• Journal of Soil and Groundwater Environment
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• v.24 no.6
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• pp.16-25
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• 2019

Anthropogenic polycyclic aromatic hydrocarbons (PAHs) are formed by the incomplete combustion of fuels and industrial waste. PAHs can be widely exposed to the environment (water, soil and groundwater). PAHs are potentially toxic, mutagenic and/or carcinogenic. Fundamental studies such as biota uptake (e.g., earthworm and plant) of PAHs are highly needed. It is necessary to develop alternative ways to evaluate bioavailability of PAHs instead of using living organisms because it is time-consuming, difficult to apply in the field, and also exaction method is tedious and time-consuming. In this study, sorption behaviors of phenanthrene were evaluated to predict the fate of PAHs in soils. Moreover, bioaccumulation of PAHs in an artificially contaminated soil was evaluated using pea plant (Pisum sativum) as a bioindicator. A novel passive sampler, organic-diffusive gradient in thin-film (o-DGT) for PAHs was newly synthesized, tested as a biomimic surrogate and compared with plant accumulation. Sorption partitioning coefficient (K_P) and sorption capacity (K_F) were in the order of natural soil > loess corresponding to the increase in organic carbon content (f_oc). Biota-to-soil accumulation factor (BSAF) and DGT-to-soil accumulation factor (DSAF) were evaluated. o-DGT uptake was linearly correlated with pea plant uptake of phenanthrene in contaminated soil (R²=0.863). The Tenax TA based o-DGT as a biomimic surrogate can be used for the prediction of pea plant uptake of phenanthrene in contaminated soil.

• Journal of Applied Biological Chemistry
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• v.63 no.4
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• pp.401-406
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• 2020

The plant uptake of endosulfan, a new persistent organic pollutants from soil environment was investigated on ginseng through the field survey in Korea. The endosulfan residues in soil for this survey were ranged on 0.013-0.136 mg kg-1. The plant uptake factor (PUF) for endosulfan in ginseng was 0.243-1.708 and the highest PUF was found on 3-year-old ginseng. The PUF for endosulfan decreased in the longer cultivation period and it might be caused by the dilution effect of ginseng growth. In addition, the soil organic matter (SOM) content affected on the PUF negatively and Pearson correlation coefficient (r) between SOM and PUF was -0.7812 (p <0.05). Thus, higher SOM would positively affect to reduce the endosulfan residue in ginseng root.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.102-106
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• 2003

The uptake of $^{14}C$-2, 4, 6-trinitrotoluene (TNT) in hydroponics was studied using onion plants. Of the total TNT mass (5 $\mu\textrm{M}$ concentration), 75% was in the roots, 4.4% in the leaves, and 21% in the external solution at 2 days, The percent distribution in roots was lower with higher concentration in the external solution, but in leaves it was comparable at all concentrations (5-500 $\mu\textrm{M}$). Root concentration factor (RCF) in hydroponics was more than 85 in constant hydroponic experiment (CHE) at 5 $\mu\textrm{M}$ and 150 in non-constant hydroponic experiment (NHE) at 5 $\mu\textrm{M}$. The maximum RCF values in the hydroponic system were greater with lower solution concentration. Transpiration stream concentration factor (TSCF) values in the present study (NHE only: 0.31-0.56) were relatively similar to the values with predicted values (0.43-0.78), increasing with higher external TNT concentration. For phytotoxicity tested in hydroponics and wet paper method, 500 $\mu\textrm{M}$ was toxic to onion plant, 50 $\mu\textrm{M}$ was non-toxic for plant growth but limited the transpiration rate, and 5 $\mu\textrm{M}$ was non-toxic as control.

• Korean Journal of Agricultural Science
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• v.47 no.2
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• pp.305-313
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• 2020

Root hair development has the potential to increase crop yields and at the same time to decrease fertilizer use, which will be required in the next 30 years to meet the demand for crop-derived commodities in a world with decreasing available natural resources. Root hair defective six (RHD6) encoding a basic helix-loop-helix transcription factor, is associated with root hair differentiation, and its roles are root hair initiation and elongation. Grass plants, rice and Brachypodium have been used as model plants to study the gene function of the root hair defective six like (RSL) subfamily which is orthologous to AtRHD6. The RSL subfamily has an identical gene function with AtRHD6 which is involved with root hair differentiation as well. Plants with longer root hairs within a species should have an improved Pi uptake efficiency; therefore, we would expect that a plant with a high Pi uptake could contribute to increasing the plant yield. We achieved increased root hair length by manipulating the RSL subfamily genes. It is expected that in these transgenic plants, the long root hairs would be sufficient to improve the Pi uptake and hence improve biomass and yield component (tiller, spikelet number, and spikelet weight) of the plant. Here, we demonstrate that Brachypodium transgenic plants overexpressing the BdRSL subfamily genes have an improved biomass and grain yield. The result of this study could be applied to important crop plants like rice.

• Applied Microscopy
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• v.47 no.3
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• pp.148-156
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• 2017

The wide distribution of redox-sensitive elements (RSE) as arsenic (As), cadmium (Cd), selenium (Se), and strontium (Sr) in the top soil of Siwaqa area are related to the weathering action of alkaline surface and groundwater on the parent rocks. The bioavailability, distribution, sorption, and ecotoxicity of As, Cd, Se, and Sr, of the wild plants and top soils in the study area were investigated. A total number of 23 surface soil samples and 23 plant samples were collected and analyzed for the most toxic elements. The uptake of elements by plants was dependent on the plant species and the concentration of elements in the soil. For example, Sr was the highest concentration in soil samples and plants, while Se was the lowest concentration in soil samples and pants. For the plants, the results showed that Bellevalia sp. had the highest elements uptake, while Allium rothii had the lowest elements uptake. The results of this work provide a valuable knowledge for understanding the bioavailability of some toxic elements in the soil and plants of Central Jordan. The results are expected to be of great help for the Jordanian Uranium Mining Company during their environmental risk assessments.

• Journal of Soil and Groundwater Environment
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• v.15 no.3
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• pp.27-33
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• 2010

The purpose of this study was in search of native plant species showing metal-resistant property and excessively accumulating heavy metals in metal-contaminated soil or abandoned mines as well as in evaluation of applicability of phytoremediation. In the study area, species showing excessively accumulating heavy metals were a shepherd´s purse, pampas grass, a Korean lettuce, a Hwansam vine, the Korean persicary, a foxtail, a goosefoot, and a water pepper. The first screened plant species in Sambo mine were as shepherd's purse, Korean lettuce and pampas grass Among them the shepherd´s purse can be excluded because it is a seasonal plant and has lower removal capacity for heavy metals. The Korean lettuce was also excluded because of having lower removal capacity for heavy metals. Pampas grass is a highly bionic plant species constantly growing from spring. However it has weak points such as little accumulation capacity for zinc as well as small values of an accumulation factor and a translocation factor. Another problem is regarded as removal of roots after the clean up if pampas grass is applied to a farmland. In Sanyang mine, wormwood and Sorijaengi were considered as adaptable species.

• Korean Journal of Soil Science and Fertilizer
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• v.5 no.1
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• pp.33-39
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• 1972

For the increase of productivity, canopy structure and nutritional status in various productivity grades (high>700, medium>600 and low>500kg/l0a as head rice) were investigated in a study using Jinheung(Oryza sativa L.) for the increase of producticity with following results: 1. High yield plot showed greater leaf area and slow decrease of it after heading stage. While low yield plot had rapidly decrease of leaf area. 2. High yield plot showed higher light transmission ratio (LTR) durnig early grow stage, low LTR. during late grow stage, and higher leaf area per LTR. 3. Net assimilation ratio was decrease with the increase of leaf area index (LAI) and it was always higher in high yield plot. 4. High yield plant had greater amount of total nitrogen uptake, slow uptake rate, and considerable uptake after heading while low yield plant showed higher uptake of nitrogen in early stage of growth and no uptake after heading. 5. The percent ratio starch at heading to total at harvesting was 40% for low yield plant and 10% for highyield plant inderting that high yield depends much on past-heading starch synthesis. 6. Main factor determining secondary yield was ripened grain ratio.

• Journal of Applied Biological Chemistry
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• v.63 no.3
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• pp.243-248
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• 2020

The long-chained perfluoroalkyl acids (PFAAs), perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), are a potential exposure risk in the environment, specifically for humans due to high levels of bioaccumulation, persistence, and toxicity. In the current study, the plant uptake factors (PUFs) of spinach and Welsh onion were investigated on the three different concentration levels of PFOA and PFOS in soil. Spinach and Welsh onion were divided into three residue groups, a control group and two levels of PFOA and PFOS. The PFAAs spiked soils were aged for six months and the extractable residue of PFOS in the aged soil was reduced to 30-59% of the initial spiked concentrations for PFOS, while PFOA showed almost the same initial spiked concentrations. The PUFs for PFOA and PFOS were 0.111-2.821 and 0.047-3.175 for spinach, and 0.203-0.738 and 0.035-0.181 for Welsh onion, respectively. The highest PUF values in both vegetable were displayed when the residual concentration of PFAAs were part-per-billion (ppb) or sub-ppb in soil.

• Molecules and Cells
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• v.40 no.3
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• pp.178-185
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• 2017

Nitrogen is one of the most important mineral elements for plant growth. We studied the functional roles of Oryza sativa DNA BINDING WITH ONE FINGER 18 (OsDOF18) in controlling ammonium uptake. The growth of null mutants of OsDOF18 was retarded in a medium containing ammonium as the sole nitrogen source. In contrast, those mutants grew normally in a medium with nitrate as the sole nitrogen source. The gene expression was induced by ammonium but not by nitrate. Uptake of ammonium was lower in osdof18 mutants than in the wild type, while that of nitrate was not affected by the mutation. This indicated that OsDOF18 is involved in regulating ammonium transport. Among the 10 ammonium transporter genes examined here, expression of OsAMT1;1, OsAMT1;3, OsAMT2;1, and OsAMT4;1 was reduced in osdof18 mutants, demonstrating that the ammonium transporter genes function downstream of OsDOF18. Genes for nitrogen assimilation were also affected in the mutants. These results provide evidence that OsDOF18 mediates ammonium transport and nitrogen distribution, which then affects nitrogen use efficiency.

• The Plant Pathology Journal
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• v.20 no.1
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• pp.1-6
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• 2004

The diseases caused by Xylella fastidiosa are associated with aggregation of the bacteria m xylem vessels, formation of a gummy matrix and subsequent blockage of water uptake. In the closely related pathogen, Xanthomonas campestris, xanthan gum is known to be an important virulence factor, probably contributing to bacterial adhesion, aggregation and plugging of xylem. Xanthan gum, produced by X. campestris, is an extra-cellular polysaccharide consisting of a cellulose backbone ($\bate$-1,4-linked D-glucose) with trisaccharide side chains composed of mannose, glucuronic acid and mannose attached to alternate glucose residues in the backbone. We had constructed a mutant of X. campestris lacking gumI gene that is responsible for adding the terminal mannose for producing modified xanthan gum which is similar to xanthan gum fromX. fastidiosa. The modified xanthan gum degrading endgphytic bacterium Acineto-bacter johnsonii GX123 isolated from the oleander infected with leaf scorch disease.