• Toxicological Research
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• v.35 no.4
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• pp.311-317
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• 2019

The transport systems for metals play crucial roles in both the physiological functions of essential metals and the toxic effects of hazardous metals in mammals and plants. In mammalian cells, Zn transporters such as ZIP8 and ZIP14 have been found to function as the transporters for Mn(II) and Cd(II), contributing to the maintenance of Mn homeostasis and metallothionein-independent transports of Cd, respectively. In rice, the Mn transporter OsNramp5 expressed in the root is used for the uptake of Cd from the soil. Japan began to cultivate OsNramp5 mutant rice, which was found to accumulate little Cd, to prevent Cd accumulation. Inorganic trivalent arsenic (As(III)) is absorbed into mammalian cells via aquaglyceroporin, a water and glycerol channel. The ortholog of aquaporin in rice, OsLsi1, was found to be an Si transporter expressed in rice root, and is responsible for the absorption of soil As(III) into the root. Since rice is a hyperaccumulator of Si, higher amounts of As(III) are incorporated into rice compared to other plants. Thus, the transporters of essential metals are also utilized to incorporate toxic metals in both mammals and plants, and understanding the mechanisms of metal transports is important for the development of mitigation strategies against food contamination.

• Korean Journal of Environmental Agriculture
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• v.28 no.2
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• pp.146-157
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• 2009

The influence of Pb-citrate complex formation on Pb uptake and the effect of Pb on organic acid exudation were investigated using four plant species, viz., sunflower (Helianthus annuus L), Indian mustard (Brassica juncea), canola (Brassica napus) and vetiver grass (Vetiveria zizanioides) under hydroponic conditions. Seedlings were exposed to different levels of Pb and Pb-citrate for 24 hrs and subsequently Pb distributions in plant shoot, root and hydroponic solution were measured. The dissolved organic carbon (DOC) concentration generally decreased as the concentration of Pb in the hydroponic solution increased. In contrast to DOC, the total organic acid concentrations exuded from Indian mustard roots significantly increased (424 to 6656 mg $kg^{-1}$) with increased Pb treatment, implying that exuding organic acids were involved in Pb accumulation in Indian mustard. The complexation of Pb with citrate enhanced Pb accumulation in the above ground portions. Lead concentration in Indian mustard increased from 2.05 mg $kg^{-1}$ to 6.42 mg $kg^{-1}$ when the concentration of citrate in solution increased from 0 to 50 mg $L^{-1}$. This result showed enhanced translocation of Pb from root to shoot with observation of transfer coefficient ($K_t$) increase from 2.03E-3 to 5.72E-3.

• Journal of Ginseng Research
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• v.34 no.3
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• pp.175-182
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• 2010

North American ginseng seedlings (Panax quinquefolius L.) were grown in pots in heated greenhouses, in a cool greenhouse, or in the field, in 11 experiments at various times over 16 years. Crop establishment, dry matter partitioning, photosynthesis, radiation use efficiency and carbon budget were measured and/or calculated in some years. Once the seedling canopy, of about $20\;cm^2$ per seedling, and a leaf area index of 0.37, was established, about 40 days after germination, full canopy display lasted about 87 days. Only 16.6% of the incoming solar radiation was intercepted by the crop, the remainder falling on the mulched soil surface. Total and root dry matter accumulations in the cool greenhouse and in the field were about double that in the heated greenhouses. Partitioning of dry matter to roots (economic yield or harvest index) in the cool greenhouse and in the field was 73% whereas it was 62.5% in the heated greenhouses. The relationship between root dry matter and radiation interception during the full canopy period was linear with growth efficiencies of $2.92\;mg\;MJ^{-1}$ at 4.8% of incoming radiation and $0.30\;mg\;MJ^{-1}$ at 68% of incoming radiation. A photosynthetic rate of $0.39\;g\;m^{-2}\;h^{-1}$ was attained at light saturation of about $150\;{\mu}mol\;m^{-2}\;s^{-1}$ (7.5% of full sunlight); dark respiration was $0.03\;g\;m^{-2}\;h^{-1}$, about 8.5% of maximum assimilation rate. Estimates of dry matter accumulation by growth analysis and by $CO_2$ uptake were similar, 6.21 vs. 7.62 mg $CO_2$, despite several assumptions in $CO_2$ uptake calculations.

• Journal of Radiation Protection and Research
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• v.29 no.2
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• pp.117-127
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• 2004

A dynamic compartment model was developed to evaluate the transport of accidently released radionuclides onto rice-fields. In the model, the surface water compartment and shoot-base absorption were introduced to account for the effect of irrigation, which is essential to a rice cultivation. The soil mixing by plough and irrigation before transplanting rice was also considered, and the rate of root-uptake and shoot-base absorption were modeled in terms of the function of biomass. In order to test the validation of the model, it was applied to the analysis of some simulated $^{137}Cs$ deposition experiments that were performed while cultivating rice in a greenhouse using soils sampled from rice-fields around Kori, Yonggwang and Ulchin nuclear power plants. The model prediction was generally agreed within about one order of magnitude with experimental data.

• Journal of Soil and Groundwater Environment
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• v.6 no.4
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• pp.3-11
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• 2001

To select a suitable indigenous plant for the phytoremediation of TNT contaminated soil, eight representative species of native grasses were tested to identify TNT toxicity thresholds. The threshold was determined based on various factors including cumulative seed germination, root and shoot length, fresh biomass, and the amount of water uptake under various TNT concentrations. Phytotoxic effect of TNT on plants was increased with the increase in TNT concentration but the degree was varied between grass species. Concentrations up to 60-80mgTNT/liter did not affect germination of Abutilion avicennae, Echinochioa crusgalli var. frumentacea, and Aeschynomene indica. Phytotoxicity threshold inhibition (50%) of Abutilion avicennae, schinochioa crusgalli var. frumentacea, Aeschynomene indica were 5-40mgTNT/liter for root length, 50-73mg TNT/Liter for shoot length and 68-99mgTNT/Liter for fresh biomass during 14 days of seedling exposure. Root and shoot growth as well as fresh biomass decreased as TNT concentration increased. In addition, the amount of water uptake decreased with increasing TNT concentration in Abutilion avicennae and Aeschynomene indica. Comparison of toxicity thresholds for the tested grass species showed that sensitivity of plants to TNT was in the order of root length > shoot length > fresh biomass > germination rate. From these results, we concluded that Abutilion avicennae and Aeschynomene indica had tolerance to TNT among the species tested.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.223-225
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• 2007

Many plant growth-promoting rhizobacteria (PGPRs) have been known for beneficial effects on plants including biological control of soilborne pathogens, induced systemic resistance to plant pathogens, phytohormone production, and improvement of nutrient and water uptake of plants. We developed a simple and rapid method for screening potential PGPR, especially phytohormone producing rhizobacteria, or for analyzing their functions in plant growth using cucumber seedling cuttings. Surface-sterilized cucumber seeds were grown in a plastic pot containing steamed vermiculite. After 7 days of cultivation, the upper part 2 cm in length of cucumber seedling, was cut and used as cucumber cuttings. The base of cutting stem was then dipped in a microcentrifuge tube containing 1.5ml of a bacterial suspension and incubated at $25^{\circ}C$ with a fluorescent light for 10 days. Number and length of developed adventitious roots from cucumber cuttings were examined. The seedling cuttings showed various responses to the isolates tested. Some isolates resulted in withering at the day of examination or in reduced number of roots developed. Several isolates stimulated initial development of adventitious roots showing more adventitious root hair number than that of untreated cuttings, while some isolate had more adventitious root hair number and longer adventitious roots than that of untreated control. Similar results were obtained from the trial with rose cuttings. Our results suggest that this bioassay method may provide a useful way for differentiating PGPR's functions involved in the development of root system.

• Korean Journal of Medicinal Crop Science
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• v.24 no.3
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• pp.198-206
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• 2016

Background: Electrical conductivity (EC) and pH are important features of nutrient solution, affecting both growth and quality of crops by altering nutrient uptake. Methods and Results: The pH values of nutrient solutions were controlled at 5.0, 5.5, 6.0, 6.5 and EC values were controlled at 0.68, 0.84, 1.23, 1.41 dS/m. Gingesng root weights were higher during the initial growth period when the plants were treated with low pH and low EC nutrient solutions. However, the higher pH and EC levels, the greater the increase in the rate of root weight between the initial and middle growth periods. The highest ginsenoside amount changed during growth period. The total ginsenoside amount was highest in the root, and the lowest in leaves at 45 and 90 days after treatment, respectively, with solution at a pH of 6.0. After 135 days of treatment, the highest total ginsenoside amount was detected in root treated with soluton with EC values of 1.23 dS/m. Conclusions: For the cultivation of ginseng using a nutriculture system, the pH and EC values of nutrient solutions should to be controlled based on the stage of growth and targeted plant organ (root or leaves).

• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.395-401
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• 2011

BACKGROUND: Potassium (K) is one of the macronutrients which are essential for plant growth and development. Its deficiency in paddy soils is becoming one of the limiting factors for increasing rice yield in Asia. METHODS AND RESULTS: To investigate physiological symptoms under K-starvation (NP) compared with complete media (NPK) condition, we measured shoot/root length, weight, nutrients, and patterns of protein expression. The shoot growth was significantly reduced, but root growth was not affected by K-starvation. However, biomasses were decreased in both shoot and root. Uptake of K was reduced up to 85%, while total concentrations of P, Ca, Mg, Na were increased in root and shoot. To better understand the starved K mechanism of rice, comparative proteome analysis for proteins isolated from rice leaves was conducted using 2-DGE. Five spots of differentially expressed proteins were analyzed by MALDI-TOF MS. Analysis of these K-starvation response proteins suggested that they were involved in metabolism and defense. CONCLUSION(s): Physiological and 2-DGE based proteomics approach used in our study results in observation of morphology or nutrients change and identification of K-starvation responsive proteins in rice root. These results have important roles in maintaining nutrient homeostasis and would also be useful for further characterization of protein function in plant K nutrition.

• Journal of Ginseng Research
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• v.47 no.3
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• pp.469-478
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• 2023

Background: Nitrogen (N) is an essential macronutrient for plant growth and development. To support agricultural production and enhance crop yield, two major N sources, nitrate and ammonium, are applied as fertilizers to the soil. Although many studies have been conducted on N uptake and signal transduction, the molecular genetic mechanisms of N-mediated physiological roles, such as the secondary growth of storage roots, remain largely unknown. Methods: One-year-old P. ginseng seedlings treated with KNO₃ were analyzed for the secondary growth of storage roots. The histological paraffin sections were subjected to bright and polarized light microscopic analysis. Genome-wide RNA-seq and network analysis were carried out to dissect the molecular mechanism of nitrate-mediated promotion of ginseng storage root thickening. Results: Here, we report the positive effects of nitrate on storage root secondary growth in Panax ginseng. Exogenous nitrate supply to ginseng seedlings significantly increased the root secondary growth. Histological analysis indicated that the enhancement of root secondary growth could be attributed to the increase in cambium stem cell activity and the subsequent differentiation of cambium-derived storage parenchymal cells. RNA-seq and gene set enrichment analysis (GSEA) revealed that the formation of a transcriptional network comprising auxin, brassinosteroid (BR)-, ethylene-, and jasmonic acid (JA)-related genes mainly contributed to the secondary growth of ginseng storage roots. In addition, increased proliferation of cambium stem cells by a N-rich source inhibited the accumulation of starch granules in storage parenchymal cells. Conclusion: Thus, through the integration of bioinformatic and histological tissue analyses, we demonstrate that nitrate assimilation and signaling pathways are integrated into key biological processes that promote the secondary growth of P. ginseng storage roots.

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.247-251
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• 2008

During a 35-day growth cycle, N, P, and K uptake was determined by measuring changes in their contents in culture solutions. At harvest, plants were separated into the roots, base organs and shoot, and dried for tissue analysis for N, P, and K. The uptake rates of N, P, and K followed cyclical patterns that was related to shoot development and harvest, but were independent of the transpiration rate. Uptake of N declined from 5.6 mmol $plant^{-1}$ $day^{-1}$ just prior to the cycle initiation to 4.0 mmol $plant^{-1}$ $day^{-1}$ at day 15. Uptake rate steadily increased as flower stems reached maturity up to 10.3 mmol $plant^{-1}$ $day^{-1}$ day 35. Uptakes rates of P and K followed similar patterns of N uptake. Tissue concentrations of N and P steadily decreased since day 15. Content of K was the lowest at day 20 and steadily increased thereafter. In the root tissue, N and K contents were the lowest at day 15, increased to day 30, and then decreased at day 35. Tissue P content was just a reverse of those of N and K.