• Journal of Plant Biology
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• v.25 no.4
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• pp.161-168
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• 1982

The activities of auxins and cytokinins have been examined in the growth of callus tissue derived from Phaseolus vulgaris L. cv. Damyang. The synthetic auxin, picloram was the most effective in promoting callus growth and the range of effective concentrations (0.1$\mu{M}$ to 32$\mu{M}$) was broad. 2, 4-D also enhanced callus growth at the optimal concentration of 3.2$\mu{M}$. NAA promoted callus growth at relatively higher concentrations than other auxins tested. IAA was less effective in supporting callus growth. Cytokinin bearing saturated side chain ($N^6$-isopentyladenine) was approximately 30 times more active than the corresponding unsaturated compound, $N^6$-($\D^2$-isopentenyl) adenine. The abilities of cytokinin-autonomous growth were also examined. Callus tissues previously grown on concentrations lower and/or higher than optimal concentrations of cytokinins were better habituated in the subsequent passage. It was suggested that the development of cytokinin autonomy may be related to dosage-concentrations of cytokinin in the previous passage.

• Journal of Plant Biology
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• v.32 no.4
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• pp.343-350
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• 1989

Calcium promoted ethylene production from mungbean hypocotyl segments incubated in the presence of either auxin or cytokinin (kinetin). Time course studies indicated that the calcium effect on ethylene production had a longer latent period (about 6 h) in combination with kinetin than with auxin. Studies on the effects of agents that are known to interfere with either action or transport (uptake) of calcium on ethylene biosynthesis indicated different patterns between auxin- and kinetin-treated tissues. Auxin-induced ethylene production was inhibited by the calmodulin inhibitor, trifluoperazine (TFP), and this inhibition was overcome by high concentrations of calcium applied, but TFP had no significant effect on kinetin-induced ethylene production regardless of calcium in the medium. The calcium channel blocker, verapamil, inhibited auxin-induced, but had little effect on kinetin-induced, ethylene producton. In vivo activity of "ethylene forming enzyme (EFE)" was found to be substantially promoted by calcium treatment. The enzyme activity was further increased by kinetin when segments were simultaneously treated with calcium, but auxin did not have such an effect.an effect.

• Journal of Plant Biotechnology
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• v.32 no.1
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• pp.15-21
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• 2005

The expression patterns of cyclin genes, which play a crucial role on cell cycle control, were analyzed with rice calli and leaf blades from seedlings. When callus was transferred from media containing the combinations of 2,4-D and kinetin under the dark conditions to medium supplemented with cytokinin-only on 7 days after the cultures, the expression levels of A-, B- and C-type cyclins from callus were increased significantly. Despite the fact that cyclin genes were well expressed on leaf blades rather than other organs in rice seedlings, rice leaf blades grown on the medium containing various combinations and concentrations of cytokinin for 24 hours had no major effect on the expression patterns of cyclins except zeatin. The relation between cytokinin regulation and the expression of cyclins of rice is discussed.

• Journal of The Korean Society of Grassland and Forage Science
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• v.21 no.1
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• pp.15-20
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• 2001

Plant growth regulators were treated on the cut perennial ryegrass (Lolium perenne L. cv. Reveille) to investigate the effect on the regrowth after cutting. The growth showed better result when 0.1 or 0.5 mg/L cytokinin were treated. Among cytokinins, kinetin or 2iP gave the better effect on the growth than BAP. In 2.4-D as an auxin. cut plants grew best at the concentration of 0.1 mg/L. The initial regrowth was very vigorous when GA$_3$ was treated as a growth regulator, but the growth was retarded after 2 weeks later of cutting. Co-treatment of kinetin as a cytokinin and 2,4-D as an auxin showed synergistic effect on the regrowth of cut perennial ryegrass. Both plant growth regulators gave the same result at the same concentrations in the suspension culture of perennial ryegrass cells.

• Applied Biological Chemistry
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• v.35 no.6
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• pp.507-512
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• 1992

A ${\beta}-1,3-glucanase$ of soybean (Glycine max) was isolated, and the effects of benzyladenine(BA) on celluar levels of the enzyme content and activity were studied. The effects of BA on callose content in cell wall and wall regeneration of protoplasts were also studied to show promoting effect of cytokinin in cell wall regeneration and to elucidate action mode of cytokinin. The polypeptide of 21 kD was identified as ${\beta}-1,3-glucanase$, and the cellular content and activity of this polypeptide were decreased by BA treatment. The callose content in cell wall of callus and the wall regeneration of protoplasts were increased by BA treatment. These results indicate that cytokinin promotes cell wall regeneration by inhibition of callose degradation via decreasing ${\beta}-1,3-glucanase$ level in cell.

• Journal of Life Science
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• v.20 no.5
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• pp.745-749
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• 2010

This study was conducted to examine the effect of cytokinin ($N^6$-benzyladenine; BA) and/or an IAA on ethylene production of maize (Zea mays) primary roots. When the two hormones were applied exogenously, both hormones synergistically increased ethylene production, which was greater than the sum of the level of each hormone's effect. For example, the ethylene production was stimulated between about 87% and 170% of the control by $10^{-4}\;M$ BA with $10^{-4}\;M$ IAA for 8 hours respectively, whereas the ethylene production was increased by about 480% of the control when the two hormones were treated simultaneously. Such a synergistic effect was also found in changes in the activity and gene expression level of ACC synthase. However, in the case of ACC oxidase did not show any observable effects. Based on our results, it is possible to conclude that BA and IAA stimulated the ethylene production synergistically by affecting the ACC synthase in maize roots.

• Journal of Plant Biotechnology
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• v.29 no.2
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• pp.111-115
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• 2002

Taraxacum platycarpum has been used as a medicinal plant. We investigated optimal condition for efficient plant regeneration through adventitious shoot formation on medium with various kinds of growth regulators. Adventitious shoot formation was achieved when cytokinin was used alone. Shoot formation was higher on MS medium containing 2 mg/L BAP compared to that with 2 mg/L kinetin and 2 mg/L 2-ip. Among root, hypocotyl and cotyledon, roots were the best explant for the adventitious shoot induction. Adventitious shoot formation from roots declined markedly by the combination of both 0.1 mg/L NAA and 2 mg/L BAP, while shoot formation from cotyledons was stimulated by the same combination. Root formation from the regenerated shoots was achieved on 1/3MS medium containing 0.2 mg/L NAA. Regenerated plantlets was acclimatized and transplanted to the soil, showing 100% survival.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2005.11a
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• pp.81-81
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• 2005

• Journal of Plant Biotechnology
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• v.36 no.2
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• pp.170-173
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• 2009

Leaf and petiole explants of Pulsatilla koreana NAKAI were cultured on MS medium supplemented with various concentrations of zeatin, kinetin or BAP combined with 0.05 mg/L IAA. After 6 weeks of culture, effects of cytokinin on adventitious shoot formation from explants were investigated. The highest frequency of shoot formation was obtained when petiole explants were cultured on medium with 0.5 mg/L zeatin and 0.05 mg/L IAA. Regenerated shoot were transferred on to root induction medium. The best root formation was observed at 1/2 MS medium with 1.5 mg/L NAA. Rooted plantlets were transplanted to a mixture of perlit and soil (1:3), where they were successfully acclimatized.

• Journal of Plant Biotechnology
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• v.29 no.2
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• pp.123-127
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• 2002

Effect of cytokinins (BA, TDZ, zeatin, 2iP, and kinetin) applied either singly or in combination on in vitro growth of two grape cultivars ('Cabernet Sauvignon' and 'Campbell Early') was investigated as a serial work for mass production of grapevine nursery stocks. In single treatment, shoot growth of two cultivars was most favorable in control. Shoot proliferation was satisfactory with 10 $\mu$M BA regardless of cultivars and cytokinin combinations, followed by TDZ. Other treatments resulted in very poor or no branching. Total explants ready for subculture produced by 10 $\mu$M BA outnumbered those by other treatments. TDZ was also effective. TDZ significantly increased the fresh weight and callus formation while shoot growth was unsatisfactory. Shoot growth response of two cultivars in combined treatments was also most favorable in control as was in single treatments. When TDZ was combined with zeatin, 2iP, and kinetin which failed to induce branching, proliferous branching was induced though the shoot number was behind that of single treatments of BA and TDZ. TDZ was very effective for total number of explants and fresh weight, showing 10-fold increase.