• Molecules and Cells
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• 제39권7호
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• pp.524-529
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• 2016

Controlling the production of diverse cell/tissue types is essential for the development of multicellular organisms such as animals and plants. The Arabidopsis thaliana root, which contains distinct cells/tissues along longitudinal and radial axes, has served as an elegant model to investigate how genetic programs and environmental signals interact to produce different cell/tissue types. In the root, a series of asymmetric cell divisions (ACDs) give rise to three ground tissue layers at maturity (endodermis, middle cortex, and cortex). Because the middle cortex is formed by a periclinal (parallel to the axis) ACD of the endodermis around 7 to 14 days post-germination, middle cortex formation is used as a parameter to assess maturation of the root ground tissue. Molecular, genetic, and physiological studies have revealed that the control of the timing and extent of middle cortex formation during root maturation relies on the interaction of plant hormones and transcription factors. In particular, abscisic acid and gibberellin act synergistically to regulate the timing and extent of middle cortex formation, unlike their typical antagonism. The SHORT-ROOT, SCARECROW, SCARECROW-LIKE 3, and DELLA transcription factors, all of which belong to the plant-specific GRAS family, play key roles in the regulation of middle cortex formation. Recently, two additional transcription factors, SEUSS and GA- AND ABA-RESPONSIVE ZINC FINGER, have also been characterized during ground tissue maturation. In this review, we provide a detailed account of the regulatory networks that control the timing and extent of middle cortex formation during post-embryonic root development.

• 한국자원식물학회지
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• 제35권6호
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• pp.770-777
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• 2022

The main objective of this study was to identify the most appropriate condition for root formation of in vitro micropropagated pear (Pyrus spp.) plants. In vitro propagation was induced on Murashige and Skoog (MS) medium with 2.0 mg/L of N6-benzyladenine (BA) and 0.2 mg/L of Indole-3-butyric acid (IBA) medium. The short pre-treatment of explants with a high concentration (1 mg/L) of NAA and IBA (R0 medium) in dark for three days, followed by transfer to five different media (R1 to R5) resulted in good rooting responses in the pear 'Oharabani (P. pyrifolia × P. communis)' genotype. For the rooting experiments, the highest rooting percentage (83.3 ± 8.3%), average root length (3.6 ± 1.9 mm), total root number (31 ± 4.0), and average root number per plant (2.6 ± 2.1) were obtained on half strength (1/2) of MS medium supplemented with 30 g/L sucrose without hormones and activated charcoal (AC) (R1 medium). The highest rooting percentage was obtained at 83.3% from explants on R1 and R3 media. The rooting procedure described in this study resulted in good root formation and significantly shorting the root induction time to within 14 days of culture. Further studies are underway to test the suitability of the protocol developed in this study for other pear genotypes.

• Journal of Plant Biotechnology
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• 제45권2호
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• pp.146-153
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• 2018

Lilium ledebourii Bioss is a wild species of Lilium, which grows naturally in some provinces of Iran. Previous studies on Lilium tissue culture have been linked to direct regeneration and a few studies have been conducted on indirect regeneration, which has been studied under bright conditions. In this study, for the first time in the world, all the stages of indirect regeneration (callus induction, shoot and root induction) have been studied under dark conditions. Callus formation and the regeneration levels of L. Ledebourii Bioss were examined for three replicates in an MS (Murashige and Skoog) medium with different hormonal compositions and by using a factorial experiment in the framework of a completely random plan. For callus initiation, 2,4-D and kinetin hormones were used in five and four levels, respectively, as auxin and cytokinin. Results showed that the highest percentage of the callus was found in $3{\mu}M$ of 2,4-D and $0.5{\mu}M$ of kinetin. In terms of callus wet weight, the highest amount was found in $3{\mu}M$ of 2,4-D and $0.5{\mu}M$ of kinetin. In addition, in terms of diameter, the highest amount was found in $3{\mu}M$ of 2,4-D, and $0.5{\mu}M$ of kinetin. In summary, the 2,4-D hormone had a major impact on the percentage of regeneration increase so that the best response was related to the composition of $3{\mu}M$ of 2,4-D, and $0.1{\mu}M$ of kinetin. This study contended that auxin and cytokinin can induce long shoots and roots through cell elongation in dark condition.

• The Plant Pathology Journal
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• 제36권5호
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• pp.476-490
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• 2020

The parasitic weed, Orobanche crenata, is one of the most devastating constraint for faba bean production in Mediterranean regions. Plant host defense induction was reported as one of the most appropriate control methods in many crops. The aim of this study was to elucidate the effect of salicylic acid (SA) and indole acetic acid (IAA) on the induction of faba bean resistance to O. crenata under the field and controlled experimental conditions. Both hormones were tested on two contrasting faba bean genotypes: Giza 843 (partially resistant to O. crenata) and Lobab (susceptible) at three different application methods (seed soaking, foliar spray, and the combination of both seed soaking and foliar spray). Soaking seeds in SA or IAA provided the highest protection levels reaching ~75% compared to the untreated control plants. Both elicitors limited the chlorophyll content decrease caused by O. crenata infestation and increased phenolic compound production in host plants. Phenylalanine ammonia lyase, peroxidase, and polyphenol oxidase activities were stimulated in the host plant roots especially in the susceptible genotype Lobab. The magnitude of induction was more obvious in infested than in non-infested plants. Histological study revealed that both SA and IAA decreased the number of attached O. crenata spikes which could be related to specific defense responses in the host plant roots.

• 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.

• 한국초지조사료학회지
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• 제19권4호
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• pp.303-308
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• 1999

버즈풋 트레포일 (Lotus corniculatus L. cv. Empire) 종자로부터 직접 캘러스를 유도하고, 형성된 캘러스로부터 식물체를 재분화하는 조건을 확립하였다. 캘러스 유도시 사용한 SH (Schenk and Hildebrandt), MS (Murashing and Skoog), N6 (Chu) 배지중에서 SH 배지가 캘러스 유도에 유리한 것으로 나타났으며, 캘러스 유도 및 중식시에는 2,4-D $3mg/{\ell}$ 을 첨가한 조건이 가장 효율이 좋았다. 식물체 재분화 조건은 BOi2Y 배지에서 20일 간격으로 계대배양하며 재분화를 완성한 조건 2가 더 좋았으며, 캘러스로부터 완전한 식물체로 재분화되는데 필요한 시간은 약 60일이었다.

• Journal of Plant Biotechnology
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• 제43권1호
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• pp.30-36
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• 2016

Brassinosteroids (BRs) are essential plant steroid hormones required for cell elongation, plant growth, development and abiotic and biotic stress tolerance. BRs are recognized by BRI1 receptor kinase that is localized in the plasma membrane, and the BRI1 protein will eventually autophosphorylate in the intracellular domain and transphosphorylate BAK1, which is a co-receptor in Arabidopsis thaliana. However, little is known of the role OsBRI1 receptor kinase plays in Oryza sativa, monocotyledonous plants, compared to that in Arabidopsis thaliana, dicotyledonous plants. As such, we have studied OsBRI1 receptor kinase in vitro and in vivo with recombinant protein and transgenic plants, whose phenotypes were also investigated. A OsBRI1 cytoplasmic domain (CD) recombinant protein was induced in BL21 (DE3) E.coli cells with IPTG, and purified to obtain OsBRI1 recombinant protein. Based on Western blot analysis with phospho-specific pTyr and pThr antibodies, OsBRI1 recombinant protein and OsBRI1-Flag protein were phosphorylated on Threonine residue(s), however, not on Tyrosine residue(s), both in vitro and in vivo. This is particularly intriguing as AtBRI1 protein was phosphorylated on both Ser/Thr and Tyr residues. Also, the OsBRI1 full-length gene was expressed in, and rescued, bri1-5 mutants, such as is seen in normal wild-type plants where AtBRI1-Flag rescues bri1-5 mutant plants. Root growth in seedlings decreased in Ws2, AtBRI1, and 3 independent OsBRI1 transgenic seedlings and had an almost complete lack of response to brassinolide in the bri1-5 mutant. In conclusion, OsBRI1, an orthologous gene of AtBRI1, can mediate normal BR signaling for plant growth and development in Arabidopsis thaliana.

• The Plant Pathology Journal
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• 제30권3호
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• pp.323-329
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• 2014

Two cultivars Buram-3-ho (susceptible) and CR-Hagwang (moderate resistant) of kimchi cabbage seedlings showed differential defense responses to anthracnose (Colletotrichum higginsianum), black spot (Alternaria brassicicola) and black rot (Xanthomonas campestris pv. campestris, Xcc) diseases in our previous study. Defense-related hormones salicylic acid (SA), jasmonic acid (JA) and ethylene led to different transcriptional regulation of pathogenesis-related (PR) gene expression in both cultivars. In this study, exogenous application of SA suppressed basal defenses to C. higginsianum in the 1st leaves of the susceptible cultivar and cultivar resistance of the 2nd leaves of the resistant cultivar. SA also enhanced susceptibility of the susceptible cultivar to A. brassicicola. By contrast, SA elevated disease resistance to Xcc in the resistant cultivar, but not in the susceptible cultivar. Methyl jasmonate (MJ) treatment did not affect the disease resistance to C. higginsianum and Xcc in either cultivar, but it compromised the disease resistance to A. brassicicola in the resistant cultivar. Treatment with 1-aminocyclopropane-1-carboxylic acid (ACC) ethylene precursor did not change resistance of the either cultivar to C. higginsianum and Xcc. Effect of ACC pretreatment on the resistance to A. brassicicola was not distinguished between susceptible and resistant cultivars, because cultivar resistance of the resistant cultivar was lost by prolonged moist dark conditions. Taken together, exogenously applied SA, JA and ethylene altered defense signaling crosstalk to three diseases of anthracnose, black spot and black rot in a cultivar-dependent manner.

• Journal of Plant Biotechnology
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• 제39권3호
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• pp.205-211
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• 2012

Pueraria lobata is a perennial legume plant, widely distributed in the countries of East Asia. It is a medicinally important leguminous plant and produces various isoflavones such as puerarin, daidzein etc which have potential for preventing several chronic diseases including osteoporosis, cardiovascular disease and cancer. In this study, we tried to induce hairy roots in vitro from Korean wild arrowroot P. lobata and investigated the effects of hormones and light conditions. Initially leaf and stem segments were infected with Agrobacterium rhizogenes and incubated in different conditions. Hairy roots were induced from only stem segments and the induction was best at dark condition and the presence of IBA during incubation. Secondary roots were also significantly much more induced at the dark condition than at the 16 hours light condition. Among plant growth regulators of auxin, IBA was best for secondary root formation while 2,4-D, IAA and NAA produced callus or less hairy roots. The presence of the foreign gene rolC transferred by A. rhizogenes that plays a major role in hairy root induction was confirmed by PCR. The accumulation of isoflavones such as puerarin and daidzin was also confirmed. These results will facilitate mass production of hairy root and can be used for the production of functional substances from wild arrowroots.

• 한국수산과학회지
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• 제14권2호
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• pp.79-85
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• 1981

김엽체의 생장에 미치는 식물흐르몬의 영향을 조사하기 위해서 Gibberellin, IAA, Kinetin, NAA및 2.4-D 등을 농도별로 회석한 배지에서 김엽편을 32일간 배양하고 또 2차적으로 Kinetin의 농도별배지에서 수온을 $5^{\circ}C$와 $10^{\circ}C$로 구분하여 18일간 배양하였다. 그 결과를 요약하면 다음과 같다. (1) Gibberellin은 10.0mg/l 농도에서, 기타는 모두 5.0mg/1 농도의 배지에시 각각 최고생장효과가 나타났다. 간종량으로 본 효율치는 Kinetin이 $312.5\%$(엽면체:$345.3\%$)로 으뜸이며 2.4-D는 $257.5\% (236.1\%)$, Gibberellin $247.9\%(241.9\%)$, IAA, $166.7\%(147.6\%)$, NAA $141.7\% (167.7\%)$의 순이였다. (2) 특히 Kinetin 5.0mg/1농도에서 배양된 엽편은 그 색채가 진한 흑갈색으로 가장 좋았으며 세포마다 생기 있는 큰 색소체가 뚜렷하고 건전하여 뛰어난 효과가 나타났으나 기타는 색채가 담갈색 또는 황록갈색으로 변하고 사세포가 많이 발견되었으며 생세포도 원형질이 위축되었거나 큰 세포가 생겨 매우 불건전하였다.(3) 저온($5^{\circ}C$)과 고온($10^{\circ}C$)에서의 Kinetin의 생장효율은 저농도에서는 대차가 없었으나, 5.0mg/1의 고농도애시는 저온이 $366.7\%$, 고온이 $318.8\%$로서 $48\%$의 효율차가 생겼으며 세포의 건전성은 1차시험때와 마찬가지로 모두 좋았다.(4) 최고생장효과가 나타난 Kinetin 5.0mg/1농도에서는 엽편의 녹변에 지름 $25.0\sim27.5\mu$ 정도의 이상대형세포가 많이 발견되었으며 그 중에는 한 세포내에 수개의 색소체가 있는 것이 관찰되었다. 두께도 $41.0\sim42.0\mu$으로 비교적 두꺼웠다.(5) Kinetia 1.0mg/l농도의 배지에서 배양된 엽편중에는 조정기을 형성하고 있는 세포군이 관찰되었다.