Takako Narumi

National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan

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Publications (8)26.12 Total impact

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    ABSTRACT: Photoperiodic floral induction has had a significant impact on the agricultural and horticultural industries. Changes in day length are perceived in leaves, which synthesize systemic flowering inducers (florigens) and inhibitors (antiflorigens) that determine floral initiation at the shoot apex. Recently, FLOWERING LOCUS T (FT) was found to be a florigen; however, the identity of the corresponding antiflorigen remains to be elucidated. Here, we report the identification of an antiflorigen gene, Anti-florigenic FT/TFL1 family protein (AFT), from a wild chrysanthemum (Chrysanthemum seticuspe) whose expression is mainly induced in leaves under noninductive conditions. Gain- and loss-of-function analyses demonstrated that CsAFT acts systemically to inhibit flowering and plays a predominant role in the obligate photoperiodic response. A transient gene expression assay indicated that CsAFT inhibits flowering by directly antagonizing the flower-inductive activity of CsFTL3, a C. seticuspe ortholog of FT, through interaction with CsFDL1, a basic leucine zipper (bZIP) transcription factor FD homolog of Arabidopsis. Induction of CsAFT was triggered by the coincidence of phytochrome signals with the photosensitive phase set by the dusk signal; flowering occurred only when night length exceeded the photosensitive phase for CsAFT induction. Thus, the gated antiflorigen production system, a phytochrome-mediated response to light, determines obligate photoperiodic flowering response in chrysanthemums, which enables their year-round commercial production by artificial lighting.
    Proceedings of the National Academy of Sciences 09/2013; · 9.74 Impact Factor
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    ABSTRACT: Chrysanthemum is a typical short-day (SD) plant that responds to shortening daylength during the transition from the vegetative to the reproductive phase. FLOWERING LOCUS T (FT)/Heading date 3a (Hd3a) plays a pivotal role in the induction of phase transition and is proposed to encode a florigen. Three FT-like genes were isolated from Chrysanthemum seticuspe (Maxim.) Hand.-Mazz. f. boreale (Makino) H. Ohashi & Yonek, a wild diploid chrysanthemum: CsFTL1, CsFTL2, and CsFTL3. The organ-specific expression patterns of the three genes were similar: they were all expressed mainly in the leaves. However, their response to daylength differed in that under SD (floral-inductive) conditions, the expression of CsFTL1 and CsFTL2 was down-regulated, whereas that of CsFTL3 was up-regulated. CsFTL3 had the potential to induce early flowering since its overexpression in chrysanthemum could induce flowering under non-inductive conditions. CsFTL3-dependent graft-transmissible signals partially substituted for SD stimuli in chrysanthemum. The CsFTL3 expression levels in the two C. seticuspe accessions that differed in their critical daylengths for flowering closely coincided with the flowering response. The CsFTL3 expression levels in the leaves were higher under floral-inductive photoperiods than under non-inductive conditions in both the accessions, with the induction of floral integrator and/or floral meristem identity genes occurring in the shoot apexes. Taken together, these results indicate that the gene product of CsFTL3 is a key regulator of photoperiodic flowering in chrysanthemums.
    Journal of Experimental Botany 12/2011; 63(3):1461-77. · 5.24 Impact Factor
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    ABSTRACT: Temperature plays a significant role in the annual cycling between growth and dormancy of the herbaceous perennial chrysanthemum (Chrysanthemum morifolium Ramat.). After exposure to high summer temperatures, cool temperature triggers dormancy. The cessation of flowering and rosette formation by the cessation of elongation are characteristic of dormant plants, and can be stimulated by exogenous ethylene. Thus, the ethylene response pathway may be involved in temperature-induced dormancy of chrysanthemum. Transgenic chrysanthemums expressing a mutated ethylene receptor gene were used to assess this involvement. The transgenic lines showed reduced ethylene sensitivity: ethylene causes leaf yellowing in wild-type chrysanthemums, but leaves remained green in the transgenic lines. Extension growth and flowering of wild-type and transgenic lines varied between temperatures: at 20 degrees C, the transgenic lines showed the same stem elongation and flowering as the wild type; at cooler temperatures, the wild type formed rosettes with an inability to flower and entered dormancy, but some transgenic lines continued to elongate and flower. This supports the involvement of the ethylene response pathway in the temperature-induced dormancy of chrysanthemum. At the highest dosage of ethephon, an ethylene-releasing agent, wild-type plants formed rosettes with an inability to flower and became dormant, but one transgenic line did not. This confirms that dormancy is induced via the ethylene response pathway.
    Journal of Experimental Botany 11/2008; 59(15):4075-82. · 5.24 Impact Factor
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    ABSTRACT: Previously, Narumi et al. (2005) generated chrysanthemum plants transformed with a mutated ethylene receptor gene (mDG-ERS1(etr1-4<), and showed that thein vitro plantlets of the transformants grown aseptically in a small plastic container had a reduced sensitivity to ethylene resulting in reduced leaf yellowing after exposure to exogenous ethylene. In the present study we evaluated ethylene sensitivity of the transformants using soil-grown mature plants. When the shoots detached from soil-grown plants were treated with exogenous ethylene under continuous light, leaf yellowing (senescence) was delayed in the transformants as compared with the non-transformed plants. Furthermore, when the detached shoots were kept in darkness without ethylene treatment, the transformants showed reduced senescence as compared with those of the non-transformed plants. These results demonstrated that the mutated ethylene receptor genemDG-ERS1(etr1-4) could confer reduced sensitivity to ethylene in the leaves of mature chrysanthemum plants. This gene may be useful to generate transgenicCompositae vegetables with leaves green for a longer time and thus having a longer shelf life.
    Journal of Plant Biology 01/2008; 51(6):424-427. · 0.99 Impact Factor
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    Postharvest Biology and Technology. 02/2007; 43(2):280–281.
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    ABSTRACT: A cDNA encoding a putative ethylene receptor (DG-ERS1) was isolated from chrysanthemum [Dendranthema grandiflorum (Ramat.) Kitamura] using a combination of reverse transcription PCR (RT-PCR), cDNA library screening and 5′-RACE techniques. The cDNA (2427 bp) contained an open reading frame of 1920 bp coding for 640 amino acids. The predicted DG-ERS1 protein has an amino-terminal ethylene sensor domain and a histidine kinase domain, but lacks a receiver domain. The DG-ERS1 protein has 72, 70 and 69% similarity to Arabidopsis ERS1, tomato Never ripe (NR) and carnation DC-ERS2, respectively. Real time PCR analysis revealed that DG-ERS1 mRNA was present in a large amount in ligulate corollas (hereafter, petals for short) and mature leaves of an ethylene-sensitive cultivar ‘Seiko-no-makoto’ at the full-opening stage of the flower, and the amount decreased with time or in response to a 12-h ethylene treatment. In an ethylene-insensitive cultivar ‘Iwa-no-hakusen’, the amount of DG-ERS1 mRNA in petals was one-fourth and that in mature leaves was only one-twentieth of the amount in ‘Seiko-no-makoto’ at the full-opening stage, and its amount in both tissues scarcely changed with time or in response to a 12-h ethylene treatment. These findings suggest the involvement of DG-ERS1 in the perception of ethylene in cut chrysanthemum plants, especially in those of ‘Seiko-no-makoto’ cultivar.
    Postharvest Biology and Technology 01/2007; 36(1):21-30. · 2.45 Impact Factor
  • Takako Narumi, Rie Sudo, Shigeru Satoh
    Engei Gakkai zasshi 01/2006; 75(4):323-327.
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    ABSTRACT: We generated mutated ethylene receptor genes (mDG-ERS1s) from the chrysanthemum ethylene receptor (DG-ERS1) cDNA by introducing one-nucleotide substitutions corresponding to those present in Arabidopsis etr1-1, etr1-2, etr1-3, and etr1-4 and tomato Nr. The promoter of a tobacco elongation factor 1α (EF1α) gene was fused to DG-ERS1 cDNA or one of the mDG-ERS1s. The resulting constructs were named EF1α∷mDG-ERS1(etr1-1), -ERS1(etr1-2) and so on, and introduced into chrysanthemum cv. Sei-Marine. We obtained putative transformants resistant to an antibiotic paromomycin with a yield of 2.4–6.2% depending on the construct. The mDG-ERS1(etr1-4) construct tended to be more effective in conferring reduced ethylene sensitivity in chrysanthemum than the others. PCR analysis gave amplification corresponding to a partial sequence of EF1α∷mDG-ERS1 transgenes. Southern blot analysis showed that, in the mDG-ERS1(etr1-4) transformant, not only the lines with reduced sensitivity to ethylene but also those sensitive to ethylene harbored the mDG-ERS1(etr1-4) transgene. The present results showed the usefulness of mutated ethylene receptor genes mDG-ERS1s for generation of transgenic chrysanthemums with reduced ethylene sensitivity.
    Postharvest Biology and Technology 01/2005; 37(2):101-110. · 2.45 Impact Factor

Publication Stats

27 Citations
26.12 Total Impact Points


  • 2013
    • National Agriculture and Food Research Organization
      Tsukuba, Ibaraki, Japan
  • 2005–2007
    • Tohoku University
      • Graduate School of Agricultural Science
      Sendai-shi, Miyagi-ken, Japan