• Title/Summary/Keyword: Floral regulators

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Structural Basis of Functional Conversion of a Floral Repressor to an Activator: A Molecular Dynamics Simulation Study

  • Kang, Suk-Ki;Lee, Ju-Yong;Lee, Myeong-Sup;Seok, Cha-Ok
    • Bulletin of the Korean Chemical Society
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    • v.29 no.2
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    • pp.408-412
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    • 2008
  • FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1) in Arabidopsis are homologous proteins that perform opposite functions: FT is an activator of flowering, and TFL1 is a repressor. It was shown before that change of a single amino acid (His88) of TFL1 to the corresponding amino acid (Tyr) of FT is enough to convert the floral repressor to an activator. However, structural basis of the functional conversion has not been understood. In our molecular dynamics simulations on modified TFL1 proteins, a hydrogen bond present in native TFL1 between the His88 residue and a residue (Asp144) in a neighboring external loop became broken by change of His88 to Tyr. This breakage induced conformational change of the external loop whose structure was previously reported to be another key functional determinant. These findings reveal that the two important factors determining the functional specificities of the floral regulators, the key amino acid (His88) and the external loop, are correlated, and the key amino acid determines the functional specificity indirectly by affecting the conformation of the external loop.

Effect of growth regulators on shoot regeneration and root formation during in vitro culture of bulb segments from Narcissus (cv. Dutck Master) (수선화 구근의 기내배양시 성장조절제의 조직별 재분화와 뿌리 형성에 미치는 효과)

  • Kim Younghee
    • Proceedings of the KAIS Fall Conference
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    • 2005.05a
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    • pp.269-271
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    • 2005
  • 본 연구는 수선화 구근의 각 조직으로부터 기내배양시 캘러스형성과 신초재분화를 위한 성장조절제의 효과를 측정하기 써하여 시행되었다. 신초형성과 callus의 형성은 기저부를 포함하는 floral axis에서 $50\%$의 신초발아율을 관찰하였고 scale 에서는 신초형성이 거의 관찰되지 않았다. 그리고 floral axis만을 치상한 경우는 아주 저조한 신초형성율이 관찰되었다. 지저부를 포함한 floral axis의 신초형성은 callus의 형성과 같은 NAA 0.5 mg/L과 BA 1.0 mg/L을 포함하는 MS 배지에서 만족할만한 결과를 얻었다. 신초형성으로부터 모든 신초가 형성되기까지는 약 140일이 소요되었다. 신초가 형성된 구근조직을 NAA 5.0 mg/L과 TDZ 0.02 mg/L을 포함하는 뿌리유도 MS배지에서 뿌리가 유도되는 결과를 얻었다. 본 실험에서는 수선화의 재 분화에 있어서 구근의 조직에 따라 신초형성이 다르게 나타남을 발견 할 수 있었다.

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Somatic Embryogenesis from Various Parts of Muscari comosum var. plumosum

  • Xudong He;Ko Jeong-Ae;Choi Jeong-Ran;Kim Hyung-Moo;Kim Myung-Jun;Choi So-Ra;Kim Young-Gon;Kim Dong-Hee;Kim Hyun-Soon
    • Korean Journal of Plant Resources
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    • v.19 no.3
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    • pp.427-431
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    • 2006
  • In vitro high-frequency plant regeneration of Muscari comosum var. plumosum through somatic embryogenesis was obtained via two developmental pathways: direct embryos and multiple shoots regenerated from embryogenic callus. Flower bud with pedicel, receptacle, petal and ovary wall, floral stalk and leaf as explants were cultured in MS medium supplemented with various plant growth regulators. Embryos formed directly from pedicel, receptacle and floral stalk. Depending on explant sources, the optimal medium was MS medium supplemented with 0.2 mg/L IBA and 0.3 mg/L BA, 3.0 mg/L IBA and 3.0 mg/L BA, and MS-free medium for pedicel, receptacle, and floral stalk, respectively. Multiple shoots regenerated from embryogenic cal]i which was initiated from petal, ovary and leaf were observed in MS medium with different concentrations and combinations of hormone. The most suitable medium for each type of explant was 3.0 mg/L IBA and 3.0 mg/L BA(petal and ovary) and 5.0 mg/L IBA and 5.0 mg/L BA (leaf) Furthermore, the combination of 0.1 mg/L 2,4-D and 1.0 mg/L BA was also good for all sources of explants not only for direct embryo formation, but also, for embryogenic callus induction.

In Vitro Flowering System (In Vitro 시스템에 의한 화호형성)

  • 류장렬;이행순;이광웅
    • Proceedings of the Botanical Society of Korea Conference
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    • 1987.07a
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    • pp.213-237
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    • 1987
  • In vitro flowering system may minimize the confounded influence of non-floral meristem parts of plants in studying the relationship of a given treatment and flowering responses. We have induced flower buds from plantlets regenerated from zygotic embryo-derived somatic embryos of ginseng, which circumvented the normal 2-year juvenile period before flowering. The result suggests that the adulthood of ginseng root explants in the experiment previously conducted by Chang and Hsing (1980; Nature 284: 341-342) is not prerequired to flowering of plantlets regenerated through somatic embryogenesis. We have also induced flower buds from elongated axillary brandches from cotyledonary nodes by culturing ginseng zygotic embryos, seedlings, and excised cotyledonary nodes. It was found that 6-benzyladenine (BA) supplemented to the medium was essential for flowering, whereas abscisic acid (ABA) was inhibitory. Gibberellic acid(GA3) was also required for flowering when ABA was present with BA in the medium. The results suggest that cytokinins, gibberellins, and inhibitors play primary, permissive, and preventive roles, respective-ly, in the induction of flowering of ginseng. Tran Thanh Van (1980; Int. Rev. Cytol., Suppl. IIA: 175-194) has developed the "thin cell layer system" in which the induction of shoots, roots, or flower buds from epidermal layer explants were controlled by culture conditions and exogenous growth regulators in the medium, Utilizing the thin cell layer system, Meeks-Wagner et al. (1989; The Plant Cell 1: 25-35) have cloned genes specifically expressed during floral evocation. However, the system is too tedious for obtaining a sufficient amount of plant materials for biochmical and molecular biological studies of flowering. We have developed a garlic callus culture system and one obvious advantaging over the thin cell layer system is that an abundant cells committed to develope into flower buds proliferate. When the above cells were compared by two-dimensional gel electrophoresis with those which have just lost the competence for developing into flower buds, a few putative proteins specific to floral evocation were detected. The garlic callus culture system can be further explored for elucidation of the molecular biological mechanism of floral evocation and morphogenesis.hogenesis.

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Adventitious Shoot and Plant Regeneration from Anther Culture of Hypericum ascyron L. (물레나물 약배양에 의한 부정 신초 및 식물체 재분화)

  • Ko, Jeong-Ae;Kim, Hyun-Soon;Kim, Hyung-Moo
    • Korean Journal of Plant Resources
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    • v.21 no.5
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    • pp.368-373
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    • 2008
  • In order to investigate the effects of low temperature pretreatment of floral bud and plant growth regulators on anther-derived callus and shoot differentiation, anthers were cultured on 1/2 MS medium supplemented with 2,4-D, NAA, BA and TDZ. This plant depends on the plant growth regulators, for these anthers couldn't respond on 1/2 MS medium without plant growth regulators. 2,4-D was a prerequisite substance in this experiment, especially 52.6% of callus formation on MS medium with 2.0mg/L 2,4-D alone. However, the optimum medium was on 1/2 MS medium with 0.1 mg/L 2,4-D and 1.0mg/L BA for continuous growth and shoot differentiation from the anther. Calli derived from on MS medium with 2.0mg/L 2,4-D transferred to the 1/2MS medium with TDZ and BA. TDZ were less superior to BA, only one anther could produce shoot on MS media with 1.0mg/L TDZ. On the other hand, when the calli transferred to the medium with 3.0mg/L BA, adventitious shoots were proliferated, subsequently, regenerated shoots elongated from the embryogenic calli. After floral buds of one week before anthesis were incubated at $5^{\circ}C$ refrigerator for eight or fifteen days, anthers seperated from floral buds were cultured on 1/2MS medium supplemented with 0.1mg/L 2,4-D and 1.0mg/L BA. Callusing and shoot differentiation on anthers from treated at $5^{\circ}C$ for eight days were more effective than those of fifteen days or control.

Effect of plant growth regulators on plant regeneration from the Sedum rotundifolium D. Lee (둥근잎꿩의비름(Sedum rotundifolium D. Lee)의 식물체 재분화에 미치는 식물생장조절제의 영향)

  • Kwon, Hye-Kyoung;Yoon, Eui-Soo
    • Journal of Plant Biotechnology
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    • v.37 no.1
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    • pp.84-88
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    • 2010
  • To establish the system of In vitro plant regeneration, the floral bud and leaf explants of Sedum rotundifolium were cultured on the MS media supplemented with different concentration of 2,4-D, NAA, and BA. The callus induction was more effective in the floral explants than the leaf explants, and was the best on MS medium containing 1.0 or 2.0 mg/L 2,4-D and 1.0 mg/L BA. The highest numbers of shoots were regenerated when callus were cultured on MS medium containing 2.0 mg/L 2,4-D and 1.0 mg/L BA for 8 weeks. The normal root formation from shoot was effective on the MS medium containing IAA alone. The regenerated plantlets were transferred to the pot and acclimatized successfully.

Casein Kinases I and 2α Phosphorylate Oryza Sativa Pseudo-Response Regulator 37 (OsPRR37) in Photoperiodic Flowering in Rice

  • Kwon, Choon-Tak;Koo, Bon-Hyuk;Kim, Dami;Yoo, Soo-Cheul;Paek, Nam-Chon
    • Molecules and Cells
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    • v.38 no.1
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    • pp.81-88
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    • 2015
  • Flowering time (or heading date) is controlled by intrinsic genetic programs in response to environmental cues, such as photoperiod and temperature. Rice, a facultative short-day (SD) plant, flowers early in SD and late in long-day (LD) conditions. Casein kinases (CKs) generally act as positive regulators in many signaling pathways in plants. In rice, Heading date 6 (Hd6) and Hd16 encode $CK2{\alpha}$ and CKI, respectively, and mainly function to delay flowering time. Additionally, the major LD-dependent floral repressors Hd2/Oryza sativa Pseudo-Response Regulator 37 (OsPRR37;hereafter PRR37) and Ghd7 also confer strong photoperiod sensitivity. In floral induction, Hd16 acts upstream of Ghd7 and CKI interacts with and phosphorylates Ghd7. In addition, Hd6 and Hd16 also act upstream of Hd2. However, whether CKI and $CK2{\alpha}$ directly regulate the function of PRR37 remains unclear. Here, we use in vitro pull-down and in vivo bimolecular fluorescence complementation assays to show that CKI and $CK2{\alpha}$ interact with PRR37. We further use in vitro kinase assays to show that CKI and $CK2{\alpha}$ phosphorylate different regions of PRR37. Our results indicate that direct posttranslational modification of PRR37 mediates the genetic interactions between these two protein kinases and PRR37. The significance of CK-mediated phosphorylation for PRR37 and Ghd7 function is discussed.

Expression of the Floral Repressor miRNA156 is Positively Regulated by the AGAMOUS-like Proteins AGL15 and AGL18

  • Serivichyaswat, Phanu;Ryu, Hak-Seung;Kim, Wanhui;Kim, Soonkap;Chung, Kyung Sook;Kim, Jae Joon;Ahn, Ji Hoon
    • Molecules and Cells
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    • v.38 no.3
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    • pp.259-266
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    • 2015
  • The regulation of flowering time has crucial implications for plant fitness. MicroRNA156 (miR156) represses the floral transition in Arabidopsis thaliana, but the mechanisms regulating its transcription remain unclear. Here, we show that two AGAMOUS-like proteins, AGL15 and AGL18, act as positive regulators of the expression of MIR156. Small RNA northern blot analysis revealed a significant decrease in the levels of mature miR156 in agl15 agl18 double mutants, but not in the single mutants, suggesting that AGL15 and AGL18 co-regulate miR156 expression. Histochemical analysis further indicated that the double mutants showed a reduction in MIR156 promoter strength. The double mutants also showed reduced abundance of pri-miR156a and pri-miR156c, two of the primary transcripts from MIR156 genes. Electrophoretic mobility shift assays demonstrated that AGL15 directly associated with the CArG motifs in the MIR156a/c promoters. AGL18 did not show binding affinity to the CArG motifs, but pull-down and yeast two-hybrid assays showed that AGL18 forms a heterodimer with AGL15. GFP reporter assays and bimolecular fluorescence complementation (BiFC) showed that AGL15 and AGL18 co-localize in the nucleus and confirmed their in vivo interaction. Overexpression of miR156 did not affect the levels of AGL15 and AGL18 transcripts. Taking these data together, we present a model for the transcriptional regulation of MIR156. In this model, AGL15 and AGL18 may form a complex along with other proteins, and bind to the CArG motifs of the promoters of MIR156 to activate the MIR156 expression.

Shortening of Breeding Cycle by Forced Flowering in Forest trees II. Enhancement of Flowering Induction by Treatment of Growth Regulators in Betula pendula Roth and Betula platyphylla var. japonica Hara (임목(林木)에 있어서 개화유도(開花誘導)에 의한 육종(育種)싸이클의 단축(短縮) II. 생장조절물질(生長調節物質) 처리(處理)에 의한 자작나무와 은자작나무의 개화유도(開花誘導) 촉진(促進))

  • Chung, Min Sup;Jo, Jinki;Park, Sang Jin
    • Journal of Korean Society of Forest Science
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    • v.84 no.4
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    • pp.495-501
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    • 1995
  • Betula pendula and B. platyphylla var. japonica seedlings and/or grafts growing inside and outside of a plastic-greenhouse were treated with growth regulators to induce flowering at early stages of seedling and graft developments. The seedlings began to develop female catkins visibly in eight to nine months after seeding and in five months after the first treatment of growth regulators. Thirty three percents of the seedlings grown under controlled environment in the plastic-greenhouse with sufficient nutrient supply developed female catkins both in control plants and in the plants treated with IAA, $GA_3$ and kinetin, while none on the control plants grown in the field showed any sign of the development of floral organs. Sixty seven percents of the seedlings treated with ABA and SADH grown in the Plastic-greenhouse developed female catkins. All the seedlings treated with 6.24 mM of SADH developed female catkins. SADH treatment to 2-5 year old seedlings and grafts of birch had a tendency of positive effect on inducing and increasing the flowering of the two birch species.

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Medium Composition and Growth Regulator on Organogenesis Platycodon grandiflorum (Jacq.) A. DC. with Yellow Green Petals ('녹색 꽃잎 도라지'의 기관분화에 미치는 배지조성 및 생장조절제의 영향)

  • Kwon, Soo Jeong;Cho, Kab Yeon;Kim, Hag Hyun
    • Korean Journal of Plant Resources
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    • v.27 no.1
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    • pp.43-50
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    • 2014
  • This study was carried out to determine the optimal medium composition and growth regulators for the micropropagation of Platycodon grandiflorum (Jacq.) A. DC. Nodes containing yellow green petals were used as plant materials to execute the study. The best performance of adventitious root development was found in 1/4 strength of MS basal salt and the growth was satisfactory in the concentration of 1/2 MS medium. The best condition for adventitious root development and growth was observed in the higher concentration (5%) of sucrose and activated charcoal free 1/4MS medium respectively. Adventitious roots were developed at the controlled culture medium at pH 4.8 with a tendency of suppression with higher levels of pH. However, it was prevailed that the development and growth depended on the concentration of agar. The lower concentration of agar (0.4%) was performed better than that of higher concentration (1.2%), whereas the agar concentration (0.4%) showed the best performance for the development and growth of adventitious roots. For the development of shoots containing node, BA combined with IAA was more effective than kinetin with IAA or NAA. The highest shoot development (3.9 shoots per explant) was performed on MS medium supplemented with 0.1 mg/L BA and 0.5 mg/L IAA.