• KSBB Journal
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• v.8 no.1
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• pp.62-68
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• 1993

Transformed rice plantlet were recovered from protoplasts by electroporation with the plasmld pB 1121, which contain the plant expressible NPT-II and GUS genes. Embryonic cell suspension culture was established with embryonic callus induced from mature seeds of rice (Oryza sativa L. cv. Dong-jin) on the MS medium supplemented with 2.0 mg/l 2,4-D, 0.5 mg/l kinetin, 3% sucrose. Protoplasts isolated from embryonic cell suspensions were electroplated and then poterltialty-transformed tissues were selected by growth on the medium containing 200 mg/l kanamycin sulfate. When subjected to GUS assay, they stained blue, indicating the expression of the inserted GUS genes. Plantlets were regenerated from electroplated protoplasts on the hormone free MS medium. Transferred foreign genes in the plants were confirmed by southern hybridization. These results support use of electroporation for transformation of these important cereal plants.

• Research in Plant Disease
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• v.8 no.4
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• pp.250-253
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• 2002

This research was conducted to develop a simple and effective method for pathogenicity assay of the causal agent of bacterial canker on kiwifruit. The developed method is a modified version of syringe-infiltration method that is used in the assay fer the hypersensitive response assay. Bacterial cell suspensions in 50 mM potassium phosphate buffer(pH 7.5) were infiltrated using a plastic syringe with 25G needle into primary leaves of five-year-old kiwifruit. Typical symptoms of bacterial canker were observed five days after infiltration. Symptoms developed on the leaves were detected in these inocula that treated above 10$^4$cfu/ml or above. Using this technique, host range of Pseudomonas syringae pv. actinidiae and three other plant pathogenic pseudomonads were investigated for 25 different plant species. The various symptoms were showed depend-ing on different plant species and inoculated pathogen combinations. This method has the advantage that symptoms can be showed faster compared to other methods and high humid conditions are not required.

• Korean Journal of Plant Tissue Culture
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• v.25 no.1
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• pp.13-19
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• 1998

We have reported previously that intact embryogenic cells can be used instead of protoplasts for electroporation-mediated transformation of zoysiagrass and rice. In this study, conditions of the tissue electroporation were examined to optimize the procedures. Embryogenic cell suspensions were established in liquid MS medium containing 2 mg/L of 2,4-D with embryogenic calluses induced from mature embryos of Z. japonica. The suspension-cultured cell clumps were electroporated with 35S-gusA expression vector DNA, and degrees of DNA introduction into the cells were determined by histological expression rates of the gusA marker gene. DNA transfer into the cell clumps occurred in wide range of voltage (100-400 V) and capacitance (10-1980 $\mu\textrm{F}$), but more in the ranges of 200-300 V and 330-800 $\mu\textrm{F}$ DNA concentrations higher than 6 $\mu\textrm{g}$/mL were adequate for GUS expression of the electroporated cells. DNA transfers were confirmed in all three embryogenic cell lines but only in one out of eleven non-embryogenic lines. Positive GUS expressions occurred with DNAs added even 20-40 h after pulse treatments. As a promoter of gusA, Act1 and Ubi1 were effective 7 and 5 times than 35S respectively in number of GUS expression units on electroporated cell clumps. Embryogenic cell clumps survived and regenerated into plantlets after pulse treatments of wide range of conditions.

• BMB Reports
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• v.42 no.7
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• pp.439-443
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• 2009

Dehydrins are group II, late embryogenesis abundant proteins that act putatively as chaperones in stressed plants. To elucidate the function of dehydrins in poplar, we isolated the $SK_2$-type dehydrin gene Podhn from Populus alba $\times$ P. tremula var. glandulosa suspension cells and analyzed its expression following treatments of abiotic stress, wounding and plant growth regulator. Sequence homology and phylogenetic analyses indicate Podhn encodes an acidic dehydrin (pI 5.14, 277 amino acids, predicted size 25.6 kDa) containing two lysine-rich "K-segments" and a 7-serine residue "S-segment", both characteristic of $SK_2$-type dehydrins. Southern blots show Podhn genes form a small gene family in poplar. Podhn was expressed in all tissues examined under unstressed conditions, but most strongly in cell suspensions (especially in the stationary phase). Drought, salt, cold and exogenous abscisic acid (ABA) treatments enhanced Podhn expression, while wounding and jasmonic acid caused its reduction. Therefore, Podhn might be involved in ABA or stress response.

• Research in Plant Disease
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• v.12 no.3
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• pp.189-196
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• 2006

Crown gall on lower stem of weeping fig(Ficus benjamina Roxb.) was first observed at Daejon in 2003. Tumors were about 15 cm in size and semi-round with rough surface texture of dark brown color. Two virulent isolates among ten bacteria isolated from the tumor tissues were characterized. Their colonies were convex, glistening, circular with an entire edge, and white or tannish cream in color on potato dextrose agar supplemented with 0.5% $CaCO_3$. They were rod shape with peritrichous flagellae, gram-negative, aerobic growth, oxidase-positive, and grew on D1M agar. The isolates were identified as Agrobacterium larrymoorei and A. tumefaciens based on biochemical and physiological characteristics, fatty acid profiles and substrate utilization patterns. Seedlings of some host plants excepting grapevine produced typical galls two to three weeks after inoculation with cell suspensions of the virulent strains. This is the first report on crown gall of weeping fig in Korea.

• The Plant Pathology Journal
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• v.34 no.6
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• pp.490-498
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• 2018

Panicle blight and seed rot disease caused mainly by Burkholderia glumae and Burkholderia gladioli is threatening rice cultivation worldwide. The bacteria have been reported as seed-borne pathogens from rice. Accurate detection of both pathogens on the seeds is very important for limiting the disease dissemination. Novel primer pairs targeting specific molecular markers were developed for the robust detection of B. glumae and B. gladioli. The designed primers were specific in detecting the target species with no apparent cross-reactions with other related Burkholderia species at the expected product size. Both primer pairs displayed a high degree of sensitivity for detection of B. glumae and B. gladioli separately in monoplex PCR or simultaneously in duplex PCR from both extracted gDNA and directly preheated bacterial cell suspensions. Limit of detection was as low as 0.1 ng of gDNA of both species and $3.86{\times}10^2cells$ for B. glumae and $5.85{\times}10^2cells$ for B. gladioli. On inoculated rice seeds, the designed primers could separately or simultaneously detect B. glumae and B. gladioli with a detection limit as low as $1.86{\times}10^3cells$ per rice seed for B. glumae and $1.04{\times}10^4cells$ per rice seed of B. gladioli. The novel primers maybe valuable as a more sensitive, specific, and robust tool for the efficient simultaneous detection of B. glumae and B. gladioli on rice seeds, which is important in combating rice panicle blight and seed rot by early detection and confirmation of the dissemination of pathogen-free rice seeds.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.3
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• pp.401-406
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• 2000

In development of the processed food, it is important not only to make the food delicious but to enhance its storage span and thermal stability without change of the food quality in color, which greatly affects the tastes of customers. Protopectinase (PPase) from Bacillus subtilis EK11 hydrolyses or dissolves protopectin in the middle lamella of plant tissues with the resultant separation of plant cells from each other, called enzymatic maceration. With the PPase, Kiwifruit was enzymatically macerated to separate cells to primary cell wall without damage. Yields of kiwifruit treated with PPase and mechanical maceration were 82% and 60%, respectively. Total and reducing sugars, crude protein and fat in the enzymatic maceration were well preserved as in the mechanical maceration. Importantly, over 95% of vitamin C, which is the most unstable component in application of the mechanical maceration, remained with intact form for one day after the enzymatic treatment. When the suspensions of kiwifruit macerated with both treatments had been stored at $4^{\circ}C for 6 days, the suspension of kiwifruit mechanically macerated was decolorized. whereas decolorization was not found in the enzymatically macerated kiwifruit. Moreover, the mechanically macerated kiwifruit was greatly deteriorated after heat treatment at $100^{\circ}C for 60 min ; the cell suspension of the exzymatically separated kiwifruit appeared to be stable, indicating the thermal stability. Thus, the PPase treatment could be a better choice for preparation of the highly valuable and functional processed food of kiwifruit as well as for prolonging the preservation period of the processed kiwifruit.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.1
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• pp.29-34
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• 2003

In development of the processed food, it is important not only to make the food delicious but to enhance its storage span and thermal stability without change in color, which greatly affects the tastes. Protopectinase (PPase) from Bacillus subtilis EK11 hydrolyses or dissolves protopectin in the middle lamella of plant tissues with the resultant separation of plant cells from each other, called enzymatic maceration. With the PPase, persimmon was enzymatically macerated to separate cells to primary cell wall without damage. Recovery rates of persimmon treated with PPase and mechanical maceration were 95% and 85%, respectively. Total and reducing sugars, crude protein and fat in the enzymatic maceration were well preserved as in the mechanical maceration. Importantly, over 50% of vitamin C, which is the most unstable component during the mechanical maceration, remained with an intact form for one day after the enzymatic treatment. When the suspensions of persimmon macerated with both treatments were stored at 4$^{\circ}C$ for 9 days, the mechanically macerated persimmon suspension was decolorized, whereas decolorization, was not found in the enzymatically macerated persimmon suspension. Moreover the mechanically macerated persimmon was greatly deteriorated after heat treatment at 10$0^{\circ}C$ for 60 min, whereas cells of the enzymatically separated persimmon suspension appeared to be stable, indicating increased thermal stability Thus, the PPase treatment of persimmon could be a better choice for preparation of highly valuable and functional processed food as well as for increase in preservation period.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.320-323
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• 2003

The effects of pH on the binding of human granulocyte-macrophage colony-stimulating factor (hGM-CSF) expressed from transgenic plant cell suspensions to cationic and anionic exchange resins were investigated. In terms of stability, the optimum pH was found to be 5-7. In the case of using buffer exchange, when CM-sepharose was used as a cationic exchange resin, the best binding pH was 4.8 (77%) and when DEAE-sepharose was used as an anionic exchange resin, the best binding pH was 5.5 (74%). Without using buffer exchange, the optimum pH was 4.6 and the adsorption yield was 84%. From these results, a possibility of overcoming the degradation and instability of secreted protein product by in firm adsorption was found.

• KSBB Journal
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• v.10 no.1
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• pp.23-29
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• 1995

Calli were induced from leaf base region of germinated rice(Oryza sativa L. cv. Nakdong) with high frequency of up to 65% on LS medium supplemented with $2.5mg/{\ell}2$, 4-D in the dark at $27^{\circ}C$. Embryogenic calli of pale yellow, globular type were selected and used for the initiation of cell suspension cultures in AA2 liquid medium with $2mg/\ell$ 2,4-D, 0.2mg/$\ell$ kinetin arid $0.1mg/\ell$ GA3. Protoplasts were isolated from the embryogenic cell suspensions after 4 months of culture and then were electroporated with 400V/cm for 1 msec. Electroporated protoplasts divided with plating efficiency of 1.1% on PCM liquid medium supplemented with $2.5mg/\ell$ 2, 4-D, $0.1mg/\ell$ kinetin and 10mM proline. The protoplasts-derived microcalli were cultured on $0.2{\mu}m$ membrane fitter placed onto LS2.5 solid medium containing fine suspension cells as a feeder cells, for 2 weeks in the dark at $27^{\circ}C$. After an additional 2 weeks of culture under fluorescent light of $30{\pm}/3{\mu}E$.m^{-2}S^{-1}, yellow calli of 2mm diameter were transferred to regeneration medium. Shoots were produced from the green spot of protoplasts-derived calli and plants were regenerated form protoplast-derived green calli with frequencies of 11∼33%.