• Molecules and Cells
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• 제25권2호
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• pp.294-300
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• 2008

Cytokinins are essential hormones in plant development. $\underline{A}$rabidopsis $\underline{h}$istidine-containing $\underline{p}$hosphotransfer proteins (AHPs) are mediators in a multistep phosphorelay pathway for cytokinin signaling. The exact role of AHP4 has not been elucidated. In this study, we demonstrated young flower-specific expression of AHP4, and compared AHP4-overexpressing (Ox) trangenic Arabidopsis lines and an ahp4 knock-out line. AHP4-Ox plants had reduced fertility due to a lack of secondary cell wall thickening in the anther endothecium and inhibition of IRREGURAR XYLEMs (IRXs) expression in young flowers. Conversely, ahp4 anthers had more lignified anther walls than the wild type, and increased IRXs expression. Our study indicates that AHP4 negatively regulates thickening of the secondary cell wall of the anther endothecium, and provides new insight into the role of cytokinins in formation of secondary cell walls via the action of AHP4.

• Journal of Plant Biology
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• 제5권2호
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• pp.1-5
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• 1962

Attempts were made in order to make clear the meiotic irregularities, male gametophyte formation and spermatogenesis for the purpose of applying these embryological facts to taxonomic works. Followings are the results obtained : 1. Meiosis is extremely irregular, giving rise to giant, micro, and empty, pollens. Meiotic division in each PMC is observed synchronizing. 2. In the microspore immediately before the vegetative-generative nuclear division, the nucleus locates appressed to the inner wall, most of the other part of the cell being occupied by large vacuoles. 3. Spindle symmetry in the microspore nuclear division is of intermediate type. 4. Nuclear divisions in each micropore are not synchronized as in meiosis. 5. Generative nucleus is located in close contact with the inner wall, while the vegetative nucleus occupies the central part of pollen grain. The pollen in this stage looks somewhat like broad bean. Afterward the generative nucleus loses contact with the wall, the nuclear shape changing from lenticular to roundsh. 6. The generative nucleus in fully matured pollen grain usually takes the shape of crescence, those in abortive pollen, lenticular or ellipsoidal, etc.

• Journal of Plant Biology
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• 제38권2호
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• pp.181-193
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• 1995

Cuticle micromorphology of four families of Korean gymnosperms, Cycadaceae, Ginkgoaceae, Taxaceae, and Cephalotaxaceae, were studied with scanning electron microscopy. The outer and inner features of abaxial and adaxial cuticles were described in details; the absent or present of Florin ring, orifice, trichome, and plug and their shape, the shape and periclinal and anticlinal wall sculpture of epidermal cells, the shape of cuticular flange of epidermal cell, guard cell, and subsidiary cell, the number of stomatal bands and rows, and stomatal apparatus including the shape of polar extension, number of subsidiary cells, the sculpture of guard cell and subsidiary cell. Most of these features have not been sufficiently substantiated by the previous reprots. Furthermore, all the species investigated showed distinctive cuticle morphology with morphological and taxonomical informations.

• 한국식품과학회지
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• 제27권6호
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• pp.934-938
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• 1995

Autoclaving, microwaving, 압출성형 등의 열 및 기계적 에너지에 대한 밀기울 세포벽의 반응성을 구명하기 위하여 수용성 분획의 특정을 연구하였다. 수용성 분획의 화학적 분석과 겔여과 크로마토그래피 결과에 의하면 밀기울에 포함되어 있는 전분의 호화가 가장 중요한 수용화 기작으로 작용하며, 이 과정에서 비전분성 세포벽 구성물질의 수용화도 일어냐는 것으로 밝혀졌다. 수용성의 비전분 다당류의 GC 분석결과 적용된 열처리 과정에서 세포벽의 arabinoxylan 부위가 많이 수용화되는 현상을 보였다. 특히, 고온파 고전단력을 동시에 제공하는 압출성형은 밀기울의 수용화에 가장 효율적이었으며, 또한 상대적으로 고분자량의 비전분성 구성성분을 수용 화시켰다.

• Journal of Plant Biotechnology
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• 제42권2호
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• pp.93-103
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• 2015

The isolation, cloning, and characterization of an R2R3-MYB transcription factor gene (MtMYB70) from the model legume Medicago truncatula is reported. MtMYB70 consists of a 768-bp coding sequence corresponding to 255 amino acids. Sequence alignment revealed that MtMYB70 cDNA contains conserved R2R3-type MYB domains with highly divergent C terminal regions. MtMYB70 was found to have relatively low sequence homology with known R2R3-MYB genes. Phylogenetic analysis placed the R2R3-MYB domain of MtMYB70 closest to PtMYB1, a known activator of lignin biosynthesis. Overexpression of MtMYB70 under the control of the 35S promoter in transgenic poplar did not cause a significant difference in total lignin content relative to the control, but glucan content was significantly increased in transgenic poplar. Therefore, MtMYB70 might have regulatory role in the biosynthesis of cell wall structural carbohydrates.

• 미생물학회지
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• 제52권2호
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• pp.226-229
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• 2016

먹물버섯 Coprinellus congregatus의 버섯조직이 자가분해되는 시기에 발현되는 chitinase (Chi2)는 사람에게 질병을 일으키는 Cryptococcus neoformans의 세포벽 두께를 정상 세포벽의 32% 수준까지 감소시킬 뿐만 아니라, 세포 외 섬유상 물질도 제거하였다. Chi2 처리에 의하여 사람에게 알레르기를 유발하는 Alternaria alternata의 생장은 물론 생쥐 모델에서 이 균에 의한 피부알레르기 증상도 감소시켰다.

• Journal of Plant Biology
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• 제30권3호
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• pp.173-179
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• 1987

The effect of polyamine, Ca2+ and calmodulin on GS ($\beta$-glucan synthetase) activity was studied in Daucus carota root. The Ca2+ is shown to have no effect on the GS activity whereas the GS II activity is increased in response to increase in concentration of the Ca2+. When the protoplasts are cultured, for 4 days, the GS II activity increases as a tunction of time and reachs a maximum after 3 days at a time when the network of cellulose microfibrils is known to be synthesized. The effect of the Ca2+ and 1mM spermine on the GS II activity turns out to be synergistic, especially more synergistic at lower concentration of the Ca2+. The GS II activity seems to be enhanced by the Ca2+. The GS II activity in the protoplast treated by the calcium channel blocker, verapamil, turns out to be lower than that of the control. Cumulative results suggest that the Ca2+ stimulates the cell wall regeneration via enhancement of the GS II activity responsible for synthesizing the cell wall component throught synergistic effect with spermine.

• 식물조직배양학회지
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• 제25권6호
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• pp.477-485
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• 1998

감자 plastid 형질전찬을 위한 새로운 DNA 절편을 확보하고자, 감자의 trnK-matK 유전자를 PCR 방법으로 클로닝하고 특성을 조사하였다. 염기서열 분석을 통하여 trnK-matK 유전자에는 두 종류의 polymerase 인지부위[Prokaryotic site(plastid encoded polymerase)와 eukaryotic site (nuclear-encoded polymerase)]가 족재함을 알 수 있었다. 이 사실은 trnK-matK 유전자의 발현이 광합성조직과 비광합성조직에서 서로 다른 polymerase에 의하여 조절됨을 시사하였다. 한편 MatK의 아미노산서열을 분석한 결과 식물에 따라 아미노산 identity가 39-75%로 다양하였으나, 감자와 담배는 98%의 아주 높은 identity를 보였다. Northern분석을 통하여 포장과 기내에서 생육된 감자 식물체 모두에서, trnK-matK 의 전사 수준이 잎에서 높고 괴경에서는 낮음을 알 수 있었다. 한편 잎에서의 16s rDNA의 전사수준은 괴경에 비해 약 50배 높았다. 이것으로 미루어보아 괴경에서 수준이 낮을 것은, 괴경에서는 plastid genome copy 수가 적거나 plastid 수가 적기 때문으로 추정된다. 이상의 결과로서 엽록체와 amyloplst 모두에서 trunK-matK 유전자가 활발하게 발현되고 있음을 알 수 있었다. Plastid genomic DNA의 Southern 분석을 통하여 trnK는 1 copy로 존재하고, matK는 trnK intron을 포함하고 있음을 확인하였다. 따라서 감자 plastid형질전환의 새로운homologous recombination 부위로 trnK-matK유전자를 이용할 수 있을 것이다.

• 한국자원식물학회지
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• 제14권2호
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• pp.102-107
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• 2001

팽이버섯 1주기를 수확한 폐배지 톱밥을 버섯재배 용으로 재활용 할 수 있는지를 알아보고자 팽이버섯을 재배한 침엽수재 의 톱밥을 현미경적 관찰을 통해 그 분해정도와 분해양태를 파악하였다. 아울러 팽이버섯 재배에 사용된 톱밥의 수종 식별도 실시하였다. 팽이버섯 재배용으로 사용된 톱밥의 수종은 대부분 소나무속 경송류로 식별되었고 극히 일부만 미송 (Douglas-fir)톱밥이 존재하였다. 팽이버섯 1주기를 수확한 폐배지 소나무 톱밥에는 균사에 노출된 부분과 방사조직에서 균사의 밀도가 높게 나타났다. 팽이버섯균의 공격을 받은 세 포벽은 박벽화현상과 침식현상을 보였으나, 이 같은 부후양태를 보인 세포벽은 극히 일부에 지나지 않았다. 이상의 현미경 관찰결과 팽이버섯을 1주기 수확한 소나무 톱밥은 버섯재배용으로 재활용하기에 충분한 세포벽 물질을 보유하고 있는 것으로 나타났다.

• The Plant Pathology Journal
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• 제31권1호
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• pp.1-11
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• 2015

Antimicrobial cyclic peptides derived from microbes bind stably with target sites, have a tolerance to hydrolysis by proteases, and a favorable degradability under field conditions, which make them an attractive proposition for use as agricultural fungicides. Antimicrobial cyclic peptides are classified according to the types of bonds within the ring structure; homodetic, heterodetic, and complex cyclic peptides, which in turn reflect diverse physicochemical features. Most antimicrobial cyclic peptides affect the integrity of the cell envelope. This is achieved through direct interaction with the cell membrane or disturbance of the cell wall and membrane component biosynthesis such as chitin, glucan, and sphingolipid. These are specific and selective targets providing reliable activity and safety for non-target organisms. Synthetic cyclic peptides produced through combinatorial chemistry offer an alternative approach to develop antimicrobials for agricultural uses. Those synthesized so far have been studied for antibacterial activity, however, the recent advancements in powerful technologies now promise to provide novel antimicrobial cyclic peptides that are yet to be discovered from natural resources.