• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.2
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• pp.93-103
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• 2020

The average growth day of 11 maize varieties from planting to silking in the first cropping (FC) was 89.5 days and in the second cropping (SC) was 46.7 days, which was 43 days faster than in the FC. The average 100-kernel weight (100 KW) in the FC was 28.4 g and 18.3 g in the SC, which was approximately 36.4% lower than that in the FC. The average crude oil content of FC was 3.97% and SC was 3.08%, which was about 0.89% lower than that of FC. The composition of stearic and oleic acid was significantly higher in FC, whereas palmitic and linoleic acid were higher in SC; however, linolenic acid was not statistically different between the two crops. The crude oil content was negatively correlated with linoleic acid (FC -0.264^ns, SC -0.504**) and positively correlated with linolenic acid (0.526**). Unsaturated fatty acid (USFA) composition showed a significant difference between FC (83.48%) and SC (82.96%). Total phytosterol content was 598.3 mg/100 g and 701.9 mg/100 g in FC and SC, respectively, and showed significant difference by planting dates. The β-sitosterol content showed no statistical difference between the planting dates, but campesterol and stigmasterol were significantly higher in SC than in FC. Therefore, it was considered that the temperature condition during the ripening period affects the 100 KW of maize, and this leads to the variation in phytosterol content. However, among phytosterols, β-sitosterol was relatively little affected by the planting dates. USFA composition showed a significantly negative correlation with phytosterol content. Considering the results, the relatively high phytosterol content in SC was mainly because of the delay in progress of starch accumulation as daily air temperature decreased from the middle of the ripening period, whereas progress of phytosterol accumulation in the maize kernel was considered relatively faster than that of starch accumulation.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.563-570
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• 2014

The shortage or surplus of minerals directly affects overall physiological metabolism of plants; especially, it strongly influences carbohydrate metabolism as a primary response. We have studied mineral uptake, synthesis and partitioning of soluble carbohydrates, and the relationship between them in N, P or K-excessive tomato plants, and examined the interaction between soluble carbohydrates and mineral elements. Four-weeks-old tomato plants were grown in a hydroponic growth container adjusted with excessive N ($20.0mmol\;L^{-1}$ $Ca(NO_3)2{\cdot}4H_2O$ and $20.0mmol\;L^{-1}$ $KNO_3$), P ($2.0mmol\;L^{-1}$ $KH_2PO_4$), and K ($20.0mmol\;L^{-1}$ $KNO_3$), respectively, for 30 days. Shoot growth rates were significantly influenced by excessive N or K, but not by excessive P. The concentrations of water soluble N (nitrate and ammonium), P and K were clearly different with each tissue of tomato plants as well as the mineral conditions. The NPK accumulation in all treatments was as follows; fully expanded leaves (48%) > stem (19%) = roots (16%) = petioles (15%) > emerging leaves (1). K-excessive condition extremely contributed to a remarkable increase in the ratio, which ranged from 2.79 to 10.34, and particularly potassium was dominantly accumulated in petioles, stem and roots. Fresh weight-based soluble sugar concentration was the greatest in NPK-sufficient condition ($154.8mg\;g^{-1}$) and followed by K-excessive (141.6), N-excessive (129.2) and P-excessive (127.7); whereas starch was the highest in K-excessive ($167.0mg\;g^{-1}$) and followed by P-excessive (146.1), NPK-sufficient (138.2) and N-excessive (109.7). Soluble sugar showed positive correlation with dry weight-based total N content (p<0.01) whereas was negatively correlated with soluble P (p<0.01) and dry weight-based total P (p<0.01). On the other hand, starch production was negatively influenced by total N (p<0.001), but, it showed positive relation with total K concentration (p<0.05). This study shows that uptake pattern of NPK and production and partitioning of soluble carbohydrate were substantially different from each mineral, and the relationship between water soluble- and dry weight-based-mineral was positive.

• Korean Journal Plant Pathology
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• v.1 no.2
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• pp.101-108
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• 1985

Histopathological changes in the witches'-broom mycoplasma (MLO) infected jujube trees after trunk injection of oxytetracycline HCl (OTC) solution were investigated by using light microscope, fluorescence microscope and electron microscope. In contrast to the healthy leaves, adaxial and abaxial bundle sheath extensions in the major veins of diseased leaves were highly developed, but mesophyll cells were very small, loose and necrosed. In the diseased leaves, excessive phloem was formed, xylem differentiation was supressed and polyphenols were accumulated. Jujube trees treated with 500ml of 2000ppm solution of OTC showed complete remission of witches'-broom symptoms above the injection site, but cells in the sheath extention were hypertrophied and sieve tube necrosis occurred in the secondary phloem of major veins. MLO-specific fluorescence was not observed in the samples of diseased jujube trees treated with OTC, while those from non-treated infectedstress distinctly showed a moderate amount of MLO-specific fluorescence. In the observation under the electron microscope, sieve element of diseased tissues and its associated companion cells were found to have collapsed. Parenchymas cells contained many large starch filled plastids and most samples of diseased and OTC-treated tissues showed an abnormal accumulation of starch compared to the healthy controls. Mycoplasma-like organisms were observed only within mature sieve elements in diseased tissues, but never in OTC-treated tissues.

• Molecules and Cells
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• v.38 no.1
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• pp.40-50
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• 2015

In the interaction between plants and pathogens, carbon (C) resources provide energy and C skeletons to maintain, among many functions, the plant immune system. However, variations in C availability on pathogen associated molecular pattern (PAMP) triggered immunity (PTI) have not been systematically examined. Here, three types of starch mutants with enhanced susceptibility to Pseudomonas syringae pv. tomato DC3000 hrcC were examined for PTI. In a dark period-dependent manner, the mutants showed compromised induction of a PTI marker, and callose accumulation in response to the bacterial PAMP flagellin, flg22. In combination with weakened PTI responses in wild type by inhibition of the TCA cycle, the experiments determined the necessity of C-derived energy in establishing PTI. Global gene expression analyses identified flg22 responsive genes displaying C supply-dependent patterns. Nutrient recycling-related genes were regulated similarly by C-limitation and flg22, indicating re-arrangements of expression programs to redirect resources that establish or strengthen PTI. Ethylene and NAC transcription factors appear to play roles in these processes. Under C-limitation, PTI appears compromised based on suppression of genes required for continued biosynthetic capacity and defenses through flg22. Our results provide a foundation for the intuitive perception of the interplay between plant nutrition status and pathogen defense.

• Horticultural Science & Technology
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• v.28 no.3
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• pp.387-393
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• 2010

The free sugar content and related enzymes of four different parts, inner, outer, stylar end and stem end, of 'Changhowon Hwangdo' peach ($Prunus$ $persica$, L. Batsch) fruit were compared from August to September in 2006, i.e., from 120 to 150 days after full bloom (DAFB). The soluble solids content (SSC) of stylar end was the highest among the four fruit parts at 150 DAFB. Changes of free sugar content were similar to that of SSC in the four parts. The starch content at the stylar end was the highest at 120 DAFB, while all the other parts showed low starch contents at 150 DAFB. The free sugar composition of peach changed during fruit development. The sucrose was low at 120 DAFB and increased gradually in all parts of peach fruit. On the contrary glucose, fructose and sorbitol decreased with fruit development. The free sugar contents and related enzymes activities were investigated during fruit development. The rapid increase of sucrose contents during fruit development was more affected by sucrose synthase than sucrose phosphate synthase. Activity of SS in the four fruit parts increased continuously over the fruit development period, but activity of acid invertase showed a downward trend. This study found that the free sugar content was affected by enzyme activity for the synthesis or the cleavage. However, it was very difficult to explain sugar accumulation of peach segments with related-enzymes.

• ALGAE
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• v.35 no.3
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• pp.253-262
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• 2020

Haematococcus pluvialis is a commercial microalga that can produce high quantities of astaxanthin. Under induced conditions, some important changes in the subcellular structures related to astaxanthin accumulation were observable. For example, a large number of astaxanthin granules, oil structures and starch granules appeared in the thick-walled cells; Astaxanthin granules gradually dissolved into the oil structures and spread throughout the entire cell with the fusion and diffusion process of oil structures during the middle and late stages of induction; The plastoglobules were closed to the newly formed structures, and some plastoglobules would abnormally increase in size under stress. Based on observations of cell damage, the degradation of membrane structures, such as chloroplasts, was found to be the primary form of damage during the early stage of induction. During the middle stage of induction, some transparent holes were exposed in the dissolving astaxanthin granules in the cytoplasm. In thick-walled cells, these transparent holes were covered by oil substances dissolving astaxanthin, thereby avoiding further damage to cells. Given the relatively few oil structures, in non-thick-walled cells, the transparent holes expanded to form multiple transparent areas, eventually resulting in the rupture and death of cells. These results suggested that the high level of synthesis and the wide range diffusion of oil explained the expansion of astaxanthin in H. pluvialis.

• Journal of Plant Biotechnology
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• v.45 no.2
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• pp.90-101
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• 2018

Strawberry (Fragaria ${\times}$ ananassa) is a globally-cultivated and popular fruit crop, prized for its flavor and nutritional value. Sweetness, a key determinant of fruit quality, depends on the sugar composition and concentration. We selected eight strawberry cultivars based on the fruit soluble solids content to represent high and low sugar content groups. The average soluble solid content was $13.6^{\circ}Brix$ (Okmae, Geumsil, Aram, and Maehyang) and $2.9^{\circ}Brix$ (Missionary, Camino Real, Portola, and Gilgyung53), for the high and low sugar content groups, respectively. Sucrose was the main sugar in the cultivars with high sugar content, whereas fructose was the main component in the low sugar content cultivars. Fruit starch concentration ranged from $3.247{\pm}0.056$ to $3.850{\pm}0.055g/100g$, with a 12% higher concentration in the high sugar content cultivars. Additionally, we identified 41 sugar metabolism-related genes in Fragaria ${\times}$ ananassa and analyzed the relationship between their transcripts and the sugar accumulation in fruit. FaGPT1, FaTMT1, FaHXK1, FaPHS1, FaINVA-3, and FacxINV2-1 were highly expressed in the high sugar content cultivars, while FapGlcT, FaTMT2-1, FaPHS2-1, FaSUSY1-1, and FaSUSY1-2 were highly expressed in the low sugar content cultivars. In general, a greater number of genes encoding sugar transporters or involved in sugar synthesis were highly expressed in the high sugar content cultivars. Contrarily, genes involved in sugar degradation were preferentially transcribed in the low sugar content cultivars. Although gene expression was not perfectly proportional to sugar content or concentration, our analysis of the genes involved in sugar metabolism and accumulation in strawberries provides a framework for further studies and for the subsequent engineering of sugar metabolism to enhance fruit quality.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.256-261
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• 2017

The effects of temperature and length of cold storage on the quality maintenance of fresh "Gold" kiwifruit were investigated. Physio-chemical properties were analyzed in kiwifruit held at $2^{\circ}C$ and $6^{\circ}C$ temperatures compared to fruit at room temperature ($20{\sim}28^{\circ}C$) during 8 weeks of storage. Low temperatures ($2^{\circ}C$ and $6^{\circ}C$) significantly delayed softening and soluble solids content (SSC) accumulation compared to higher temperature ($20{\sim}28^{\circ}C$). Physico-chemical properties of fruits, including weight losses, firmness, SSC, titratable acidity (TA), SSC/TA ratio, and flesh color properties were monitored during storage. Fast firmness loss was detected in fruit stored at higher temperatures compared to low temperature ($2^{\circ}C$). Similar results were observed for acidity according to storage temperature and length of cold storage, whereas SSC increased to the limited values (%Brix) during storage. The soluble solids content (SSC) increased markedly during the first 60 days of storage and remained almost constant thereafter for all treatments. SSC accumulation rates decreased from 5 weeks after storage probably due to differences between initial and ripe kiwifruits, and SSC decreased with each passing week due to natural starch conversion over time. The SSC/acid ratio increased from 18 to 27 until 5 weeks after storage and then slowly declined in all kiwifruit stored at different low temperatures. Sensory evaluation results showed no differences in kiwifruit flesh color stored at two storage temperatures of $2^{\circ}C$ and $6^{\circ}C$.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.351-358
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• 2013

A suitable supply of mineral elements into shoot via a root system from growth media makes plants favorable growth and yield. The shortage or surplus of minerals directly affects overall physiological reactions to plants and, especially, strongly influences carbohydrate metabolism as a primary response. We have studied mineral uptake and synthesis and translocation of soluble carbohydrates in N, P or K-deficient tomato plants, and examined the interaction between soluble carbohydrates and mineral elements. Four-weeks-old tomato plants were grown in a hydroponic growth container adjusted with suboptimal N ($0.5mmol\;L^{-1}\;Ca(NO_3)2{\cdot}4H_2O$ and $0.5mmol\;L^{-1}\;KNO_3$), P ($0.05mmol\;L^{-1}\;KH_2PO_4$), and K ($0.5mmol\;L^{-1}\;KNO_3$) for 30 days. The deficiency of specific mineral element led to a significant decrease in its concentration and affected the concentration of other elements with increasing treatment period. The appearance of the reduction, however, differed slightly between elements. The ratios of N uptake of each treatment to that in NPK sufficient tomato shoots were 4 (N deficient), 50 (P deficient), and 50% (K deficient). The P uptake ratios were 21 (N deficient), 19 (P deficient), and 28% (K deficient) and K uptake ratios were 11 (N deficient), 46 (P deficient), and 7% (K deficient). The deficiency of mineral elements also influenced on carbohydrate metabolism; soluble sugar and starch was substantially enhanced, especially in N or K deficiency. In conclusion, mineral deficiency leads to an adverse carbohydrate metabolism such as immoderate accumulation and restricted translocation as well as reduced mineral uptake and thus results in the reduced plant growth.

• Journal of Microbiology and Biotechnology
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• v.13 no.6
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• pp.969-975
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• 2003

Two conserved amino acid residues in the extra sugar-binding space near the catalytic site of Thermus maltogenic amylase (ThMA) were analyzed for their role in the hydrolysis and transglycosylation activity of the enzyme. Site-directed mutagenesis was carried out by replacing N33l with a lysine (N331K), E332 with a histidine (E332H), or by replacing both residues at the same time (N331K/E332H). The measured $K_m$ values indicated that affinities toward all substrates tested, including starch, pullulan, ${\beta}-cyclomaltodextrin$, and acarbose, were lower in all the mutants compared to that of wild-type ThMA, leading to reduced hydrolysis activity. In addition, the lower ratio of transglycosylation to hydrolysis in the mutants compared to that in the wild-type ThMA indicated that these mutants preferred hydrolysis to the transglycosylation reaction. These results demonstrated that the conserved dipeptide at 331 and 332 of ThMA is directly involved in the formation and accumulation of transfer products by accommodating acceptor sugar molecules.