Plant Reaction: Tracking the Wave Calcium Signaling in Wounded Mimosa Leaf Tissue

Original video: https://youtu.be/MiLaVWFuoQM

This video visualises the wound-induced calcium signaling pathway that triggers rapid leaf movements in Mimosa pudica. Using a calcium indicator (GCaMP6f), we monitored the dynamics of cytosolic calcium concentration ([Ca²⁺]cyt) in real time from the underside of the leaves. Upon wounding a leaflet with scissors, we observed an immediate [Ca²⁺]cyt increase at the wound site. This signal then propagated through a leaflet vein at an average speed of 1.31 mm/s. The arrival of this calcium wave at the tertiary pulvinus (the motor organ at the base of the leaflet) was followed by a rapid rise in [Ca²⁺]cyt within the pulvinus, which in turn triggered the characteristic leaflet movement. Subsequently, the calcium signal was seen to spread along the rachilla in two directions: towards the base of the leaf (basipetally at 3.11 mm/s) and towards the tip (acropetally at 2.65 mm/s), exhibiting a bimodal pattern. To further investigate the role of calcium, we pretreated leaves with La3+ (a calcium channel blocker). This pretreatment significantly retarded the propagation of the [Ca²⁺]cyt increase throughout the leaf, as well as the calcium increase specifically in the pulvinus. Interestingly, only a slight change in [Ca²⁺]cyt was observed at the immediate wound site in these pretreated leaves. Crucially, pretreatment with La³⁺ completely prevented both the [Ca²⁺]cyt increase and the resulting leaf movement in response to wounding. These results strongly suggest that [Ca²⁺]cyt acts as a crucial and rapid long-distance signaling molecule that triggers the characteristic leaf movements in Mimosa pudica upon injury.

Keywords:

Plant wound response, Calcium signaling, Leaf movement, Tertiary pulvinus, Rachilla, Mimosa pudica, La³⁺ effect, Calcium channel blocker, Plant physiology, Plant biology, Signal transduction, Wound-induced signaling

Citation:

Hagihara, T., Mano, H., Miura, T. et al. Calcium-mediated rapid movements defend against herbivorous insects in Mimosa pudica. Nat Commun 13, 6412 (2022). https://doi.org/10.1038/s41467-022-34106-x

Published on: 14 November 2022

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