• Horticultural Science & Technology
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• v.17 no.6
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• pp.742-746
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• 1999

Contents of mineral element and cytokinin in the xylem sap of 'Keumdongee' and 'Tongilhwang' oriental melons were compared with those in oriental melons grafted onto 8 rootstocks. The effect of grafting on the fruit quality of oriental melon was also investigated. Flesh firmness varied with rootstocks. Soluble solids contents in the placenta tissue of grafted 'Tongilhwang' were higher than that in the 'Keumdongee'. Electric conductivity of the xylem sap in own-rooted plants was higher in 'Keumdongee' than in 'Tongilhwang', but it increased in 'Tongilhwang' once they were grafted. The sap volume per plant was greater in 'Keumdongee' than in 'Tongilhwang'. The mineral concentrations varied considerably depending on the rootstock used. Xylem sap of grafted oriental melons contained a higher amount of mineral ions, especially $NO_3{^-}$ and $PO_4{^-}$, than did the sap in own-rooted plants. The increase in the mineral levels in sap due to grafting was most apparent in 'Tongilhwang'. Xylem sap from both 'Keumdongee' and 'Tongilhwang' contained trans-zeatin (t-Z), trans-zeatin riboside (t-ZR), and dihydrozeatin riboside (DHZR). Small amounts of isopentenyl adenine (IPA) and isopentenyl adenine riboside (IPAR) were also detected. Trans-zeatin riboside was the most abundant, followed by t-Z. Cytokinin concentration in 'Keumdongee' was not significantly influenced by rootstock type used, although the highest concentration of cytokinins in 'Keumdongee' was obtained with 'Chamtozwa' rootstock. However, the cytokinin concentration in 'Tongilhwang' increased with grafting irrespective of rootstock type used.

• Journal of Life Science
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• v.16 no.3 s.76
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• pp.447-453
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• 2006

Histidine kinase plays important roles in signal transduction in plant. We characterized the function of Arabidopsis histidine kinase 3 (AHK3) and analyzed the expression patterns of genes and proteins in its mutant ahk3 by trans-zeatin (t-zeatin). The ahk3 exhibited decreased sensitivity to t-zeatin during callus formation, seedling growth, and leaf senescence. From proteomic analysis of ahk3, eukaryotic translation initiation factor 5A-2, auxin binding glutathione S-transferase, and NDPK1 were identified not to be induced by t-zeatin, when compared to the wild-type. In addition, the expression levels of ARR4 and ARR16 among A-type response regulators (ARRs) markedly decreased in ahk3 by t-zeatin treatment. These results suggest that AHK3 plays an important role in cytokinin signaling and the proteins identified from proteomic analysis and specific ARRs, ARR4 and ARR16 may be directly or indirectly associated in AHK3-mediated cytokinin signaling.

• Journal of Plant Biotechnology
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• v.32 no.4
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• pp.251-256
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• 2005

Cytokinins are essential plant hormones that play crucial roles in various aspects of plant growth and development. To better understand the molecular mechanisms of cytokinin action, we identified cytokinin related proteins by a proteomic approach. Proteins extracted from control and trans-zeatin treated Arabidopsis seedlings were separated and analyzed by two dimensional gel analysis. Differentially expressed protein spots were identified with peptide mass fingerprinting based on matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and database searching, We obtained ten up-regulated and one down-regulated proteins upon t-zeatin treatment. The expression of the following proteins was induced; pollen allergen like protein, L-ascorbate peroxidase, tetrapyrrole methylase family protein, SGT1 protein homolog, disease resistance related protein, maternal embryogenesis control protein, paxneb related protein, gluthathione S-transferase and IAA amino acid hydrolase homolog.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.1
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• pp.8-12
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• 2003

To find out the relationship between pod development and cytokinin contents during reproductive stage of peanut, the cytokinin contents, trans-zeatin ribo-side (t-ZR) and dihydrozeatin riboside (diZR), were investigated at 0, 7, 14, 21 and 28 days after flowering (DAF). The amounts of t-ZR and diZR in cotyledon and first branch among primary branches were 3, 448 pmol/g (FW) and 4, 824 p/g (FW), respectively, which were higher than those of other branches. The t-ZR and diZR contents of lower parts on the branch from cotyledon node at 7 DAF were 579 pmol/g (FW) and 2, 028 pmol/g (FW), respectively, which were higher than those of upper parts. The cytokinin contents of reproductive organs as flowering progressed were increased at 0 and 14 DAF on branch and position of node. The cytokinin contents of upper part with pruning the lower part on the branch from cotyledon node were high 112-337% at 7 DAF and 14 DAF compared with those of the control. In case of remove the upper part of the first internode on main axis, t-ZR contents was 4.7 times higher than diZR contents at 7 DAF. The pod setting rate of flower and position on the branch from cotyledon node was closely related to the cytokinin contents during floral reproductive stage.

• Journal of Bio-Environment Control
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• v.17 no.3
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• pp.221-225
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• 2008

Lilium formolongi 'Fl August' plantlets with scale-leaves and scale-bulb were treated at 10, 15, 20, $25^{\circ}C$ for 15, 30, or 45 days and planted in February, March, April and May. In the April planting, flowering percentage was below 10% and in the May planting no flowering occurred. Sprouting and flowering percentages were lower at the late planting times. Days to flowering of the April planting was 110.8 days compared to 128 days for the February planting. Plant height and numbers of leaves were reduced to 7.2 in May planting, compared to 40.5 leaves in February planting, and almost no flowers emerged in either the April or May plantings. Plantlets exposed to 10 or $15^{\circ}C$ flowered at 80 percent or higher at all treatment durations, but at 20 or $25^{\circ}C$ flowering percentages were lower, with 30% or less in the $25^{\circ}C$ treatment. In the $15^{\circ}C$ treatment days to flowering were less than 100 days, while the number of flowers and flower bud differentiation were greatest in the $15^{\circ}C$ treatment. Cytokinin and auxin were analyzed in bulblets grown at 15, 20 and $25^{\circ}C$. T-zeatin content was three times greater in the $15^{\circ}C$ treatment than at $25^{\circ}C$, but the content of indoleacetic acid (IAA) was less at $15^{\circ}C$ than at 20 and $25^{\circ}C$. In the $15^{\circ}C$ treatment, T-zeatin content was about twice the IAA content in the scale- bulblet. The auxin and cytokinin balance may affect flower bud differentiation. $15^{\circ}C$ with 30 days was most effective for flowering in scale-bulblet and planting of February and March were effective for flowering too.

• Journal of Plant Biology
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• v.38 no.2
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• pp.143-151
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• 1995

Addition of plant growth hormones [0.01 mg/L NAA and 0.2mg/L benzyladenine (BA)] to a woody plant medium stimulated the adventitious bud formation of poplar explants during culture. Endogenous IAA content increased rapidly at the initial culture stage and then decreased, being followed by rapid increment again at the late culture. But the content of trans-zeatin riboside (t-ZR) increased continuously during the culture. Cytoplasmic soluble proteins were analyzed by one- and two-dimensional SDS-PAGE. Increased amount of 40 kD band was detected by one-dimensional electrophoresis using Coomassie Blue staining during the culture and two distinctive proteins whose mol wt is 40,000 were detected by two-dimensional electrophoresis using autoradiography and these proteins were synthesized continuously prior to the adventitious bud formation. When the midvein segments were transferred to the actinomycin D-containing medium, the spots of adventitious bud-related proteins(ABRPs) did not disappeared but weakened in intensity. So, it is concluded that genes coding for the ABRPs are regulated to some degree at the transcriptional level. Also, they were not observed in BA-free medium, suggesting that these proteins be regulated by cytokinin, which made then possible to form the adventitious bud.

• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1622-1628
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• 2006

Bacteria from the Methylobacterium genus, called pink-pigmented facultative methylotrophic bacteria (PPFMs), are common inhabitants of plants, potentially dominating the phyllosphere population, and are also encountered in the rhizosphere, seeds, and other parts of plants, being versatile in nature. The consistent success of the Methylobacterium plant association relies on methylotrophy, the ability to utilize the one-carbon compound methanol emitted by plants. However, the efficiency of Methylobacterium in plant growth promotion could be better exploited and thus has attracted increasing interest in recent years. Accordingly, the present study investigated the inoculation effects of Methylobacterium sp. strains CBMB20 and CBMB 110 on seed imbibition to tomato and red pepper on the growth and accumulation of phytohormone levels under gnotobiotic conditions. Seeds treated with the Methylobacterium strains showed a significant increase in root length when compared with either the uninoculated control or Methylobacterium extorquens $miaA^-$ knockout mutanttreated seeds. Extracts of the plant samples were used for indole-3-acetic acid (IAA), trans-zeatin riboside (t-ZR), and dihydrozeatin riboside (DHZR) assays by immunoanalysis. The treatment with Methylobacterium sp. CBMB20 or CBMB 110 produced significant increases in the accumulation of IAA and the cytokinins t-ZR and DHZR in the red pepper extracts, whereas no IAA was detected in the tomato extracts, although the cytokinin concentrations were significantly increased. Therefore, this study proved that the versatility of Methylobacterium as a plant-growth promoting bacteria could be better exploited.