Stigma/style cell cycle inhibitor 1 (SCI1), a tissue-specific cell cycle regulator that controls upper pistil development

Authors

  • Henrique C. DePaoli,

    1. Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil
    2. Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14049-900, Brazil
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  • Michael S. Brito,

    1. Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil
    2. Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14049-900, Brazil
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  • Andréa C. Quiapim,

    1. Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil
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  • Simone P. Teixeira,

    1. Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-903, Brazil
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  • Gustavo H. Goldman,

    1. Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-903, Brazil
    2. Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Campinas 13083-970, Brazil
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  • Marcelo C. Dornelas,

    1. Departamento de Biologia Vegetal, Instituto de Biologia, Universidade de Campinas, Campinas 13083-970, Brazil
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  • Maria Helena S. Goldman

    1. Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil
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Author for correspondence:
Maria Helena S. Goldman
Tel: +55 16 3602 3702
Email: mgoldman@ffclrp.usp.br

Summary

  • A cDNA encoding a small lysine-rich protein of unknown function was identified in a tobacco (Nicotiana tabacum) stigma/style suppression subtractive hybridization cDNA library. After its characterization, the corresponding gene was designated stigma/style cell cycle inhibitor 1 (SCI1).
  • Fluorescence microscopy with an SCI1-GFP protein fusion demonstrated its nuclear localization, which was confined to the interchromatic region. Real-time RT-PCR and in situ hybridization experiments showed that SCI1 is stigma/style-specific and developmentally regulated.
  • SCI1 RNAi knockdown and overexpression plants had stigmas/styles with remarkably enlarged and reduced areas, respectively, which was attributable to differences in cell numbers. These results indicate that SCI1 is a tissue-specific negative cell cycle regulator.
  • The differences in cell division had an effect on the timing of the differentiation of the stigmatic papillar cells, suggesting that their differentiation is coupled to stigma cell divisions. This is consistent with a role for SCI1 in triggering differentiation through cell proliferation control. Our results revealed that SCI1 is a novel tissue-specific gene that controls cell proliferation/differentiation, probably as a component of a developmental signal transduction pathway.

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