title: Release of an acid phosphatase activity during lily pollen tube growth involves components of the secretory pathway.
abstract: 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 microM) and cytochalasin D (1 microM), which block the production and transport of secretory vesicles, respectively, inhibited the acPase secretion. The Ca2+ channel blocker gadolinium (100 microM 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 (beta-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.
authors.affiliation: Institute of Plant Physiology, University of Salzburg, Salzburg, Austria.
authors.forename: Hala
authors.initials: H
authors.lastname: Ibrahim
authors.forename: Heidi
authors.initials: H
authors.lastname: Pertl
authors.forename: Klaus
authors.initials: K
authors.lastname: Pittertschatscher
authors.forename: Ezzat
authors.initials: E
authors.lastname: Fadl-Allah
authors.forename: Ahmed
authors.initials: A
authors.lastname: el-Shahed
authors.forename: Friedrich-Wilhelm
authors.initials: FW
authors.lastname: Bentrup
authors.forename: Gerhard
authors.initials: G
authors.lastname: Obermeyer
mesh_terms: D000135:Acid Phosphatase / Q000737:chemistry / Q000378:metabolism*; D020126:Brefeldin A / Q000494:pharmacology; D002110:Caffeine / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism; D015638:Cytochalasin D / Q000378:metabolism; D035264:Flowers / Q000201:enzymology / Q000254:growth & development; D018525:Germination / Q000187:drug effects; D005960:Glucosides / Q000378:metabolism; D027762:Lilium / Q000201:enzymology* / Q000254:growth & development*; D008982:Molybdenum / Q000378:metabolism; D010696:Phloroglucinol / Q000031:analogs & derivatives* / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013997:Time Factors
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D005960:Glucosides; C104977:Yariv reagent; C044659:molybdate; D020126:Brefeldin A; D015638:Cytochalasin D; D002110:Caffeine; D008982:Molybdenum; D010696:Phloroglucinol; D000135:Acid Phosphatase