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Reactive oxygen species produced by NADPH oxidase are involved in pollen tube growth

Authors

  • Martin Potocký,

    1. Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, 16502 Prague 6, Czech Republic;
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    • *

      These authors contributed equally to the experimental work.

  • Mark A. Jones,

    1. School of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK;
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    • *

      These authors contributed equally to the experimental work.

  • Radek Bezvoda,

    1. Department of Plant Physiology, Faculty of Science, Charles University, Viničná 5, 12844 Prague 2, Czech Republic
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  • Nicholas Smirnoff,

    1. School of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK;
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  • Viktor Žárský

    1. Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, 16502 Prague 6, Czech Republic;
    2. Department of Plant Physiology, Faculty of Science, Charles University, Viničná 5, 12844 Prague 2, Czech Republic
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Author for correspondence: Viktor Žárský Tel. +420 2 20390457 Fax: +420 2 20390456 Email: zarsky@ueb.cas.cz

Summary

  • • Tip-localized reactive oxygen species (ROS) were detected in growing pollen tubes by chloromethyl dichlorodihydrofluorescein diacetate oxidation, while tip-localized extracellular superoxide production was detected by nitroblue tetrazolium (NBT) reduction.
  • • To investigate the origin of the ROS we cloned a fragment of pollen specific tobacco NADPH oxidase (NOX) closely related to a pollen specific NOX from Arabidopsis. Transfection of tobacco pollen tubes with NOX-specific antisense oligodeoxynucleotides (ODNs) resulted in decreased amount of NtNOX mRNA, lower NOX activity and pollen tube growth inhibition.
  • • The ROS scavengers and the NOX inhibitor diphenylene iodonium chloride (DPI) inhibited growth and ROS formation in tobacco pollen tube cultures. Exogenous hydrogen peroxide (H2O2) rescued the growth inhibition caused by NOX antisense ODNs. Exogenous CaCl2 increased NBT reduction at the pollen tube tip, suggesting that Ca2+ increases the activity of pollen NOX in vivo.
  • • The results show that tip-localized ROS produced by a NOX enzyme is needed to sustain the normal rate of pollen tube growth and that this is likely to be a general mechanism in the control of tip growth of polarized plant cells.

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