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The transcript composition of egg cells changes significantly following fertilization in wheat (Triticum aestivum L.)

Authors

  • Stefanie Sprunck,

    1. Developmental Biology and Biotechnology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany
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  • Ute Baumann,

    1. Australian Center for Plant Functional Genomics, University of Adelaide, Waite Campus, Hartley Grove, SA 5064, Australia
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  • Keith Edwards,

    1. Department of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
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  • Peter Langridge,

    1. Australian Center for Plant Functional Genomics, University of Adelaide, Waite Campus, Hartley Grove, SA 5064, Australia
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  • Thomas Dresselhaus

    Corresponding author
    1. Developmental Biology and Biotechnology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany
      For correspondence (fax +49 40 42816 229; e-mail dresselh@botanik.uni-hamburg.de).
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For correspondence (fax +49 40 42816 229; e-mail dresselh@botanik.uni-hamburg.de).

Summary

Here, we report the transcript profile of wheat egg cells and proembryos, just after the first cell division. Microdissected female gametophytes of wheat were used to isolate eggs and two-celled proembryos to construct cell type-specific cDNA libraries. In total, 1197 expressed sequence tags (ESTs) were generated. Analysis of these ESTs revealed numerous novel transcripts. In egg cells, 17.6% of the clustered ESTs represented novel transcripts, while 11.4% novel clusters were identified in the two-celled proembryo. Functional classification of sequences with similarity to previously characterized proteins indicates that the unfertilized egg cell has a higher metabolic activity and protein turnover than previously thought. Transcript composition of two-celled proembryos was significantly distinct from egg cells, reflecting DNA replication as well as high transcriptional and translational activity. Several novel transcripts of the egg cell are specific for this cell. In contrast, some fertilization induced novel mRNAs are abundant also in sporophytic tissues indicating a more general role in plant growth and development. The potential functions of genes based on similarity to known genes involved in developmental processes are discussed. Our analysis has identified numerous genes with potential roles in embryo sac function such as signaling, fertilization or induction of embryogenesis.

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