† These authors contributed equally to this study.
Uncoupling secretion and tip growth in lily pollen tubes: evidence for the role of calcium in exocytosis
Article first published online: 5 JAN 2002
The Plant Journal
Volume 19, Issue 4, pages 379–386, August 1999
How to Cite
Roy, S. J., Holdaway-Clarke, T. L., Hackett, G. R., Kunkel, J. G., Lord, E. M. and Hepler, P. K. (1999), Uncoupling secretion and tip growth in lily pollen tubes: evidence for the role of calcium in exocytosis. The Plant Journal, 19: 379–386. doi: 10.1046/j.1365-313X.1999.00515.x
- Issue published online: 5 JAN 2002
- Article first published online: 5 JAN 2002
- Received 18 March 1999; revised 1 June 1999; accepted 4 June 1999.
Cytoplasmic calcium concentration ([Ca2+]i) and extracellular calcium (Ca2+o) influx has been studied in pollen tubes of Lilium longliflorum in which the processes of cell elongation and exocytosis have been uncoupled by use of Yariv phenylglycoside ((β-D-Glc)3). Growing pollen tubes were pressure injected with the ratio dye fura-2 dextran and imaged after application of (β-D-Glc)3, which binds arabinogalactan proteins (AGPs). Application of (β-D-Glc)3 inhibited growth but not secretion. Ratiometric imaging of [Ca2+]i revealed an initial spread in the locus of the apical [Ca2+]i gradient and substantial elevations in basal [Ca2+]i followed by the establishment of new regions of elevated [Ca2+]i on the flanks of the tip region. Areas of elevated [Ca2+]i corresponded to sites of pronounced exocytosis, as evidenced by the formation of wall ingrowths adjacent to the plasma membrane. Ca2+o influx at the tip of (β-D-Glc)3-treated pollen tubes was not significantly different to that of control tubes. Taken together these data indicate that regions of elevated [Ca2+]i, probably resulting from Ca2+o influx across the plasma membrane, stimulate exocytosis in pollen tubes independent of cell elongation.