Pharmacological Evidence for Calcium Involvement in the Long-Term Processing of Abiotic Stimuli in Plants

Abstract

AbbReViATioNSEDTA ethylenediaminetetraacetic acid EGTA ethylene glycol tetraacetic acid RR ruthenium red SCT slow cold treatment AbSTRACTInformation about abiotic conditions is stored for long periods in plants and, in flax seedlings, can lead to the production of meristems. To investigate the underlying mechanism, flax seedlings were given abiotic stimuli that included a mechanical stimulus (by manipulation), one or two cold shocks, a slow cold treatment and a drought stress and, if these seedlings were then subjected to a temporary (1 to 3 days) depletion of calcium, epidermal meristems were produced in the seedling hypocotyls. This production was inhibited by the addition to the nutrient media of EGTA, ruthenium red, lanthanum or gadolinium that affect calcium availability or calcium transport. Use of these agents revealed a period of vulnerability in information processing that was less than two min for mechanical stimuli and over five min for other abiotic stimuli, consistent with information about mechanical stimuli being stored particularly fast. We propose that external calcium is needed for the transduction/storage of the information for meristem production whilst a temporary depletion of external calcium is needed for the actual production of meristems. Such roles for calcium would be consistent with a mechanism based on ion condensation on charged polymers.

The Role of Calcium in the Recall of Stored Morphogenetic Information by Plants

“…Each experimental point corresponds to the mean value of the numbers of meristems counted in 10 seedlings. For more detail about the experimental conditions, see Verdus et al (1996Verdus et al ( , 1997Verdus et al ( , 2007.…”

“…This low N value is probably not due to an effect on the RCL function but rather to an effect on the STO function since it is known that information storage is progressive (Sect. 4.2; Verdus et al (1997)) and requires the presence of a sufficient amount of calcium (Verdus et al 2007). …”

“…For brevity, we say that a STO function has been switched on (or activated) when the seedlings have stored the information corresponding to an abiotic stimulus and that a RCL function has been switched on (or activated) when the seedlings have been enabled to recall the stored information by being subjected to transient calcium depletion. In a preceding paper, we focussed on the calcium-dependent nature of the STO function (Verdus et al 2007). Here, we focus on the RCL function with a view to build a conceptual model of the plantmemorization system.…”

Plants and Animals: Convergent Evolution in Action?

“…These plant memories allow them to make fairly good predictions about their future circumstances (Trewavas 2005a , b;Tafforeau et al 2006 ;Bruce et al 2007 ;Ruuhola et al 2007 ;Ripoll et al 2009) . Similar to animal memories, these plant memories are based on electricity, chemicals and calcium (Verdus et al 2007 ;Volkov et al 2008) . Plants are known to use touch genes to mechanically sense their environment (Trewavas and Knight 1997) .…”

The theater management model of plant memory

“…15,[31][32][33] Consistent with this importance of calcium, plant memory is perturbed by treatment with pharmacological agents that are known to affect cytosolic calcium and hence any transient increase of cytosolic calcium that might follow stimulus perception. 16,34 With its multiple bridging roles, calcium might increase the probability of colocalisation of specific proteins, nucleic acids and lipids and hence contribute to the formation and the stabilization of FDSs. The condensation of calcium onto charged membranes and linear polymers and might also underpin the organization of FDSs and chromatin and their putative action in memory.…”