Protoplasma

, Volume 219, Issue 3–4, pp 176–183 | Cite as

Release of an acid phosphatase activity during lily pollen tube growth involves components of the secretory pathway

  • Hala Ibrahim
  • Heidi Pertl
  • Klaus Pittertschatscher
  • Ezzat Fadl-Allah
  • Ahmed El-Shahed
  • Friedrich-Wilhelm Bentrup
  • Gerhard Obermeyer

Summary.

An acid phosphatase (acPAse) activity was released during germination and tube growth of pollen of Lilium longiflorum Thunb. By inhibiting components of the secretory pathway, the export of the acPase activity was affected and tube growth stopped. Brefeldin A (1 μM) and cytochalasin D (1 μM), which block the production and transport of secretory vesicles, respectively, inhibited the acPase secretion. The Ca2+ channel blocker gadolinium (100 μM Gd3+) also inhibited acPase secretion and tube growth, whereas 3 mM caffeine, another Ca2+ uptake inhibitor, stimulated the acPase release, while tube growth was inhibited. The Yariv reagent (β-D-glucosyl)3 Yariv phenylglycoside stopped tube growth by binding to arabinogalactan proteins of the tube tip cell wall but did not affect acPase secretion. A strong correlation between tube growth and acPase release was detected. The secreted acPase activity had a pH optimum at pH 5.5, a KM of 0.4 mM for p-nitrophenyl phosphate, and was inhibited by zinc, molybdate, phosphate, and fluoride ions, but not by tartrate. In electrophoresis gels the main acPase activity was detected at 32 kDa. The conspicuous correlation between activity of the secretory pathway and acPase secretion during tube elongation strongly indicates an important role of the acPase during pollen tube growth and the secreted acPase activity may serve as a useful marker enzyme assay for secretory activity in pollen tubes

Keywords: Acid phosphatase; Exocytosis; Lilium longiflorum; Pollen; Secretion; Tip growth 

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Copyright information

© Springer-Verlag Wien 2002

Authors and Affiliations

  • Hala Ibrahim
    • 1
  • Heidi Pertl
    • 1
  • Klaus Pittertschatscher
    • 3
  • Ezzat Fadl-Allah
    • 2
  • Ahmed El-Shahed
    • 2
  • Friedrich-Wilhelm Bentrup
    • 1
  • Gerhard Obermeyer
    • 1
  1. 1. Institute of Plant Physiology, University of Salzburg, SalzburgAT
  2. 2. Botany Department, Faculty of Sciences, Minia University, Minia
  3. 3. Institute of Chemistry and Biochemistry, University of Salzburg, SalzburgAT

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