• Journal of Plant Biology
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• 제27권3호
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• pp.173-178
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• 1984

Callus culture of Phaseolus vulgaris L. was carried out to examine the ability to grow on cytokinin-free medium. Of the sixteen cultivars of P. vulgaris, eight were classified as completely cytokinin-autonomous phenotype and five were found to be cytokinin-dependent phenotype. Intermediate phenotype was shown in three cultivars. Using cv. Palgong and ca 21 as cytokinin-dependent genotypes, the genotype responses to the cytokinin requirements of callus tissue were studied in detail. The callus tissue of cv. Palgong and ca 21 were never habituated in cytokinin-free medium, regardless tissue origin and cytokinin concentration in previous passages. The result suggests that cytokinin dependency of callus tissue of P. vulgaris cv. Palgong and ca 21 may be due to inactivation of cytokinin biosynthetic pathway.

• Applied Biological Chemistry
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• 제29권1호
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• pp.10-15
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• 1986

Cytokinin과 단백질의 결합을 간단하게 결정하는 방법으로서 전기 영동법을 시도하고, 대두의 잎단백질과 cytokinin의 결합여부, cytokinin에 대한 affinity가 있는 단백질의 종류와 상대적 affinity를 조사하였다. 검토된 전기 영동법은 cytokinin과 단백질의 결합뿐만 아니라, cytokinin에 대한 상대적 affinity를 동시에 검정할 수 있는 장점을 가지고 있었다. Ammonium sulfate 침전법, Sephadex G-25 chromatography, paper chromatography, 그리고 전기영동법으로 대두의 잎단백질 중에 BA와 결합하는 단백질이 있음을 확인할 수 있었다. 전기영동법으로 검정한 결과 BA와 결함하는 것이 3 group이 있고, 이중에서 전기영동 이동도로보아 분자량이 작은 단백질 분획과 전기영동 이동도 0.4부근의 분획은 BA에 대한 affinity가 비교적 낮은 반면, 이동도 $0.0{\sim}0.2$의 분획은 affinity가 큰 것으로 생각되었다.

• Molecules and Cells
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• 제19권3호
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• pp.342-349
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• 2005

Cytokinins are adenine derivatives that regulate numerous plant growth and developmental processes, including apical and floral meristem development, stem growth, leaf senescence, apical dominance, and stress tolerance. However, not much is known about how cytokinin biosynthesis and metabolism is regulated. We identified a novel Arabidopsis gene, ALL, encoding an aldolase-like enzyme that regulates cytokinin signaling. An Arabidopsis mutant, all-1D, in which ALL is activated by the nearby insertion of the 35S enhancer, exhibited extreme dwarfism with rolled, dark-green leaves and reduced apical dominance, symptomatic of cytokinin-overproducing mutants. Consistent with this, ARR4 and ARR5, two representative primary cytokinin-responsive genes, were significantly induced in all-1D. Whereas SHOOT MERISTEMLESS (STM) and KNAT1, which regulate meristem development, were also greatly induced, expression of REV and PHV that regulate lateral organ polarity was inhibited. ALL encodes an aldolase-like enzyme that belongs to the HpcH/HpaI aldolase family in prokaryotes and is down-regulated by exogenous cytokinin, possibly through a negative feedback pathway. We propose that ALL is involved in cytokinin biosynthesis or metabolism and acts as a positive regulator of cytokinin signaling during shoot apical meristem development and determination of lateral organ polarity.

• 자연과학논문집
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• 제10권1호
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• pp.33-37
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• 1998

식물의 주요 phytohormone의 하나인 cytokinin은 식물체의 줄기와 뿌리성장 그 외에도 영양의 전달이나 노화방지, 열매숙성 등 식물의 성장과 발달에 미치는 영향은 크고 다양하다. Cytokinin 생합성에 관여하는 효소를 생산하는 것으로 알려져 있으며 토양박테리아 Agrobacterium tumefaciens에 존재하는 유전자인 isopentenyl transferase (jpt)를 이용한 많은 분자생물학적 연구가 진행되어 왔는데 그 중 하나로 이 연구에서 jpt 유전자에 의한 cytokinin의 overproduction이 식물체에 성장과 발달에 어떠한 영향을 주는지 관찰하고 그 결과가 제시할 수 있는 작물의 유전 공학적 이용가능성에 대하여 알아본다.

• Journal of Plant Biology
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• 제25권4호
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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.

• 농업과학연구
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• 제4권2호
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• pp.121-125
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• 1977

딸기의 휴면기(休眠期)에 있어서의 내생(內生) Cytokinin-like 물질(物質)의 활성(活性)은 휴면(休眠)의 정도(程度)에 따라 변화(變化)를 보였고, 이 활성(活性)의 변화(變化)는 생육상(生育相)의 변화와 비슷한 결과(結果)를 나타냈다. 딸기의 Crown 부분(部分) 20g을 Methyl alcohol로 추출하여 Column chromatography로 분류, Soybean callus bioassay 한 결과 두 부분(部分)에서 활성(活性)을 보였고, 이 중 Ethyl acetate/methyl alcohol; 50/50 및 90/10에서 강한 활성(活性)을 보였다. 생육상과의 관계는 생육(生育)이 비교적 왕성한 시기에 강한 활성(活性)이 나타났으며, 휴면(休眠)이 깊은 시기에 활성(活性)이 낮았다. 그러나 일정(一定)한 저온기간(低溫期間)의 경과와 함께 다시 활성화(活性化)되었으며, 이 결과로 휴면(休眠)의 깊이의 정도(程度)와 내생(內生) Cytokinin의 양적증대(量的增大)와는 역비례적인 상관성을 보여주고 있다.

• Molecules and Cells
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• 제28권4호
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• pp.375-382
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• 2009

The 26S proteasome is a 2-MDa complex with a central role in protein turn over. The 26S proteasome is comprised of one 20S core particle and two 19S regulatory particles (RPs). The RPN12a protein, a non-ATPase subunit of the 19S RP, was previously shown to be involved in cytokinin signaling in Arabidopsis. To further investigate cellular roles of RPN12a, RNAi transgenic plants of RPN12a were constructed. As expected, the 35S:RNAi-RPN12a plants showed cytokinin signaling defective phenotypes, including abnormal formation of leaves and inflorescences. Furthermore, RNAi knock-down transgenic plants exhibited additional unique phenotypes, including concave and heart-shape cotyledons, triple cotyledons, irregular and clustered guard cells, and defects in phyllotaxy, all of which are typical for defective cytokinin signaling. We next examined the mRNA level of cytokinin signaling components, including type-A ARRs, type-B ARRs, and CRFs. The expression of type-A ARRs, encoding negative regulators of cytokinin signaling, was markedly reduced in 35S:RNAi-RPN12a transgenic plants relative to that in wild type plants, while type-B ARRs and CRFs were unaffected. Our results also indicate that in vivo stability of the ARR5 protein, a negative regulator of cytokinin signaling, is mediated by the 26S proteasome complex. These results suggest that RPN12a participates in feedback inhibitory mechanism of cytokinin signaling through modulation of the abundance of ARR5 protein in Arabidopsis.

• Journal of Plant Biotechnology
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• 제32권1호
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• pp.15-21
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• 2005

세포 주기의 조절에 있어 중요한 역할을 담당하고 있는 cyclin 유전자들을의 발현 양상을 벼에서 유도한 캘러스와 엽신을 이용하여 관찰하였다. 특히 캘러스를 이용한 분석결과 2,4-D와 kinetin이 조합된 배지 러에 7일 동안 암 배양한 후 이를 cytokinin만이 첨가된 배치로 옮겼을 때 A-, B-, C-type cyclin 유전자들의 발현이 더 증가되었다. 또한 벼실생의 각 기관에서 cyclin 유전자의 발현양을 조사한 결과 다른 기관들에 비해 잎에서 A-, B, C-type cyclin 유전자들이 더 많이 발현하였으나 잎에 cytokinin의 종류와 농도를 다르게 처리하여 24시간동안 배양한 결과에서는 zeatin을 제외하고는 cytokinin의 종류와 양이 cyclin 유전자들의 발현에 큰 영향을 미치지 못함을 알 수 있었다. 본 실험에서는 벼 cyclin유전자의 발현과 식물생장조절제 처리와의 상관 관계에 대해서 조사하였다.

• Applied Biological Chemistry
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• 제35권6호
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• pp.507-512
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• 1992

대두(Glycine max)의 ${\beta}$-1,3-glucanase를 분리동정하고 benzyladenine(BA)이 이 효소의 세포내 함량과 활동도에 미치는 영향을 조사하였다. 또 세포벽의 callose함량과 protoplast의 세포벽재생에 미치는 BA의 영향을 조사하여, cytokinin이 식물의 세포벽재생을 촉진하는 기능이 있음을 확인하고 세포벽재생에 있어서 cytokinin의 작용기구를 검토하였다. 대두 ${\beta}-1,3-glucanase$는 21 kD의 polypeptide로 동정되었는데 이 polypeptide의 세포내함량과 효소활성은 BA처리에 의하여 저하되었다. 그리고 callus세포벽의 callose함량과 protoplast의 세포벽재생율이 BA처리에 의하여 증가되었다. 이 결과들은 cytokinin이 세포의 ${\beta}-1,3-glucanase$수준을 저하시켜 callose분해를 억제함으로써 세포벽 재생을 촉진할 수 있음을 보여주었다.

• 한국작물학회지
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• 제48권1호
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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.