. 2010 Oct 1;5(10):1211–1221. doi: 10.4161/psb.5.10.12658

Table 1.

Hypothetical mechanisms of seismonastic movements of Mimosa pudica leaf

Hypotheses	Pro	Contra
Diffusion of a chemical compounds¹ referred to turgorins or leaf movement factors.²	Gallic acid 4-O-(β-D-glucopyranosyl-6′-sulfate) can induce leaf closing.²,³ Gallic acid is a product of acid hydrolysis of the tannins. A sulfotransferase involved in sulfation of the turgorins, gallic acid 4-O-(β-D-glucopyranosyl-6′-sulfate), is pulvini-localized in Mimosa pudica.⁴ If leaves of Mimosa pudica exposed to ¹⁴CO₂, considerable amounts of labeled photoassimilates are accumulated in the pulvinus of the stimulated leaf.⁵ There is a correlation between movements of the leaf and sucrose translocation in the phloem of Mimosa pudica.⁵	Mechanoreceptors of Mimosa pudica elicit also electrical and hydraulic signals, which induce transport of K⁺, Cl⁻, Ca²⁺ ions and fast water translocation in the pulvinus. The leaf movements are reversible. Some anesthetics reversibly block the seismonastic movements of a petiole.⁶ Aquaporins are involved in the seismonastic movements of a petiole.⁷ The mechanical stimulation triggers a large decrease of K⁺ ions in the extensor site.⁸
Muscular movements.⁶,⁹–¹¹	The degree of bending of a peyiole is correlated with actin tyrosine-phosphorylation in the pulvinus.¹¹ Fragmentation of actin filaments and microtubules occurs during bending, although the actin cytoskeleton, but not the microtubules, is involved in the regulation of the movement.¹² Cytochalasin B and phallodin inhibit the bending of the petiole.¹³,¹⁴ The ATP level in the pulvinus decreases to 30% during falling of a petiole and returns to the initial level after recovery of a petiole and pulvinus.¹⁵ Ca, Mg-dependent ATPase in the pulvinus is similar to the ATPases from muscle and non-muscle motile cells.¹⁶ A tubulin from Mimosa pudica may be involved in the regulation the movements in Mimosa pudica.¹⁷Mimosa pudica has a gelsolin/fragmin family actin-modulating protein that severs actin filament in a Ca²⁺-dependent manner.¹⁸ The central vacuole of the motor cell contains a contractile protein which undergoes a conformational change during seismonastic movement.¹⁹ The seismonastic movement of a petiole may be more efficient than typical animal muscle movements.⁹	Some anesthetics reversibly block the seismonastic movements of a petiole.⁶ Aquaporins are involved in the seismonastic movements of a petiole.⁷ The mechanical stimulation triggers a large decrease of K⁺ ions in the extensor site.⁸
Osmotic motor	Migration of calcium regulates the seismonastic response in Mimosa pudica. Volume and conformational changes of the contractive tannin vacuoles in the pulvinus correlate with the seismonastic leaf movement.¹⁹ Stimulation of Mimosa pudica causes the secretion of K⁺ from the cytoplasm into the apoplast.²⁰ The mechanical stimulation triggers a large decrease of K⁺ ions in the outer extensor.⁸,²¹ Shrinking of extensor cells and swelling of flexor cells bend a pulvinus.²²	The degree of bending of a petiole is correlated with actin tyrosine-phosphorylation in the pulvinus.¹¹ Fragmentation of actin filaments and microtubules occurs during bending, although the actin cytoskeleton, but not the microtubules, is involved in the regulation of the movement.¹² Cytochalasin B and phallodin inhibit the bending of the petiole.¹³,¹⁴ Gallic acid 4-O-(β-D-glucopyranosyl-6′-sulfate) can induce leaf closing.²,³ A sulfotransferase involved in sulfation of the turgorins, gallic acid 4-O-(β-D-glucopyranosyl-6′-sulfate) is pulvini-localized in Mimosa pudica.⁴ Cells in flexor and extensor sites have opposite response to the same action potential.