• Plant Biotechnology Reports
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• v.4 no.3
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• pp.213-222
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• 2010

Within their natural habitat, crops are often subjected to drought and heat stress, which suppress crop growth and decrease crop production. Causing overaccumulation of glycinebetaine (GB) has been used to enhance the crop yield under stress. Here, we investigated the response of wheat (Triticum aestivum L.) photosynthesis to drought, heat stress and their combination with a transgenic wheat line (T6) overaccumulating GB and its wild-type (WT) Shi4185. Drought stress (DS) was imposed by controlling irrigation until the relative water content (RWC) of the flag leaves decreased to between 78 and 82%. Heat stress (HS) was applied by exposing wheat plants to $40^{\circ}C$ for 4 h. A combination of drought and heat stress was applied by subjecting the drought-stressed plants to a heat stress as above. The results indicated that all stresses decreased photosynthesis, but the combination of drought and heat stress exacerbated the negative effects on photosynthesis more than exposure to drought or heat stress alone. Drought stress decreased the transpiration rate (Tr), stomatal conductance (Gs) and intercellular $CO_2$ concentration (Ci), while heat stress increased all of these; the deprivation of water was greater under drought stress than heat stress, but heat stress decreased the antioxidant enzyme activity to a greater extent. Overaccumulated GB could alleviate the decrease of photosynthesis caused by all stresses tested. These suggest that GB induces an increase of osmotic adjustments for drought tolerance, while its improvement of the antioxidative defense system including antioxidative enzymes and antioxidants may be more important for heat tolerance.

• Journal of Environmental Science International
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• v.11 no.11
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• pp.1165-1172
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• 2002

The effects of salicylic acid(SA) and water deficit on growth and proline accumulation were investigated in cucumber(Cucurmis sativus L.) seedlings. Exogenous application of SA(100 $\mu$M-1 mM) led to a noticeable decrease in root and shoot growth, and dry weight of seedlings. Anatomical observation on leaf of cucumber revealed that the thickness of all leaf tissue components decreased in SA-treated plants. The effect was most pronounced on the width of the adaxial epidermis. In the separate effects of SA(0, 100, 500 and 1000 $\mu$M) and water deficit induced by PEG(0, 4.4, 7.0 and 9.6 %) on growth, the water deficit treatments had greater effects on growth traits than SA. Combinations of SA and PEG(SA+PEG) decreased shoot and root dry matter, and root length. Proline increased slightly in SA-treated seedlings, but exhibited a marked increase in water deficit application. Combinations of SA+PEG induced higher proline in both shoots and roots than SA stress alone. Shoots had higher proline than roots. Our data support a role of SA potentiating the osmotic stress response of germinating cucumber seedling.

• Journal of Aquaculture
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• v.20 no.4
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• pp.205-211
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• 2007

Stress-inducible proteins may function in part as molecular chaperones, protecting cells from damage due to various stresses and helping to maintain homeostasis. We examined the mRNA expression patterns of a 68-kDa heat shock protein (HSP68) and 78-kDa glucose-regulated protein (GRP78) in relation to physiological changes in Pacific oyster Crassostrea gigas under osmotic stress. Expression of HSP68 and GRP78 mRNA in the gill significantly increased until 48 h in a hypersaline environment (HRE) and 72 h in a hyposaline environment (HOE), and then decreased. Osmolality and the concentrations of $Na^+$, $Cl^-$, and $Ca^{2+}$ in the hemolymph of HRE oysters significantly increased until 72 h (the highest value) and then gradually decreased; in HOE oysters, these values significantly decreased until 72 h (the lowest value), and then increased. These results suggest that osmolality and $Na^+$, $Cl^-$, and $Ca^{2+}$ concentrations were stabilized by HSP68 and GRP78, and indicate that these two stress-induced proteins play an important role in regulating the metabolism and protecting the cells of the Pacific oysters exposed to salinity changes.

• Journal of Plant Biotechnology
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• v.39 no.3
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• pp.175-181
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• 2012

Drought and high salinity stresses often imposes adverse effects on crop yield. MYB transcription factors have been shown to be an important regulator in defense responses to these environmental stresses. In this study, we have cloned and characterized a soybean gene GmMYB184 (Glycine max MYB transcription factor 184). Deduced amino acid sequences of GmMYB184 show highest homology with that from Vitis vinifera legume plant (75%). Different expression patterns of GmMYB184 mRNA were observed subjected to drought, cold, high salinity stress and abscisic acid treatment, suggesting its role in the signaling events in the osmotic stress-related defense response. Subcellular localization studies demonstrated that the GFP-GmMYB184 fusion protein was localized in the nucleus. Using the yeast assay system, the C-terminal region of GmMYB184 was found to be essential for the transactivation activity. These results indicate that the GmMYB184 may play a role in abiotic stress tolerance in plant.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.676-684
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• 2021

Euryhaline teleost have extraordinary ability to deal with a wide range of salinity changes. To study the seawater adaptability of rainbow trout Oncorhynchus mykiss (body weight 638±54 g, length 38.6±2 cm) to salinity increase fish were transferred from freshwater to 7, 14, 21, 28 and 32 psu and checked for mortality over 5 days. No mortality was observed in 0-32 psu. In fish transferred to 0-32 psu, blood osmolality was maintained within physiological range. The changes of serum enzyme activities (aspartate transaminase, AST and alanine transaminase, ALT) showed no significant level during experimental period. To explore the underlying molecular physiology of gill and kidney responsible for body fluid regulation, we measured mRNA expression of five genes, Na⁺/K⁺/2Cl^- cotransporter1 (NKCC1), aquaporin3 (AQP3), cystic fibrosis transmembrane conductance regulator (CFTR), glucocorticoid receptor (GR) and growth hormone receptor (GHR) in response to salt stress. Based on our result, rainbow trout could tolerate gradual transfer up to 32 psu for 5 days without mortality under physiological stress. This study suggests to alleviate osmotic stress to fish, a gradually acclimation to increasing salinity is recommended.

• The Plant Pathology Journal
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• v.37 no.6
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• pp.566-579
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• 2021

Ralstonia syzygii subsp. indonesiensis (Rsi, former name: Ralstonia solanacearum phylotype IV) PW1001, a causal agent of potato wilt disease, induces hypersensitive response (HR) on its non-host eggplant (Solanum melongena cv. Senryo-nigou). The disaccharide trehalose is involved in abiotic and biotic stress tolerance in many organisms. We found that trehalose is required for eliciting HR on eggplant by plant pathogen Rsi PW1001. In R. solanacearum, it is known that the OtsA/OtsB pathway is the dominant trehalose synthesis pathway, and otsA and otsB encode trehalose-6-phosphate (T6P) synthase and T6P phosphatase, respectively. We generated otsA and otsB mutant strains and found that these mutant strains reduced the bacterial trehalose concentration and HR induction on eggplant leaves compared to wild-type. Trehalose functions intracellularly in Rsi PW1001 because addition of exogenous trehalose did not affect the HR level and ion leakage. Requirement of trehalose in HR induction is not common in R. solanacearum species complex because mutation of otsA in Ralstonia pseudosolanacearum (former name: Ralstonia solanacearum phylotype I) RS1002 did not affect HR on the leaves of its non-host tobacco and wild eggplant Solanum torvum. Further, we also found that each otsA and otsB mutant had reduced ability to grow in a medium containing NaCl and sucrose, indicating that trehalose also has an important role in osmotic stress tolerance.

• Genomics & Informatics
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• v.2 no.2
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• pp.67-74
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• 2004

Cells consistently face stressful conditions, which cause them to modulate a variety of intracellular processes and adapt to these environmental changes via regulation of gene expression. Hyperosmotic and oxidative stresses are significant stressors that induce cellular damage, and finally cell death. In this study, oligonucleotide microarrays were employed to investigate mRNA level changes in cells exposed to hyperosmotic or oxidative conditions. In addition, since heat shock protein 70 (HSP70) is one of the most inducible stress proteins and plays pivotal role to protect cells against stressful condition, we performed microarray analysis in HSP70-overexpressing cells to identify the genes expressed in a HSP70-dependent manner. Under hyperosmotic or oxidative stress conditions, a variety of genes showed altered expression. Down­regulation of protein phosphatase1 beta (PP1 beta) and sphingosine-1-phosphate phosphatase 1 (SPPase1) was detected in both stress conditions. Microarray analysis of HSP70-overexpressing cells demonstrated that diverse mRNA species depend on the level of cellular HSP70. Genes encoding Iysyl oxidase, thrombospondin 1, and procollagen displayed altered expression in all tested conditions. The results of this study will be useful to construct networks of stress response genes.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.1
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• pp.101-107
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• 1993

Zygosaccharomyces rouxii is a salt-tolerant yeast which plays an important role during the ripening stage of soy sauce fermentation. Z. rouxii used in the experiment could grow in YPD (1 % yeast extract, 2% peptone and 2% glucose, pH5.0) medium with 18% (w/v) NaCl, whereas Saccharomyces cerevisiae could only grow in YPD medium with less than 8% NaCl. In the presence of 15% NaCl, Z. rouxii accumulates a large amount of glycerol as a compatible solute within the cells in the exponential phase. It is a characteristic of salt-tolerant yeasts. From the chemical analyses on membrane lipid fluidity, the membrane structure of the cells grown in 15% NaCl was suggested to become more rigid and its fluidity was decreased to keep glycerol within the cells in response to surrounding medium with high concentrations of salt.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.133-138
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• 2006

To differentiate barley responses to drought and salt stress, barley seedlings at the second leaf stage were treated with 218 mM NaCl and 29.5% PEG6000 iso-osmotic to 218 mM NaCl for 6 days. Shoot fresh weight and leaf relative water content of barley seedlings were more reduced by drought compared to salt stress. Hydrogen peroxide content increased under both stress conditions, but its accumulation was more severe at 6 days after salt stress. The activity of ascorbate peroxidase, glutathione reductase (GR) and catalase (CAT) was enhanced until 4 days after salt stress. On the other hand, the activity of GR and CAT increased gradually until 6 days after drought. Among the amino acids measured in this study, the accumulation of glycine, arginine and GABA (${\gamma}-aminobutyric$ acid) was lower under salt stress than drought. However, considerably larger amount of proline was accumulated by salt stress. It is concluded that the antioxidant enzymes activity and amino acid content of barley seed-lings were differently regulated in response to the isoosmotic condition of salt and drought stress.

• Horticultural Science & Technology
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• v.32 no.1
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• pp.18-25
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• 2014

This study was conducted to investigated effects of water relation of mulching and trickle irrigation on the external and internal fruit quality in Satsuma mandarin grafted on trifoliate orange rootstock in a orchard assigned to randomly three groups; whole period of Tyvex mulching (TM), Tyvex mulching with trickle irrigation once a week from October 22 to harvesting season (WM) and non-mulching treatment (NM). The average soil moisture content in the TM was lower than the WM during the time of trickle irrigation from Oct. 21 to Nov. 28. The leaf water potential was at the level of ${\Psi}max$ of -1.5 to -2.5 MPa during whole period of Tyvex mulching treatment but gradually increased at the point of supplement of water. The water and osmotic potential in juice vesicle was decreased by drought but increased again in response to the supply of water in WM. The total soluble solids (TSS) in fruit juice was increased by drought stress, but diminished in response to supply of water after drought. The content of titratible acidity was increased by drought stress but gradually decreased due to supplement of water after drought, reached it at the level of 1%. It was suggested that the accumulation of the total soluble solids compensates the degree of active osmoregulation and the decrease in content of acidity accounts for the fast respiration and water uptake resulted of the water after drought.