Effects of drought and root injury on plant-generated CS2 emissions in soil

Conditions under which some plants emit carbon disulfide (CS₂) in the soil are unknown. A pot assembly was constructed to measure soil CS₂ emissions by Mimosa pudica under conditions of undisturbed growth, root injury, and drought stress. When M. pudica was grown without disturbance, soil CS₂ emissions were below the limit of detection (0.1 ng CS₂ mL^–1) for the entire 8-wk sampling period. However, when the roots of 6-wk-old M. pudica plants were cut to a depth of 10 cm, a maximum of 0.5 and 0.4 ng CS₂ mL^–1 was emitted within minutes at the 5- and 10-cm depths, respectively. These emissions declined slowly to undetectable levels after 50 min. No detectable CS₂ emissions were observed at the 0- and 15-cm depths. No CS₂ was emitted when 6-wk-old M. pudica plants were subjected to drought stress, however, when the same plants were watered, a maximum of 0.3, 0.4, and 0.5 ng CS₂ mL^–1 was emitted within minutes at the 5-, 10- and 15-cm depths, respectively. These emissions were detectable for at least 2 hr at the 10- and 15-cm depths. No detectable CS₂ emissions were observed at the 0-cm depth after watering. No detectable CS₂ emissions were observed at any depth under any conditions of undisturbed growth, root injury, or drought stress followed by watering for assemblies containing either no plants or Albizia julibrissin, a plant that is closely related to M. pudica but does not emit CS₂. Mimosa pudica emitted detectable CS₂ under conditions of root injury and rewetting of dry soil but not under conditions of undisturbed growth. Release of such a biocidal sulfide only during conditions of root injury or rewetting of dry soil would be advantageous to M. pudica.     

Thigmomorphogenesis: The Interaction of Wind and Temperature in the Field on the Growth of Phaseolus vulgaris L.

Field and laboratory experiments were performed to determinethe interaction of wind and temperature on thigmomorphogenesis(defined here as decreased elongation and increased internodalradial enlargement due to mechanical perturbation). Kidney beanplants (Phaseolus vulgaris L. cv. Red Cherokee Wax) were shelteredor exposed to wind for 10 days. Wind velocity, wind gusting,temperature, light and rainfall were measured for the durationof each of ten experiments. Stem elongation and diameter weremeasured and it was found that thigmomorphogenesis due to windoccurs naturally. There was more internodal secondary xylemproduced in the wind-exposed plants than in the sheltered plants.The experimental data were analyzed by multiple linear regressionand the wind was found to be a significant factor in the predictionof bean stem elongation and thickening. Laboratory experimentsshow that as wind velocity increases, thigmomorphogenesis increasesin an approximate linear fashion. Furthermore, it was foundthat low temperatures interact with mechanical perturbationto reduce the amount of thigmomorphogenesis, both in the fielddue to wind and in the laboratory due to rubbing. Other environmentalfactors do not seem to interact with the wind to modulate thigmomorphogenesiseven though these factors affect plant growth. Phaseolus vulgaris L., kidney bean, thigmomorphogenesis, wind, temperature, ethylene, multiple linear regression     

Factors affecting production of COS and CS2 in Leucaena and Mimosa species

Carbon disulfide (CS₂) and carbonyl sulfide (COS) are colorless, foul-smelling, volatile sulfur compounds with biocidal properties. Some plants produce CS₂ or COS or both. When used as an intercrop or forecrop, these plants may have agronomic potential in protecting other plants. Most of the factors which affect production of these plant-generated organic sulfides are unknown. We determined the effects of sulfate concentration, plant age, nitrogen fixation, drought stress, root injury (through cutting), and undisturbed growth on COS production in Leucaena retusa or Leucaena leucocephala and the effect of some of these factors on CS₂ production in Mimosa pudica. In addition, we determined if organic sulfides were produced in all Leucaena species. When L. retusa and M. pudica seedlings were grown in a plant nutrient medium with different sulfate concentrations (50 to 450 mg SL^-1), COS or CS₂ from crushed roots generally increased with increasing sulfate concentration. COS production was highest (74 ng mg^-1 dry root) for young L. retusa seedlings and declined to low amounts (<5 ng mg^-1 dry root) for older seedlings. Nitrogen fixation reduced the amounts of COS or CS₂ produced in L. leucocephala and M. pudica. Under conditions of undisturbed growth, root cutting, or drought stress, no COS production was detected in 4-to 8-weeks-old L. retusa plants. COS or CS₂ or both was obtained from crushed roots or shoots of all 13 known Leucaena species.     

Memory elements in the electrical network of Mimosa pudica L.

The fourth basic circuit element, a memristor, is a resistor with memory that was postulated by Chua in 1971. Here we found that memristors exist in vivo. The electrostimulation of the Mimosa pudica by bipolar sinusoidal or triangle periodic waves induce electrical responses with fingerprints of memristors. Uncouplers carbonylcyanide-3-chlorophenylhydrazone and carbonylcyanide-4-trifluoromethoxy-phenyl hydrazone decrease the amplitude of electrical responses at low and high frequencies of bipolar sinusoidal or triangle periodic electrostimulating waves. Memristive behavior of an electrical network in the Mimosa pudica is linked to the properties of voltage gated ion channels: the channel blocker TEACl reduces the electric response to a conventional resistor. Our results demonstrate that a voltage gated K⁺ channel in the excitable tissue of plants has properties of a memristor. The discovery of memristors in plants creates a new direction in the modeling and understanding of electrical phenomena in plants.     

Lithium Inhibition of the Thigmomorphogenetic Response in Bryonia dioica

Pretreatment of young Bryonia dioica plants with lithium prevents the inhibition of elongation due to rubbing. Lithium treatment also suppresses the appearance of a specific cathodic isoperoxidase characteristic of rubbed plants.     

Mimosa pudica,Dionaea muscipula and anesthetics

Some studies showed that anesthetics reduce the response of physical stimuli in Mimosa pudica and in Venus Flytrap (Dionaea muscipula), peculiar plants that have the ability to respond to touch stimuli. In this research we tested the effects of ketamine, lidocaine, diethyl ether, and amlodipine on the movements of Mimosa pudica and Venus Flytrap. With a literature review, we tried to bring elements to theorize about the interaction of these substances with these plants. The angular displacement in Mimosa´s petiole and in Dionaea leaves is what was measured to compare the drugs group with control groups.     

Mimosa pudica: Electrical and mechanical stimulation of plant movements

Thigmonastic movements in the sensitive plant Mimosa pudica L., associated with fast responses to environmental stimuli, appear to be regulated through electrical and chemical signal transductions. The thigmonastic responses of M. pudica can be considered in three stages: stimulus perception, electrical signal transmission and induction of mechanical, hydrodynamical and biochemical responses. We investigated the mechanical movements of the pinnae and petioles in M. pudica induced by the electrical stimulation of a pulvinus, petiole, secondary pulvinus or pinna by a low electrical voltage and charge. The threshold value was 1.3–1.5 V of applied voltage and 2 to 10 µC of charge for the closing of the pinnules. Both voltage and electrical charge are responsible for the electro‐stimulated closing of a leaf. The mechanism behind closing the leaf in M. pudica is discussed. The hydroelastic curvature mechanism closely describes the kinetics of M. pudica leaf movements.     

Electrical Pulse Generation from Mimosa pudica by Administering Other Plant Extracts

While observing the weak electrical potential in Mimosa pudica, strong electrical pulses were recorded when the methanolic extract of other plants was administered. Sodium glutamate was identified as the active compound responsible for the pulses in the methanolic extract of Melia azedarach L.     

Ricerche Morfologiche e Anatomiche Su Mimosa Pudica L.

Summary

Firstly, the author describes the anatomical and histological structures of Mimosa pudica L. during the stages of development of the young plant prior to the appearing of cambium. She then discusses, in the light of previous literature on the subject, the three principal features of Mimosa pudica: herbaceous bearing, stable tetrarchy with intercotyledonal bundles along the plumule, and small sized germination.

Finally, the author concludes that Mimosa pudica appears to be an individual with tree-like rather than herbaceous symmetry (stable tetrarchy), in which the size of germination has diminished parallelly to reduction in size of the adult individual.     

Specific Inhibition of Lignification in Bryonia dioica: Effects on Thigmomorphogenesis

Rubbing-induced lignification in Bryonia dioica internodes is significantly impaired by N(o-hydroxyphenyl) and N(o-aminophenyl) sulfinamoyl tertiobutyl acetate, specific inhibitors of cinnamyl alcohol dehydrogenase, an enzyme which is strictly associated with lignin monomer synthesis. Along with the reduction of lignification, these inhibitors counteract the inhibition of elongation due to rubbing. These results indicate that lignification participates in the thigmomorphogenetic growth response of Bryonia dioica internodes. In a general way, the data point to the causal role of lignification in the limitation of plant growth.     

Tubulin from Mimosa pudica and its involvement in leaf movement

The sensitive plant Mimosa pudica is made insensitive by a brief treatment with colchicine. A high concentration of colchicine binding protein is present in the fresh actively moving leaves of M. pudica. This protein was partially characterized and compared with the animal brain tubulin. This colchicine binding activity is very low in the insensitive variety of Mimosa, namely Mimosa rubricaulis.     

Cytological indication of the involvement of calcium and calcium-related proteins in the early responses ofBryonia dioica to mechanical stimulus

Summary The distribution of membrane-bound calium, activated calmodulin, and callose synthesis was visualized inBryonia dioica internodes before and after mechanical stimulus, using fluorescent probes, respectively, chlorotetracycline, fluphenazine, and aniline blue. Bright chlorotetracycline fluorescence remains localized in the plasma membrane of control cells, 30 s after stimulation calcium left the plasmalemma. A delocalization of activated calmodulin was observed after wounding and deposition of callose, which could not be detected before, appeared in the same times in most cells. The callose formation and the decrease in membrane-associated calcium suggest a rapid influx of calcium in the cytosol and an intervention of this ion in the cascade of the early events underlyingBryonia dioica thigmomorphogenesis.Abbreviation CTC chlorotetracycline     

Mechanical and electrical anisotropy in Mimosa pudica pulvini

Thigmonastic or seismonastic movements in Mimosa pudica, such as the response to touch, appear to be regulated by electrical, hydrodynamical and chemical signal transduction. The pulvinus of Mimosa pudica shows elastic properties, and we found that electrically or mechanically induced movements of the petiole were accompanied by a change of the pulvinus shape. As the petiole falls, the volume of the lower part of the pulvinus decreases and the volume of the upper part increases due to the redistribution of water between the upper and lower parts of the pulvinus. This hydroelastic process is reversible. During the relaxation of the petiole, the volume of the lower part of the pulvinus increases and the volume of the upper part decreases. Redistribution of ions between the upper and lower parts of a pulvinus causes fast transport of water through aquaporins and causes a fast change in the volume of the motor cells. Here, the biologically closed electrochemical circuits in electrically and mechanically anisotropic pulvini of Mimosa pudica are analyzed using the charged capacitor method for electrostimulation at different voltages. Changing the polarity of electrodes leads to a strong rectification effect in a pulvinus and to different kinetics of a capacitor discharge if the applied initial voltage is 0.5 V or higher. The electrical properties of Mimosa pudica''s pulvini were investigated and the equivalent electrical circuit within the pulvinus was proposed to explain the experimental data. The detailed mechanism of seismonastic movements in Mimosa pudica is discussed.Key words: electrophysiology, plant electrostimulation, pulvinus, Mimosa pudica, charged capacitor method, electrical circuits, ion channels     

Actin dynamics mediates the changes of calcium level during the pulvinus movement of Mimosa pudica

The bending movement of the pulvinus of Mimosa pudica is caused by a rapid change in volume of the abaxial motor cells, in response to various environmental stimuli. We investigated the relationship between the actin cytoskeleton and changes in the level of calcium during rapid contractile movement of the motor cells that was induced by electrical stimulation. The bending of the pulvinus was retarded by treatments with actin-affecting reagents and calcium channel inhibitors. The actin filaments in the motor cells were fragmented in response to electrical stimulation. Further investigations were performed using protoplasts from the motor cells of M. pudica pulvini. Calcium-channel inhibitors and EGTA had an inhibitory effect on contractile movement of the protoplasts. The level of calcium increased and became concentrated in the tannin vacuole after electrical stimulation. Ruthenium Red inhibited the increase in the level of calcium in the tannin vacuole and the contractile movement of the protoplasts. However, treatment with latrunculin A abolished the inhibitory effect of Ruthenium Red. Phalloidin inhibited the contractile movement and the increase in the level of calcium in the protoplasts. Our study demonstrates that depolymerization of the actin cytoskeleton in pulvinus motor cells in response to electrical signals results in increased levels of calcium.Key words: actin, calcium, pulvinus movement, the tannin vacuole, Mimosa pudica     

Mechanosensing and thigmomorphogenesis,a physiological and biomechanical point of view

Plant sensitivity to mechanical stimuli is obvious when observing the movements of Mimosa pudica leaflets when they are touched [1] or those of the Venus fly trap [2]. It is now well established that other plants are also sensitive to mechanical stimuli even if they do not exhibit such rapid movements [1]. There is a renewal of interest in mechanical stimuli as very important cues for the control of plant growth [3] and morphogenesis [4], [5]. This review focuses on mechanosensing in the case of external mechanical loading and its effect on the growth patterns of plant organs (thigmomorphogenesis). The first part of this paper deals with the responses at the whole plant level and their ecological significance. The second part deals with the perception process, with emphasis on the variable that is perceived by the plant. Knowledge about mechanosensors is not presented in great detail because this area of intensive research has been recently reviewed [6], [7]. The third part focuses on transduction, i.e., early responses at the cellular level, and particularly focuses on the importance of the kinetics of loading and the kinetics of cellular responses for the interpretation of experimental results. The fourth part focuses on parameters that regulate the mechanosensing process and points out the importance of quantitative studies. Because thigmomorphogenesis and gravitropism are difficult to disentangle, the review ends with data on gravitropism where mechanosensing is involved.     

Transmission of action potentials inBiophytum

By cooling or by electrical stimulus an action potential, (60 to 100 mv negative) was propagated throughout the length of a pinna-rachis or a peduncle ofBiophytum sp. A cutting stimulus evoked a series of two to four transmission of actions of action potentials. The transmission did not pass through the base of the leaf or peduncle. The velocity of the transmission in the rachis and penduncle was about 0.2 cm/sec, and no difference in the velocity was found between the acropetal and basipetal directions. In the stimulated site a local response (a negative bulge of potential) was seen with threshold stimulus. The absolute refractory period for the transmission of action potential was estimated at 20 to 50 sec, and the relative one at 30 to 70 sec. The mechanism of the transmission seemed to be similar to that inMimosa pudica.     

Relationships between jasmonates and auxin in regulation of some physiological processes in higher plants

Growth and development of plants are regulated by interactions among different plant growth substances. During stress conditions, both abiotic and biotic, interaction of the some hormones activates defense responses. The present review describes the interaction between jasmonates and auxin in regulation of some physiological processes in plant growth and development. Some jasmonate-induced processes reduced by auxins and some auxin stimulated physiological processes inhibited by jasmonates are the focus of this review. Therefore, the following physiological processes are described: stem cell growth, abscission, secondary abscission zone formation, tendril coiling, opening of the pulvinules in Mimosa pudica, wounding and induced gene expression, nicotine biosynthesis and auxin biosynthesis in Brassicaceae.     

Molecular electronics in pinnae of Mimosa pudica

Bioelectrochemical circuits operate in all plants including the sensitive plant Mimosa pudica Linn. The activation of biologically closed circuits with voltage gated ion channels can lead to various mechanical, hydrodynamical, physiological, biochemical and biophysical responses. Here the biologically closed electrochemical circuit in pinnae of Mimosa pudica is analyzed using the charged capacitor method for electrostimulation at different voltages. Also the equivalent electrical scheme of electrical signal transduction inside the plant''s pinna is evaluated. These circuits remain linear at small potentials not exceeding 0.5 V. At higher potentials the circuits become strongly non-linear pointing to the opening of ion channels in plant tissues. Changing the polarity of electrodes leads to a strong rectification effect and to different kinetics of a capacitor. These effects can be caused by a redistribution of K⁺, Cl⁻, Ca²⁺ and H⁺ ions through voltage gated ion channels. The electrical properties of Mimosa pudica were investigated and equivalent electrical circuits within the pinnae were proposed to explain the experimental data.Key words: electrophysiology, plant cell electrostimulation, charged capacitor method, electrical circuits, electrical signaling, Mimosa pudica     

An analytical model of memristors in plants

The memristor, a resistor with memory, was postulated by Chua in 1971 and the first solid-state memristor was built in 2008. Recently, we found memristors in vivo in plants. Here we propose a simple analytical model of 2 types of memristors that can be found within plants. The electrostimulation of plants by bipolar periodic waves induces electrical responses in the Aloe vera and Mimosa pudica with fingerprints of memristors. Memristive properties of the Aloe vera and Mimosa pudica are linked to the properties of voltage gated K⁺ ion channels. The potassium channel blocker TEACl transform plant memristors to conventional resistors. The analytical model of a memristor with a capacitor connected in parallel exhibits different characteristic behavior at low and high frequency of applied voltage, which is the same as experimental data obtained by cyclic voltammetry in vivo.     

Thigmomorphogenesis: Ethylene evolution and its role in the changes observed in mechanically perturbed bean plants

Mechanical perturbations, in the form of either rubbing or wounding, cause ethylene evolution from bean internodes ( Phaseolus vulgaris L. cv. Cherokee Wax). This evolution begins 45 to 60 min after perturbation or wounding and peaks about 2 h later. Maximal thigmomorphogenesis occurs if internodes are perturbed when they are 10 mm or less in length. Maximal ethylene evolution, however, occurs in longer internodes. When one internode is perturbed, ethylene evolution is not observed from other internodes even though they respond thigmomorphogenetically by exhibiting decreased elongation. Ethylene evolution is apparently a result of increased 1-amino-cyclopropane-1-carboxylic acid (ACC) production after perturbation. Inhibitors of ACC and ethylene synthesis block increased radial growth but not reduced elongation. Ethylene may therefore be only one of several factors causing thigmomorphogenesis.