• 식물조직배양학회지
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• 제27권3호
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• pp.175-180
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• 2000

발아를 위한 MS 액체배지에서 체세포배를 1주일간 배양하다가 고형배지로 옮겨 배양하면 92%가 발아하지만 액체배지 배양기간이 길어지면 발아율이 낮아져서 4주간 배양 후 고체 배지로 옮기면 26％ 밖에 발아하지 않았다. 액체배지에서 발아처리된 체세포배는 배축과 유근의 생장은 충실하게 일어나데 일부에서는 배축에 2차배가 발생되거나 배축과 유근 기부에서 캘러스가 형성된 경우도 있었다. 주사전자현미경에 의한 관찰 결과 경정분열조직을 이루고 있는 세포는 엉성하게 배열되어 있고 제1엽원기가 발생된 경우 그 구조가 충실하지 못하여 생장이 중단되어 있으며 엽원기의 발생이 않된 경우도 있었다. 그러므로 액체배지에서 체세포배의 발아가 억제된 원인은 경정분열조직의 구조적 결함으로 경엽부 형성이 일어나지 못하기 때문으로 사료된다.

• 한국산림과학회지
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• 제87권3호
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• pp.493-500
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• 1998

본 연구는 광도가 층층나무 자엽단계 유묘의 생장에 미치는 영향과 생장에 필요로 하는 한계광도를 구명하기 위하여 자엽단계의 유묘를 대상으로 385, 32, 17, 8 및 $5{\mu}mol\;m^{-2}s^{-1}$의 광도로 설계된 growth chamber내에서 자엽하축의 길이생장, 자엽의 팽창, 본엽의 발생시기, 부위별 건중량 등을 측정하였다. 자엽은 유묘의 초기생장에 영향을 미쳐 자엽의 크기가 증가할수록 유묘의 생장도 좋았다. 자엽하축의 길이 생장은 $385{\mu}mol\;m^{-2}s^{-1}$ 광도에서 보다 상대적으로 낮은 광도인 32, 17, 8, $5{\mu}mol\;m^{-2}s^{-1}$에서 증가되었으나 건중량은 광도가 낮아질수록 감소되었다. 광도가 낮아짐에 따라 본엽의 발생시기가 늦어졌으며 발생수도 감소되었고, $8{\mu}mol\;m^{-2}s^{-1}$와 $5{\mu}mol\;m^{-2}s^{-1}$ 광도에서는 본엽이 발생 조차 되지 않았다. 자엽은 $385{\mu}mol\;m^{-2}s^{-1}$ 광도에서 보다 $32{\mu}mol\;m^{-2}s^{-1}$와 $17{\mu}mol\;m^{-2}s^{-1}$ 광도에서 더 많이 팽창하였지만 건중량은 적었다. 광도가 낮아짐에 따라 자엽, 자엽하축, 뿌리, 본엽의 건중량이 감소되었으며 자엽의 건중량 감소율용보다 뿌리의 감소율이 더 높아 T/R율은 급격히 증가되었다. $8{\mu}mol\;m^{-2}s^{-1}$와 $5{\mu}mol\;m^{-2}s^{-1}$ 광도에서는 뿌리가 거의 발달하지 못하였다. 본 실험을 통해 볼 때 층층나무 발아유묘의 생육가능 최저광도는 $17{\mu}mol\;m^{-2}s^{-1}$ 이상인 것으로 사료된다.

• Journal of Plant Biotechnology
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• 제7권3호
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• pp.161-167
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• 2005

Brassinosteroids are steroidal plant hormones and are known to modulate physiological and cellular response in a wide range of plant species. Considerable insights has been achieved of the physiological role of brassinosteroid in Brassica species in the past few years, but their effect on direct organogenesis has not been extensively studied. In this sense, under optimal basal media and growth conditions we tested the cellular and organogenic response of 24-epibrassinolide (EBL) in a variable concentration (0.1 to $5.0\;{\mu}M$) and Zeatin (Z) (1.0 to $100\;{\mu}M$) and their synergic effect on hypocotyl explants of cauliflower and broccoli. The isolated EBL accelerated cell elongation and promotes direct organogenesis. One micromolar EBL + $10\;{\mu}M$ of Z was the most efficient combination for cell elongation, cell differentiation as well as for organogenesis. A suppressing effect on root induction was confirmed for all the tested hormone levels. The general results indicate a synergic effect of EBL-Z and EBL potentates Zeatin activity, at least in certain tissues. Besides de genetic factors, we can speculate that the natural hormone concentration in the explants might affect the responses by application of exogenous growth regulators. Experiments with new plant growth regulators, like brassinolide, are important aiming to maximize or accelerate plant regeneration for in vitro multiplication or for genetic transformation.

• The Korean Journal of Ecology
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• 제9권1호
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• pp.19-24
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• 1986

Effects of temperature, pH, light-and-dark and degree of oxygen supply on germination of Papaver somniferum L. seeds were investigated. The optimum temperature of the germination was 2$0^{\circ}C$, but the germination was decreased as temperatures changed to the upper and lower. The largest elongation of both radicle and hypocotyl also occurred at 2$0^{\circ}C$. The best germination occurred at pH 7 but this decreased suddenly the above and below of that pH value. Although no effect of light-and-dark on the germination was, this was restricted under limited. oxyten supply in terms of underwater germination as compared with abovewater one.

• Molecules and Cells
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• 제23권2호
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• pp.154-160
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• 2007

An Arabidopsis hy4 mutant that is specifically impaired in its ability to undergo blue light dependent photomorphogenesis was used to identify cryptochrome 1 signaling-related components. Proteomic analysis revealed about 205 differentially expressed protein spots in the blue light-irradiated hy4 mutant compared to the wild-type. The proteins corresponding to 28 up-regulated and 33 down-regulated spots were identified. Obvious morphological changes in the hy4 mutant were closely related to the expression of various transcription factors. Our findings suggest that blue light signals may be involved in many cellular processes including disease resistance and stress responses.

• BMB Reports
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• 제50권7호
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• pp.343-344
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• 2017

Plants are able to recognize even small changes in surrounding temperatures to optimize their growth and development. At warm temperatures, plants exhibit diverse architectural adjustments, including hypocotyl and petiole elongation, leaf hyponasty, and reduced stomatal density. However, it was previously unknown how such warm temperatures affected the early stages of seedling development. In our recent study, we demonstrated that the RNA-binding protein, FCA, is critical for sustaining chlorophyll biosynthesis during early seedling development, which is a prerequisite for autotrophic transition at warm temperatures. FCA plays a dual role in this thermal response. It inhibits the rapid degradation of protochlorophyllide oxidoreductases (PORs) that mediate chlorophyll biosynthesis. In addition, it induces the expression of POR genes at the chromatin level, which contributes to maintaining functional enzyme levels. Our findings provide molecular basis for the thermal adaptation of chlorophyll biosynthesis during the early stages of seedling development in nature.

• 한국작물학회지
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• 제37권6호
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• pp.506-513
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• 1992

대두 성력재배에 있어서 저조한 출아ㆍ입묘율을 제고시키기 위한 기초연구의 일환으로 종자조건과 토양조건이 한국 주요 대두 장려품종들의 출아에 미치는 영향을 조사하였던 바 그 결과를 요약하면 다음과 같다. 1. 포장출아율은 저하축신장이 양호한 품종이 불량한 품종에 비해 뚜렷하게 높았다. 2. 파종심도가 깊을수록 종자표면적이 작은 소립종자가 큰 중, 대립종자에 비하여 출아저항력이 작아 파종심도 5cm이하에서는 대립종자가 7.5cm에서 소립종자가 출아율이 높았다. 3. 토양별 출아율은 진흙에서 65%, 진흙 : 모래(1 : 1) 모래 : vermiculite(1 : 1)에서 각각 80, 84%였고 vermiculite, 모래 및 진흙 : vermiculite(1 : 1)에서 각각 80, 90, 91%로 높은 출아율을 나타냈다. 4. 토양수분 potential이 -0.1bar에서 -0.5bar까지 점차 낮아짐에 따라 출아율은 순차적으로 높아져 -0.5bar에서 87.2%로 최고 출아율을 보였으나 이후 낮은 potential에서는 수분부족으로 인하여 -0.7bar 출아율이 25.2%로 최저치를 보였다.

• Journal of Plant Biotechnology
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• 제2권2호
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• pp.61-71
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• 2000

By screening a cDNA library of auxin-treated mung bean (Vigna radiata L.) hypocotyls, we have isolated two full-length cDNA clones, pVR-ACS6 and pVR-ACS7, for 1-aminocyclopropane-1-carboxylate (ACC) synthase, the rate-limiting enzyme in the ethylene biosynthetic pathway. While PVR-ACS6 corresponds to the previously identified PCR fragment pMBA1, pVR-ACS7 is a new cDNA clone. A comparison of deduced amino acid sequences among auxin-induced ACC synthases reveal that these enzymes share a high degree of homology (65-75%) to VR-ACS6 and VR-ACS7 polypeptides, but only about 50% to VR-ACS1 polypeptide. ACS6 and ACS7 are specifically induced by auxin, while ACS1 is induced by cycloheximide, and to lesser extent by excision and auxin treatment. Results from nuclear run-on transcription assay and RNA gel blot studies revealed that all three genes were transcriptionally active displaying unique patterns of induction by IAA and various hormones in etiolated hypocotyls. Particularly, 24-epibrassinolide (BR), an active brassinosteroid, specifically enhanced the expression of VR-ACS7 by distinct temporal induction mechanism compared to that of IAA. In addition, BR synergistically increased the IAA-induced VR-ACS6 and VR-ACS7 transcript levels, while it effectively abolished both the IAA- and kinetin-induced accumulation of VR-ACS1 mRNA. In light-grown plants, VR-ACS1 was induced by IAA in roots, whereas W-ACS6 in epicotyls. IAA- and BR-treatments were not able to increase the VR-ACS7 transcript in the light-grown tissues. These results indicate that the expression of ACC synthase multigene family is regulated by complex hormonal and developmental networks in a gene- and tissue-specific manner in mung bean plants. The VR-ACS7 gene was isolated, and chimeric fusion between the 2.4 kb 5'-upstream region and the $\beta$-glucuronidase (GUS) reporter gene was constructed and introduced into Nicotiana tobacum. Analysis of transgenic tobacco plants revealed the VR-ACS7 promoter-driven GUS activity at a highly localized region of the hypocotyl-root junction of control seedlings, while a marked induction of GUS activity was detected only in the hypocotyl region of the IAA-treated transgenic seedlings where rapid cell elongation occurs. Although there was a modest synergistic effect of BR on the IAA-induced GUS activity, BR alone failed to increase the GUS activity, suggesting that induction of VR-ACS7 occurs via separate signaling pathways in response to IAA and BR.

• Journal of Plant Biology
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• 제39권1호
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• pp.71-77
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• 1996

배발생 캘러스의 선발은 1.0mg/L 2,4-D를 첨가한 MS 기본배지에서 배양한 당근 유식물의 배축절편으로부터 유도된 캘러스에서 이뤄졌다. 체세포배 발생을 유도하기 위해서 배발생 캘러스로부터 얻어진 세포괴는 2,4-D를 제거한 MS 배지에 옮겼다. 세포괴를 1.0mg/L 2,4-D 첨가배지에서 1주간 그리고 2,4-D 제거 배지에서 2주간 배양한 후에 2자엽배의 발생은 63%에 그쳤고 나머지는 1자엽 5%, 3자엽 21%, 4자엽 6%, 5자엽 5%, 6자엽 0.2% 및 나팔형 자엽 1%의 발생빈도를 나타냈다. 체세포배의 발아율은 다자엽 체세포배에서 보다 2자엽 배에서 높았다. 나팔형 자엽의 체세포배는 경엽부 발생없이 자엽과 뿌리가 다소 신장 확대되는데 그치는 등 정상적으로 발아되지 못했다. 해부학적인 관찰에서 체세포배의 뿌리와 환상 전형성층은 배축의 중간부위에서 분지되기 시작하고 자엽절을 거쳐서 자엽으로 이어지는데 배축에서 전형성층속은 자엽수와 같은 수였다. 1자엽 체세포배는 다자엽 체세포배의 각각의 자엽보다 크고 전형성층과 함께 말굽형 자엽을 가지고 있었다. 따라서 체세포배의 자엽구조는 전형성층 배열상태와 밀접한 관련이 있다는 것을 확인할 수 있었다.

• Journal of Photoscience
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• 제9권2호
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• pp.90-93
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• 2002

Phytochrome A (phyA) and phytochrome B (phyB) perceive light and adapt to fluctuating circumstances by different manners in terms of effective wavelengths, required fluence and photoreversibility. Action spectra for induction of seed germination and inhibition of hypocotyl elongation using phytochrome mutants of Arabidopsis showed major difference. PhyA is the principal photoreceptor for the very low fluence responses and the far-red light-induced high irradiance responses, while phyB controls low fluence response in a red/far-red reversible mode. The structural requirement of their bilin chromophores for photosensory specificity of phyA and phyB was investigated by reconstituting holophytochromes through feeding various synthetic bilins to the following chromophore-deficient mutants: hy1, hyl/phyA and hyl/phyB mutants of Arabidopsis. We found that the vinyl side-chain of the D-ring in phytochromobilin interacts with phyA apoprotein. This interaction plays a direct role in mediating the specific photosensory function of phyA. The ethyl side-chain of the D-ring in phycocyanobilin fails to interact with phyA apoprotein, therefore, phyA specific photosensory function is not observed. In contrast, both phytochromobilin and phycocyanobilin interact with phyB apoprotein and induce phyB specific photosensory functions. Structural requirements of the apoproteins and the chromophores for the specific photoperception of phyA and phyB are discussed.