Auxin induces an increase of Ca2+ concentration in the cytosol of wheat leaf protoplasts

Abstract

Auxin addition to protoptasts isolated from leaves of 6-day-old wheat seedlings (Triticum aestivum L. cv. Kadett) induced a rapid increase in the cytosolic calcium concentration [Ca2+](cyt). The shifts in [Ca2+](cyt) were detected by use of fluorescence microscopy in single protoplasts loaded with the calcium binding tetra[acetoxymethyl]ester of the fluorescent dye, Fura 2. Addition of the synthetic auxin naphthyl acetic acid, 1-NAA, induced an increase in [Ca2+](cyt) within 5-10s, while the physiologically non-active analogue, 2-NAA, did not. The amplitude of calcium increase depended on the concentration of 1-NAA. Since the process was affected by different concentrations of Ca2+ in the external medium, and since the calcium channel blockers (nifedipine and verapamil) postponed and inhibited the reaction, it is suggested that auxin primarily activates Ca2+-permeable channels in the plasma membrane. In the presence of low external calcium concentration (0.1 mM), 5 mM LiCl almost totally blocked the increase in [Ca2+](cyt), indicating a possible involvement of tonoptast Ca2+-channels in the auxin-induced [Ca2+](cyt) shift. Thus, calcium signalling induced by auxin involves both external and internal Ca2+ pools. (C) 2004 Elsevier GmbH. All rights reserved

Keywords

auxin; cytoplasmic calcium; fluorescence microscopy; Triticum aestivum; wheat

Published in

Journal of Plant Physiology
2004, Volume: 161, number: 8, pages: 937-945
Publisher: URBAN & FISCHER VERLAG

SLU Authors

• Lindberg, Sylvia

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Agricultural Science


Publication identifier

DOI: https://doi.org/10.1016/j.jplph.2003.12.005

Permanent link to this page (URI)

https://res.slu.se/id/publ/4385