Pulsatile influxes of H+, K+ and Ca2+ lag growth pulses of Lilium longiflorum pollen tubes

Mark A. Messerli, Gaudenz Danuser, Kenneth R. Robinson

Research output: Contribution to journalArticle

114 Scopus citations

Abstract

Fluxes of H+, K+ and Ca2+ were measured with self-referencing ion-selective probes, near the plasma membrane of growing Lilium longiflorum pollen tubes. Measurements from three regions around short, steady-growing tubes showed small, steady influx of H+ over the distal 40 μm and a region of the tube within 50-100 μm of the grain with larger magnitude efflux from the grain. K+ fluxes were immeasurable in short tubes. Measurements of longer tubes that were growing in a pulsatile manner revealed a pulsatile influx of both H+ and K+ at the growing tip. The average fluxes at the cell surface during the peaks of the H+ and K+ pulses were 489 ± 81 and 688 ± 144 pmol cm-2 second-1, respectively. Growth was measured by tracking the pollen tips with a computer vision system that achieved a spatial resolution of approximately 1/10 pixel. The high spatial resolution enabled the detection of growth, and thus the changes in growth rates, with a temporal sampling rate of 1 frame/second. These data show that the H+ and K+ pulses have a phase lag of 103 ± 9 and 100 ± 11 degrees, respectively, with respect to the growth pulses. Calcium fluxes were also measured in growing tubes. During steady growth, the calcium influx was relatively steady. When pulsatile growth began, the basal Ca2+ influx decreased and a pulsatile component appeared, superimposed on the reduced basal Ca2+ flux. The peaks of the Ca2+ pulses at the cell surface averaged 38.4 ± 2.5 pmol cm-2 second-1. Longer tubes had large pulsatile Ca2+ fluxes with smaller baseline fluxes. The Ca2+ influx pulses had a phase lag of 123 ± 9 degrees with respect to the growth pulses.

Original languageEnglish (US)
Pages (from-to)1497-1509
Number of pages13
JournalJournal of cell science
Volume112
Issue number10
StatePublished - Jun 16 1999

Keywords

  • Ca influx
  • Computer vision
  • H influx
  • K influx
  • Lilium longiflorum
  • Pollen tube
  • Pulsatile growth

ASJC Scopus subject areas

  • Cell Biology

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