Abstract:

Ecological evidence indicates a worldwide trend of dramatically decreased soil Ca²⁺ levels caused by increased acid deposition and massive timber harvesting. Little is known about the genetic and cellular mechanism of plants' responses to Ca²⁺ depletion. In this study, transcriptional profiling analysis helped identify multiple extracellular Ca²⁺ ([Ca²⁺]_ext) depletion-responsive genes in Arabidopsis thaliana L., many of which are involved in response to other environmental stresses. Interestingly, a group of genes encoding putative cytosolic Ca²⁺ ([Ca²⁺]_cyt) sensors were significantly upregulated, implying that [Ca²⁺]_cyt has a role in sensing [Ca²⁺]_ext depletion. Consistent with this observation, [Ca²⁺]_ext depletion stimulated a transient rise in [Ca²⁺]_cyt that was negatively influenced by [K⁺]_ext, suggesting the involvement of a membrane potential-sensitive component. The [Ca²⁺]_cyt response to [Ca²⁺]_ext depletion was significantly desensitized after the initial treatment, which is typical of a receptor-mediated signaling event. The response was insensitive to an animal Ca²⁺ sensor antagonist, but was suppressed by neomycin, an inhibitor of phospholipase C. Gd³⁺, an inhibitor of Ca²⁺ channels, suppressed the [Ca²⁺]_ext-triggered rise in [Ca²⁺]_cyt and downstream changes in gene expression. Taken together, this study demonstrates that [Ca²⁺]_cyt plays an important role in the putative receptor-mediated cellular and transcriptional response to [Ca²⁺]_ext depletion of plant cells.

Wang J, Tergel T, Chen J, Yang J, Kang Y, Qi Z (2015) Arabidopsis transcriptional response to extracellular Ca²⁺ depletion involves a transient rise in cytosolic Ca²⁺. J Integr Plant Biol 57: 138–150. doi: 10.1111/jipb.12218

Key words: Arabidopsis, aequorin, calcium depletion, cytosolic calcium, transcriptional response