• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.244-244
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• 2017

Soil salinity due to accumulation of salts particularly sodium chloride affects agricultural lands and their vegetation. Generally, rice is a moderately sensitive plant with some cultivars with varying tolerance to salinity. Though there are physiological differences between salt-sensitive and salt-tolerant rice cultivars, both are still affected especially during high salinity and prolonged exposure. This also ultimately affects their indigenous bacterial endophytes particularly those that inhabit the rice seed endosphere. This study investigates the dynamic structure of seed bacterial endophytes of salt-sensitive and tolerant rice cultivars grown in different levels of soil salinity. Endophytic bacterial diversity was studied Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis. Results revealed a very interesting pattern of diversity and shifts in community structure of bacterial endophytes in the rice seeds. There is a general decrease in diversity for the salt-sensitive rice cultivar, IR29 as soil salinity increases. For the salt-tolerant cultivars, IC32 and IC37, diversity interestingly increased at moderate salinity then decreased at high soil salinity. The patterns of community structure is also strikingly different for the salt-sensitive and salt-tolerant rice cultivars. IR29 has a more even distribution of abundance, but under soil salinity, the community shifted where Curtobacterium, Pantoea, Flavobacterium and Microbacterium become the more dominant bacterial communities. For IC32 and IC37, the dominant bacterial groups under normal stress conditions were also the dominant bacterial groups during salt stress conditions. Their seed bacterial community is dominated by endophytes belonging to Microbacterium, Flavobacterium, Pantoea, Kosakonia and Enterobacter. Stenotrophomonas and Xanthomonas have not changed in terms of abundance under different salinity stress level in the salt-sensitive and salt-tolerant rice cultivars. This study showed that soil salinity greatly influenced the seed bacterial communities of rice seeds irrespective of their physiological tolerance to salinity.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.113-113
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• 2022

Salinity in surface waters is increasing around the world. Many factors, including increased water extraction, poor irrigation management, and sea-level rise, contribute to this change, and posing a threat to plant development and agricultural production. Seeds exposed to high salinity, have a lower probability of germinating and various physiological and biochemical effects. Salinity stress affects more than 20% of agricultural land and about 50% of irrigated land. In the current study, our objective is to identify the salt-tolerant peanut (Arachis hypogaea L.) Korean genotypes under salinity stress. Thus, two-week-old 19 diverse peanut Korean genotypes were exposed to 10 days of salinity (150 mM NaCl) stress. Based on the growth attributes investigation, Baekjung and Ahwon genotypes showed significantly higher shoot lengths compared to control plants. Whereas, the Sinpalwang genotype exhibited a significantly positive response for plant growth and reduced wilting symptoms compared to other genotypes. This study was able to find out peanut tolerant and sensitive genotypes for salt stress. These results may provide a good template for further salt-tolerant peanut cultivar improvement programs. Identified diverse salt-responsive genotypes can be utilized as source material in Korean breeding schemes for peanut crop improvement for salt and other abiotic stress tolerance.

• Journal of The Korean Society of Grassland and Forage Science
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• v.43 no.1
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• pp.56-61
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• 2023

The germination process is critical for plant growth and development and it is largely affected by environmental stress, especially salinity. Recently, hydrogen sulfide (H₂S) is well known to act as a signaling molecule in a defense mechanism against stress conditions but poorly understood regulating seed germination. In this study, the effects of NaHS (the H₂S donor) pretreatment on various biochemical (hydrogen peroxide (H₂O₂) content and amylase and protease activity) and physiological properties (germination rate) during seed germination of oilseed rape (Brassica napus L. cv. Mosa) were examined under salt stress. The seed germination and seedling growth of oilseed rape were inhibited by NaCl treatment but it was alleviated by NaHS pretreatment. The NaCl treatment increased H₂O₂ content leading to oxidative stress, but NaHS pre-treatments maintained much lower levels of H₂O₂ in germinating seeds under salt stress. Amylase activity, a starch degradation enzyme, significantly increased over 2-fold in control, NaHS pretreatment, and NaHS pretreatment under NaCl during seed germination compared to NaCl treatment. Protease activity was highly induced in NaHS-pretreated seeds compared to NaCl treatment, accompanied by a decrease in protein content. These results indicate that NaHS pretreatment could improve seed germination under salt stress conditions by decreasing H₂O₂ accumulation and activating the degradation of protein and starch to support seedling growth.

• Korean Journal of Environmental Agriculture
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• v.24 no.2
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• pp.153-158
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• 2005

To investigate alleviation effects of salt stress by low dose gamma-irradiation on seedling growth of rice (Oryza shrive L), in plants of two rice cultivars (Ilpumbyeo and Gancheokbyeo), seeds were irradiated with the different doses $(0{\sim}32\;Gy)$ of gamma-ray by irradiator ($^{60}Co$, ca.150 TBq of capacity, AECL). The salt stress caused a remarkable decrease of seedling growth, particularly for dry weight. In addition, relative growth rate was decreased over 50% by the salt stress. However, the salt stress-induced inhibition of growth was alleviated by gamma-irradiation. Especially, the relative growth rate of shoot showed the reduction effect over 30% at 4 Gy-irradiated groups as compared with that of control. Also, electrolyte leakage and relative water content were damaged, respectively 4 times and 30% by the salt stress but the damages were alleviated by the gamma-irradiation. These alleviation effects were observed similarly in both the cultivars tested. These results suggest that the low dose gamma-irradiation may have a better protection or the salt stress.

• Journal of Microbiology and Biotechnology
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• v.20 no.9
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• pp.1288-1294
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• 2010

Rhizobium phaseoli strains were isolated from the mung bean (Vigna radiata L.) nodules, and the most salt tolerant and high auxin producing rhizobial isolate N20 was evaluated in the presence and absence of L-tryptophan (L-TRP) for improving the growth and yield of mung bean under saline conditions in a pot experiment. Mung bean seeds were inoculated with peat-based inoculum and NP fertilizers were applied at 30-60 kg/ha, respectively. Results revealed that imposition of salinity reduced the growth and yield of mung bean. On the contrary, the separate application of L-TRP and Rhizobium appeared to mitigate the adverse effects of salt stress. However, their combined application produced more pronounced effects and increased the plant height (28.2%), number of nodules per plant (71.4%), plant biomass (61.2%), grain yield (65.3%), and grain nitrogen concentration (22.4%) compared with untreated control. The growth promotion effect might be due to higher auxin production in the rhizosphere and improved mineral uptake that reduced the adverse effects of salinity. The results imply that supplementing Rhizobium inoculation with L-TRP could be a useful approach for improving the growth and yield of mung bean under salt stress conditions.

• Journal of Nutrition and Health
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• v.30 no.8
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• pp.920-929
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• 1997

This study examined the effect of dietary salt levels on the incidence and cure of gastric ulcer in rats. Two sets of experiment were conducted . In the first experiment, the rats were divided into 3 groups. The 3 groups were fed 0%, 4%, and 8% NaCl diets respectively for 20days. The rats were given water -immersion restraint stress at the end of the dietary period , and sacrificed. The ulcer index by histological test was higher in rats fed the 8% NaCl diet than those in the other groups. The hexosamine and glutathione levels were significantly lower in the rats fed the 8% NaCl diet. Hematocrit and total iron binding capacity(TIBC) showed lower values caused by bleeding of gastric mucosa. The second experiment was designed to determine the effect of soldium concentration on the cure of gastric ulcer . As the gastric ulcer was recovered, ulcer length was gradually deceased in the control group but not changed in the 8% NaCl diet group. The gastric hexosamine and hepatic glutathione were increased in the control group but decreased in the 8% NaCl diet group. The hematologic indices of stressed rats showed the same tendency. As a result, dietary salt per se did not cause gastric ulcer . Once an ulcer is formed by stress or any other factor, higher levels of dietary salt may be detrimental to gastric mucosa, thereby delaying the healing of the ulcer. It is recommended that dietary salt intake be reduced in stress-prone people.

• The Plant Pathology Journal
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• v.28 no.2
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• pp.202-206
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• 2012

Root colonization by the rhizobacterium Pseudomonas chlororaphis O6 in Arabidopsis thaliana Col-0 plants resulted in induced tolerance to drought and salinity caused by halide salt-generated ionic stress but not by osmotic stress caused by sorbitol. Stomatal apertures decreased following root colonization by P. chlororaphis O6 in both wild-type and ABA-insensitive Arabidopsis mutant plants. These results suggest that an ABA-independent stomatal closure mechanism in the guard cells of P. chlororaphis O6-colonized plants could be a key phenotype for induced systemic tolerance to drought and salt stress.

• Journal of Plant Biotechnology
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• v.5 no.3
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• pp.157-161
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• 2003

Proline is known as an osmoprotectant accumulating in response to salt and dehydration stresses. An increased level of proline is achieved by either an induced synthesis or a reduced degradation of proline. In an attempt to increase salt tolerance in carrot, a P5CS gene from mothbean was introduced via an Agrobacterium-mediated transformation. The resulting carrot cells and the regenerated plants containing the transgene showed increased levels of proline compared to nontransgenics. The transgenic cell line, Pj2 showed about 6 times increased degree of tolerance determined by relative growth after a treatment in 250 mM NaCl. In facts, due to the retarded growth shown in non-saline condition, Pj2 cells grow only about 1.2 times better than nontransgenic control under salt stress condition. Taken together, it appears that a P5CS is a key enzyme in proline biosynthesis and the increased accumulation of proline by overexpression of the enzyme is enough to enhance tolerance to salt stress in carrot.

• Korean Journal of Agricultural Science
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• v.47 no.1
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• pp.105-117
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• 2020

Abiotic stress is one of the most serious problems in plant productivity because it dramatically delays plant growth and development. One of the abiotic stresses, soil salinity, has an adverse effect on plant growth, particularly in areas where irrigation is necessary like semiarid Asia and Africa. Among several physiological parameters, anthocyanin accumulation is a valuable indicator of the condition of the plant, and it tends to increase under salt stress conditions because of its protective role in such an environment. Consequently, it may be important to search for well adapted genotypes for upcoming climate changes. Anthocyanins are known to have important roles in defense against biotic and abiotic stresses, providing important functions for protecting plant cells from reactive oxygen species. In this study, we investigated the anthocyanin accumulation between two Korean sorghum genotypes, Sodamchal and Nampungchal. The two genotypes were subjected to a regulated salinity condition, and the anthocyanin contents were evaluated in both. In Nampungchal, the anthocyanin content increased with 150 mM NaCl treatment during the time course of the experiment. However, the anthocyanin content of Sodamchal decreased in the same condition. The measured values of the anthocyanin content should be useful to identify the intensity of the salt tolerance in Sorghum bicolor L. Furthermore, we studied gene expression profiling of salt stress related genes with qRT-PCR. These results suggest that Nampungchal is a more tolerant genotype to salt stress compared to Sodamchal. This information should be useful for breeding salt-resistant cultivars in sorghum.

• Molecules and Cells
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• v.39 no.6
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• pp.447-459
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• 2016

Many studies have been conducted to understand plant stress responses to salinity because irrigation-dependent salt accumulation compromises crop productivity and also to understand the mechanism through which some plants thrive under saline conditions. As mechanistic understanding has increased during the last decades, discovery-oriented approaches have begun to identify genetic determinants of salt tolerance. In addition to osmolytes, osmoprotectants, radical detoxification, ion transport systems, and changes in hormone levels and hormone-guided communications, the Salt Overly Sensitive (SOS) pathway has emerged to be a major defense mechanism. However, the mechanism by which the components of the SOS pathway are integrated to ultimately orchestrate plant-wide tolerance to salinity stress remains unclear. A higher-level control mechanism has recently emerged as a result of recognizing the involvement of GIGANTEA (GI), a protein involved in maintaining the plant circadian clock and control switch in flowering. The loss of GI function confers high tolerance to salt stress via its interaction with the components of the SOS pathway. The mechanism underlying this observation indicates the association between GI and the SOS pathway and thus, given the key influence of the circadian clock and the pathway on photoperiodic flowering, the association between GI and SOS can regulate growth and stress tolerance. In this review, we will analyze the components of the SOS pathways, with emphasis on the integration of components recognized as hallmarks of a halophytic lifestyle.