Present address: School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK.
Cytoplasmic free calcium distributions during the development of root hairs of Arabidopsis thaliana
Article first published online: 5 MAR 2002
The Plant Journal
Volume 12, Issue 2, pages 427–439, August 1997
How to Cite
Wymer, C. L., Bibikova, T. N. and Gilroy, S. (1997), Cytoplasmic free calcium distributions during the development of root hairs of Arabidopsis thaliana. The Plant Journal, 12: 427–439. doi: 10.1046/j.1365-313X.1997.12020427.x
- Issue published online: 5 MAR 2002
- Article first published online: 5 MAR 2002
- Received 23 September 1996; revised 18 March 1997; accepted 18 April 1997.
- Cited By
In this study, confocal ratio analysis was used to image the relationship between cytoplasmic free calcium concentration ([Ca2+]c) and the development of root hairs of Arabidopsis thaliana. Although a localized change in [Ca2+]c that preceded or predicted the site of root hair initiation could not be detected, once initiated the majority of emerging root hairs showed an elevated [Ca2+]c (>1 μM) in their apical cytoplasm, compared with 100– 200 nM in the rest of the cell. These emerging root hairs then moved into a 3–5 h phase of sustained elongation during which they showed variable growth rates. Root hairs that were rapidly elongating exhibited a highly localized, elevated [Ca2+]c at the tip. Non-growing root hairs did not exhibit the [Ca2+]c gradient. The rhd-2 mutant, which is defective in sustained root hair growth, showed an altered [Ca2+]c distribution compared with wild-type. These results implicate [Ca2+]c in regulating the tip growth process. Treatment of elongating wild-type root hairs with the Ca2+ channel blocker verapamil (50 μM) caused dissipation of the elevated [Ca2+]c at the tip and cessation of growth, suggesting a requirement for Ca2+ channel activity at the root hair tip to maintain growth. Manganese treatment also preferentially quenched Indo-1 fluorescence in the apical cytoplasm of the root hair. As manganese is thought to enter cells through Ca2+-permeable channels, this result also suggests increased Ca2+ channel activity at the tip of the growing hair. Taken together, these data suggest that although Ca2+ does not trigger the initiation of root hairs, Ca2+ influx at the tip of the root hair leads to an elevated [Ca2+]c that may be required to sustain root hair elongation.