The Arabidopsis Ca2+-dependent protein kinase CPK12 negatively regulates abscisic acid signaling in seed germination and post-germination growth

Authors

  • Rui Zhao,

    1. College of Biological Sciences, China Agricultural University, 100094 Beijing, China
    2. Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
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    • These authors contributed equally to this work.

  • Hai-Li Sun,

    1. College of Biological Sciences, China Agricultural University, 100094 Beijing, China
    2. Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
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    • These authors contributed equally to this work.

  • Chao Mei,

    1. Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
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  • Xiao-Jing Wang,

    1. College of Biological Sciences, China Agricultural University, 100094 Beijing, China
    2. Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
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  • Lu Yan,

    1. College of Biological Sciences, China Agricultural University, 100094 Beijing, China
    2. Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
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  • Rui Liu,

    1. College of Biological Sciences, China Agricultural University, 100094 Beijing, China
    2. Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
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  • Xiao-Feng Zhang,

    1. Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
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  • Xiao-Fang Wang,

    1. College of Biological Sciences, China Agricultural University, 100094 Beijing, China
    2. Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
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  • Da-Peng Zhang

    1. Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China
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Author for correspondence:
Da-Peng Zhang
Tel: +86 10 62781956
Email: zhangdp@tsinghua.edu.cn

Summary

  • Ca2+-dependent protein kinase (CDPK) is believed to be involved in abscisic acid (ABA) signaling, and several members of the Arabidopsis CDPK superfamily have been identified as positive ABA signaling regulators, but it remains unknown if CDPK negatively regulates ABA signaling.
  • Here, we investigated the function of an Arabidopsis (Arabidopsis thaliana) CDPK, CPK12, in ABA signaling pathway.
  • We generated Arabidopsis CPK12-RNAi lines, and observed that downregulation of CPK12 resulted in ABA hypersensitivity in seed germination and post-germination growth, and altered expression of a set of ABA-responsive genes. Expression assay showed that CPK12 was ubiquitously expressed and localized to both cytosol and nucleus. Biochemical assays showed that CPK12 interacted with, phosphorylated and stimulated a type 2C protein phosphatase ABI2, and phosphorylated two ABA-responsive transcription factors (ABF1 and ABF4) in vitro.
  • Our findings show that the Arabidopsis CPK12 is a negative ABA-signaling regulator in seed germination and post-germination growth, suggesting that different members of the CDPK family may constitute a regulation loop by functioning positively and negatively in ABA signal transduction.

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