The effect of calcium antagonists and inhibitors of secretory processes on auxin-induced elongation and fine structure ofPisum sativum stem segments |
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Authors: | M E Cunninghame J L Hall |
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Institution: | (1) Department of Biology, University of Southampton, Building 44, SO9 5NH Southampton, UK |
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Abstract: | Summary The treatment of dark grown pea stem segments with chelators of divalent cations (EGTA, EDTA, CTC), various Ca2+ antagonists (LaCl3, A-23187, verapamil) and inhibitors of secretory processes (monensin, CB) reduced elongation in the presence of indole-3-acetic acid (IAA). Generally the inhibition increased with increasing concentrations of the substances. The timing of the responses can be correlated with maximum auxin-stimulated secretion of cell wall material. Examination of cell ultrastructure showed that changes in dictyosome activity could explain a reduced deposition of cell wall material and so cause inhibition of elongation.The inhibitors affected the morphology and vesiculation of the dictyosomes, and the appearance of the plasma membrane, ER and mitochondria in different ways. The most pronounced effects on ultrastructure resulted from monensin and LaCl3 treatments with the dictyosomes being most affected; large vesicles appeared in the cytoplasm. Less pronounced effects on cell structure were seen in EGTA, A-23187 and verapamil treated tissue. The effects on the dictyosomes are considered to be due to disturbances of Ca2+ and other ionic levels within the cells.Abbreviations ATPase
adenosine triphosphatase
- CB
cytochalasin B
- CTC
chlorotetracycline
- DMSO
dimethyl sulphoxide
- EDTA
ethylene diamine tetraacetic acid
- EGTA
ethyleneglycol-bis-(B-amino ethyl ether)N,N1-tetraacetic acid
- ER
endoplasmic reticulum
- ver
verapamil |
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Keywords: | Calcium Cell elongation Indole-3-acetic acid Pisum sativum Secretion |
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