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A Putative Calcium-Permeable Cyclic Nucleotide-Gated Channel, CNGC18, Regulates Polarized Pollen Tube Growth

Authors

  • Fang Chang,

    1. National Key Laboratory of Plant Physiology and Biochemistry
    2. CAU-UCR Joint Center for Biological Sciences, China Agricultural University, Beijing 100094, China
    3. Center for Plant Cell Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA)
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  • An Yan,

    1. National Key Laboratory of Plant Physiology and Biochemistry
    2. CAU-UCR Joint Center for Biological Sciences, China Agricultural University, Beijing 100094, China
    3. Center for Plant Cell Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA)
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  • Li-Na Zhao,

    1. National Key Laboratory of Plant Physiology and Biochemistry
    2. CAU-UCR Joint Center for Biological Sciences, China Agricultural University, Beijing 100094, China
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  • Wei-Hua Wu,

    1. National Key Laboratory of Plant Physiology and Biochemistry
    2. CAU-UCR Joint Center for Biological Sciences, China Agricultural University, Beijing 100094, China
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  • Zhenbiao Yang

    Corresponding author
    1. CAU-UCR Joint Center for Biological Sciences, China Agricultural University, Beijing 100094, China
    2. Center for Plant Cell Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA)
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  • Supported by a Natural Science Foundation of China grant (Outstanding Overseas Young Scientist Award # 30428020 to ZY and WW) and a US National Science Foundation grant to ZY.

*Author for correspondence.
Tel: +86 951 827 7351;
Fax: +86 951 827 4437;
E-mail: <yang@ucr.edu>.

Abstract

A tip-focused Ca2+ gradient is tightly coupled to polarized pollen tube growth, and tip-localized influxes of extracellular Ca2+ are required for this process. However the molecular identity and regulation of the potential Ca2+ channels remains elusive. The present study has implicated CNGC18 (cyclic nucleotide-gated channel 18) in polarized pollen tube growth, because its overexpression induced wider and shorter pollen tubes. Moreover, CNGC18 overexpression induced depolarization of pollen tube growth was suppressed by lower extracellular calcium ([Ca2+]ex). CNGC18-yellow fluorescence protein (YFP) was preferentially localized to the apparent post-Golgi vesicles and the plasma membrane (PM) in the apex of pollen tubes. The PM localization was affected by tip-localized ROP1 signaling. Expression of wild typeROP1 or an active form of ROP1 enhanced CNGC18-YFP localization to the apical region of the PM, whereas expression of RopGAP1 (a ROP1 deactivator) blocked the PM localization. These results support a role for PM-localized CNGC18 in the regulation of polarized pollen tube growth through its potential function in the modulation of calcium influxes.

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