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  • The EMBO Journal (2006) 25, 5579 - 5590
  • doi:10.1038/sj.emboj.7601434

Published online: 16 November 2006

Increased frequency of homologous recombination and T-DNA integration in Arabidopsis CAF-1 mutants

Masaki Endo1,2,a, Yuichi Ishikawa1,3,a, Keishi Osakabe1, Shigeki Nakayama1, Hidetaka Kaya4, Takashi Araki4, Kei-ichi Shibahara5, Kiyomi Abe1, Hiroaki Ichikawa1, Lisa Valentine6, Barbara Hohn6 and Seiichi Toki1

  1. Division of Plant Sciences, National Institute of Agrobiological Sciences, Kannondai, Tsukuba, Ibaraki, Japan
  2. Graduate School of Life Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Ibaraki, Japan
  3. Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai, Miyagi, Japan
  4. Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, Japan
  5. Department of Integrated Genetics, National Institute of Genetics, Mishima, Shizuoka, Japan
  6. Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland

Correspondence to:

Seiichi Toki, Division of Plant Sciences, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan. Tel.: +81 29 838 8450; Fax: +81 29 838 8450; E-mail: stoki@affrc.go.jp

aThese authors contributed equally to this work

Received 26 January 2006; Accepted 11 October 2006

Chromatin assembly factor 1 (CAF-1) is involved in nucleo some assembly following DNA replication and nucleotide excision repair. In Arabidopsis thaliana, the three CAF-1 subunits are encoded by FAS1, FAS2 and, most likely, MSI1, respectively. In this study, we asked whether genomic stability is altered in fas1 and fas2 mutants that are lacking CAF-1 activity. Depletion of either subunit increased the frequency of somatic homologous recombination (HR) in planta approx40-fold. The frequency of transferred DNA (T-DNA) integration was also elevated. A delay in loading histones onto newly replicated or repaired DNA might make these DNA stretches more accessible, both to repair enzymes and to foreign DNA. Furthermore, fas mutants exhibited increased levels of DNA double-strand breaks, a G2-phase retardation that accelerates endoreduplication, and elevated levels of mRNAs coding for proteins involved in HR—all factors that could also contribute to upregulation of HR frequency in fas mutants.

  • Keywords:

    • Arabidopsis,
    • CAF-1,
    • cell cycle,
    • DNA damage,
    • homologous recombination