• Journal of Photoscience
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• v.9 no.2
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• pp.94-97
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• 2002

Light is one of the most important environmental factors that influence plant growth and development. It does not function independently but exerts its role through coordinated interactions with intrinsic developmental programs, such as hormonal regulation. One typical example is hypocotyl growth in which light signals are modulated through growth hormones. However, the underlying molecular mechanisms are largely unknown. We demonstrated that brassinosteroids play an important role in the light signal transduction in etiolated hypocotyl growth. A light-responsive Ras-like G-protein, Pra2 from pea, physically and functionally interacts with a cytochrome P450 that specifically catalyzes C-2 hydroxylation in brassinosteroid biosynthesis. The cytochrome P450 expression, along with Pra2, is induced in the dark and predominantly localized in the rapidly elongating zone of etiolated pea epicotyls. Transgenic plants with a reduced level of Pra2 exhibit a dark-specific dwarfism, which is completely rescued by brassinosteroid application. On the contrary, overexpression of the cytochrome P450 results in enhanced hypocotyl growth even in the light, which phenocopies the etiolated hypocotyl growth. It is therefore envisioned that Pra2 is a molecular switch that mediates the crosstalk between light and brassinosteroids in the etiolation process.

• Journal of Plant Biology
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• v.33 no.2
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• pp.105-110
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• 1990

Physiological gradient of IAA-oxidizing enzyme activities was investigated in order to elucidate the mechanism of shoot differentiation in Cymbidium sp. (‘Jungfrau’) protocorms by using phenolic compounds (2, 4-dichlorophenol, catechol), auxin-inhibitors (PCIB, TIBA), and hormones (GA3, ABA, BA). The activity of IAA oxidase was decreased in protocorms treated with catechol decreased the catalytic activity of IAA oxidase or TIBA but this enzyme activity was increased after a temporary decrease at initial stages in the presence of 2, 4-dichlorophenol or PCIB. The activity of IAA oxidase in BA-treated protocorms (white and crown gall-like) was the highest of all. However, the catalytic activity of peroxidase increased after a temporary decrease at initial period. These results suggest that shoot differentiation and growth may be influenced by effective IAA levels in the protocorms causing IAA-oxidizing enzyme and phenolic compounds.

• Journal of Plant Biotechnology
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• v.30 no.2
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• pp.161-165
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• 2003

The effect of NAA and Benzyladenine(BA) for determination times on the formation of adventitious shoots, roots trichmoes and calli in MS basal medium was investigated in leaf segments from ecotype 'Nosses' of Arabidopsis thalliana. Adventitious shoots, roots, trichomes and calli were formed fromed from leaf segments in a wede range of NAA and BA. The optimal combination of hormones for adventitious shoots formation, 20mg/L NAA for trichome formation, 100mg/L for callus formation. Inductive times for formation of adventitious shoots, roots, trichomes and calli were determined at 14, 4, 6 and 18 days respectively by periodical transfer of leaf segments from hormines containing media to hormone free medium.

• Journal of Plant Biology
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• v.33 no.4
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• pp.253-257
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• 1990

Callus-inducing ability of Alnus hirsuta was examined by culturing various tissues (leaf, hypocotyl, cotyledon and seed) on NT (Nagata & Takebe) medium, supplemented with 2.5$\mu$M 2,4-D. Leaf-originated callus was cultured on media varying in auxin (IBA and NAA) and cytokinin (BAP) concentrations to examine the effects of auxin and cytokinin on callus growth. Maximum growth was obtained at 10 $\mu$M IBA+10$\mu$M BAP and 10$\mu$M NAA without cytokinin. Cell suspensions established from cotyledon-originated callus yielded viable protoplasts after incubation for 16-18 hours in an enzyme mixture (1% (w/v) Onozuka R-10 0.5% (w/v) Macerozyme, CPW salts and 13% (w/v) mannitol, pH 5.8). Protoplasts were cultured on NT medium, supplemented with glucose, hormones and coconut milk. After 6 weeks of culture, protoplasts sustained cell divisions to form microcallus, which showed various colors from red to white.

• Journal of Plant Biology
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• v.36 no.3
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• pp.251-257
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• 1993

The size variation of the cambial initials and their derivatives, in relation to the increase of girth, in the intact and decapitated stem of Populus euramericana was anatomically studied. In the typical nonstoried cambium of P. euramericana, the cell size of fusiform initials, vessel member, and sieve tube member were gradually increased and thus it reached a maximal state. In the intact plants, the size of the cambial initials and their derivatives was larger then in the decapitated ones. On the other hand, the frequency of anticlinal division of the cambial cells, the rate of the elongation and loss of the daughter initials in the intact plants was higher than in the decapitated ones. The cambium of the intact plants had higher ray compared with that of the decapitated ones. It was interpreted that these results were caused by the decapitation, which could block the supply of certain substances for cell growth such as hormones and metabolites.

• Journal of Plant Biology
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• v.33 no.1
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• pp.41-48
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• 1990

Changes in polamine titers during shoot differentiation in Cymbidium sp. (Jungfrau) protocorms were studied in order to investigate the mechanism of shoot differentiation by using auxin-inhibitors(PCIB, TIBA), hormones(GA3, ABA, BA), and phenolic compounds (2,4-dichlorophenol, catechol). The shoot differentiation and propagation of protocorms were promoted by PCIB or 2,4-dichlorophenol, and the growth of differentiated shoot were promoted by TIBA or catechol. In BA-treated protocorms, white or brown protocorms were observed. Putrescine was the most abundant polyamine during the propagation and differentiation processes. As compared with putrescine, spermidine did not show significant changes and spermine was not detected at all. Putrescine titers decreased after a temporary increase, and then again increased in the presence of GA3, ABA, 2,4-dichlorophenol, and then again increased in the presence of GA3, ABA, 2,4-dichlorophenol, catechol, or PCIB. But, in BA-treated protocorms, putrescine level was much lower than spermidine.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.721-726
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• 2021

Plant cells have a totipotencial capacity, the ability of each cell to produce a new complete individual through development. By applying this, several technologies are being developed for widespread application of somatic embryogenesis by processing hormones in vitro as a method of propagation of plants. In order to use this technology, in Kalanchoe pinnata, a plant capable of asexual reproduction with more regular cell division, kinetin belonging to cytokinin and picloram among hormones belonging to auxin were added in combination and treated for 8 weeks, and then the typical performance was evaluated. As a result of our experiment, the rooting effect in leaf slices showed a 70% incidence rate at a picloram concentration of 0.1 mg/L. It has been proven that a concentration difference of 1:5-1:10 in the ratio of kinetin and picloram is effective. It is the experimental result that the effect of auxin is essential for the development of Kalanchoe roots. As for the effect of shooting, the incidence rate was 60% at the picloram concentration of 0.5 mg/L. The kinetin concentration from 0.5 and 1.0 mg/L and has a significant effect on development. It has been proven that the ratio of kinetin to picloram is effective with a concentration difference of 1:1-1:2. These results show that the combination of cytokinin and auxin is crucially important for shooting. It is thought that it can be the basis of a technology for inducing mass proliferation in vitro by inducing direct organogenesis with a combination of hormones.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1996.05a
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• pp.1-10
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• 1996

Factory-style plant production systems of various kinds are the final goal of greenhouse production systems. These systems facilitate planning for constant productivity per unit area and labor under various outside weather conditions, although energy consumption is intensive. Physical environmental control in combination with biological control can replace the use of agricultural chemicals such as insecticides, herbicides and hormones to regulate plants. In this way, closed systems which do not use such agricultural chemicals are ideal for environmental conservation for the future. Nutrient components in plants can be regulafied by physical environmental control including nutrient solution control in hydroponics. Therefore, specific contents of nutrients for particular plants can be listed on the container and be used as the basis of customer choice in the future. Plant production systems can be classified into three types based on the type of lighting: natural lighting, supplemental lighting and completely artificial lighting (Plant Factory). The amount of energy consumption increases in this order, although the degree of weather effects is in the reverse order. In the addition to lighting, factory-style plant production systems consist of mechanized and automated systems for transplanting, environmental control, hydroponics, transporting within the facility, and harvesting. Space farming and development of pharmaceutical in bio-reactors are other applications of these types of plant production systems. Various kinds of state-of-art factory-style plant production systems are discussed in the present paper. These systems are, in general, rather sophisticated and mechaized, and energy consumption is intensive. Factory-style plant production is the final goal of greenhouse production systems and the possibilities for the future are infinte but not clear.

• Journal of Plant Biotechnology
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• v.42 no.3
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• pp.168-179
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• 2015

We previously identified the rice gene, OsSAP, as an encoder of a highly conserved putative senescence-associated protein that was shown to have anti-apoptotic activity. To confirm the role of OsSAP in inducing abiotic stress tolerance in rice, we introduced OsSAP and AtBI-1, a plant homologue of Bax inhibitor-1, under the control of the CaMV 35S promoter into the rice genome through Agrobacterium-mediated transformation. The OsSAP transformants showed a similar chlorophyll index after salinity treatments with AtBI-1. Furthermore, we compared the effects of salinity stress on leaves and roots by examining the hormone levels of abscisic acid (ABA), jasmonic acid (JA), gibberellic acid (GA3), and zeatin in transformants compared to the control. With the exception of phytohormones, stress-induced changes in hormone levels putatively related to stress tolerance have not been investigated previously. Hormonal level analysis confirmed the lower rate of stress in the transformants compared to the control. The levels of ABA and JA in OsSAP and AtBI-1 transformants were similar, where stress rates increased after one week and decreased after a two week period of drought; there was a slightly higher accumulation compared to the control. However, a similar trend was not observed for the level of zeatin, as the decrease in the level of zeatin accumulation differed in both OsSAP and AtBI-1 transformants for all genotypes during the early period of salinity stress. The GA3 level was detected under normal conditions, but not under salinity stress.

• Journal of Crop Science and Biotechnology
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• v.10 no.4
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• pp.281-286
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• 2007

Gibberellins are growth hormones that play a pivotal role in the growth and development of plants. Present investigations were carried to check the effect of nitrogen(N) and silicon(Si) on bioactive $GA_1$ and its immediate precursor $GA_{20}$ at different growth stages of two rice cultivars with different maturity traits. It was observed that the endogenous bioactive $GA_1$ level gradually increased during vegetative stage and anthesis stage of both Junghwabyeo(early flowering cultivar) and Daesanbyeo(late flowering cultivar). However, the $GA_1$ and $GA_{20}$ content start decreasing during the seed filling stage in both rice cultivars, which indicated a possible relationship of bioactive $GA_1$ and floral development. Our results also confirmed that early 13-hydroxylation pathway was operated at all developmental stages of rice plant. Variation in the levels of the endogenous gibberellins in rice shoots were measured by GCMS-SIM using $^2H_2$-labeled gibberellins as internal standards. Combined application of N and Si enhanced growth parameters and reduced lodging index of both rice cultivars. It was thus concluded that the level of physiologically active $GA_1$ increased during vegetative and early reproductive stage, but starts declining at seed filling stage.