• Korean Journal of Plant Resources
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• v.11 no.1
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• pp.93-100
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• 1998

This study was to investigate the dry weight, the amount of Na+ and K+ water potential and leaf photosynthesis rate in plants for determining the salt tolerance mechanism in rice cultivars on soil and solution culture with NaCl. The results obtained in this study are summarized as follows ; In general, rice cultivars, cv. Tetep and Jinbu, having high salt tolerance in ID(identified on dry matter production level) showed the higher salt tolerance in RGR (relative growth rate), compared with rice cultivars(cv. Nonglim 41ho, Dunraebyeo and Sobackbyeo) having low salt tolerance. The contents of Na in rice differed depending on culivars and plant parts. Tetep contained 2.9times higher amounts of Na+ than leaf blade and root part. High salt tolerance cultivar Obongbyeo showed a larger decrease in osmotic potential than low salt tolerance cultivar Dunraebyeo suggesting that osmotic adjustment was developed under salt stress conditions in a salt tolerant cultivar . In order to know the IY(identified on grain yeild level using rice cultivars having different salt tolerance the capacity of photosyntheiss was investigated. The capapcity of photosynthesis in cv. Tetep and Obongbyeo having high salt tolerance was much higher that in cv.Dunraebyeo and Nonglim 41 having low salt tolerance.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.08a
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• pp.22-27
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• 1999

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2003.10a
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• pp.179-183
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• 2003

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.662-671
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• 2015

To enrich the genetic resource of microbial xylanases with high activity and stability under alkaline conditions, a xylanase gene (xynSL4) was cloned from Planococcus sp. SL4, an alkaline xylanase-producing strain isolated from the sediment of soda lake Dabusu. Deduced XynSL4 consists of a putative signal peptide of 29 residues and a catalytic domain (30-380 residues) of glycosyl hydrolase family 10, and shares the highest identity of 77% with a hypothetical protein from Planomicrobium glaciei CHR43. Phylogenetic analysis indicated that deduced XynSL4 is closely related with thermophilic and alkaline xylanases from Geobacillus and Bacillus species. The gene xynSL4 was expressed heterologously in Escherichia coli and the recombinant enzyme showed some superior properties. Purified recombinant XynSL4 (rXynSL4) was highly active and stable over the neutral and alkaline pH range from 6 to 11, with maximum activity at pH 7 and more than 60% activity at pH 11. It had an apparent temperature optimum of 70℃ and retained stable at this temperature in the presence of substrate. rXynSL4 was highly halotolerant, retaining more than 55% activity with 0.25-3.0 M NaCl and was stable at the concentration of NaCl up to 4M. The enzyme activity was significantly enhanced by β-mercaptoethanol and Ca²⁺ but strongly inhibited by heavy-metal ions and SDS. This thermophilic and alkaline- and salt-tolerant enzyme has great potential for basic research and industrial applications.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.237-237
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• 2017

Rice is highly sensitive to salt stress especially in its early growth stage, which thus is one of the major constraints in rice production. In rice plants, salt sensitivity is associated with the accumulation of $Na^+$ in the shoots, especially in the photosynthetic tissues. High salt concentrations in soil cause high $Na^+$ and $Cl^-$ transport to the shoot and preferential accumulation of those ions in older leaves, which decreases $K^+$ in the shoot, photosynthetic activity and grain yield. Salt exclusion capacity at the leaf sheath is therefore considered to be one of the main mechanisms of salt tolerance. In addition, it is suspected that the lamina joint might be involved in the salt transport from leaf sheath to leaf blade. This research aims to determine if leaf sheaths of rice exclude a large amount of $Na^+$ only or other ions such as $K^+$, $Ca^{2+}$, $Mg^{2+}$, and $Cl^-$ as well, to identify tissues in the leaf sheath, which accumulate $Na^+$, and to examine if the lamina joint is involved in the salt exclusion by the leaf sheath. The rice seedlings of salt tolerant genotype FL478 and salt sensitive genotype IR29 were independently treated with NaCl, KCl, $MgCl_2$ and $CaCl_2$, and Taichung 65 and its near-isogenic liguleless line (T65lg) were treated with NaCl. Then, the content of $Na^+$, $K^+$, $Ca^{2+}$, $Mg^{2+}$, and $Cl^-$ ions and their specific location were determined using Atomic Absorption Spectrometer, Ion Chromatograph, and Energy Dispersive X-ray Spectroscopy. Results showed that leaf sheaths of FL478 and IR29 accumulated a large amount of $Na^+$, $K^+$, $Ca^{2+}$, $Mg^{2+}$, and $Cl^-$ ons, and thus excluded them from leaf blades when treated with high concentration of each salt. When treated with NaCl, the highest $Na^+$ concentration was found in the basal part of leaf sheaths of both cultivars. Moreover, energy-dispersive X-ray spectroscopy revealed that the central parenchyma cells of the leaf sheath were the site where most Na, Cl, and K were retained under salinity in the salt tolerant genotype FL478. Also, the concentration of $Na^+$, $K^+$ and $Cl^-$ ions in leaf sheaths and leaf blades was comparable between T65 and T65lg, indicating that the lamina joint may not be involved in the exclusion of $Na^+$, $Cl^-$ and $K^+$ by the leaf sheath from the leaf blade under salinity. Therefore, we conclude that the central parenchyma cells of basal part of leaf sheath are the site that plays a physiological role to exclude $Na^+$ in the shoots of rice without the involvement of the lamina joint.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.195-195
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• 2022

Abiotic stress is a major problem in global agriculture as it negatively affects crop growth, yield, and quality. Wheat (Triticum aestivum) is the world's second-highest-producing food resource, so the importance of mitigating damage caused by abiotic stress has been emerging. In this study, we performed GWAS to search for SNPs associated with salt tolerance and drought tolerance. NaCl (200 mM) treatment was performed at the seedling stage using 613 wheat varieties in Korean wheat core collection. Root length, root surface area, root average diameter, and root volume were measured. Drought stress was applied at the seedling stage, and the above phenotypes were measured. GW AS was performed for each phenotype data using the MLM, MLMM, and FarmCPU models. The best salt-tolerant wheat varieties were 'MK2402', 'Gyeongnam Geochang-1985-3698', and 'Milyang 13', showing superior root growth. The significant SNP AX-94704125 (BA00756838) were identified in all models. The genes closely located to the significant SNP were searched within ± 250 kb of the corresponding SNP. A total of 11 genes were identified within the region. NB-ARC involved in the defense response, FKSI involved in cell wall biosynthesis, and putative BP Ml involved in abiotic stress responses were discovered in the 11 genes. The best drought-tolerant wheat varieties were 'PI 534284', 'Moro of Sind', and 'CM92354-33M-0Y-0M-6Y-0B-0BGD', showing superior root growth. This study discovered SNPs associated with salt tolerance in Korean wheat core collection through GWAS. GWAS of drought tolerance is now proceeding, and the GWAS results will be represented on a poster. The SNPs identified by GWAS can be useful for studying molecular mechanisms of salt tolerance and drought tolerance in wheat.

• Current Research on Agriculture and Life Sciences
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• v.21
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• pp.1-9
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• 2003

Plants are often subjected to periods of soil and atmospheric water deficit during their life cycle. To find critical levels for identification of tolerant rice variety to salt- and drought-stresses, we investigated the water deficiency in the leaf of a Dongjinbyeo (DJ) cultivar, identified as intolerant variety, subjected to NaCl- and Polyethylene glycol 6000 (PEG)- treatments. The relative water content and water potential in leaf of DJ plant sharply declined along the high concentration and time after treatment in NaCl- and PEG-treated rice plants. To elucidate the method of simple screening of tolerant variety to salt- and drought-stresses, we examined the relationship between relative water content and water potential of leaves in NaCl- and PEG-treated rice plants. The relationship between relative water content and water potential in leaf of DJ plant showed the highest correlation in 80 mM NaCl-treatment, and showed high correlation only 8% PEG treatment. These results indicate that the critical level of salt stress for screening of tolerant rice was 80 mM NaCl at 48 h after NaCl treatment, and the critical concentration of drought stress for screening of tolerant rice was 8% PEG at 96 h after PEG treatment.

• Korean Journal of Medicinal Crop Science
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• v.11 no.2
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• pp.161-166
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• 2003

Korean ginseng(Panax gmseng C.A. Meyer) is very difficult to obtain stable production of qualified ginseng roots because of variable stresses in soil environments. In environment stresses, soil condition is the most important factor, among which nutrients, especially inorganic materials such as N, P, K, Ca, Mg, Fe, etc., influence greatly on the ginseng growth. However, present ginseng field soils in Korea contain so much amount of such inorganic materials that a variety of remarkable disorders were noted in many ginseng plantations, resulting in decrease of qualitative ginseng production. Therefore, it is required to search for genetic resources and genes tolerant to salt stress for the development of ginseng cultivars. Selection of stress-tolerant ginseng lines in fields is very difficult because it is almost impossible to control properly the environmental conditions of soil. On the contrary, it can be studied with ease to search for stress-tolerant ginseng lines through in vitro culture because of easy manipulation of stress conditions. Murashige & Skoog(MS) media with 2.5 folds of $KNO_3,\;NH_4NO_3,\;MgSO_4\;7H_2O,\;KH_2PO_4,\;and\;CaCl_2\;2H_2O$ was established for the selection of ginseng lines tolerant to salt stress under the embryo culture.

• Journal of Plant Biotechnology
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• v.5 no.3
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• pp.173-179
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• 2003

The combination of a radiation technique with an in vitro culture system was appiled to develop submergence tolerant rice. The 3,000 $M_3$ lines with an average 80 percent of fertile grain were utilized for the selection of submergence tolerance. Salt tolerant lines were selected based on high plant height, root length and root number after submergence in plastic pots. Of the lines tested, the tolerant line (403-6) showed a dramatic difference in morphological traits under submergence compared to its original variety (Dongjinbyeo). It was suggested that genetic variations between the original variety and $M_3$-403-6 did exist. The levels of $\alpha$-amylase and alcohol dehydrogenase activities were significantly increased in the mutant line compared to its original variety. The mutant with greater tolerance showed less electrolyte leakage indicating a greater membrane integrity and better survival. Also, this line was much more resistant to a salt stress of $1.25\%$ than the original variety. The proline level of the line was significantly (p<0.01> higher than that of the original variety. The relationships between the inhibition of growth caused by stress and the physiological changes in the plant cell were discussed.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.238-238
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• 2017

Salt stress is one of the deteriorating abiotic stresses due to the climate change, which causes over-accumulation of $Na^+$ and $Cl^-$ ions in plants and inhibits the growth and yield of rice especially in coastal Southeastern Asia. The yield components of rice plant (panicle number, spikelet number per panicle, 1000-grain weight, % of ripened grains) that are majorly affected by salt stress vary with growth stages at which the plant is subjected to the stress. In addition, the salt sensitivity of each yield component differs among rice varieties even when the salt-affected growth stage was same, which indicates that the physiological mechanism to maintain each yield component is different from each other. Therefore, we hypothesized that rice plant has different genes/QTLs that contribute to the maintenance of each yield component. Using a Japanese leading rice cultivar, Koshihikari, and salt-tolerant Nona bokra's chromosome segment substitution lines (CSSLs) with the genetic background of Koshihikari (44 lines in total) (Takai et al. 2007), we screened higher yielding CSSLs under salinity in comparison to Koshihikari and identified the yield components that were improved by the introgression of chromosome segment(s) of Nona bokra. The experiment was conducted in a salinized paddy field. One-month-old seedlings were transplanted into a paddy field without salinity. These were allowed to establish for one month, and then the field was salinized by introducing saline water to maintain the surface water at 0.4% salinity until harvest. The experiments were done twice in 2015 and 2016. Although all the CSSLs and Koshihikari decreased their yield under salinity, some CSSLs showed relatively higher yield compared with Koshihikari. In Koshihikari, all the yield components except panicle number were decreased by salinity and % of ripened grains was mostly reduced, followed by spikelet number per panicle and 1000-grain weight. When compared with Koshihikari, keeping a higher % of ripened grains under salinity attributed to the significantly greater yield in one CSSL. This indicated that the % of ripened grains is the most sensitive to salt stress among the yield components of Koshihikari and that the Nona bokra chromosome segments that maintained it contributed to increased yield under salt stress. In addition, growth analyses showed that maintaining relative growth rate in the late grain filling stage led to the increased yield under salt stress but not in earlier stages.