• Research in Plant Disease
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• v.19 no.4
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• pp.288-293
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• 2013

In worldwide, viral diseases of apple plants has caused the serious problems like reduced production and malformation of fruits. Also, the damages of apple plants by virus and/or viroid infection (Apple chlorotic leaf spot virus, Apple stem grooving virus, Apple mosaic virus, and Apple scar skin viroid) were reported in Korea. However there is few report about the protection approach against the infection by apple viruses. Therefore, this paper introduced the experimental protocol for the development of virus-free apple cultivars (Danhong, Hongan, Saenara, Summerdream). Apple plants were treated at $37^{\circ}C$ for 4 weeks and shoot tips were cultured in vitro. After heat treatment, the detection of apple viruses was performed by RT-PCR using virusspecific detection primers in new apple cultivars. With the heat treatments followed by in vitro shoot tip culture, the proportion of virus-free stocks of 'Danhong', 'Hongan', 'Saenara', and 'Summerdream' was 28%, 16%, 12%, and 12%, respectively. Taken together, this approach can be a good tool for production of virus-free apple stocks.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.365-372
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• 2020

This study was conducted to compare the effects of foliar spray and sub-irrigation of the triazole fungicide diniconazole on the regulation of stem elongation and to investigate the stimulation of root system development during the seedling stage. Comparing the two application approaches, there were significant differences in the leaf area, leaf area ratio (LAR), plant height, compactness, fresh shoot and root production, relative growth rate (RGR), and root to shoot ratio (R/S). At the same application concentration, the sub-irrigation showed a better retarding effect on growth than the foliar spray, because the PGR activity of diniconazole in root absorption was higher than that in shoot absorption. For reaching a target of 20% to 30% inhibition rate of stem length, foliar application concentration of diniconazole exceeded 10, however, only approximately 1 was required in the sub-irrigation application. The root system of tomato seedlings responded strongly to diniconazole application. Total root length, root volume, root average diameter, and the number of root tips increased when diniconazole was sub-irrigation application at 1. A reduction in fine roots (diameter range of 0 to 0.3 mm) and an increase in the roots with a diameter range of 0.3 to 0.6 mm was observed, and this may contribute to the increase in average diameter. The increase in root average diameter may be positive because root penetration increases with root diameter. Our results suggested that sub-irrigation maximized the PGR activity of diniconazole to enhance the retarding effect. And it also possible to enhance the tomato seedling root system by diniconazole stimulating with a lower concentration.

• Journal of Korean Society of Forest Science
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• v.84 no.1
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• pp.41-47
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• 1995

A micropropagation system for black Locust(Robinia pseudoacacia) was established by using shoots and pin-punctured leaves of in vitro germinated seedlings. The greatest number of shoots (an average of 10.5 shoots) was obtained when shoot tips were cultured on MS medium supplemented with 1.0 mg/l BAP and 0.01 mg/l NAA. When pin-punctured leaf explants were cultured on the same medium, mean number of 13.5 shoots were produced. Shoot growth was accelerated by adding 50 mg/l of silver nitrate ($AgNO_3$), an anti-ethylene compound to the culture medium. Each shoot was excised from the mass and transferred onto half strength MS medium for rooting. Zygotic embryos at different developmental stages were cultured on LS medium supplemented with various growth regulators to induce somatic embryos. When cultured on LS medium with 1.0 mg/l 2,4-D. 14.3% of the zygotic embryos induced somatic embryos. Upon transfer onto the basal medium, somatic embryos sporadically converted into plantlets.

• Journal of Plant Biotechnology
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• v.42 no.1
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• pp.49-54
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• 2015

Based on the results in this study, here we propose a systematic micropropagation process for 'Gisela 5' that is one of the important dwarfing cherry rootstocks. When the apical tips detached from newly developed shoot in spring season were cultured on the half strength MS media with 0.5 mg/L IBA and 0.5 ~ 1.0 mg/L BA, the cultures scored the highest acquisition rate at 90% for normal shoot with vigorous growth and without hyperhydricity. As next step, the young shoots maintained in vitro well multiplied on the full strength MS medium supplemented with 0.5 mg/L IBA and 0.5 mg/L BA, in which multiplication rate was approximately nine-fold. Given the half strength MS medium containing 2.0 mg/L IBA, each transplanted shoot further developed robust roots. Finally, the plantlets were easily acclimatized in the compost consisted of vermiculite, perlite, and peatmoss in the proportion of 1:1:1. We expect that the results are useful for cherry cultivation and its rootstock production.

• Korean Journal of Plant Tissue Culture
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• v.27 no.3
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• pp.213-217
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• 2000

To investigate the cucumber regeneration from embryogenic calli, shoot tips of aseptically-grown cucumber seedlings were used as explants for establishing tissue cultures. Growth and differentiation of callus were studied by using Murashige and Skoog's (MS) medium containing 0.5 to 2 mg/L 2,4-D. Plantlets were induced from shoot tip culture on the plant growth regulators-free MS medium. Non-embryogenic calli and viscous calli were induced on the medium supplemented with 0.5 to 2 mg/L 2,4-D, but embryogenic callus was not induced on the same medium. Segments (ca. 5∼10 mm) of aseptically-grown hypocotyl from five to seven days old seedlings after germination were placed on MS medium supplemented with 1 mg/L 2,4-D for 50 days. Embryogenic calli and embryoids were induced only from the seedlings grown in dark condition, and hypocotyl was placed on the media explanted in light condition. Foully-five point one percent of white fragile calli and 0.6% yellowish compact calli formed roots. Yellowish callus lines were investigated to have a considerably higher concentration of crude proteins than white callus lines. Plantlets derived from embryogenic calli or embryoids have been transferred to pots containing sterile vermiculite and perlite. Normal fruits were harvested from nutrient culture on aggregated hydroponics in the F-clean house.

• Journal of Plant Biotechnology
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• v.43 no.3
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• pp.391-396
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• 2016

In this study, in vitro-cultured 'Mansoo' pear (Pyrus pyrifolia L.) plants infected with Apple stem grooving virus (ASGV) were used for testing the efficiency of the virus elimination methods. The shoot tips cut from infected plants were treated by thermotherapy ($37^{\circ}C$), cold therapy ($4^{\circ}C$), chemotherapy with ribavirin, and combination of these methods. Treatment periods were 2, 4, and 8 weeks, and concentrations of ribavirin were 20 and $40mg{\cdot}L^{-1}$. The efficiency of ASGV elimination was evaluated by reverse transcription polymerase chain reaction. The shoot survival rate was the highest at 100% after cold therapy, chemotherapy, and combination of two methods, while the rate was the lowest at 33.3% after thermotherapy for 2 weeks. The shoot survival rate after chemotherapy decreased gradually as the treatment period was prolonged. The ASGV elimination rate was the highest at 100% after ribavirin treatment at a concentration of $40mg{\cdot}L^{-1}$ and combination of ribavirin treatment and thermotherapy for 2 weeks, whereas the ASGV elimination rate after cold therapy was the lowest at 16.7%. However, the efficiency of ASGV elimination was enhanced up to 43.3% by the combination of cold therapy and ribavirin treatment. The efficiency of ASGV elimination for all treatments was increased as the treatment period was prolonged. Based on these results, we suggest that ribavirin treatment at a concentration of $20mg{\cdot}L^{-1}$ for 4 weeks or at a concentration of $40mg{\cdot}L^{-1}$ for 2 weeks combined with shoot tip culture was efficient for the elimination of ASGV from pear.

• Korean Journal of Plant Resources
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• v.32 no.1
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• pp.53-62
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• 2019

The purpose of this study was to establish the in vitro propagation system by shoot tip culture of six Hosta species native to Korea (Hosta capitata (Koidz.) Nakai, H. clausa Nakai, H. jonesii M.G.Chung, H. minor (Baker) Nakai, H. venusta F.Maek., and H. yingeri S.B.Jones) for mass proliferation and a new cultivar development. The shoot tips of each Hosta species were cultured on MS medium containing eight combinations of 0.5, 1.0, 2.0, 4.0 mg/L BA with 0.1 mg/L NAA, 0.1, 0.5, 1.0, 2.0 mg/L TDZ with 0.1 mg/L NAA, and without any PGRs (control). They were investigated on callus, somatic embryo, crown bud, differentiation and growth of shoot and root, total fresh weight after 8 weeks of culture. In all six Hosta species, callus and somatic embryo induction rate and multiple shooting rate of the PGRs treatment group were higher than that of the control group. The highest number of differentiated shoots were obtained on medium supplemented with 2.0 ㎎/L TDZ in H. capitata (5.4), 1.0 mg/L TDZ in H. clausa and H. jonesii (3.3 and 5.8, respectively), 0.5 mg/L BA in H. minor (11.1), 1.0 mg/L BA and 0.1 mg/L TDZ in H. venusta (8.1), and 0.5 mg/L TDZ in H. yingeri (9.8). In somatic embryo formation, the PGRs treatment group of H. jonesii and H. yingeri were more effective than the control group, and the effects were relatively less in H. capitata, H. clausa Nakai, H. minor, H. venusta. Crown bud formation of four Hosta species (H.capitata, H. clausa, H. jonesiig, and H. yingeri) were also higher in the PGRs treatment group than in the control group. Crown bud formation of four Hosta species (H.capitata, H. clausa, H. jonesiig, and H. yingeri) were also higher in the PGRs treatment group than in the control group. H. clausa showed no significant effect on callus and shoot differentiation regardless of the type and concentration of cytokinin, but slightly increased in formation of crown bud in TDZ.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.304-304
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• 2017

In semi-arid countries such as Namibia, the flooding unexpectedly happens in a rainy season, causing losses in the yield of upland-adapted cereal crop. In flooding conditions, rice roots sequentially form aerenchyma and a barrier to radial oxygen loss (ROL), and oxygen is released into the rhizosphere near the root tips. Iijima et al. (2016) and Awala et al. (2016) reported that close mixed-planting with rice can mitigate the flood stress of co-growing upland-adapted cereal crop by modifying their rhizosphere microenvironments via the oxygen released from the rice roots. Moreover, by using the model system of hydroponic culture, it was confirmed that oxygen from rice roots was transferred to co-growing upland-adapted cereal crop in close mixed planting system (Kawato et al., 2016). However, it is not sure whether the ability of oxygen release varies among rice cultivars, because Kawato et al. (2016) used only one japonica cultivar, Nipponbare (Oryza sativa). The objective of this study was to compare the ability of oxygen release in rhizosphere among rice cultivars. The experiment was conducted in a climate chamber in Kindai University. We used 10 rice cultivars from three different rice species (O. sativa (var. japonica (2), var. indica (3)), Oryza glaberrima Steud. (2) and their interspecific progenies (3)) to compare the ability of oxygen release from the roots. According to the method by Kawato et al. (2016), the dissolved oxygen concentration of phase I (with shoot) and phase II (without shoot) were measured by a fiber optic oxygen-sensing probe. The oxygen released from rice roots was calculated from the difference of the measurements between phase I and phase II. The result in this study indicated that all of the rice cultivars released oxygen from their roots, and the amount of released oxygen was significantly correlated with the above-ground biomass (r = 0.710). The ability of oxygen release (the amount of the oxygen release per fresh root weight) of indica cultivars (O. sativa) tended to be higher as compared with the other cultivars. On the other hand, that of African rice (O. glaberrima) and the interspecific progenies tended to be lower. These results suggested that the ability of oxygen release widely varies among rice cultivars, and some of indica cultivars (O. sativa) may be suitable for close mixed-planting to mitigate flood stress of upland-adapted cereal crop.

• Korean Journal of Environmental Agriculture
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• v.6 no.1
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• pp.7-16
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• 1987

A study was undertaken to investigate the absorption, translocation and metabolism of carbofuran in rice paddies. Ring-3-$^{14}C-carbofuran$ applied onto the paddy soil surface was rapidly absorbed and translocated into rice plants. Within 2 days after treatment, it was observed that carbofuran reached shoot tips and accumulated. More than 15% of total radioactivity was recovered in rice plant from 3 to 20 days after treatment. In organic soluble fraction of rice plant extract, 3-hydroxycarbofuran was the major metabolite recording 43% and 4% of total organic soluble radioactivity in shoot and root at 20 days respectively. 3-Ketocarbofuran and phenolic metabolites including carbofuran phenol, 3-hydroxycarbofuran phenol and 3-ketocarbofuran phenol were also detected in the organic soluble fractions. Some glycosidic conjugates of carbofuran metabolites were found in water soluble fraction of rice plant extract and 3-hydroxycarbofuran was the most abundant aglycone. Radioactivity in paddy soil was rapidly decreased until 3 days after treatment and then maintained almost constant level. A significant portion (42∼56 %) of the total radioactivity remained in soil as nonextractable residue from 5 to 20 days after treatment. The nonextractable radioactivity was mainly located in soil organic matter distributing in humin, fulvic acid and humic acid fractions with the decreasing order. Evolution of $^{14}CO_2$ from ring cleavage of $3-^{14}C-carbofuran$ was negligible recording only 1.8% of total radioactivity during 20 days after treatment.

• Journal of Plant Biotechnology
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• v.2 no.3
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• pp.123-128
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• 2000

To enhance in vitro plantlet regeneration efficiency of soybean through embryogenesis, the culture conditions such as material part and size of immature seed, 2,4-D, pH and solidifying agents for somatic embryogenesis were investigated. Somatic embryogenesis was induced from the immature embryo, immature cotyledon and embryonic axis explants of the immature seed on MS medium supplemented with 2.0 mg/L 2,4-D. The highest rate (up to 22.9%) of somatic embryogenesis was obtained from the immature cotyledon, following embryonic axis and the immature embryo. The rate varied with the developmental stages of seed. The maximum rate (25.4%) of embryogenesis was obtained from 3-4 mm length of the seed (after 25 days of flowering). The optimum concentration of 2,4-D for embryogenesis was 10 mg/L. The optimum pH was at 5.8 and solidifying agent for medium was better with 0.4% gelrite than with agar. For rapid multiplication of shoot tips from the germinating somatic embryos, they were cultured on MS medium containing 2 mg/L indole-3-butyyic acid (IBA) and 1 mg/L 6-benzyladenine (BA). After then somatic embryos with one and three cotyledons were transferred to the growth regulator free medium. The medium exhibited the higher rate (ca. 50%) of development than the multiplication medium.