Nobuo Kobayashi

Publications (5)4.63 Total impact

• Article: Chimeric inheritance of organelle DNA in variegated leaf seedlings from inter-subgeneric crossing of azalea

  Nobuo Kobayashi, Masashi Matsunaga, Akira Nakatsuka, Daiki Mizuta, Masayoshi Shigyo, Masaru Akabane
  Euphytica 01/2013; · 1.55 Impact Factor
• Article: Attaining inter-subgeneric hybrids in fragrant azalea breeding and the inheritance of organelle DNA

  Nobuo Kobayashi, Daiki Mizuta, Akira Nakatsuka, Masaru Akabane
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  ABSTRACT: Inter-subgeneric hybrids were successfully obtained in reciprocal cross combinations between evergreen azaleas (Rhododendron nakaharae and its hybrids) and fragrant deciduous azaleas (R.arborescens and R.viscosum) for the purpose of fragrant evergreen azalea breeding. Nuclear and organelle DNA of these hybrids was investigated using PCR-RFLP markers. Viable hybrid seedlings have nuclear ribosomal DNA (nrDNA) inherited biparentally, mitochondrial DNA (mtDNA) from the seed parent, and chloroplast DNA (cpDNA) from the deciduous azalea, regardless of cross combination. These results suggest that the chloroplast genome from deciduous azaleas and the nuclear genome from evergreen azaleas are compatible in viable hybrid progenies.
  Euphytica 04/2012; 159(1):67-72. · 1.55 Impact Factor
• Article: Isolation and expression analysis of flavonoid biosynthesis genes in evergreen azalea

  Akira Nakatsuka, Daiki Mizuta, Yutaka Kii, Ikuo Miyajima, Nobuo Kobayashi
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  ABSTRACT: As a tool for breeding new floral colors into azalea, we obtained basic gene information for flavonoid synthesis in floral tissues of azalea (Rhododendron × pulchrum Sweet cv. Oomurasaki). The partial- or full-length cDNA sequences of eight structural genes involved in the flavonoid biosynthetic pathway were isolated: chalcone synthase (CHS), chalcone isomerase (CHI), flavonone-3-hydroxylase (F3H), flavonoid-3′hydroxylase (F3′H), flavonoid-3′,5′-hydroxylase (F3′5′H), dihydroflavonol reductase (DFR), anthocyanidin synthase (ANS), and flavonol synthase (FLS). These genes were isolated from petals of R. × pulchrum by PCR using degenerate and gene-specific primers and their expression levels were analyzed. Deduced amino acid sequences of obtained genes showed 76–80% identities with the corresponding flavonoid biosynthetic pathway sequences from other dicotyledonous species. Expression of these eight genes during azalea flower development was investigated. A real-time PCR analysis showed that transcripts of CHS, F3H and ANS genes decreased as flowering progressed, and those of CHI, DFR, F3′H, and FLS genes transiently increased at the stage of pigmentation initiation. In addition, maximum expression of the F3′5′H gene was expressed concomitant with anthocyanin synthesis. Spatial expression showed that the CHS, DFR, and FLS genes are more abundant in other floral organs or leaves than petals. The levels of CHI, F3H, ANS, and F3′H gene transcripts were highest in leaf tissue compared with floral organs. The highest level of F3′5′H expression was in the petal at stage 3. These results indicated that F3′5′H gene is strongly correlated to pigmentation in azalea petals, but expression of other genes are unclear for anthocyanin synthesis.
  Scientia Horticulturae.
• Article: Comparison of flower color with anthocyanin composition patterns in evergreen azalea

  Daiki Mizuta, Takuya Ban, Ikuo Miyajima, Akira Nakatsuka, Nobuo Kobayashi
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  ABSTRACT: In evergreen azaleas, major anthocyanins were detected from petals of wild species and cultivars by HPLC analysis. Depending on flower color, all samples were divided into three groups: red, purple or white, using the Japan color standard for horticultural plants. The chromatic components a* and b* values of red group samples showed a convergent distribution, whereas those of purple group samples showed a wider distribution. According to the HPLC analysis, red group samples had two to four major anthocyanins, and those of the purple group had two to six major ones. In contrast, no anthocyanins were detected in the white group petals, although anthocyanidins were detected. These results suggest that the anthocyanin constitution of the purple group flowers is more varied than that of the red group flowers, and this wider variety among purple flowers contributes to extending the diversity of flower color in evergreen azalea.
  Scientia Horticulturae 122(4):594-602. · 1.53 Impact Factor
• Article: Light-induced expression of basic helix-loop-helix genes involved in anthocyanin biosynthesis in flowers and leaves of Asiatic hybrid lily

  Akira Nakatsuka, Masumi Yamagishi, Michiharu Nakano, Keisuke Tasaki, Nobuo Kobayashi
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  ABSTRACT: Transcription of anthocyanin biosynthetic genes is usually controlled by transcription factors such as basic-helix-loop-helix (bHLH) and R2R3-MYB. To know the regulatory mechanisms of anthocyanin accumulation in Asiatic hybrid lily (Lilium spp.), cDNA clones encoding bHLH transcription factors were isolated from tepals and their expression was examined in this study. This is the first report about cDNAs for bHLH genes among the species in monocots other than Gramineae. Two cDNAs corresponding to LhbHLH1 and LhbHLH2 genes were isolated; the former encoded the protein having the similarity to AmDELILA and PhJAF13 and the latter one did to PhAN1. LhbHLH1 and LhbHLH2 were expressed in tepals, stems and leaves. In filaments and pistils, only LhbHLH2 was transcribed. During tepal development, transcriptions of LhbHLH genes were always detected, and the peak of LhbHLH2 expression preceded the peak of LhDFR expression. When lily buds were exposed to light, anthocyanin accumulation was induced in leaves and peaked at 4 days after light exposure. The transcription of LhbHLH2 peaked at 2 days after light exposure and decreased after that. LhbHLH1 transcription was affected by light to a lesser extent than LhbHLH2 at 2 days. These expressional changes preceded the change of anthocyanin amount. Similarly in tepals, both anthocyanin amount and the transcription of LhDFR and LhbHLH2 decreased in the dark after 6 days, but LhbHLH1 transcription was not affected. These results suggest that LhbHLH1 and LhbHLH2, especially LhbHLH2, are involved in anthocyanin biosynthesis, and that response to light exposure was different between LhbHLH1 and LhbHLH2.
  Scientia Horticulturae.