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4. Rapid osmocontractile response of motor cells of Mimosa pudica pulvini induced by short light signals.

Author

Roblin, Gabriel, Moyen, Christelle, Fleurat‐Lessard, Pierrette, and Dédaldéchamp, Fabienne

Subjects
*SENSITIVE plant, *MEMBRANE potential, *CELL membranes, *CELL motility, *PHYTOCHROMES, *BLUE light
Abstract

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]

Published
2024
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41. Diagnosis of grapevine esca disease by immunological detection of Phaeomoniella chlamydospora

Author

Fleurat-Lessard, Pierrette, Luini, Estelle, Berjeaud, Jean-Marc, Roblin, Gabriel, Equipe Physiologie Moléculaire du Transport de Sucres (PhyMoTS), Laboratoire de catalyse en chimie organique (LACCO), Université de Poitiers-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie et Microbiologie de l'Eau (LCME), and Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers-Institut de Chimie du CNRS (INC)

Subjects
[SDV.BV]Life Sciences [q-bio]/Vegetal Biology
Abstract

International audience; 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. chlamydospora secreted into its culture medium a variety of polypeptides, the biochemical nature of which permitted us to develop a method of detection based on a serological test. Methods and Results: Polyclonal antibodies raised in rabbit against the polypeptide fraction recognised secreted fungal proteins in low amounts (commonly 1 ng). These antibodies showed a valuable specificity because they cross-reacted with polypeptides excreted by various strains of P. chlamydospora but not with those secreted by many other fungal pathogens commonly found in other grapevine infections. Importantly, as shown by the enzyme-linked immunosorbent assay test and immunolocalisation on ultrathin sections, they did not cross-react with the secreted polypeptides of various fungi intervening in other wood decay diseases, namely Eutypa dieback (Eutypa lata) and Black Dead Arm (Diplodia seriata and Neofusicoccum parvum). Using a serological approach, the presence of P. chlamydospora was detected in canes of selectively infected cuttings. Conclusions: The antibodies raised in rabbit against polypeptides secreted by P. chlamydospora are useful tools to specifically detect the presence of the pathogen. Significance of the Study: These results allow us to propose a reliable dot blot method to detect grapevine infection by P. chlamydospora. This method is non-destructive for grapevines, simple and rapid.

Published
2010
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42. DEVELOPMENTAL AND ULTRASTRUCTURAL FEATURES OF PHAEOMONIELLA CHLAMYDOSPORA AND PHAEOACREMONIUM ALEOPHILUM IN RELATION TO XYLEM DEGRADATION IN ESCA DISEASE OF THE GRAPEVINE

Author

Valtaud, Christophe, Larignon, Philippe, Roblin, Gabriel, Fleurat-Lessard, Pierrette, Physiologie Moléculaire du Transport des Sucres chez les Végétaux (PhyMoTS), Université de Poitiers-Centre National de la Recherche Scientifique (CNRS), Institut Français de la Vigne et du Vin (IFV), and Clercy-Morel, Sylvie

Subjects
fungi, [SDV.BV]Life Sciences [q-bio]/Vegetal Biology, [SDV.BV] Life Sciences [q-bio]/Vegetal Biology
Abstract

International audience; 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 optimum growth rates for P. chlamydospora at 25°C, and for P. aleophilum at 30°C. Low temperatures (5°C) applied over a long period (40 days) did not affect the viability of either fungus, whereas high temperatures (35°C for P. chlamydospora and 40°C for P. aleophilum) rapidly suppressed their growth. Alkaline pH, which reduced mycelial growth, increased the formation of conidia in P. chlamydospora, whereas the same effect was observed for acidic pH in P. aleophilum. Unlike P. chlamydospora, P. aleophilum penetrated the lignified walls in host xylem cells degrading the hemicellulose, cellulose and lignin components. However, the deleterious effect of these two fungi cannot explain all the observed wood-degrading processes occurring during esca disease. These agents may facilitate the access of opportunistic saprophytes whose mode of action should now be investigated.

Published
2009

43. Detection immunologique des agents pathogènes de l'eutypiose et de l'esca

Author

Roblin, Gabriel, Fleurat-Lessard, Pierrette, Physiologie Moléculaire du Transport des Sucres chez les Végétaux (PhyMoTS), Université de Poitiers-Centre National de la Recherche Scientifique (CNRS), and Clercy-Morel, Sylvie

Subjects
[SDV.BV]Life Sciences [q-bio]/Vegetal Biology, [SDV.BV] Life Sciences [q-bio]/Vegetal Biology
Published
2008

44. Les maladies fongiques du bois chez la vigne

Author

Roblin, Gabriel, Transport des assimilats (TA), Université de Poitiers-Centre National de la Recherche Scientifique (CNRS), and Clercy-Morel, Sylvie

Subjects
[SDV.BV]Life Sciences [q-bio]/Vegetal Biology, [SDV.BV] Life Sciences [q-bio]/Vegetal Biology
Published
2006

46. Recherche d'un traitement curatif par des molécules naturelles

Author

Roblin, Gabriel, Clercy-Morel, Sylvie, Transport des assimilats (TA), and Université de Poitiers-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDV.BV]Life Sciences [q-bio]/Vegetal Biology, [SDV.BV] Life Sciences [q-bio]/Vegetal Biology
Published
2004

47. Modifications of the chemical structure of phenolics differentially affect physiological activities in pulvinar cells of Mimosa pudica L. II. Influence of various molecular properties in relation to membrane transport.

Author

Rocher, Françoise, Roblin, Gabriel, and Chollet, Jean-François

Subjects
PHENOLS, BIOLOGICAL transport, BENZOIC acid, MOLECULAR volume, MOLECULAR weights, QSAR models
Abstract

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 (growth, flowering, allelopathy, defense processes). Using the partial least squares (PLS) regression method, the impact of molecular descriptors that have been shown to play an important role concerning the uptake of pharmacologically active compounds by animal cells was analyzed in terms of the modification of membrane potential, variations in proton flux, and inhibition of the osmocontractile reaction of pulvinar cells of Mimosa pudica leaves. The hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA), polar surface area (PSA), halogen ratio (Hal ratio), number of rotatable bonds (FRB), molar volume (MV), molecular weight (MW), and molar refractivity (MR) were considered in addition to two physicochemical properties (log D and the amount of non-dissociated form in relation to p Ka). HBD + HBA and PSA predominantly impacted the three biological processes compared to the other descriptors. The coefficient of determination in the quantitative structure-activity relationship (QSAR) models indicated that a major part of the observed seismonasty inhibition and proton flux modification can be explained by the impact of these descriptors, whereas this was not the case for membrane potential variations. These results indicate that the transmembrane transport of the compounds is a predominant component. An increasing number of implicated descriptors as the biological processes become more complex may reflect their impacts on an increasing number of sites in the cell. The determination of the most efficient effectors may lead to a practical use to improve drugs in the control of microbial attacks on plants. [ABSTRACT FROM AUTHOR]

Published
2017
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