|
|
|
|
|
|
|
|
|||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | |||||
Journal of Cell Science, Vol 110, Issue 15 1729-1740, Copyright © 1997 by Company of Biologists
JOURNAL ARTICLES |
MD Fricker, NS White and G Obermeyer
Department of Plant Sciences, University of Oxford, UK.
The cytoplasmic pH of growing pollen tubes of Lilium longiflorum Thunb. was measured using the pH-sensitive fluorescent dye 2',7'-bis-(carboxyethyl)-5(6')-carboxyfl uorescein and confocal fluorescence ratio imaging. The average cytoplasmic pH in the clear zone of the pollen tube tip was pH 7.11, and no consistent pH gradients were detected in the clear zone, averaging around -1.00 milli pH unit microm(-1), or along the first 50 microm of the tube (3.62 milli pH units microm[-1]). In addition, no correlation was observed between the absolute tip cytoplasmic pH or the pH gradient and the pollen tube growth rates. Shifts of external pH to more acidic pH values (pH 4.5) caused a relatively small acidification by 0.18 pH units, whereas a more alkaline external pH >7.0 caused a dramatic increase in cytoplasmic pH and growth stopped immediately. Stimulation of the plasma membrane H+-ATPase by fusicoccin, resulted in an increase of tube growth but no change in cytoplasmic pH. On the other hand, vanadate (250-500 microM), a putative inhibitor of the pump, stopped tube growth and a slight cytoplasmic alkalinisation of 0.1 pH units was observed. Vanadate also arrested fusicoccin-stimulated growth and stimulated an increased alkalinisation of around 0.2 pH units. External application of CaCl2 (10 mM) caused a small acidification of less than 0.1 pH units in the clear zone, whilst LaCl3 (250 microM) caused slight and rather variable perturbations in cytoplasmic pH of no more than 0.1 pH units. Both treatments stopped growth. It was inferred from these data that tip-acid cytoplasmic pH gradients do not play a central role in the organisation or maintenance of pollen tube tip growth.
This article has been cited by other articles:
|
|
 |
|
  J.-Z. Wu, Y. Lin, X.-L. Zhang, D.-W. Pang, and J. Zhao IAA stimulates pollen tube growth and mediates the modification of its wall composition and structure in Torenia fournieri J. Exp. Bot., June 1, 2008; 59(9): 2529 - 2543. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Lovy-Wheeler, J. G. Kunkel, E. G. Allwood, P. J. Hussey, and P. K. Hepler Oscillatory Increases in Alkalinity Anticipate Growth and May Regulate Actin Dynamics in Pollen Tubes of Lily PLANT CELL, September 1, 2006; 18(9): 2182 - 2193. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C.-P. Song, Y. Guo, Q. Qiu, G. Lambert, D. W. Galbraith, A. Jagendorf, and J.-K. Zhu A probable Na+(K+)/H+ exchanger on the chloroplast envelope functions in pH homeostasis and chloroplast development in Arabidopsis thaliana PNAS, July 6, 2004; 101(27): 10211 - 10216. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. R. Robinson and M. A. Messerli Pulsating Ion Fluxes and Growth at the Pollen Tube Tip Sci. Signal., December 10, 2002; 2002(162): pe51 - pe51. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J.A. Feijo, J. Sainhas, G.R. Hackett, J.G. Kunkel, and P.K. Hepler Growing Pollen Tubes Possess a Constitutive Alkaline Band in the Clear Zone and a Growth-dependent Acidic Tip J. Cell Biol., February 8, 1999; 144(3): 483 - 496. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Bibikova, T Jacob, I Dahse, and S Gilroy Localized changes in apoplastic and cytoplasmic pH are associated with root hair development in Arabidopsis thaliana Development, January 8, 1998; 125(15): 2925 - 2934. [Abstract] [PDF]
|
|
