinetin was the best to increase adventitious shoot induction (95.8%) and a number of shoots (8.4). Adventitious shoots were rooted on 1/2 WPM medium and the plantlets were acclimated 100% on composed soil (peatmoss : vermiculite 1 : 1).

• Journal of Korean Society of Forest Science
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• v.77 no.2
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• pp.208-215
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• 1988

The leaf mesophyll protoplasts of Populus alba ${\times}$ glandulosa were isolated from leaf of plantlet in vitro and cultured for plant regeneration. The MS medium (minus $NH_4NO_3$) with 0.5 mg/l BAP and 2.0 mg/l 2, 4-D showed the moderate frequency of dividing protoplasts cultured by the liquid plating method during the first week of culture. The percentage of colony formation was revealed the highest frequency by the gauze contained semi-solid agar plating method after 5 weeks cultured. Ridding out the gauze, the micro-callus was formed on the same semi-solid medium in 8 weeks after protoplasts culture. For proliferation of callus, mini-callus was transferred on the MS solid medium with 0.5 mg/l 2, 4-D and 0.1 mg/l BAP 12 weeks after culture. Shoot regeneration occurred when the calli derived from protoplasts were cultured on MS medium with 1.0 mg/l zeatin and such shoots could be readily rooted on the one half strengthen MS medium with non-phytohormone. Rooting shoots were planted in green-house 22 weeks after protoplast culture.

• Journal of Plant Biotechnology
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• v.30 no.1
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• pp.27-33
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• 2003

The optimal condition of in vitro regeneration and transformation were investigated for newly bred potato varieties in Korea. Leaf and internodal stem tissues of 'Chubak', 'Namsuh', 'Jasim', 'Jopung' and 'Jowon' were used to investigate the influence of growth regulator on regeneration efficiency The effect of phenolic compound acetosyringone on gene transformation efficiency was also investigated. Leaf tissue of 'Jowon' and internodal stem tissues of 'Jopung' were showed high regeneration efficiency on M5 medium supplemented with 0.1 mg/L GA₃, 2.0 mg/L Zeatin and 0.01 mg/L NAA. The other three potato cultivars were showed low regeneration efficiency less than 25%. The effect of acetosyringone on Agrobacterium-mediated gene transformation with leaf and internodal stem tissues were noticeable. By adding the 75 μM of acetosyringone during the Agrobacterium innoculation, the transformation efficiency was increased up to 1.5∼4.0 fold compare to non-treated control. In case of 'Jowon' the transformation efficiency was 87.9% in leaf tissue and 'Jopung' was 68.4% in internodal stem tissues.

• Korean Journal of Plant Tissue Culture
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• v.26 no.4
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• pp.281-287
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• 1999

Codonopsis lanceolata ("Deoduck" in Korea) is a perennial herb, and belongs to family, Campanulaceae. Its taproot is used a good source of a wild vegetable as well as an herbaceous medicine. In this study, to develop a bialaphos-resistant transgenic Codonopsis, seed germination mechanism and somatic embryogenesis of the plant were investigated, and Agrobacterium-mediated transformation with bar gene encoding phosphinothricin acetyltransferase (PAT) was performed. Attempt were made to regenerate plant from cells via somatic embryogenesis. When the cotyledons, nodes and leaf disks were cultured on MS medium containing 2,4-D and zeatin, embryogenic calli were induced. Upon transferring the somatic embryos to N6 solid medium without plant growth regulators, they developed into plantlets under continuous illumination. All plants were dead on MS basal medium containing 10 mg/L phosphinothricin (PPT) and Basta, respectively. The explants did not produce calli in the medium containing 200 mg/L kanamycin. The explants were cocultured with Agrobacterium tumefaciens for 2 days, and transformants were selected in MS basal medium containing 1.0 mg/L 2,4-D, 100 mg/L kanamycin and 500 mg/L carbenicillin. After the selection, embryogenic calli were induced and then somatic embryos were produced by subsequent subculturing. The somatic embryos were germiated on N6 basal medium containing 200 mg/L kanamycin and 500 mg/L carbenicillin. PCR analysis showed that nptII and bar genes were introduced in the Deoduck transformants. After the confirmation of bar gene expression in RNA and protein level, the transgenic Deoduck will be used to study the genetics of filial generation with the herbicide control gene, bar.gene, bar.