The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Kee-yoeup Paek - One of the best experts on this subject based on the ideXlab platform.
-
mass production of eleutherococcus koreanum Plantlets via somatic embryogenesis from root cultures and accumulation of eleutherosides in regenerants
Plant Science, 2005Co-Authors: Soyoung Park, Hosakatte Niranjana Murthy, Jinkwon Ahn, Wiyoung Lee, Kee-yoeup PaekAbstract:Abstract Eleutherococcus koreanum ( E. koreanum ) is an endangered medicinal plant, which has been used for the treatments of rheumatism, diabetes and hepatitis. An in vitro methodology has been developed for mass propagation of E. koreanum by using adventitious root explants in liquid cultures. Among the various strengths of Murashige and Skoog media sucrose and growth regulators tested, 1/3 strength hormone-free medium supplemented with 60 g l −1 sucrose was found suitable for embryo induction and development from the root segments. Embryos which were developed on the root segments were able to mature and germinate in the same 1/3 MS hormone-free medium. Bioreactor cultures were established for large-scale cultivation of Plantlets. Adventitious roots, embryos and Plantlets could be simultaneously harvested after 12 weeks cultivation of adventitious roots in 1/3 strength MS medium supplemented with 60 g l −1 sucrose. HPLC analysis revealed that biomass harvested (somatic embryos, Plantlets and adventitious roots) contained eleutheroside B and E in considerable amount, and this could be used for the extraction of these phytochemicals. The present system for plantlet production from root explants would provide an efficient means to produce both Plantlets and phytochemicals from E. koreanum .
-
somatic embryogenesis and plant regeneration in gymnema sylvestre
Plant Cell Tissue and Organ Culture, 2002Co-Authors: H Ashok G Kumar, Hosakatte Niranjana Murthy, Kee-yoeup PaekAbstract:Somatic embryogenesis and whole plant regeneration were achieved in callus cultures derived from hypocotyl, cotyledon and leaf explants excised from seedlings of Gymnema sylvestre. Embryogenic callus was induced on Murashige and Skoog (MS) medium containing 2,4-D (0.5–5.0 μM) +BA (0.5–2.0 μM) and 2% (w/v) sucrose in 6–8 weeks of culture. Globular/heart stage embryos developed on induction medium. These embryos produced torpedo and cotyledon stage embryos upon sub-culturing on embryo maturation medium EM8 (medium containing MS salts, B5 vitamins, 0.5 μM BA and 2% sucrose). Embryo germination and plantlet formation was achieved by sub-culturing mature embryos on fresh EM8 medium. The Plantlets were acclimatized in the greenhouse.
-
number of air exchanges sucrose concentration photosynthetic photon flux and differences in photoperiod and dark period temperatures affect growth of rehmannia glutinosa Plantlets in vitro
Plant Cell Tissue and Organ Culture, 2000Co-Authors: Eunjoo Hahn, Toyoki Kozai, Kee-yoeup PaekAbstract:Rehmannia glutinosa Plantlets were cultured for 4 weeks under different culture conditions to determine the optimum environment for in vitro growth and ex vitro survival. Plantlet growth increased with an increasing number of air exchanges of the culture vessel, exhibiting greatest shoot weight, total fresh weight, leaf area, and chlorophyll content at 4.4 h−1 of air exchanges. High sucrose concentration (30 g l−1) increased root weight but reduced shoot growth. Net photosynthetic rates of the Plantlets were greatest when sucrose was not added to the medium. On the other hand, ex vitro survival of the Plantlets was not influenced by sucrose concentration. In the experiment on difference in photoperiod and dark period temperatures (DIF) and photosynthetic photon flux (PPF), plantlet growth increased as DIF and PPF levels increased. Particularly, increasing PPF level had a more distinctive effect on plantlet growth than increasing DIF level. The interaction of DIF × PPF was also significant, showing the greatest plantlet growth in positive DIF (+8 DIF) and a high PPF (210 μmol m−2 s−1). In conclusion, the results of this experiment suggest that increased number of air exchanges of the culture vessel, decreased sucrose concentration, and positive DIF in combination with high PPF level enhanced growth and acclimatization of Rehmannia glutinosa Plantlets.
Toyoki Kozai - One of the best experts on this subject based on the ideXlab platform.
-
number of air exchanges sucrose concentration photosynthetic photon flux and differences in photoperiod and dark period temperatures affect growth of rehmannia glutinosa Plantlets in vitro
Plant Cell Tissue and Organ Culture, 2000Co-Authors: Eunjoo Hahn, Toyoki Kozai, Kee-yoeup PaekAbstract:Rehmannia glutinosa Plantlets were cultured for 4 weeks under different culture conditions to determine the optimum environment for in vitro growth and ex vitro survival. Plantlet growth increased with an increasing number of air exchanges of the culture vessel, exhibiting greatest shoot weight, total fresh weight, leaf area, and chlorophyll content at 4.4 h−1 of air exchanges. High sucrose concentration (30 g l−1) increased root weight but reduced shoot growth. Net photosynthetic rates of the Plantlets were greatest when sucrose was not added to the medium. On the other hand, ex vitro survival of the Plantlets was not influenced by sucrose concentration. In the experiment on difference in photoperiod and dark period temperatures (DIF) and photosynthetic photon flux (PPF), plantlet growth increased as DIF and PPF levels increased. Particularly, increasing PPF level had a more distinctive effect on plantlet growth than increasing DIF level. The interaction of DIF × PPF was also significant, showing the greatest plantlet growth in positive DIF (+8 DIF) and a high PPF (210 μmol m−2 s−1). In conclusion, the results of this experiment suggest that increased number of air exchanges of the culture vessel, decreased sucrose concentration, and positive DIF in combination with high PPF level enhanced growth and acclimatization of Rehmannia glutinosa Plantlets.
-
a combination of vermiculite and paper pulp supporting material for the photoautotrophic micropropagation of sweet potato
Plant Science, 2000Co-Authors: F Afreenzobayed, Toyoki Kozai, Chieri Kubota, S M A Zobayed, Osamu HasegawaAbstract:A mixture of vermiculite (hydrous silicates) and paper pulp (waste product of paper industry) was used as a supporting material for the in vitro photoautotrophic micropropagation of Plantlets. Sweet potato was used as a model plant to find out the appropriate proportion of vermiculite and paper pulp for the optimum growth of the Plantlets. The Plantlets grown in the conventional supporting material, agar, were used as the control. The study revealed that in all aspects, the Plantlets grown in vermiculite mixed with 30% (w:w) paper pulp exhibited the highest growth performance. The shoot and root fresh mass were 2.7 greater than those in agar (control); the leaf, stem and root dry mass were also greater and at least two fold in this treatment compared with those in the control. The net photosynthetic rate per plantlet was highest in this treatment, and on day 20 it was 15.3 mmol CO2 h 1 as compared with 9.8 mmol CO2 h 1 in the control. The growth of both shoots and roots decreased gradually with the increase or decrease of percentage of paper pulp in the supporting material. In general, the growth was significantly poorer in the Plantlets grown in 100% vermiculite than that in vermiculite mixed with 30% paper pulp but still greater than in the control. The porosity of the supporting materials increased with the increase in the percentage of paper pulp in the supporting material. After transplanting to the ex vitro condition the survival percentage did not vary significantly (90‐100%) among the treatments, except in control where it was only 73%. The number of unfolded leaves and the stem height were similar among the treatments except those in the control. © 2000 Published by Elsevier Science Ireland Ltd. All rights reserved.
-
effect of the difference between photoperiod and dark period temperatures and photosynthetic photon flux density on the shoot length and growth of potato Plantlets in vitro
Journal of The Japanese Society for Horticultural Science, 1992Co-Authors: Toyoki Kozai, Sunao Kushihashi, Chieri Kubota, Kazuhiro FujiwaraAbstract:Potato Plantlets (Solanum tuberosum L. cv. Benimaru) under CO2 enriched and photoauto-trophic culture conditions were subjected to three different photo-/dark period temperature combinations (25°/15°C, 20°/20°C and 15°/25°C) and two levels of photosynthetic photon flux densities (74 and 147 μmol-m -2.sec-1). The shoot length of the Plantlets under the same photosytnthetic photon flux density (PPF) was reduced with decreasing the difference between photoperiod and dark period temperatures (it is named DIF, photoperiod temperature minus dark period temperature). No marked differences in the fresh and dry weights per plantlet were observed among the three DIF treatments in each PPF treatment. The higher PPF led to a decrease in the shoot length, an increase in the fresh weight, dry weight and leaf area per plantlet in each DIF treatment. It is suggested that shoot length of Plantlets in vitro under CO2 enriched and photoautotrophic culture conditions can be controlled without reducing the weight increments and leaf area per plantlet by regulating the difference between photoperiod and dark period temperatures.
Richard G Kulka - One of the best experts on this subject based on the ideXlab platform.
-
hormonal control of root development on epiphyllous Plantlets of bryophyllum kalanchoe marnierianum role of auxin and ethylene
Journal of Experimental Botany, 2008Co-Authors: Richard G KulkaAbstract:Epiphyllous Plantlets develop on leaves of Bryophyllum marnierianum when they are excised from the plant. Shortly after leaf excision, plantlet shoots develop from primordia located near the leaf margin. After the shoots have enlarged for several days, roots appear at their base. In this investigation, factors regulating plantlet root development were studied. The auxin transport inhibitor 2,3,5-triiodobenzoic acid (TIBA) abolished root formation without markedly affecting shoot growth. This suggested that auxin transport from the plantlet shoot induces root development. Excision of plantlet apical buds inhibits root development. Application of indole-3-acetic acid (IAA) in lanolin at the site of the apical buds restores root outgrowth. Naphthalene acetic acid (NAA), a synthetic auxin, reverses TIBA inhibition of plantlet root emergence on leaf explants. Both of these observations support the hypothesis that auxin, produced by the plantlet, induces root development. Exogenous ethylene causes precocious root development several days before that of a control without hormone. Ethylene treatment cannot bypass the TIBA block of root formation. Therefore, ethylene does not act downstream of auxin in root induction. However, ethylene amplifies the effects of low concentrations of NAA, which in the absence of ethylene do not induce roots. Ag2S2O3, an ethylene blocker, and CoCl2, an ethylene synthesis inhibitor, do not abolish plantlet root development. It is therefore unlikely that ethylene is essential for root formation. Taken together, the experiments suggest that roots develop when auxin transport from the shoot reaches a certain threshold. Ethylene may augment this effect by lowering the threshold and may come into play when the parent leaf senesces.
-
cytokinins inhibit epiphyllous plantlet development on leaves of bryophyllum kalanchoe marnierianum
Journal of Experimental Botany, 2006Co-Authors: Richard G KulkaAbstract:When leaves of Bryophyllum marnierianum are detached from the plant, Plantlets develop from primordia located at their margins. Leaves excised with a piece of stem attached do not produce Plantlets. Severing the major leaf veins overcomes the inhibitory effect of the attached stem, indicating that the control agent is transmitted through the vascular system. A possible mechanism is that an inhibitory substance, possibly a known plant hormone, transported from the stem to the leaf, suppresses plantlet development. A number of hormones were tested for their ability to inhibit plantlet primordium development in whole isolated leaves. Auxins had no effect, indicating that apical dominance is not involved. The cytokinins zeatin, kinetin, and benzylaminopurine (BAP) strongly inhibited plantlet development, suggesting that they may be the or a factor involved in maintenance of plantlet primordium dormancy when the leaf is attached to the plant. This hypothesis was strongly supported by the finding that treatment of leaves attached to stems with a cytokinin antagonist (purine riboside) released the primordia from inhibition. In contrast to whole leaves, plantlet primordium development on leaf explants incubated on Murashige Skoog medium containing 3% sucrose was strongly stimulated by cytokinins. A possible explanation of these observations is that in whole leaves the cytokinin signal is transduced into an inhibitory signal whereas in the isolated primordium cytokinin has a direct stimulatory effect. The inhibitory cytokinin pathway must be dominant as long as the leaf is attached to the plant. A model is proposed which could explain these findings. This study points to a novel role of cytokinins in the maintenance of foliar plantlet primordium dormancy.
H S Dhaliwal - One of the best experts on this subject based on the ideXlab platform.
-
microtuberization in potato solanum tuberosum l
Plant Cell Reports, 1998Co-Authors: J Gopal, J L Minocha, H S DhaliwalAbstract:Twenty-two genotypes of potato (Solanum tuberosum L.) were induced to form microtubers under six in vitro culture conditions. Cultures maintained under a short photoperiod (10 h of 6–12 μmol m–2 s–1) and low temperatures (day 20°±2°C and night 18°±2°C) had both a higher yield (255 mg/plantlet) and a greater number (2/plantlet) of microtubers than those maintained under long days (16 h of 38–50 μmol m–2 s–1) combined with high temperatures (day 28°±2°C and night 25°±2°C) (yield 207 mg/plantlet; microtuber number, 0.9/plantlet), over a wide range of genotypes. After the Plantlets had been cultured under long days for an initial period of 60 days, continuous darkness advanced microtuberization by 2–3 months in various genotypes. Under short-day and low-temperature conditions the addition of 6-benzylaminopurine increased microtuber yield from 255 mg/plantlet to 645 mg/plantlet and average microtuber weight from 115 mg to 364 mg. A similar pattern was observed under conditions of long days and high temperature, and continuous darkness and low-temperature. Microtubers produced under light had a greater number of eyes (maximum average: 5.96/microtuber) than those produced in the dark (maximum average: 3.50/plantlet). The genotype × cultural conditions interactions were significant indicating the importance of developing genotype-specific protocols to maximize microtuberization.
Chieri Kubota - One of the best experts on this subject based on the ideXlab platform.
-
a combination of vermiculite and paper pulp supporting material for the photoautotrophic micropropagation of sweet potato
Plant Science, 2000Co-Authors: F Afreenzobayed, Toyoki Kozai, Chieri Kubota, S M A Zobayed, Osamu HasegawaAbstract:A mixture of vermiculite (hydrous silicates) and paper pulp (waste product of paper industry) was used as a supporting material for the in vitro photoautotrophic micropropagation of Plantlets. Sweet potato was used as a model plant to find out the appropriate proportion of vermiculite and paper pulp for the optimum growth of the Plantlets. The Plantlets grown in the conventional supporting material, agar, were used as the control. The study revealed that in all aspects, the Plantlets grown in vermiculite mixed with 30% (w:w) paper pulp exhibited the highest growth performance. The shoot and root fresh mass were 2.7 greater than those in agar (control); the leaf, stem and root dry mass were also greater and at least two fold in this treatment compared with those in the control. The net photosynthetic rate per plantlet was highest in this treatment, and on day 20 it was 15.3 mmol CO2 h 1 as compared with 9.8 mmol CO2 h 1 in the control. The growth of both shoots and roots decreased gradually with the increase or decrease of percentage of paper pulp in the supporting material. In general, the growth was significantly poorer in the Plantlets grown in 100% vermiculite than that in vermiculite mixed with 30% paper pulp but still greater than in the control. The porosity of the supporting materials increased with the increase in the percentage of paper pulp in the supporting material. After transplanting to the ex vitro condition the survival percentage did not vary significantly (90‐100%) among the treatments, except in control where it was only 73%. The number of unfolded leaves and the stem height were similar among the treatments except those in the control. © 2000 Published by Elsevier Science Ireland Ltd. All rights reserved.
-
effect of the difference between photoperiod and dark period temperatures and photosynthetic photon flux density on the shoot length and growth of potato Plantlets in vitro
Journal of The Japanese Society for Horticultural Science, 1992Co-Authors: Toyoki Kozai, Sunao Kushihashi, Chieri Kubota, Kazuhiro FujiwaraAbstract:Potato Plantlets (Solanum tuberosum L. cv. Benimaru) under CO2 enriched and photoauto-trophic culture conditions were subjected to three different photo-/dark period temperature combinations (25°/15°C, 20°/20°C and 15°/25°C) and two levels of photosynthetic photon flux densities (74 and 147 μmol-m -2.sec-1). The shoot length of the Plantlets under the same photosytnthetic photon flux density (PPF) was reduced with decreasing the difference between photoperiod and dark period temperatures (it is named DIF, photoperiod temperature minus dark period temperature). No marked differences in the fresh and dry weights per plantlet were observed among the three DIF treatments in each PPF treatment. The higher PPF led to a decrease in the shoot length, an increase in the fresh weight, dry weight and leaf area per plantlet in each DIF treatment. It is suggested that shoot length of Plantlets in vitro under CO2 enriched and photoautotrophic culture conditions can be controlled without reducing the weight increments and leaf area per plantlet by regulating the difference between photoperiod and dark period temperatures.
