A possible mechanism and sequence of events that lead to the Al3+-induced [Ca2+]cyt transients and inhibition of root growth

Abstract

Fluorescence resonance energy transfer (FRET)-sensitized emission imaging of Arabidopsis thaliana roots expressing the yellow cameleon 3.60 calcium (Ca2+) reporter showed that the concentration of calcium in the cytosol ([Ca2+] 2+) increased upon aluminum ion (Al3+) treatment in root cells from the transition zone within seconds. The Al3+-induced [Ca2+]2+ transients were biphasic and were modified by Ca2+ channel blockers and by an antagonist of neuronal glutamate receptors, 2-amino-5-phosphonopentanoate (AP-5), and by the anion channel blocker, 5-nitro-2-(3'-phenylpropyl-amino) benzoate (NPPB). The [Ca2+]cyt transients were not uniquely associated with Al3+ toxicity mechanisms since lanthanum (La3+) and gadolinium (Gd3+) also elicited [Ca2+]cyt transients that were similar to those induced by Al3+. Here a testable model that describes a possible mechanism and sequence of events that lead to the Al3+-induced [Ca2+]2+ transients and inhibition of root growth is proposed. This model can be applied to study also the signal-response coupling of the trivalent ions La3+ and Gd3+. © 2010 Landes Bioscience.