Tertiary Pulvini Research Articles

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Genes to CellsVolume 28, Issue 5 p. 329-332 ISSUE INFORMATIONFree Access Issue Information First published: 05 May 2023 https://doi.org/10.1111/gtc.12962AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Abstract Front cover: Stimulated to the leaves, the sensitive plant (Mimosa pudica) folds its leaves one after another. To elucidate the mechanism, a transgenic M. pudica was produced so that the cytosolic Ca2+ concentration can be observed as fl uorescence by GCaMP6f (Hagihara et al. (2022) Nat. Commun. 13: 6412, DOI: 10.1038/s41467-022-34106-x). When a leafl et was wounded, the fl uorescent signal caused by Ca2+ propagated through the veins to the tertiary pulvinus at the base of the leafl et, immediately followed by a movement of the pair of leafl ets to fold inwards. And, Ca2+ signals were propagated to the adjacent tertiary pulvini sequentially, and the leafl ets were also folded successively. At this time, electrical signals were transmitted simultaneously with the fl uorescent signals. The authors also observed that the immotile M. pudica was more susceptible to feeding damage by insects, suggesting that the movement above protects the plant from feeding damage. Designed by TRAIS Co., Ltd. (Kobe, Japan). Volume28, Issue5May 2023Pages 329-332 RelatedInformation

Mechanoreceptor Cells on the Tertiary Pulvini of Mimosa pudica L.

Special red cells were found on the adaxial surface of tertiary pulvini of Mimosa pudica and experiments performed to determine the origin and function of these cells. Using anatomical (light, scanning electron and transmission electron microscopy) and electrophysiological techniques, we have demonstrated that these red cells are real mechanoreceptor cells. They can generate receptor potential following mechanical stimuli and they are in connection with excitable motor cells (through plasmodesmata). We also provide evidence that these red cells are derived from stomatal subsidiary cells and not guard cells. As histochemical studies show red cells contain tannin, which is important in development of action potentials and movements of plants. These cells could be one of unidentified mechanoreceptors of mimosa.

Secondary and Tertiary Pulvini in the Unifoliate Leaf of Cercis canadensis L. (Fabaceae) with Comparison to Bauhinia purpurea L.

There are three leaf types in the Cercideae tribe (Caesalpinioideae, Fabaceae): unifoliate, bilobate, and bifoliate. By the fusion hypothesis, the ancestral leaf type within the Cercideae was bifoliate, and the unifoliate leaf was derived from the fusion of the bifoliate leaflets. In the opposing splitter hypothesis, the unifoliate leaf was the ancestral leaf type within the Cercideae, and the bifoliolate leaf was derived from the splitting of the unifoliate leaf into two separate leaflets. Palmate venation in leaflets is problematic for the fusion hypothesis. Watari proposed derivation from a palmately compound leaf with many leaflets and interpreted the primary vein as homologous to a single midrib in a leaflet. The structure and function of the upper pulvinus in the unifoliate leaf of Cercis canadensis L. were examined to test the two hypotheses. Microscopic observations and measurement of leaf movement over a 12‐h period indicate that the upper pulvinus in the unifoliate leaf is a compound structure consisting of an apical common joint composed of three secondary pulvini and two lateral laminar joints separated by a laminar joint associated with the midrib. A lateral laminar joint consists of three tertiary pulvini, one at the base of each primary vein, and the midrib is formed from a rachilla and two or more pinnules. Structure comparisons were made between the upper pulvinus of a unifoliate leaf of C. canadensis and a bilobate leaf of Bauhinia purpurea. The secondary and tertiary nature of the upper pulvinus indicates that the unifoliate leaf in Cercis was derived from an extinct ancestor with bipinnately compound leaves. Results add support for Watari’s interpretation of the primary vein and for the splitter hypothesis.

The enzyme involved in sulfation of the turgorin, gallic acid 4-O-(beta-D-glucopyranosyl-6'-sulfate) is pulvini-localized in Mimosa pudica.

A sulfotransferase (ST) which catalyzes the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to gallic acid glucoside was characterized from microsomal preparations of Mimosa pudica. The product of the reaction was found to co-elute on HPLC with the periodic leaf movement factor 1 (PLMF-1)(gallic acid beta-D-gluco-pyranosyl-6'-sulfate). The distribution of the enzyme activity was restricted to plasma membrane preparations from primary, secondary and tertiary pulvini. The M. pudica ST activity was inhibited in a dose-dependent manner in the presence of an antibody raised against the flavonol 3-sulfotransferase of Flaveria chloraefolia, suggesting structural similarities between the two proteins. Western blot analysis of M. pudica protein extracts using these antibodies indicated the presence of a cross-reactive polypeptide with an apparent molecular mass of 42,000 Da whose distribution correlates with the presence of the gallic acid glucoside ST activity. Indirect immunogold labeling of resin-embedded sections from tertiary pulvini showed a specific localization of gold particles on the sieve-tube plasma membranes. The label distribution was uniform and other cellular organelles and membrane systems displayed little or no labeling. The results of the Western blot and immunocytochemical studies are consistent with the detection of the gallic acid glucoside ST activity in plasma membrane preparations of M. pudica pulvini cells. The specific tissue distribution of the ST in motor organ phloem cells suggests that this is the site of synthesis and/or accumulation of PLMF-1 and supports the proposed hypothesis that PLMF-1 may be acting as a chemical signal during the seismonastic response of M. pudica.

On the role of tannin vacuoles in several nastic leaf responses

Experiments were done to relate the presence of tannin vacuoles to plant movements. When surveyed, 4 out of 10 species exhibited rapid thigmonastic or nyctinastic movements, and only those 4 species had tannin vacuoles in their motor cells. Interestingly, plants ofAlbizzia julibrissin whose seed was obtained in New Haven, Connecticut had rapid nyctinasty and tannin vacuoles in the tertiary pulvini, whereasAlbizzia collected in Winston-Salem, North Carolina had neither. Nyctinasty ofMimosa pudica andAlbizzia NH, both of which had tannin vacuoles, was at the rate of 4.2 °/min, whereasAlbizzia WS andSamanea saman, neither of which had tannin vacuoles, exhibited leaflet closure at the rate of 2.0–2. 1 °/min. Pretreatment with the Ca2+ channel agonist Bay K-8644 increased, and with the antagonist verapamil decreased, the rate of leaflet closure only inMimosa andAlbizzia NH. Pretreatment with the Ca2+ inhibitor Erythrosin B substantially blocked reopening only inMimosa andAlbizzia NH. We conclude that tannin vacuoles assist nastic movements to be rapid by acting as a store of Ca2+ and releasing it as a second messenger upon mechanical perturbation or darkness.

Transport processes in stimulated and non-stimulated leaves of Mimosa pudica

Adenosine diphosphate (ADP), adenosine triphosphate (ATP) and orthophosphate were determined in non-stimulated, stimulated and relaxed pulvini of mature Mimosa pudica L. leaves. Additional determinations were made with leaflets, rhachillae, petiole and the stem in the stimulated condition. Results show that the content of adenine nucleotides is approximately twice as high in the pulvini as in the tissues between the pulvini. Orthophosphate, in contrast, occurs at higher concentrations in the connecting tissues than in the pulvini. ATP content is highest in the primary pulvini (0.8 μmol/mg dry wt.) and lowest in the tertiary pulvini. Stimulation causes consumption of ATP with a simultaneous increase in ADP content; however, the response is different in each type of pulvinus. This difference is best expressed in the ATP∶ADP ratio. Stimulation causes the most marked reduction of the ratio (9.5-1.4) in the secondary pulvini which react nyctinastically. Orthophosphate content is reduced by stimulation in all types of pulvini, and is increased during the recovery phase. By using a stylet bundle severed from a feeding aphid by a laser shot as tip for the microelectrode, changes of sieve tube membrane potentials were recorded. The changes of the electropotentials following stimulation show that the sieve tube is the pathway for the transmission of the excitation signal in the form of an action potential.

Cation Chelating Agents Affect Leaf Movement via Leakage and not by Inhibition of Contractile Proteins)

Vanden Driessche (1978) proposed that EDTA prevents the seismonastic leaf movement (the closing movement) of the pinnules (tertiary pulvini) ofMimosa via inhibition of the contraction of Ca (2)?,?-regulated contractile proteins. However, the effects of EGTA and EDTA on the leaf movement of the laminar pulvinus ofPhaseolus coccineus L. and the primary pulvinus ofMimosa pudica L. are contrary to the effects measured at the tertiary pulvini (pinnules) ofMimosa or Al- bizzia. EGTA and EDTA (5 to 25 m M) inhibit the upward (opening) movement and induce a downward (closing) movement of the laminar pulvinus ofPhaseolus and the primary pulvinus ofMimosa. High EGTA and EDTA concentrations «freeze» these pulvini in the night (closed) position of the leaves, whereas the tertiary pulvini ofMimosa andAlbizzia in the day (open) position. However, there is evidence that these contrary leaf movement reactions of the different pulvini are due to structural differences and not to different actions of these substances. In excised flexor and extensor tissues of the laminar pulvinus ofPhaseolus EDTA and EGTA induce a netto efflux of osmotica in hypotonic solutions. DMSO (5 to 10%, v/v), which change also the permeability of membranes, induces, similar to EDTA, an opening of the pinnules (tertiary pulvini) ofMimosa in light and dark and inhibit the seismonastic or dark-induced closing movement. However, in the laminar pulvinus ofPhaseolus , DMSO (3 to 5 %) induces a closing movement and «freezes» the lamina in the physiological night position. We conclude therefore, that leakage of osmotica induces night (closed) position in such pulvini, which are lowered during the night and elevated during the day, and day (open) position in such pulvini, which are elevated during the night and lowered during the day. Thus experiments with EDTA give no evidence that contractile proteins play an essential role in the mechanism of circadian, nyctin- astic, or seismonastic leaf movements.

Movements, Bioelectrical Events and Proton Excretion Induced in the Pulvini of Mimosa pudica L. by a Period of Darkness

Summary When plants of Mimosa pudica L. are suddenly darkened during the photophase of the photo-periodic cycle, scotonastic movements are performed by the primary, secondary and tertiary pulvini of the leaf. Bioelectrical variations recorded in the primary pulvini by extracellular electrodes show different time-course patterns in the two halves of the organ: the potential becomes more positive in the lower halves and an earlier hyperpolarization is followed by a slow depolarization in the upper halves. When plants are returned to light, the pulvini reassume to their initial position (photonasties); large depolarizations are recorded in the two halves following light restoration. Very earlier proton migrations are promoted in the two halves of excised primary pulvini following light signals: a proton excretion by the light-off and a proton absorption by the light-on signal. No causal connection can be found yet between these proton transports and pulvinus movement.

Ultrastructure of mimosa leaflet and pulvinule

The ultrastructure of leaflet and tertiary pulvini (pulvinule) of the sensitive plant, Mimosa pudica L., as well as the distribution of ATPase were studied before and after stimulation.There are two zones in the majority of upper epidermis cells of the leaflet (Fig. 1). The upper zone contains a thin layer of cytoplasma, a large central vacuole and much tannin. The lower zone of these cells is electron-transparent and has a lens-like shape. It is filled with fibrillar-foamy material (Fig. 2). “The foam” fibrills are 30-100 Å in diameter. “The foam” is stained with ruthenium red and is supposed to be a mucilaginous inner (lower) wall of the epidermal cell. The cells of the lower epidermis of the leaflet and the pulvinule epidermis do not contain “the foam”. The lens-shaped foamy material might focus light, promote its reception and transfer the light stimuli within the leaflets and pulvini, thus regulating the heliotropic and nyctinastic position of the leaf itself.

Phytochrome-controlled rapid contraction and recovery of contractile vacuoles in the motor cells of Mimosa pudica as an intracellular correlate of nyctinasty

Using living thin sections (ca. 70-80 μ thick) of tertiary pulvini of Mimosa pudica, we have quantitatively determined that the bahavior of the contractile tannin vacuoles in the motor cells is under phytochrome control. Using material in which these vacuoles were in their most expanded state in white light, contraction was observable 3 min after the material was placed in continuous darkness. No contraction occurred if the cells were irradiated with 90 sec of far-red light; red light reversed this effect. Futhermore, the kinetics of change of the vacuolar conformation was closely paralled by that of the nyctinastic changes of the pinnule closure during the different treatments. When the section of pulvinus was irradiated with a microbeam of far red light in one part of the section, and the motor cell vacuoles in another area were monitored for contraction, they almost always responded.We therefore conclude that the contractile vacuole of the motor cell is an excellent cellular correlate of phytochrome-mediated nyctinasty in M. pudica, and discuss its possible causal role in regulating the phenomenon. It is further concluded that functional phytochrome is present in all parts of the pulvinus and that, upon absorption of the stimulus energy, an intercellular messenger is released which stimulates all the motor cells in the pulvinus.

An ATPase in sensitive plant Mimosa pudica I. Purification and characterization

Leaflets from the primary, secondary, and tertiary pulvini of Mimosa pudica contain a highly active ATPase. The level of this enzyme is highest in actively responding healthy fresh leaflets; no activity can be detected in the insensitive plant extracts. This enzyme is dependent on cation for its activity, the optimal concentration of Mg 2+ being 5 × 10 −3 m. It has been purified approximately 60-fold. The optimal activity of the enzyme is pH 5.5. The enzyme hydrolyzes dATP and ITP at a much slower rate than ATP. Other nucleoside triphosphates and phosphocompounds are not hydrolyzed. In the final step of purification five distinct protein fractions are obtained after passage through a DEAE cellulose column, and fraction III exhibits the ATPase activity and shows a single peak of 4.3 S by sedimentation analysis. This activity is increased several-fold after the addition of fraction IV and V, the latter being most effective. This ATPase is not inhibited by pCMB, iodoacetamide, and dinitrophenol. The crude enzyme preparation exhibits a viscosity change upon the addition of ATP; however, this viscosity change is not observed with the purified enzyme (fraction III) until fraction IV and V are added. The presence of ATPase in the sensitive leaflets of Mimosa, its increased activity and the viscosity change in presence of ATP with other protein fractions suggest that the ATPase is involved in the rapid movement of Mimosa leaflets.

Pulvini as the Photoreceptors in the Phytochrome Effect on Nyctinasty in Albizzia julibrissin

The fact that far-red pretreatment slows the closing response of Albizzia julibrissin pinnules to darkness was used to locate the photoreceptor region for the role of phytochrome in nyctinasty, and to determine whether the effect is localized or translocated. Illumination of pinnule tissue alone induced no response, while illumination of an area as narrow as 1 mm, including only the tertiary pulvini and adjacent portions of rachilla and pinnules, was sufficient for a full response. This suggests that the pulvini themselves, the sites of the response, act as photoreceptors. In experiments with various shielding devices, pinnules on the same rachilla responded independently to local illumination, suggesting the absence of any translocatable effects.