• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2002.04a
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• pp.41-47
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• 2002

Adverse environmental conditions such as drought, high salt and cold/freezing are major factors that reduces crop productivity worldwide. According to a survey, $50-80\%$ of the maximum potential yield is lost by these 'environmental or abiotic stresses', which is approximately ten times higher than the loss by biotic stresses. Thus, Improving stress-tolerance of crop plants is an important way to improve agricultural productivity. In order to develop such stress-tolerant crop plants, we set out to identify key stress signaling components that can be used to develop commercially viable crop varieties with enhanced stress tolerance. Our primary focus so far has been on the identification of transcription factors that regulate stress responsive gene expression, especially those involved in ABA-mediated stress response. Be sessile, plants have the unique capability to adapt themselves to the abiotic stresses. This adaptive capability is largely dependent on the plant hormone abscisic acid (ABA), whose level increases under various stress conditions, triggering adaptive response. Central to the response is ABA-regulated gene expression, which ultimately leads to physiological changes at the whole plant level. Thus, once identified, it would be possible to enhance stress tolerance of crop plants by manipulating the expression of the factors that mediate ABA-dependent stress response. Here, we present our work on the isolation and functional characterization of the transcription factors.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2002.04b
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• pp.41-47
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• 2002

Adverse environmental conditions such as drought, high salt and cold/freezing are major factors that reduces crop productivity worldwide. According to a survey, 50-80% of the maximum potential yield is lost by these 'environmental or abiotic stresses', which is approximately ten times higher than the loss by biotic stresses. Thus, improving stress-tolerance of crop plants is an important way to improve agricultural productivity. In order to develop such stress-tolerant crop plants, we set out to identify key stress signaling components that can be used to develop commercially viable crop varieties with enhanced stress tolerance. Our primary focus so far has been on the identification of transcription factors that regulate stress responsive gene expression, especially those involved in ABA-mediated stress response. Be sessile, plants have the unique capability to adapt themselves to the abiotic stresses. This adaptive capability is largely dependent on the plant hormone abscisic acid (ABA), whose level increases under various stress conditions, triggering adaptive response. Central to the response is ABA-regulated gene expression, which ultimately leads to physiological changes at the whole plant level. Thus, once identified, it would be possible to enhance stress tolerance of crop plants by manipulating the expression of the factors that mediate ABA-dependent stress response. Here, we present our work on the isolation and functional characterization of the transcription factors.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.170-179
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• 2022

Glutamic acid is a precursor of essential amino acids that play an important role in plant growth and development. It is one of the biostimulants that reduce cold stress damage by stimulating biosynthetic pathways leading to cryoprotectants. This study evaluated the effects of glutamic acid foliar application on Kimchi cabbage under low-temperature stress. There were six treatments, combining three photo-/dark periods temperature levels (11/-1℃ extremely low, E; 16/4℃ moderately low, M; and 21/9℃ optimal, O) with and without glutamic acid foliar application (0 and 10 mg·L^-1; Glu 0 and Glu 10). Glutamic acid foliar application was sprayed once 10 days after transplanting, and then temperature treatment immediately after glutamic acid foliar application was conducted for up to four days. After four days of treatment, abscisic acid (ABA), phaseic acid (PA), dihydrophaseic acid (DPA), and abscisic acid-glucose ester (ABA-GE) contents were higher with Glu 10 treatment than Glu 0 treatment in M treatment. Glucose content was highest in E with Glu 10 treatment (52.1 mg·100 g^-1 dry weight), while fructose content was highest in O with Glu 0 treatment (134.6 mg·100 g^-1 dry weight). The contents of glucolepiddin (GLP), glucobrassicin (GBS), 4-methoxyglucobrassicin (4MGBS), neoglucobrassicin (GNBS), and gluconasturtiin (GNS) were highest among all treatments in E with Glu 10 treatments (0.72, 2.05, 1.67, 9.40 and 0.85 µmol·g^-1 dry weight). After two days of treatment, rapid changes in PA and DPA contents of E with Glu 10 treatments were confirmed, and several individual glucosinolate contents (GLP, GBS, 4MGBS, GNBS, and GNS) were significantly different depending on low temperature and glutamic acid treatment. In addition, the content of fructose was significantly lower than that of O treatment in E and M treatments after four days of treatment. Therefore, although the changes in PA, DPA, glucose, fructose, and individual glucosinolates according to low temperature and glutamic acid foliar treatment were shown. A clear correlation between low temperature and glutamic acid effects could not be evaluated. Results indicated that Brassica crops are cryophilic vegetables, do not react sensitively to low temperatures, and mostly have cold resistance.

• Journal of Environmental Science International
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• v.4 no.4
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• pp.15-15
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• 1995

ABA and SA showed different effect on stomatal closing on same condition. The addition of 1 M salicylic acid to fully opened stomata resulted in a significant reductionn of 22 % in stomatal aperture. However, 1 mM ABA reduced 73 % of stomatal aperture. The light absorption spectra of the salicylic acid solution showed that SA was degraded within 1 hour. Therefore, SA solution was resupplied % the detached epidermis every 30 min. during incubation and it was found that even at 10 $mu$M SA induced stomatal closing significantly. Its effect was also greatly pH dependent. The reduction of stomatal aperture caused by 1 mM SA was most effective at lower pH (pH 7.2, 5 %: pH 6.2, 40 %; pH 5.2, 78 %). Therefore, if SA was properly treated to the epidermal strips in the medium, the effects of SA on stomatal closing were similar with those of ABA.

• Journal of Environmental Science International
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• v.4 no.4
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• pp.317-321
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• 1995

ABA and SA showed different effect on stomatal closing on same condition. The addition of 1 M salicylic acid to fully opened stomata resulted in a significant reductionn of 22 % in stomatal aperture. However, 1 mM ABA reduced 73 % of stomatal aperture. The light absorption spectra of the salicylic acid solution showed that SA was degraded within 1 hour. Therefore, SA solution was resupplied % the detached epidermis every 30 min. during incubation and it was found that even at 10 $\mu$M SA induced stomatal closing significantly. Its effect was also greatly pH dependent. The reduction of stomatal aperture caused by 1 mM SA was most effective at lower pH (pH 7.2, 5 %: pH 6.2, 40 %; pH 5.2, 78 %). Therefore, if SA was properly treated to the epidermal strips in the medium, the effects of SA on stomatal closing were similar with those of ABA.

• Journal of Plant Biotechnology
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• v.45 no.2
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• pp.83-89
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• 2018

The interplay of plant hormones is one of the essential mechanisms for plant growth and development. A recent study reported that Brassinosteroids (BR) and ABSCISIC ACID (ABA) interact antagonistically in early seedling developments through the BR-mediated epigenetic repression of ABSCISIC ACID-INSENSITIVE 3 (ABI3). However, the other physiological roles of the BR-mediated regulation of ABI3 and ABA responses beyond early seedling developments remain largely unknown. Here, we showed that the activation of BR signaling by high temperatures promotes flowering time through the suppression of ABI3 expressions. Elevated ambient temperature induced early flowering in wild type Col-0 plants, but not in BR-defective bri1-116 mutant plants. Conversely, a hyper BR biosynthetic dwf4-D mutant displayed more sensitive thermomorphic long shoot elongation and early flowering. Both expression patterns and physiological responses supported the biological roles of ABI3 in the regulation of floral transition and reproduction under high temperature conditions. Finally, we confirmed that the lowered expressions of the transcript and protein levels of ABI3 brought on by elevated temperature were correlated with warmth-induced early flowering phenotypes. In conclusion, our data suggest that the BR- and warmth-mediated regulation of ABI3 are important in thermomorphic reproductive phase transitions in plants.

• Journal of Microbiology and Biotechnology
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• v.33 no.3
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• pp.378-386
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• 2023

The CYP707A family genes encoding ABA 8'-hydroxylase catabolize abscisic acid (ABA), a plant stress hormone that plays an important role in stress condition, such as drought, heat, cold and salinity. Phaseic acid (PA) is a catabolic product of ABA. Recent studies have shown that PA is important for the physiological functions in plants. It is also a neuroprotective molecule that protects against ischemic brain injury in mice. To obtain enzymes for the PA production, four CaCYP707A genes (CaCYP707A1, CaCYP707A2, CaCYP707A3 and CaCYP707A4) were isolated from hot pepper. They were heterologously expressed in Escherichia coli. Among them, CaCYP707A2 showed significantly higher expression levels in both the membrane fraction and the soluble fraction. Preferred redox partners were investigated to improve the efficiency of CaCYP707A2's catalytic reaction, and NADPH-cytochrome P450 reductase (CPR) from hot pepper (CaCPR) was preferred over other redox partners (i.e., rat CPR and ferredoxin reductase/ferredoxin). The production of 8'-hydroxy ABA and PA by ABA hydroxylation activity was confirmed in CaCYP707A2 from both membrane and soluble fractions. Therefore, CaCYP707A2 is the first identified plant CYP protein that is expressed a soluble form in cytosolic fraction having stable activity. Taken together, we propose a new CYP707A protein with industrial applications for PA production without additional modifications in E. coli heterologous expression.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.1
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• pp.25-34
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• 2018

This study was conducted to investigate the germination and proteome profile characteristics of wheat seeds treated under various concentrations of abscisic acid (ABA). After-ripening, the seeds of three wheat cultivars (Baegjoong, Keumkang, and Uri) showing different levels of dormancy were used. Germination index and germination rate of the cultivars was higher than 0.95% and 98%, respectively, and these were not significantly different under 0, 10, 30, and $50{\mu}M$ ABA at 7 d after germination. However, the growth of the shoot and radicle was significantly inhibited at 10, 30, and $50{\mu}M$ ABA compared to that at $0{\mu}M$ ABA. Mean ABA content of the embryos of seeds germinated at 0 and $50{\mu}M$ ABA for 7 d was 0.8 and $269.0ngmg^{-1}DW$, respectively. Proteins extracted from embryos germinated for 4 d were analyzed by two-dimensional gel electrophoresis, and proteins showing a difference of 1.5-fold or greater in their spot volume relative to that of $0{\mu}M$ ABA were identified. The expression of four protein spots increased at $50{\mu}M$ ABA and two protein spots were detected only at $50{\mu}M$ ABA; these six proteins were all identified as globulin types. Conversely, the expression of three protein spots decreased at $50{\mu}M$ ABA and were identified as cytosolic glutamine sysnthetase, isocitrate dehydrogenase, and S-adenosylmethionine synthetase 2. In conclusion, ABA did not inhibit the germination rate regardless of pre-harvest sprouting characteristics of the cultivars. However, the growth of the shoot and radicle was significantly inhibited by ABA, most likely through the down regulation of glutamine, methyl group donor, and polyamines biosynthesis, among others, while accompanied by globulin accumulation in the embryos.

• Journal of Life Science
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• v.34 no.6
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• pp.426-433
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• 2024

The environmental stress that plants are most susceptible to is water stress. Abscisic acid (ABA) is a plant hormone synthesized by plants to counteract environmental stress. The role of stomata in plants is to allow the synthesis of sucrose by absorbing CO₂, which greatly affects photosynthetic activity. In addition, stomata are pathways for transpiration, which releases H₂O and help establish a water potential gradient that allows plant roots to continuously absorb water and inorganic substances from the soil. Plants have a mechanism to minimize water loss by closing their stomata when exposed to water-stressed environments. The most well-studied hypothesis concerning the mechanism of stomatal closure is the response to water stress. When a plant receives sufficient water, its stomata open during the day and close at night due to its circadian rhythm. In addition, stomatal closure occurs when the concentration of CO₂ in the intercellular space increases. However, the mechanism of stomatal closure due to circadian rhythm and increased CO₂ concentration in the intercellular space is not well understood. When plants undergo water stress, the increased concentration of ABA in the guard cell cytoplasm induces an increase in Ca²⁺ concentration, resulting in cytoplasmic depolarization. As a result, the outward K⁺-channel of the tonoplast and the slow-type anion channels SLAC1 and SLAH3 are activated, releasing K⁺, Cl^-, and malate^2-, causing the stomata to close. Therefore, in this paper, the mechanism of stomatal closure caused by water stress was investigated.

• Korean Journal of Medicinal Crop Science
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• v.12 no.6
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• pp.508-514
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• 2004

Chrysanthemum boreale M. is an important medicinal plant that has been historically used in herbal medicine and in the health food throughout East Asia. This study was conducted to investigate the influence of abscisic acid (ABA) and salicylic acid (SA) on plant growth, mineral content and effective components, such as essential oil, amino acid and cumambrin A, by means in order to increase the productivity and the quality of flowerheads in the plant. Yields of flowerheads were increased by 12.7%, 21.7% and 15.5% by ABA, SA and both treatments, respectively, as compared with the control. Inorganic nutrient content was changed by PGRs; SA treatment was increased by nitrogen, phosphorus and magnesium content but decreased by potassium of C. boreale M. flowerheads. Total content of amino acid was increased by SA but decreased by ABA treatment. Essential oil content and yields were increased to 9.7% and 33.8% by SA treatment. Moreover, the content of terpene, monoterpenoids and sesquiterpenoids, were improved by ABA treatment, especially, germacrene-D content was increased by 39.1%, as compared to control. In addition, yields of cumambrin A, sesquiterpene compound exhibiting blood-pressure activity, increased in all PGRs treatments, but its concentration in the C. boreale M. flowerheads only increased by ABA and both treatment. The experiment suggests that PGRs using ABA and SA could increase the yields and quality of C. boreale M. flowerheads.