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The Mimosa pudica leaf has motor organs allowing movements driven by cell osmotic changes in the parenchyma cells in response to various stimuli. Short white light pulses induce rapid and large seismonastic‐like movements (denoted “photostimulation”) of the primary pulvini in various leaves within 120 s after the onset of light. An early event recorded is a wavelength‐related modification of the plasma membrane difference: potential depolarization under white, blue, green, and red wavelengths, and hyperpolarization under far red wavelengths (and also in darkness). The photoreactivity of the pulvini is controlled by a circadian rhythm and modulated by the applied diurnal photoperiod cycle (photophase ranging from 6 to 18 h). The reactivity varied among plants and even between leaves on the same plant. The level of reactivity is related to the photon fluence rate in the range from 10 to 140 μmol m−2 s−1 under white light and to the experimental temperature in the range 15°C–35°C. An “accommodation” to light supply is evidenced by a modulation of the reactivity in relation to the schedule of light application under low fluence rates and the introduction of short darkness intervals during the first 30‐s light pulse. The blue light‐induced photostimulation is under phytochrome control. [ABSTRACT FROM AUTHOR]

Some amino acids have been shown to be signalling molecules in various developmental and stress processes, besides their roles in plant nutrition. Glycine is absorbed by pulvinar motor cells of Mimosa pudica according to an H + -Gly cotransport mechanism and under the control of calcium availability. Noteworthy, glycine triggers early plasma membrane depolarization and H + migration. The unicellular model of protoplasts isolated from pulvini absorbed glycine with characteristics similar to those determined on multicellular motor tissues, considering metabolism regulation, plasma membrane functionality and calcium control. This model allows to observe that a rapid increase of glycine uptake rate occurs in the first 3 min following 10 mM glycine application. Additionally, we monitored a rapid transient increase (within 5-11 s) of the cytoplasmic free calcium ([Ca 2+ ]c) measured by cytofluorimetric determination using Indo-1-loaded protoplasts. The low [Ca 2+ ]c increase seen in nominally Ca 2+ -free medium and the inhibition of [Ca 2+ ]c increase after treatment with channel inhibitors (LaCl 3 , nifedipine) argue for a Ca 2+ mobilization from external stores. This observation emphasized the signalling role of glycine at the plasma membrane site., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)