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Cambial meristem dormancy in trees involves extensive remodelling of the transcriptome

Authors

  • Jarmo Schrader,

    1. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
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    • Present address: ZMBP, Developmental Genetics, Auf der Morgenstelle 3, 72076 Tübingen, Germany.

  • Richard Moyle,

    1. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
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    • Present address: Department of Botany, University of Queensland, QLD 4072 Brisbane, Australia.

  • Rupali Bhalerao,

    1. Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, 90187 Umeå, Sweden
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  • Magnus Hertzberg,

    1. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
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    • §Present address: SweTree Technologies, PO Box 7981, S-907 19, Umeå, Sweden.

  • Joakim Lundeberg,

    1. Department of Biotechnology, Royal Institute of Technology, 10044 Stockholm, Sweden
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  • Peter Nilsson,

    1. Department of Biotechnology, Royal Institute of Technology, 10044 Stockholm, Sweden
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  • Rishikesh P. Bhalerao

    Corresponding author
    1. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
      *For correspondence (fax +46 90 7868165; e-mail rishi.bhalerao@genfys.slu.se).
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*For correspondence (fax +46 90 7868165; e-mail rishi.bhalerao@genfys.slu.se).

Summary

The establishment of the dormant state in meristems involves considerable physiological and metabolic alterations necessary for surviving unfavourable growth conditions. However, a global molecular analysis of dormancy in meristems has been hampered by the difficulty in isolating meristem cells. We used cryosectioning to isolate purified cambial meristem cells from the woody plant Populus tremula during active growth and dormancy. These samples were used to generate meristem-specific cDNA libraries and for cDNA microarray experiments to define the global transcriptional changes underlying cambial dormancy. The results indicate a significant reduction in the complexity of the cambial transcriptome in the dormant state. Although cell division is terminated in the dormant cambium, the cell cycle machinery appears to be maintained in a skeletal state as suggested by the continued presence of transcripts for several cell cycle regulators. The downregulation of PttPIN1 and PttPIN2 transcripts explains the reduced basipetal polar auxin transport during dormancy. The induction of a member of the SINA family of ubiquitin ligases implicated in auxin signalling indicates a potential mechanism for modulation of auxin sensitivity during cambial dormancy. The metabolic alterations during dormancy are mirrored in the induction of genes involved in starch breakdown and the glyoxysomal cycle. Interestingly, the induction of RGA1 like gene suggests modification of gibberellin signalling in cambial dormancy. The induction of genes such as poplar orthologues of FIE and HAP2 indicates a potential role for these global regulators of transcription in orchestrating extensive changes in gene expression during dormancy.

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