• Korean Journal of Plant Tissue Culture
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• v.28 no.4
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• pp.227-230
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• 2001

Kiwi (Actinidia deliciosa) is exotic plant and thus susceptible to cold climate in the middle part of Korean peninsular. Several hybrids have recently been developed to enhance cold tolerance by crossing them with domestic species (A. arguta), We have developed an efficient micropropagation technique for the hybrids using both axillary bud and callus culture systems. Shoot proliferation from axillary buds was possible on St medium supplemented with 0.2 mg/L Bh and 3.0 mg/L GA$_3$. In vivo cuttings of the proliferated shoots were more effective for root induction and subsequent survival than in vitro rooting. More than 95% of the plantlets were successfully transferred to field. Effective callus induction was achieved on MS or B$_{5}$ medium with 2,4-D or NAA. Although callus induction could be made from any combinations of media and auxins, shoot regeneration was observed only from the callus induced on medium containing NAA.A.

• Plant Biotechnology Reports
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• v.2 no.1
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• pp.87-92
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• 2008

An improved protocol for high frequency plant regeneration via somatic embryogenesis from zygotic embryo-derived cell suspension cultures of watershield (Brasenia schreberi) was developed. Zygotic embryos formed pale-yellow globular structures and white friable callus at a frequency of 80% when cultured on halfstrength MS medium supplemented with $0.3mg\;l^{-1}$ 2,4-D. However, the frequency of formation of pale-yellow globular structures and white friable callus decreased slightly with increasing concentrations of 2,4-D up to $3mg\;l^{-1}$, where the frequency reached ~50% of the control. Cell suspension cultures from zygotic embryoderived white friable callus were established using half-strength MS medium supplemented with $0.3mg\;l^{-1}$ 2,4-D. Upon plating of cell aggregates on half-strength MS basal medium, approximately 8.3% gave rise to somatic embryos and developed into plantlets. However, the frequency of plantlet development from cell aggregates was sharply increased (by up to 55%) when activated charcoal and zeatin were applied. Regenerated plantlets were successfully transplanted to potting soil and grown to normal plants in a growth chamber. The distinctive feature of this study is the establishment of a high frequency plant regeneration system via somatic embryogenesis from zygotic embryo-derived cell suspension cultures of water-shield, which has not been previously reported. The protocol for plant regeneration of watershield through somatic embryogenesis could be useful for the mass propagation and transformation of selected elite lines.

• Journal of Plant Biotechnology
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• v.47 no.1
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• pp.40-45
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• 2020

An efficient protocol for multiple shoot induction and plant regeneration from axillary bud culture of Magnolia 'Vulcan' was developed in the present study. Primary shoots were obtained from axillary bud explants cultured on Murashige and Skoog (MS) medium containing 1.0 mg/L 6-benzylaminopurine (BA). To induce multiple shoots effectively, primary shoot tips were cultured on MS medium supplemented with different concentrations of BA and zeatin at 0, 0.2, 0.5, and 1.0 mg/L. Of these treatments, the MS medium with 0.5 mg/L BA resulted in the highest number of shoots per explant with an average value of 5.9, and it produced the greatest shoot height at 4.8 cm after 12 weeks of culturing. In the rooting of in vitro produced shoots, the greatest percentage of explants forming roots (91.3%), number of roots per explant (9.7), and root length (2.8 cm) were obtained in half-strength MS medium supplemented with 6.0 mg/L indole-3-butyric acid (IBA). Regenerated plantlets were successfully acclimatized and hardened off inside the culture room with 87.5% survival rate. Plants were transferred to a greenhouse with a 97.2% survival rate. The highly efficient shoot multiplication and plant regeneration system reported herein can be used for large-scale clonal propagation of valuable Magnolia species or cultivars.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.65.2-65
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• 2003

To protect the plant against several soil-borne pathogens, we are currently constructing disease-resistant transgenic root stock for the growth of cucurbitaceae vegetable plants, watermelon and gourd. We made a watermelon cDNA library from Cladosporium cucumerinum-Infected leaves for substractive hybriazation and differential screening. We isolated the several pathogen inducible cDNA clones, such as caffeoyl-CoA-methyltransferase, LAA induced protein, receptor-like kinase homolog, hydroxyproline-rich glycoprotein, catalase, calmodulin binding protein, mitochondrial ATPase beta subunit, methyl tRNA synthetase and WRKY transcription factors. We previously obtained CaMADS in pepper and galactinol synthase ( CsGolS) in cucumber that were confirmed to be related with disease-resistance. CaMADS and CsGolS2 were transformed into the inbred line 'GO701-2' gourd, the inbred line '6-2-2' watermelon and the Kong-dye watermelon by Agrobacterium tumerfaciens LBA4404. Plant growth regulators (zeatin, BAP and IAA) were used for shoot regeneration and root induction for optimal condition. Putative transgenic plants were selected in medium containing 100mg/L kanamycin and integration of the CaMADS and CsGO/S2 into the genomic DNA were demonstrated by the PCR analysis. We isolated major soil-borne pathogens, such as Monosporascus cannonballus, Didymella bryoniae, Cladosporium cuvumerinum from the cultivation area of watermelon or root stock, and successfully established artificial inoculation method for each pathogen. This work was supported by a grant from BioGreen 21 program, Rural Development Administration, Republic of Korea.

• Journal of Korean Society of Forest Science
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• v.81 no.3
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• pp.273-279
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• 1992

Protoplasts isolated from leaf mesophyll tissues of Populus koreana ${\times}$ P. nigra var. italica were fused with those of P. euramericana cv. Guardi. Well expended healthy leaves of 5 to 7 week-old-plantlet grown in vitro were used as source materials. Leaves from P. koreana ${\times}$ P. nigra var. italica and P. euramericana cv. Guardi were digested in enzyme solution I (2.0% Cellulase, 1.2% Hemicellulase, 0.4% Macrozyme, 2.0% Driselase, 0.05% Pectolyase ; w/v) and enzyme solution II (1.0% Cellulase, 1.2% Hemicellulase, 0.4% Macrozyme, 2.0% Driselase, 0.05% Pectolyase ; w/v), respectively, The highest frequency of fusion among the protoplasts originated from the two source materials was approximately 21% using 40% PEG or 15% dextran. In addition, fusion frequency was enhanced by incorporating 30mM of $Ca^{2+}$ in eluting solution at pH 10.5. Dividing cells and/or mint-calli were obtained by culturing the fusion products in a liquid 8p-KM medium supplemented with 0.6M sucrose, $0.45{\mu}M$ 2, 4-D, and $0.5{\mu}M$ BA. Shoots were regenerated from the fusion product-derived calli after culture on MS medium containing $5.0{\mu}M$ zeatin. To verify the putative hybrid or cybrid, SDS-PAGE was carried out. From the 24 regenerants, just two plants showed intermediate protein band patterns compared with those of the original source plants.

• Korean Journal of Plant Tissue Culture
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• v.21 no.4
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• pp.215-220
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• 1994

Pollen-derived embryos cultured on the hormone-free medium showed a low germination frequency (12.5%) and poor growth response after germination. The greatest frequency of germination (81.3%) was obtained from the embryos cultured on medium with 0.3mg/L GA$_3$.The greatest frequency of generation (81.3) was obtained from embryos cultured on medium with 0.3mg/L GA$_3$. The embryos precultured for 20 days on medium with 0.3mg/L GA$_3$were transferred to the medium with various combination of hormones such as IAA, kinetin, zeatin, 6-benzylaminopurin (BA) and Gh$_3$. The germination frequency of cotyledonary stage embryos showed above 72% on media with all of the hormonal combinations, but the embryos germinated on medium with 2mg/L BA or 0.1mg/L kinetin and 0.3mg/L GA$_3$ developed more vigorously into plantlets than those of other hormonal combinations. Torpedo-stage embryos cultured on medium with 0.3 mg/L Gh$_3$ were pretreated for 8 weeks at 2-week intervals at 4$^{\circ}C$, The germination frequency of the cold-preheated embryos increased with the increment of pretreatment period from 2 to 8 weeks. The greatest frequency of germination (73.3%) was obtained from the embryos pretreated for 8 weeks at 4$^{\circ}C$. The chromosomes of the root-tip cells of W plane grown for 40 days after germination were observed. Most of the regenerated plants were haploid (55.8%) or diploid (315%), but triploid (1.3%), tetraploid (5.2%), or aneuploid (6.5%) were also detected among them.

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.163-169
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• 1999

This study was conducted to produce herbicide resistant plants by transferring phosphinothricin acetyltransferase (PAT) gene into Populus alba $\times$ Populus glandulosa No .3 using Agrobacterium tumefaciens MP 90/PAT. Leaf segments from in vitro grown shoots of hybrid poplar No. 3 were soaked in a AB medium containing Agrobacterium tumefaciens MP 90/PAT for 10 min and cocultivated for 2 days on MS medium containing 1.0 mg/L 2,4-D and 0.2mg/L kinetin (CIM). Putative transformed calli could be selected after cocultivation of leaf segments on CIM supplemented with 50mg/L kanamycin and 500mg/L cefotaxime for 3 weeks. The selected calli were cultured on CIM supplemented with 50 mg/L kanamycin and 500 mg/L cefotaxime for 5~8 weeks before transfer to WPM containing 1.0mg/L zeatin, 0.1mg/L BAP, 50 mg/L kanamycin and 500mg/L cefotaxime for shoot regeneration. Shoots were regenerated from the callus after 4 week cultivation, and the regenerants were grown on the same medium for 7~l0 weeks. The plants rooted on 1/2 WPM containing 0.2 mg/L IBA and 50 mg/L kanamycin. To confirm the gene insertion into plants, GUS activity was detected by histochemical assay in the transformed plants. Finally, the presence of both NPT II and PAT genes from the transgenic plants were confirmed by PCR amplification with the gene specific primers and subsequent PCR-Southern blot with DIG-labeled PAT gene probe. After acclimatization in pots for 4 weeks, the plants were sprayed by 3 mL/L of Basta to test resistance to the herbicide. The transgenic plants remained green, whereas all the control plants died after one week.

• Korean Journal of Plant Resources
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• v.19 no.5
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• pp.634-639
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• 2006

In order to develop a disease-resistant root stock for the growth of watermelon, an efficient regeneration system of the gourd(Lagenaria leucantha Duch.) inbred line GO701-2 via organogenesis was established in this experiment. Using proximal parts of cotyledon explant excised from germinated seedling in vitro, maximum adventitious shoot formation (39%) was achieved on MS medium where cytokinin (BA) and auxin (IAA) were added at a concentration of 3mg/L and 0.1mg/L, respectively. Roots of the elongated shoots were successfully formed on MS medium without adding any plant growth regulators. The cucumber CsGolS1 gene known as a resistance gene against biotic and abiotic stresses, was constructed into the binary vector pBI121 under the control of CaMV 35S promoter. When the gene was introduced into the genome of gourd by Agrobacterium-mediated transformation, putative transgenic plants were obtained with the transformation efficiency of approximately 20 percent.

• Korean Journal of Plant Tissue Culture
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• v.28 no.2
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• pp.103-108
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• 2001

The in vitro plantlets of cassava (Manihot esculenta Crantz cv. MColl 22) could be regenerated from nodal explant cultures in a liquid MS basal medium containing 0.01 mg/L zeatin for 2 weeks. The plantlets of 1.5∼2.5 cm in shoot length were transplanted to a glass bottle containing fine sand and acclimated under non-sterile conditions after excising their intact roots by: 1) prune leaving roots base of 1∼1.5 cm; 2) complete removal of roots; and 3) cutting off the rooting zone. The majority of in vitro-formed intact roots continued growth after transferred to soil, and all of the damaged roots stopped further growth. The plantlets with excised roots began to develop new roots within 7∼10 days after being transferred to a glass bottle, and a few of the pruned roots developed lateral roots from the remaining portion. Pruning and removal of in vitro roots resulted in a high survival rate (>87%), and did not significantly affect ex vitro root regeneration and acclimation, but the plantlets in which the rooting zone had been cut-off showed 73% survival rate. Pruning or removal of in vitro roots before transfer of plantlets is recommended for useful method of commercial micropropagation because of easier handling and high survival rate of plantlets.

• Korean Journal of Plant Tissue Culture
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• v.27 no.3
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• pp.185-189
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• 2000

For the micropropagation, node explants of cassava were cultured in liquid MS medium with various concentrations of cytokinins on a rotary shaker (100 rpm) for 2 weeks. The adventitious roots and shoots from the explants were differentiated more efficiently in liquid medium than in solid. But root formation was not inhibited in medium with BAP and kinetin at low concentration (＞0.05 mg 1/sup -1/), while in medium added with BAP and zeatin at high level (＜0.25 mg 1/sup -1/), it was inhibited by callus forming on cut end of the cuttings. However, all of plantlets grown in liquid medium for more than 2 weeks showed symptoms of hyperhydricity. The plantlets grown in liquid medium were transferred into culture bottles filled with fine sand or artificial soil (pitmoss：perlite：vermiculite, 1：1：1 v/v) wetted with half strength of Knop's solution. After transplanted to culture bottles, some of vitriscent leaves were defoliated and new leaves were normally formed from shoot apex. Most of plantlets (＞95%) were hardened-off successfully only in culture bottles with fine sand, and grew into 3-5 cm seedlings possessing 4-6 nodes after 4 weeks. Thus, the mass propagation of cassava on medium containing cytokinin could be established based on the suspension culture using node explants.