Gabriel Roblin

• PhD
• Université de Poitiers

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 reco...

Three abiotic stresses, copper application (CS), mechanical rubbing (MS) and water deprivation (WS) applied on miniature rose bushes specifically activate the expression of the CuZn-Superoxide dismutase (SOD). The Cu/Zn-SOD protein immunodetected in the 4th internode was shown engaged in lignification in phloem, cambium and xylem cells. The SOD occ...

In esca disease affecting grapevines, Phaeomoniella chlamydospora and Phaeoacremonium minimum colonize the woody parts of the trunks and arms, where they obtain nutrition from xylem sap and, potentially, from residues resulting from the enzymatic breakdown of lignified cell walls, particularly osidic residues. We quantified the secretion of lignin...

Key message The miniature rose-bush architecture may be improved by abiotic stresses applied to plants grown under short cultivation mode, which results in their enhanced robustness, branching and blooming capacity. Abstract Miniature rose-bushes of the Meikanrou variety, grown in the annual cycle and submitted to vegetative break during winter (“...

Actin microfilaments (F‐actin) are major components of the cytoskeleton essential for many cellular dynamic processes (vesicle trafficking, cytoplasmic streaming, organelle movements). The aim of this study was to examine whether cortical actin microfilaments might be implicated in the regulation of nutrient uptake in root and leaf cells of Beta vu...

Two Fabaceae exhibiting rapid osmocontractile pulvinar movements were used in this study because this activity is modified by natural auxin and dramatically by 2,4D. A short chain with a carboxylic group being required for auxinic properties, a critical point to analyze is whether the recently synthesized proherbicide ε-(2,4-dichlorophenoxyacetyl)-...

Tryptophan at concentrations higher than 0.1 mM, triggered characteristic early physiological effects such as rapid (within 5 min) dose-dependent membrane hyperpolarization in Mimosa pudica motor cells and modification of the time course of the spontaneous proton efflux monitored in the incubation medium of pulvinar tissues. The rapid modifications...

Wood degrading diseases are escalating in vineyards all over the world, inducing heavy economic losses. The diseases are caused by fungal pathogens that invade the innermost xylem part of the trunk and trigger many metabolic disorders of vines leading to hindered productivity. In particular, esca disease in which Phaemoniella chlamydospora and Phae...

Early effects induced by cysteine were monitored using the model of Mimosa pudica pulvinar cells. Rapid dose-dependent membrane depolarization (within seconds) and modification of proton secretion (within minutes) were triggered at cysteine concentrations higher than 0.1 mM. These effects did not result from a modification of the plasma membrane H+...

Early prediction of compound absorption by cells is of considerable importance in the building of an integrated scheme describing the impact of a compound on intracellular biological processes. In this scope, we study the structure-activity relationships of several benzoic acid-related phenolics which are involved in many plant biological phenomena...

Unsaturated amino acids (UnsAA) have been shown to affect the activity of various biological processes. However, their mode of action has been investigated poorly thus far. We show in this work that 2-amino-3-methyl-4-pentenoic acid (C2) and 2-amino-3-methyl-4-pentynoic acid (C3) structurally derived from isoleucine (Ile) exhibited a multisite acti...

Vacuoles of different types frequently coexist in the same plant cell, but the duality of the tannin/tannin-less vacuoles observed in Mimosa pudica L. is rare. In this plant, which is characterized by highly motile leaves, the development and original features of the double vacuolar compartment were detailed in primary pulvini from the young to the...

A study of the structure–activity relationship carried out on several benzoic acid-related phenolics indicates that this type of compounds hinders the osmocontractile reaction of pulvinar cells in the range of 0–100%. Tentatively, we tried to find a way that could explain this differential action. With this aim, the relationship between the inhibit...

Phaeoacremonium aleophilum is a fungal pathogen implicated in esca, a devastating disease affecting grapevines around the world. We have previously reported that the fungus secreted in its culture medium a variety of polypeptides, which allowed us to develop a serological method of detection. In this method, rabbit antibodies raised against the pol...

In this paper, the salicylic acid (o-hydroxy benzoic acid) (SA) uptake by the pulvinar tissues of Mimosa pudica L. pulvini was shown to be strongly pH-dependent, increasing with acidity of the assay medium. This uptake was performed according to a unique affinity system (Km = 5.9 mM, Vm = 526 pmol mgDW(-1)) in the concentration range of 0.1-5 mM. T...

Compared to healthy canes of Ugni-Blanc grapevines, structural modifications were observed in August in wood of growing canes showing foliar symptoms induced by esca and Eutypa Dieback. The observed changes appeared attenuated in canes of the current season sampled in December. In contrast, Black Dead Arm (BDA) did not induce significant modificati...

Occurrence of functional interactions between Sr(2+) and Ca(2+) were investigated on maize plants grown under hydroponic conditions in presence of various mixtures of SrCl2 [0-0.01-1-10mM] and CaCl2 [0-0.2-2-20mM]. External [Ca(2+)] modulated the effect of Sr(2+) on the plant dry weight, and on the Sr(2+), Ca(2+) and Mg(2+) contents of roots and sh...

Salicylic acid (o-hydroxy benzoic acid) (SA) induced a rapid dose-dependent membrane hyperpolarization (within seconds) and a modification of the proton secretion (within minutes) of Mimosa pudica pulvinar cells at concentrations higher than 0.1mM. Observations on plasma membrane vesicles isolated from pulvinar tissues showed that SA acted directly...

The present study aimed to determine the most efficient experimental conditions of iron sulfate use leading to optimal inhibition in the development of fungal pathogens. Assays have been focused on fungal species inducing severe grapevine diseases. FeSO4 directly inhibited the in vitro mycelial growth of Botrytis cinerea, Eutypa lata, Phaeomoniella...

The typical fungal membrane component ergosterol was previously shown to trigger defence responses and protect plants against pathogens. Most of the elicitors mobilize the second messenger calcium, to trigger plant defences. We checked the involvement of calcium in response to ergosterol using Nicotiana plumbaginifolia and Nicotiana tabacum cv Xant...

When released in plant environment, strontium (Sr2+) can be absorbed predominantly by the plant roots. As the plasma membrane of root cells is amongst the first barriers encountered by Sr2+ during its soil/plant transfer and the main entry point of Sr2+ into the roots, the main objective of this work aimed to enlighten on some of the Sr2+-induced e...

Background and Aims: Esca is a devastating disease affecting grapevines all around the world induced by a complex of xylem-inhabiting fungi. Among them, Phaeomoniella chlamydospora has been considered as an early causal agent of the disease facilitating the access of opportunistic saprophytes whose mode of action should be further investigated. P....

Esca is a devastating disease affecting grapevines all around the world induced by a complex of xylem-inhabiting fungi. In order to elucidate the mechanisms of virulence of the esca-associated fungi Phaeomoniella chlamydospora (Pch) and Phaeoacremonium aleophilum (Pal), the phytotoxic activities of the polypeptides secreted in their culture medium...

Strontium is an element which can be found in the environment in a large range of concentrations, as a result of natural mineral degradation or consecutively to polluting anthropic activities. The transfer of such a contaminant from the environment to plants is a first step leading to contamination of the food pathway. Therefore the main objective...

This study investigates the role of the fungal sterol ergosterol as a general elicitor in the triggering of plant innate immunity in sugar beet. Evidence for this specific function of ergosterol is provided by careful comparison with cholesterol and three plant sterols (stigmasterol, campesterol, sitosterol), which do not enable the integrity of re...

Eutypa lata is the causal agent of a devastating disease affecting grapevines around the world. We have previously reported that the fungus secretes in its culture medium a variety of polypeptides, and we have developed serological method of detecting these. Rabbit antibodies raised against the polypeptide fraction, recognized secreted fungal prote...

Esca is a devastating disease of grapevines involving xylem-inhabiting fungi. Among these, Phaeomoniella chlamydospora and Phaeoacremonium aleophilum are considered as the causal agents. We show that they present different structural features and act on plant cells by very different mechanisms. Their sensitivity to temperature differed, with optimu...

Eutypa dieback is a devastating disease of Vitis vinifera L. caused by the fungal pathogen Eutypa lata (Pers.: Fr.) Tul. et C. Tul., which colonizes the vascular tissues of the trunk. Symptoms observed in developing shoots and in the foliage indicate that a necrotic signal spreads at a distance from the infected area. Previous studies have shown th...

Chitosan (a polymer of β-1,4-glucosamine residues) is a deacetylated derivative of chitin which presents antifungal properties and acts as a potent elicitor of plant resistance against fungal pathogens. Attention was focused in this study on the chitosan-induced early events in the elicitation chain. Thus, it was shown that chitosan triggered in a...

2,4-dichlorophenoxyacetic acid applied to excised leaves of Mimosa pudica L. inhibited in a dose-dependent manner the shock-induced pulvinar movement. This inhibition was negatively correlated with the amount of [(14)C] 2,4-dichlorophenoxyacetic acid present in the vicinity of the motor cells. Although 2,4-dichlorophenoxyacetic acid is a weak acid,...

Eutypa dieback is a devastating disease induced in vineyards by the fungal pathogen Eutypa lata. The fungus colonizes the xylem tissues of trunk and cordons but is never found in the annual canes. Nevertheless, dwarfed shoots and leaf necrosis observed in diseased plants indicate that a necrotic signal can spread at a distance from the infected are...

Dimethylsulfoxide (DMSO) acts on dark- and light-induced movements exhibited by leaflets of isolated leaves of Cassia fasciculate Michx. The closing movement (scotonasty), induced when the leaves are placed in darkness during the normal period of daylight, was inhibited, whereas the opening movement (photonasty), when the leaves arc transferred to...

Eutypa dieback is a devastating disease of Vitis vinifera L. caused by the fungal pathogen Eutypa lata. This wood-inhabiting fungus degrades tissues in the trunk and cordons of infected vines and induces symptoms in the foliage. These symptoms have been attributed to the production of toxic metabolites by the pathogen, in particular eutypine. Recen...

Ergosterol (a fungal membrane component) was shown to induce transient influx of protons and membrane hyperpolarization in cotyledonary cells of Mimosa pudica L. By contrast, chitosan (a fungal wall component with known elicitor properties) triggered membrane depolarization. In the processes induced by ergosterol, a specific desensitization was obs...

Cysteine inhibited mycelial growth of the pathogenic fungus affecting grapevines Eutypa lata Pers. Fr. Tul. and C. Tul. in a concentration-dependent manner. The threshold value (defined by the concentration inducing a growth inhibition higher than 5%) was 0.5 mM. A 10 mM concentration induced a complete inhibition of growth and triggered necrotic p...

Eutypa dieback, a devastating disease in grapevines, is caused by the fungal pathogen Eutypa lata, a wood-inhabiting fungus. E. lata acts by degrading wood tissues in the colonisation areas, and produces foliar symptoms. These striking symptoms have been attributed to the production of toxic metabolites by the pathogen, the most widely studied bein...

Eutypa dieback (dying arm disease, eutypiosis) is a very devastating disease in many grape-producing areas around the world. This vascular disease is induced by the ascomycete Eutypa lata Pers. Fr. Tul & C. Tul. invading the trunk by pruning wounds. The environmental factors and the nutritional requirements regulating fungus development are yet poo...

Given the lack of data on the absorption of amino acids in the tap root of Beta vulgaris, we studied the uptake of valine and compared it with that of sucrose at the same concentration (1 mM). The uptake of both substrates shared some similar characteristics. In particular, the absorption in both cases was controlled by an active process as evidenc...

The uptake of cholesterol has been characterized in leaf discs from mature leaves of sugar beet ( Beta vulgaris L.). This transport system exhibited a simple saturable phase with an apparent Michaelis constant ranging from 30 to 190 microM depending on the sample. When present at 10 M excess, other sterols were able to inhibit cholesterol uptake. M...

Ergosterol (a fungal membrane component) induced modification of proton fluxes and membrane hyperpolarization in motor cells of Mimosa pudica. These reactions appear specific since they were not induced by the other sterols tested. A specific desensitization was observed, since cells did not react to a second ergosterol application. Exposed at firs...

Salicylic acid (SA) inhibited mycelial growth of Eutypa lata (Pers. Fr.)Tul. in a solid as well as in a liquid culture medium, in a concentration-dependent manner, the threshold value being 0.1 mM. In conditions mimicking the plant environment (in particular, a pH near the apoplastic value, i.e. 5.5), 1 mM SA showed only fungistatic properties. How...

Eutypine, 4-hydroxy-3-(3-methyl-3-butene-1-ynyl) benzaldehyde, is a toxin produced by Eutypa lata, the causal agent of eutypa dieback. An essential target of eutypine action lies at the plasmalemma as shown by the data obtained during this study on three experimental models (Beta vulgaris, Mimosa pudica, Vitis vinifera). The fungal toxin at 100 μM...

The protein phosphatase inhibitor okadaic acid (OA) either provided directly to sugar beet (Beta vulgaris L.) leaf discs or infiltrated in the leaf blade rapidly inhibited sucrose uptake. Methyl okadaic acid, a biologically inactive analogue of OA, had only a marginal effect on uptake. OA inhibited proton-motive force-driven uptake of sucrose into...

Previous experiments have shown that calcium is involved in glycine uptake by pulvinar tissues of Mimosa pudica plants. Present data show that either inorganic (CdCl2) or organic calcium channels blockers from the dihydropyridine class (nifedipine, nisoldipine) and benzodiazepine class (diltiazem) reduced the glycine uptake whereas blockers from th...

2,4-dichlorophenoxyacetic (2,4-D) applied to excised leaves of Cassia fasciculata modified the dark-induced (scotonasty) and light-induced (photonasty) leaflet movements, showing that this compound acts on rapid turgor variation and the concomitant ion migrations, in particular K+. 2,4-D inhibited the scotonastic closure in a dose-dependent manner...

Blue/UV-A light regulates numerous physiological processes in plants. Several steps between the photo-excitation of the pigment involved and the physiological response are still unknown. Under irradiation by a laser beam (360 nm), a modification of the cell organization was observed in protoplasts isolated from motor cells of Mimosa pudica pulvini....

To understand contradictory data published in the literature, the sensitivity of sucrose and of valine uptake to N-ethylmaleimide (NEM) was reinvestigated in detail with plasma membrane vesicles purified by phase partitioning from mature sugar beet (Beta vulgaris) leaves. Uptake in the vesicles was energized by an artificial proton-motive force com...

Previous experiments have evidenced that calcium is functionally implicated in glycine uptake by pulvinar motor cells of Mimosa pudica L. The present data show that compounds having anticalmodulin properties, compound 48/80 and the sulfonamide W-7, inhibited the amino acid uptake suggesting that a step in this process may be regulated by calmodulin...

When applied to pulvini of Mimosa pudica, jasmonic acid (JA) affected neither proton fluxes nor the membrane potential of the motor cells. When added to leaflets of Cassia fasciculata, JA increased the rate of dark-induced pulvinar movements in a concentration-dependent manner. This effect was observed within as little as 15 min after a 1-h treatme...

Glycine uptake by pulvinar tissues of Mimosa pudica was inhibited by citrate and this effect was reversed by addition of CaCl2 in the incubation medium. The promotive effect of calcium may occur in a definite concentration range since glycine uptake was hindered by addition of CaCl2 at concentrations higher than 10-4M in a Mes buffered medium. Func...

Methylxanthines (theophylline, aminophylline, caffeine) inhibit the seismonastic reaction of primary pulvini of Mimosa pudica leaves, showing that these compounds act on rapid turgor variations and the concomitant ion migrations. Compared with theophylline, aminophylline is more effective and caffeine is less effective in triggering the inhibitory...

Glycine uptake by pulvinar tissues of Mimosa pudica was inhibited by citrate and this effect was reversed by addition of CaCl2 in the incubation medium. The promotive effect of calcium may occur in a definite concentration range since glycine uptake was hindered by addition of CaCl2 at concentrations higher than 10-4M in a Mes buffered medium. Func...

Opening of Cassia fasciculata leaflets was induced in darkness after application of indole-3-acetic acid (IAA). This movement was obtained with concentrations from 10−6 M to 10−4 M, after a corresponding time-lag ranging from 120 to 30 min. IAA (5×10−5 M) allowed leaflet opening at all the pH values tested (from 3·5 to 7·5), the largest aperture be...

Theophylline and aminophylline, applied on excised leaves of Cassia fasciculata inhibited the phytochrome-mediated movements induced by a light-off signal and the blue light absorbing pigment-mediated movements induced by a light-on signal. Biological activity was given at the xanthine molecule by methyl groups substituted in positions 1 and 3. Ami...

Abstract— Leaflet movements of Cassia fasciculata are induced by transferring leaves from light to darkness or from darkness to light. Phytochrome mediates the dark-induced closure whereas a blue and far red light absorbing pigment (cryptochrome?) is the photoreceptor triggering the light-induced opening. These movements are the result of reversibl...

Effects of plant hormones were examined on the dark- and light-induced movements of Cassia fasciculata. Indole-3-acetic acid (IAA), gibberellic acid (GA3) and 6-benzylaminopurine (6-BAP) inhibited the scotonastic movement whereas abscisic acid (ABA) enhanced it. After brief treatments (5 to 30 min), the ABA effect was inhibitory rather than promoti...

Verapamil and nifedipine, known as calcium channel blockers, inhibited the phytochrome-mediated movements induced on Cassia fasciculata leaflets by a light-off signal, whereas they had no effect on the ;blue' pigment-mediated movements induced by a light-on signal. LaCl(3) inhibited both types of reactions, but the inhibition of light-induced openi...

Fleurat-Lessard, P., Roblin, G., Bonmort, J. and Besse, C. 1988. Effects of colchicine, vinblastine, cytochalasin B and phalloidin on the seismonastic movement of Mimosa pudica leaf and on motor cell ultrastructure.—J. exp. Bot. 39: 209–221. Colchicine at 1 × 10−3 mol dm−3 does not affect the seismonastic movement of Mimosa pudica leaves but disru...

Benzoic acid and its o-, m- and p-hydroxy derivatives applied on excised leaves of Cassia fasciculata modified the dark-induced (scotonasty) and light-induced (photonasty) leaflet movements. Benzoic acid inhibited the scotonastic closure in a dose-dependent manner from 10-4M to 10-3M and promoted the photonastic opening at optimum concentration of...

When the leaves of Mimosa pudica are changed from their normal position in the gravitational field, they perform reversible compensatory movements by means of pulvini. These movements are not the result of growth processes but involve reversible turgor variations. These variation are concomitant with ion migrations within pulvini: during the gravit...

Respiration inhibitors, in particular KCN and NaN(3), inhibited slightly the dark-induced (scotonasty) as well as the light-induced (photonasty) leaflet movements of Cassia fasciculata: they act only at concentrations higher than 1 millimolar and 0.1 millimolar, respectively. Amytal induced a stronger inhibitory effect on scotonasty. Salicylhydroxa...

Heating of leaf blade in Vicia faba triggered bioelectrical events (“variation potential”) spreading throughout the shoot, preferentially in the acropetal direction. The spreading of a variation potential, previously described in Mimosa and other plants, is related to a concomitant transport of a stimulating substance in the transpiration stream. T...

Uptake of [3H]-glycine by sections of Mimosa pudica L. pulvini is pH dependent (maximum at pH 5.5) and exhibits biphasic saturation kinetics in the range of concentrations tested (1–75 mM). Effects of compounds which increase [fusicoccin (FC)] or decrease (uncouplers, ATPase inhibitors) the proton-motive force were tested both on the pH variations...

Primary pulvini of Mimosa pudica L. displaced from their position display gravitropic movements beginning about 15 minutes after their reorientation. Ethephon, an ethylene-releasing compound, and 1-aminocyclopropane-1-carboxylic acid, an intermediate in ethylene biosynthesis, enhance these movements at a concentration as low as 10 nanomolar. Inhibi...

Earlier work suggested that glycine uptake by the pulvinus motor cell of Mimosa pudica is a H+ -cotransport mechanism. This hypothesis is sustained by the present investigations showing that glycine is transported electrogenically across the motor cell membrane as evidenced by concentration — dependent depolarizations observed upon addition of glyc...

Following burning of a leaf portion, a bioelectrical wave called “variation potential” spread throughout the whole plant. Bioelectrical variations are recorded by two types of electrodes (platinum wires and Ag/AgCl nonpolarizable electrodes) in the stem of Vicia faba and in the petiole of Lycopersicon esculentum and Mimosa pudica. The time course o...

Salicylic and acetylsalicylic acids applied on excised leaves of Cassia fasciculata modify the dark-induced (scotonastic) and light-induced (photonastic) leaflet movements. They inhibit the scotonastic movements in a dose-dependent manner from 1 x 10(-4) to 1 x 10(-3) molar and they promote the photonastic movements at an optimum concentration of 5...

The calcium chelator ethylene glycol-bis-(β-amino ethyl ether)- N,N,N',N' -tetraacetic acid (EGTA) inhibited the dark-induced (scotonastic) and light-induced (photonastic) leaflet movements of Cassia fasciculata , while the calcium-ionophore A 23187 increased the rates of both movements. At concentration as low as 10-6M, the inhibitors of calmoduli...

Glycine (1-50 mM) increases the rate of the dark-induced (scotonastic) movements and decreases the amplitude and the rate of the light-induced (photonastic) movements of the secondary pulvini of Mimosa pudica leaves. The uptake of glycine is accompanied by a long-lasting dose-dependent increase in the alkalinity of the bathing medium of the excised...

Prostaglandin E1 and prostaglandin E2 speed up the dark-induced (scotonastic) and light-induced (photonastic) leaflet movements of Cassia fasciculata. The precursors of prostaglandin biosynthesis, homo γ-linolenic and arachidonic acids, and an intermediary product, prostaglandin-interm-5, act in the same manner on these movements. Inhibitors of pro...

The content of K, Cl and Ca were determined in various parts of Mimosa pudica plant, namely in young internode, aged internode, upper half and lower half of the primary pulvinus, secondary pulvinus, petiole and leflet blade. Potassium is localized in parts showing a great metabolic activity. chloride follows the distribution of K. Ca content is low...

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 org...

In Mimosa pudica, the main pulvinus, which brings about leaf movements, presents unusual structural characteristics in comparison with the petiole. Peculiar cellular features which exist in the cortex, epidermis, parenchyma and endodermal regions include the shape of the cells, their disposition and the location of the organelles. The central cylin...

It is well known that different stimulating agents can induce spectacular movements of the primary pulvinus in Mimosa pudica L. A photostimulation can also evoke the same type of movement. But in many cases the pulvinus reacts with more gradual curvatures. The bioelectrical variations recorded concomitantly with the movements suggest that there is...

Abstract The nutational movements performed by the leaves of the “Sensitive plant”,Mimosa pudica L., result from periodical turgor variations taking place in the parenchymatous cells of specialized motor organs. The trajectories in the three kinds of leaf motor organs usually show irregular elliptical paths with a period ranging from 10 to 60 min....

In excised leaves of Cassia fasciculata and in excised pinae of Mimosa pudica, ABA produces a closure of the leaflets (Cassia) and pinnules (Mimosa) in diurnal position, whereas FC induces their opening during the night. The apparent action threshold of ABA is about 10-7M and 10-8M in Cassia and Mimosa respectively; that of FC is about 10-6M in bot...

Endogenous Rhythms in Mimosa pudica L. Leaf Movements. The rhythmic movements performed by the leaves of the “Sensitive plant”, Mimosa pudica L., observed by time lapse photography, result of periodical turgor variations taking place in the parenchymatous cells of specialized motor organs. These turgor variations are associated with membrane permea...

Primary pulvini ofMimosapudica L.displaced fromtheir position display gravitropic movements beginning about 15minutes after their reorientation. Ethephon, anethylene-releasing compound, and1-amino- cyclopropane-l-carboxylic acid, anintermediate inethylene biosynthesis, enhance these movements ataconcentration aslowas10nanomolar. Inhibitors ofethyle...