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J. Köhl - One of the best experts on this subject based on the ideXlab platform.
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Comparative Analysis of the Role of Substrate Specificity in Biological Control of Botrytis Elliptica in Lily and B. Cinerea in Cyclamen with Ulocladium Atrum
European Journal of Plant Pathology, 2001Co-Authors: G.j.t. Kessel, B.h. De Haas, C.h. Lombaers-van Der Plas, J.e. Van Den Ende, M.g. Pennock-vos, W. Van Der Werf, J. KöhlAbstract:Biological control of Botrytis spp. by the fungal antagonist Ulocladium atrum is based on their interaction in plant tissue. U. atrum is effective against B. cinerea in commercial Cyclamen crops but not effective against B. elliptica in lily crops. Based on the necrotrophic nature of the Botrytis spp. and the saprophytic nature of U. atrum it is hypothesised, and experimentally confirmed, that the interaction between Botrytis spp. and U. atrum , resulting in a biocontrol effect, only takes place in necrotic plant tissue. The role of necrotic tissue in the epidemiology of B. cinerea in Cyclamen and B. elliptica in lily was found to be different. Removal of symptomless senescing leaves resulted in a significant reduction of the area under the disease severity progress curve (AUDPC) for B. cinerea in Cyclamen but had no effect on the disease severity in lily. U. atrum applications significantly reduced B. cinerea AUDPC values in Cyclamen but were less efficient than the removal of senescing leaves. In lily, disease severity was not affected by applications of U. atrum . It is concluded that necrotic Cyclamen tissue, not killed by B. cinerea , plays an important role in the onset of disease. Colonisation of this tissue by U. atrum prevents saprophytic colonisation of those leaves by B. cinerea . In contrast, conidia of B. elliptica directly infect healthy lily leaf tissue. U. atrum applications aimed at blocking the infection pathway from a saprophytic base are therefore not effective against B. elliptica . Control options based on competitive interactions in and around B. elliptica lesions resulted in a reduced production of conidia by B. elliptica but proved ineffective against disease development. The potential of U. atrum as a biocontrol agent against Botrytis spp. and possibly against other necrotrophs appears to be determined by the competitive saprophytic ability of the antagonist in mutual substrates of pathogen and antagonist and by the role of these substrates in disease epidemiology.
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biocontrol of botrytis cinerea by ulocladium atrum in different production systems of Cyclamen
Plant Disease, 2000Co-Authors: J. Köhl, M Gerlagh, G GritAbstract:ABSTRACT Ten experiments in six different commercial greenhouses were conducted to study the effect of spraying conidial suspensions of the saprophytic fungus Ulocladium atrum (1 × 106 conidia per ml) on infection of leaves and flower petioles of Cyclamen by Botrytis cinerea (gray mold). The greenhouses represented the range of Dutch growing systems of Cyclamen, differing considerably in the arrangement of plants, irrigation system, heating system, and material of pots. Applications of U. atrum suspensions were carried out at 4-week intervals only twice on young plants or were continued during the whole growing season until 4 weeks before plants were marketable. The antagonistic treatments were compared with untreated or water-treated controls and with fungicide applications as applied by growers. After applications of U. atrum at 4-weeks intervals, disease development was significantly reduced in experiments carried out in five different greenhouses. In no case did treatments with fungicides give better ...
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quantification of mycelium of botrytis spp and the antagonist ulocladium atrum in necrotic leaf tissue of Cyclamen and lily by fluorescence microscopy and image analysis
Phytopathology, 1999Co-Authors: G.j.t. Kessel, B.h. De Haas, W. Van Der Werf, C Lombaersvan Der H Plas, E M J Meijer, F M Dewey, J Goudriaan, J. KöhlAbstract:Kessel, G. J. T., de Haas, B. H., Lombaers-van der Plas, C. H., Meijer, E. M. J., Dewey, F. M., Goudriaan, J., van der Werf, W., and Kohl, J. 1999. Quantification of mycelium of Botrytis spp. and the antagonist Ulocladium atrum in necrotic leaf tissue of Cyclamen and lily by fluorescence microscopy and image analysis. Phytopathology 89:868-876. A technique was developed to localize and quantify the internal mycelial colonization of necrotic leaf tissue of Cyclamen ( Cyclamen persicum) or lily (Lilium) by pathogenic Botrytis spp. and the antagonist Ulocladium atrum. This technique allows investigation of competitive substrate colonization by both fungi, which is a key process for biological control of Botrytis spp. by U. atrum. A combination of differential fluorescent labeling and image analysis was applied on cryostat sections of necrotic leaf tissue. Botrytis mycelium was labeled specifically by indirect immunofluorescence using a monoclonal antibody specific for Botrytis spp. and an antimouse fluorescein conjugate. Wheat germ agglutinin conjugated to the fluorochrome TRITC was used to label mycelium of both fungi. Image analysis was used to measure the relative surface area of the cryostat section covered by fluorescing hyphae of Botrytis spp. and by fluorescing hyphae of both fungi. A mathematical conversion was derived and used to calculate the relative mycelial volume of each f ungal species in the necrotic tissue based on the measured relative surface areas. Temporal aspects of substrate colonization were studied in a short time series. An analysis of components of variance provided insight into spatial colonization patterns for the fungal species involved and allowed the design of efficient sampling strategies for future experiments.
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Competitive ability of the antagonists Ulocladium atrum and Gliocladium roseum at temperatures favourable for Botrytis spp. development
BioControl, 1999Co-Authors: J. Köhl, G.j.t. Kessel, C.h. Lombaers-van Der Plas, W.m.l. Molhoek, H.m. Goossen-van Der GeijnAbstract:Ulocladium atrum and Gliocladium roseum are fungal antagonists capable of suppressing sporulation of Botrytis spp. on dead plant parts. The effect of temperature (3 to 36 °C) on antagonist conidial germination and mycelial growth was assessed on agar. In addition conidial germination of U. atrum was measured on dead lily leaves. The optimum temperature of both antagonists for both conidial germination and mycelial growth was between 27 and 30 °C. U. atrum was less affected by lower temperatures than G. roseum. At optimum temperature, 50% of conidia of U. atrum and G. roseum germinated within 2.6 and 10.0 hrs, respectively. At low sub-optimal temperatures (6 °C), 50% of conidia germinated within 18 and 96 hours, respectively. In bioassays on dead onion leaves, U. atrum suppressed sporulation of B. cinerea and B. aclada at all temperatures tested (6 to 24 °C) by more than 85%. On dead Cyclamen leaves, G. roseum was more efficient than U. atrum at 21 and 24 °C but, in contrast to U. atrum, showed no antagonistic activity at temperatures below 21 °C. On dead hydrangea leaves, U. atrum significantly reduced sporulation of B. cinerea at temperatures as low as 3 and 1 °C. Under Dutch growing conditions, the mean air temperature during leaf wetness periods in onion and lily fields was 15 °C with temperatures only occasionally above 20 °C. In greenhouse crops of Cyclamen, the mean temperature during high humidity periods was 17 °C. It is therefore concluded that U. atrum is better adapted than G. roseum to temperatures which occur in the field, in greenhouse crops such as Cyclamen, or during cold storage of plant stocks.
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biological control of botrytis cinerea in Cyclamen with ulocladium atrum and gliocladium roseum under commercial growing conditions
Phytopathology, 1998Co-Authors: J. Köhl, B.h. De Haas, M Gerlagh, M C KrijgerAbstract:ABSTRACT The effect of treatments with conidial suspensions of Ulocladium atrum and Gliocladium roseum on leaf rot of Cyclamen caused by Botrytis cinerea was investigated under commercial greenhouse conditions. Spraying U. atrum (1 × 106 conidia per ml) or G. roseum (2 × 106 conidia per ml and 1 × 107 conidia per ml) at intervals of 2 to 3 weeks during the production period and spraying U. atrum (1 × 106 conidia per ml) at intervals of 4 to 6 weeks resulted in a significant reduction of natural infections of petioles by B. cinerea. U. atrum or G. roseum (1 × 107conidia per ml) was as effective as the standard fungicide program. B. cinerea colonized senesced leaves within the plant canopy and infected adjacent petioles and leaves later. The antagonists colonized senesced leaves and reduced B. cinerea development on these leaves. Thus, the inoculum potential on petioles adjacent to necrotic leaf tissues was reduced. The fate of U. atrum conidia on surfaces of green Cyclamen leaves during a 70-day period aft...
Traud Winkelmann - One of the best experts on this subject based on the ideXlab platform.
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thermotolerant Cyclamen with reduced acrolein and methyl vinyl ketone
Journal of Experimental Botany, 2012Co-Authors: Hiroomi Kai, Traud Winkelmann, Keita Hirashima, Osamu Matsuda, Hidetoshi Ikegami, Takao Nakahara, Koh IbaAbstract:Reduced levels of trienoic fatty acids (TAs) in chloroplast membranes induce thermotolerance in several plant species, but the underlying mechanisms remain unclear. TA peroxidation in plant cell membranes generates cytotoxic, TA-derived compounds containing α,β-unsaturated carbonyl groups. The relationship between low TA levels and the amounts of cytotoxic TA-derived compounds was examined using thermotolerant transgenic Cyclamen (Cyclamen persicum Mill.) with low TA contents. Changes in the levels of the cytotoxic TA-derived acrolein (ACR), methyl vinyl ketone (MVK), (E)-2-hexenal, 4-hydroxy-2-nonenal, and malondialdehyde were analysed in the leaf tissues of wild-type (WT) and thermotolerant transgenic Cyclamen under heat stress. Levels of ACR and MVK in the WT increased in parallel with the occurrence of heat-induced tissue damage, whereas no such changes were observed in the thermotolerant transgenic lines. Furthermore, exogenous ACR and MVK infiltrated into leaves to concentrations similar to those observed in heat-stressed WT leaves caused similar disease symptoms. These results suggest that thermotolerance in transgenic Cyclamen depends on reduced production rates of ACR and MVK under heat stress, due to the low level of TAs in these plants.
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from callus to embryo a proteomic view on the development and maturation of somatic embryos in Cyclamen persicum
Planta, 2012Co-Authors: Christina Rode, Hanspeter Braun, Kathrin Lindhorst, Traud WinkelmannAbstract:In this study, the proteome structures following the pathway in somatic embryogenesis of Cyclamen persicum were analysed via high-resolution 2D-SDS-PAGE with two objectives: (1) to identify the significant physiological processes during somatic embryogenesis in Cyclamen and (2) to improve the maturation of somatic embryos. Therefore, the effects of maturation-promoting plant growth regulator abscisic acid (ABA) and high sucrose levels on torpedo-shaped embryos were investigated. In total, 108 proteins of differential abundance were identified using a combination of tandem mass spectrometry and a digital proteome reference map. In callus, enzymes related to energy supply were especially distinct, most likely due to energy demand caused by fast growth and cell division. The switch from callus to globular embryo as well as from globular to torpedo-shaped embryo was associated with controlled proteolysis via the ubiquitin-26S proteasome pathway. Storage compound accumulation was first detected 21 days after transfer to plant growth regulator (PGR)-free medium in early torpedo-shaped embryos. Increase in abundance of auxin-amidohydrolase during embryogenesis suggests a possible increase in auxin release in the late embryo stages of Cyclamen. A development-specific isoelectric point switch of catalases has been reported for the first time for somatic embryogenesis. Several proteins were identified to represent markers for the different developmental stages analysed. High sucrose levels and ABA treatment promoted the accumulation of storage compounds in torpedo-shaped embryos. Additionally, proteins of the primary metabolic pathways were decreased in the proteomes of ABA-treated embryos. Thus, ABA and high sucrose concentration in the culture medium improved maturation and consequently the quality of somatic embryos in C. persicum.
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enolases storage compounds in seeds evidence from a proteomic comparison of zygotic and somatic embryos of Cyclamen persicum mill
Plant Molecular Biology, 2011Co-Authors: Christina Rode, Sebastien Gallien, Dimitri Heintz, Alain Van Dorsselaer, Hanspeter Braun, Traud WinkelmannAbstract:Somatic embryogenesis is well established for the economic relevant ornamental crop Cyclamen and thus could supplement the elaborate propagation via seeds. However, the use of somatic embryogenesis for commercial large scale propagation is still limited due to physiological disorders and asynchronous development within emerged embryos. To overcome these problems, profound knowledge of the physiological processes in Cyclamen embryogenesis is essential. Thus, the proteomes of somatic and zygotic embryos were characterised in a comparative approach. Protein separation via two dimensional IEF-SDS PAGE led to a resolution of more than 1,000 protein spots/gel. Overall, 246 proteins were of differential abundance in the two tissues compared. Mass spectrometry analysis of the 300 most abundant protein spots resulted in the identification of 247 proteins, which represent 90 distinct protein species. Fifty-five percent of the 247 proteins belong to only three physiological categories: glycolysis, protein folding and stress response. The latter physiological process was especially predominant in the somatic embryos. Remarkably, the glycolytic enzyme enolase was the protein most frequently detected and thus is supposed to play an important role in Cyclamen embryogenesis. Data are presented that indicate involvement of “small enolases” as storage proteins in Cyclamen. A digital reference map was established via a novel software tool for the web-based presentation of proteome data linked to KEGG and ExPasy protein-databases and both were made publicly available online.
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regeneration of different Cyclamen species via somatic embryogenesis from callus suspension cultures and protoplasts
Scientia Horticulturae, 2010Co-Authors: Anika Nadja Sabine Prange, Melanie Bartsch, Margrethe Serek, Traud WinkelmannAbstract:The present study is the first report of the establishment of embryogenic callus cultures from seedling tissue, the regeneration of plants via somatic embryogenesis and the development of a regeneration system from protoplast to plant, using three wild species of Cyclamen, Cyclamen graecum Link, Cyclamen mirabile Hildebrand, Cyclamen trochopteranthum Schwarz (syn. Cyclamen alpinum hort. Dammann ex Sprenger). The ability to form embryogenic callus and to regenerate via somatic embryogenesis was strongly genotype-dependent for each species. From 0.5 g callus, up to 1461 somatic embryos were formed in the case of C. mirabile. Culture media with different concentrations of plant growth regulators, CaCl2 and activated charcoal significantly influenced embryo formation in this species. Up to 1.4 × 106 protoplasts were isolated from 1 g of C. graecum cell suspension. Diverse growth responses of the protoplasts in two embedding agents, agarose and alginate, were observed for the different Cyclamen species. These specific growth characteristics could be used as a selection marker for future fusion experiments. From both protoplast culture systems, somatic embryos were regenerated, grown to plantlets and acclimatised to greenhouse conditions.
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germination of encapsulated somatic embryos of Cyclamen persicum
Hortscience, 2004Co-Authors: Traud Winkelmann, L Meyer, Margrethe SerekAbstract:Somatic embryos of Cyclamen (Cyclamen persicum Mill.) were produced using a liquid culture system. Two encapsulation techniques, conventional alginate beads and alginate hollow beads, were tested for globular Cyclamen somatic embryos with the aim of develop- ing synthetic seeds. Final germination from alginate beads was as high as observed for non encapsulated control embryos (97%), but germination was delayed. In contrast, germination from hollow beads was lower (71%) and occurred later. In hollow beads somatic embryos developed within the capsule, and outgrowth seemed to be more diffi cult than from alginate. Storage at 4 °C for four weeks resulted in a reduction of viability for controls as well as for encapsulated embryos. Incorporation of medium into the capsules improved the speed of germination for both capsule types. However, somatic embryos were not able to germinate on a medium-free support, even if encapsulated in beads containing medium.
Christian Steinberg - One of the best experts on this subject based on the ideXlab platform.
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Fusarium oxysporum f. sp cyclaminis: underestimated genetic diversity
European Journal of Plant Pathology, 2016Co-Authors: Charline Lecomte, Veronique Edel-hermann, Agnès Langlois, Claude Alabouvette, Fabien Robert, Marc-antoine Cannesan, Nadine Gautheron, Christian SteinbergAbstract:Fusarium oxysporum f. sp. cyclaminis (Focy) is the most damaging pathogen of Cyclamen (Cyclamen persicum). Control measures are limited and not efficient enough to ensure a healthy production. The development of a tool allowing the early detection of Focy and an effective control method relies on the knowledge of Focy diversity. We obtained 27 Focy strains from international collections, and recovered 24 additional F. oxysporum isolates from Cyclamen. A pathogenicity test revealed 15 pathogenic isolates out of the 24 isolates from Cyclamen, with substantial differences in aggressiveness among isolates. The other nine were non-pathogenic endophytic strains of Cyclamen. We described the genetic diversity of pathogenic and non-pathogenic strains by sequencing part of the translation elongation factor 1-alpha gene and the full-length nuclear ribosomal intergenic spacer region. We found high genetic diversity within the forma specialis, with 42 Focy strains distributed into six two-locus sequence types (ST). No relationship was found between genotypic grouping, geographic origin and aggressiveness within the collection of strains. Genetic diversity was much higher among non-pathogenic strains: the nine strains were distributed into nine ST, all of them distinct from pathogenic ST. As both pathogenic strains and endophytic strains can be present in Cyclamen, an efficient tool to detect Focy is badly needed.
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Fusariose du Cyclamen : vers un outil de détection précoce
Phytoma, 2016Co-Authors: Charline Lecomte, Agnès Langlois, Claude Alabouvette, Fabien Robert, Christian Steinberg, Marc-antoine Cannesan, Veronique Edel-hermannAbstract:Fusariose du Cyclamen : vers un outil de détection précoce
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Fusariose du Cyclamen : travaux sur la lutte biologique. Phytoma-La défense des végétaux
Phytoma, 2016Co-Authors: Charline Lecomte, Veronique Edel-hermann, Claude Alabouvette, Fabien Robert, Marc-antoine Cannesan, Nicolas Jeannin, Christelle Cordier, Christian SteinbergAbstract:Fusariose du Cyclamen : travaux sur la lutte biologique. Phytoma-La défense des végétaux
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Fusariose du Cyclamen : vers une gestion intégrée de la maladie
2015Co-Authors: Charline Lecomte, Veronique Edel-hermann, Claude Alabouvette, A. Langlois, R. Robert, Christian SteinbergAbstract:Fusarium oxysporum est un champignon tellurique ubiquiste présentant une grande diversité de souches pathogènes et non pathogènes. Les souches phytopathogènes sont groupées en formae speciales selon leur spécificité d’hôte. Ainsi, la forma specialis cyclaminis (Focy) est responsable de la fusariose vasculaire du Cyclamen. C’est le pathogène le plus destructeur sur Cyclamen. Le pathogène, et donc la maladie peuvent intervenir à tout moment du cycle de culture causant d’importantes les pertes. Malheureusement, la détection préventive de Focy n’est pas possible, la lutte chimique inefficace et la résistance variétale inexistante. La lutte biologique apparaît comme l’alternative à promouvoir. Afin de fournir aux producteurs un système de gestion de la maladie efficace, nous proposons de : (1) rechercher un marqueur moléculaire spécifique pour détecter précocement le pathogène, (2) sélectionner un ou plusieurs agents de lutte biologique (ALB) efficaces parmi les produits commercialisés mais sans allégation contre Focy. Pour cela, une collection comprenant 27 souches de Focy de collections internationales, 25 isolats de F. oxysporum isolés de Cyclamens et une centaine d’autres souches de champignons a été constituée. L’identité des isolats de F. oxysporum a été vérifiée en séquençant la totalité de l’espaceur interne transcrit (ITS) de l’ADN ribosomique (ADNr) et une partie du gène codant pour le facteur d’élongation 1-α (EF1-α) et en évaluant leur pathogénicité sur Cyclamen. La diversité génétique de Focy a été caractérisée en combinant les séquences de l’EF1-α et de l’espaceur intergénique (IGS) de l’ADNr. Cette analyse a révélé une grande diversité, les souches étant réparties dans six groupes. Un fragment d’ADN spécifique et commun à ces groupes a été recherché par amplification aléatoire d’ADN polymorphe (RAPD). Un fragment de 1650 pb a été identifié à partir duquel des amorces ont été dessinées. Leur spécificité et sensibilité sont en cours d’évaluation. Parallèlement, l’efficacité de contrôle de 7 ALB seuls ou en combinaison a été testée contre une souche agressive de Focy. L’essai a été réalisé en serre. Les ALB ont été incorporés au substrat, au semis puis au rempotage. Le pathogène a été apporté une semaine post rempotage. Trois ratio ALB/agent pathogène (1/1, 10/1, 100/1) ont été testés. Les premiers résultats ont permis la sélection de 3 ALB. Ces produits seront testés à nouveau dans un essai de plus de 1500 plantes en serre, qui sera dupliqué à Dijon et Rouen. Il permettra de valider le choix et la méthode d’application de l’ALB retenu.
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Fusarium oxysporum f. sp. cyclaminis: Identification of specific molecular markers for improved disease prevention
2014Co-Authors: Charline Lecomte, Veronique Edel-hermann, Agnès Langlois, Claude Alabouvette, Fabien Robert, Christian SteinbergAbstract:Fusarium oxysporum is a well-known soil-borne and ubiquitous fungus. The species includes a high diversity of saprophytic and pathogenic populations. The phytopathogenic ones are subdivided into formae speciales according to their host specificity. The forma specialis cyclaminis (FoCy) is causing Fusarium wilt only on Cyclamen. It causes damages during the entire production line and can raise more than 50 % losses. FoCy is considered as the more destructive pathogen on Cyclamen. To achieve a better understanding of the disease and a more efficient and eco-friendly way of control, we aim at finding a specific molecular marker allowing for early detection and quantification of the pathogen and at selecting efficient BioControl Agents (BCA). We first created a collection of 74 strains of putative FoCy from international collections and diseased Cyclamens. We also collected other strains of F. oxysporum, other Fusarium species, saprophytic and soil-borne fungi, and other fungi known to be pathogenic on Cyclamen. The identity of the putatively FoCy strains was assessed by sequencing the Internal Transcribed Spacer (ITS) and the Elongation Factor 1 α (EF) and by testing their pathogenicity. Their genetic diversity was characterized by combining data from the EF and the InterGenic Spacer (IGS) sequencing and provided 7 cluster types. One strain was taken from each cluster and used for searching for a common specific marker by Random Amplified Polymorphic DNA (RAPD). So far, one band appears specific for 6 cluster types and one is specific of the 7th cluster type. SCAR (Sequences Characterized Amplified Region) primers are being designed. Primers specificity and sensitivity will be estimated using the whole strains collection. To complete this prophylactic tool, we are currently evaluating the antagonistic activity of several commercial BCA to select the most efficient one to control FoCy.
Charline Lecomte - One of the best experts on this subject based on the ideXlab platform.
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Fusariose du Cyclamen : Détection préventive du risque et contrôle biologique
2016Co-Authors: Charline LecomteAbstract:La fusariose vasculaire du Cyclamen est une maladie causée par le champignon tellurique Fusarium oxysporum f. sp. cyclaminis. Elle est considérée comme l’une des maladies les plus graves du Cyclamen et se traduit par des pertes atteignant jusqu’à 50 % de la production. Actuellement, les moyens de lutte ne permettent pas de contrôler la maladie. Dans ce contexte, une collaboration s’est engagée entre l’institut technique de l’horticulture, Astredhor, représentant les producteurs, l’INRA de Dijon pour son expertise sur F. oxysporum et la société Agrene pour son expertise en lutte biologique. Les objectifs de cette collaboration étaient doubles : i) identifier un marqueur spécifique de la forme spéciale cyclaminis et développer un outil de détection de l’agent pathogène permettant de mettre en place des méthodes de lutte appropriées ; ii) identifier un agent de lutte biologique efficace contre le pathogène. Le travail s’est donc structuré autour de ces deux objectifs. Une collection de souches représentatives de la diversité des populations de F. oxysporum f. sp. cyclaminis a été constituée. Elle regroupe des souches provenant de collections internationales et des isolats obtenus de Cyclamens symptomatiques ou non. L’analyse moléculaire de cette collection a permis de caractériser son importante diversité génétique et a mis en exergue la difficulté d’identifier un marqueur moléculaire spécifique. Néanmoins, un fragment d’ADN spécifique de l’agent pathogène a pu être mis en évidence par amplification aléatoire d’ADN polymorphe. A partir de ce fragment, un couple d’amorces spécifiques a été dessiné et un outil moléculaire a été développé. Ce dernier permet une détection du champignon in planta en PCR conventionnelle et en PCR en temps réel. Parallèlement, une étude bibliographique approfondie relative aux méthodes de lutte biologique contre les fusarioses induites par F. oxysporum sur les plantes ornementales a été effectuée. Cette revue a souligné la possibilité d’utiliser des ressources d’origine microbienne et d’origine végétale pour contrôler F. oxysporum, mais cette stratégie impliquant une étape de sélection nous est apparue lourde et laborieuse. Nous avons opté pour une autre démarche visant à identifier, parmi des produits déjà sur le marché, ceux susceptibles de réduire significativement la gravité de la maladie. Des bioessais ont été conduits en serre, dans des conditions proches de celles de la production pour tester sept produits reposant sur la formulation de bactéries, de champignons ou de combinaisons de ces microorganismes. Les produits les moins performants ont été éliminés à l’issue d’un premier essai. Des bioessais ont été conduits à nouveau avec trois produits. Un seul de ces produits donne satisfaction mais son efficacité devra être validée en conditions de production réelles. En conclusion, l’outil de détection spécifique permettra aux producteurs de s’assurer de la qualité sanitaire de la culture et des supports de culture. L’agent de lutte biologique retenu à l’issue de nos essais permettra dans un premier temps aux producteurs de prévenir le risque d’activité infectieuse de F. oxysporum f. sp. cyclaminis. Cependant, un travail de recherche d’un agent de lutte plus performant s’avère nécessaire. Des pistes sont proposées.
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Fusarium oxysporum f. sp cyclaminis: underestimated genetic diversity
European Journal of Plant Pathology, 2016Co-Authors: Charline Lecomte, Veronique Edel-hermann, Agnès Langlois, Claude Alabouvette, Fabien Robert, Marc-antoine Cannesan, Nadine Gautheron, Christian SteinbergAbstract:Fusarium oxysporum f. sp. cyclaminis (Focy) is the most damaging pathogen of Cyclamen (Cyclamen persicum). Control measures are limited and not efficient enough to ensure a healthy production. The development of a tool allowing the early detection of Focy and an effective control method relies on the knowledge of Focy diversity. We obtained 27 Focy strains from international collections, and recovered 24 additional F. oxysporum isolates from Cyclamen. A pathogenicity test revealed 15 pathogenic isolates out of the 24 isolates from Cyclamen, with substantial differences in aggressiveness among isolates. The other nine were non-pathogenic endophytic strains of Cyclamen. We described the genetic diversity of pathogenic and non-pathogenic strains by sequencing part of the translation elongation factor 1-alpha gene and the full-length nuclear ribosomal intergenic spacer region. We found high genetic diversity within the forma specialis, with 42 Focy strains distributed into six two-locus sequence types (ST). No relationship was found between genotypic grouping, geographic origin and aggressiveness within the collection of strains. Genetic diversity was much higher among non-pathogenic strains: the nine strains were distributed into nine ST, all of them distinct from pathogenic ST. As both pathogenic strains and endophytic strains can be present in Cyclamen, an efficient tool to detect Focy is badly needed.
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Fusariose du Cyclamen : vers un outil de détection précoce
Phytoma, 2016Co-Authors: Charline Lecomte, Agnès Langlois, Claude Alabouvette, Fabien Robert, Christian Steinberg, Marc-antoine Cannesan, Veronique Edel-hermannAbstract:Fusariose du Cyclamen : vers un outil de détection précoce
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Fusariose du Cyclamen : travaux sur la lutte biologique. Phytoma-La défense des végétaux
Phytoma, 2016Co-Authors: Charline Lecomte, Veronique Edel-hermann, Claude Alabouvette, Fabien Robert, Marc-antoine Cannesan, Nicolas Jeannin, Christelle Cordier, Christian SteinbergAbstract:Fusariose du Cyclamen : travaux sur la lutte biologique. Phytoma-La défense des végétaux
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Fusariose du Cyclamen : vers une gestion intégrée de la maladie
2015Co-Authors: Charline Lecomte, Veronique Edel-hermann, Claude Alabouvette, A. Langlois, R. Robert, Christian SteinbergAbstract:Fusarium oxysporum est un champignon tellurique ubiquiste présentant une grande diversité de souches pathogènes et non pathogènes. Les souches phytopathogènes sont groupées en formae speciales selon leur spécificité d’hôte. Ainsi, la forma specialis cyclaminis (Focy) est responsable de la fusariose vasculaire du Cyclamen. C’est le pathogène le plus destructeur sur Cyclamen. Le pathogène, et donc la maladie peuvent intervenir à tout moment du cycle de culture causant d’importantes les pertes. Malheureusement, la détection préventive de Focy n’est pas possible, la lutte chimique inefficace et la résistance variétale inexistante. La lutte biologique apparaît comme l’alternative à promouvoir. Afin de fournir aux producteurs un système de gestion de la maladie efficace, nous proposons de : (1) rechercher un marqueur moléculaire spécifique pour détecter précocement le pathogène, (2) sélectionner un ou plusieurs agents de lutte biologique (ALB) efficaces parmi les produits commercialisés mais sans allégation contre Focy. Pour cela, une collection comprenant 27 souches de Focy de collections internationales, 25 isolats de F. oxysporum isolés de Cyclamens et une centaine d’autres souches de champignons a été constituée. L’identité des isolats de F. oxysporum a été vérifiée en séquençant la totalité de l’espaceur interne transcrit (ITS) de l’ADN ribosomique (ADNr) et une partie du gène codant pour le facteur d’élongation 1-α (EF1-α) et en évaluant leur pathogénicité sur Cyclamen. La diversité génétique de Focy a été caractérisée en combinant les séquences de l’EF1-α et de l’espaceur intergénique (IGS) de l’ADNr. Cette analyse a révélé une grande diversité, les souches étant réparties dans six groupes. Un fragment d’ADN spécifique et commun à ces groupes a été recherché par amplification aléatoire d’ADN polymorphe (RAPD). Un fragment de 1650 pb a été identifié à partir duquel des amorces ont été dessinées. Leur spécificité et sensibilité sont en cours d’évaluation. Parallèlement, l’efficacité de contrôle de 7 ALB seuls ou en combinaison a été testée contre une souche agressive de Focy. L’essai a été réalisé en serre. Les ALB ont été incorporés au substrat, au semis puis au rempotage. Le pathogène a été apporté une semaine post rempotage. Trois ratio ALB/agent pathogène (1/1, 10/1, 100/1) ont été testés. Les premiers résultats ont permis la sélection de 3 ALB. Ces produits seront testés à nouveau dans un essai de plus de 1500 plantes en serre, qui sera dupliqué à Dijon et Rouen. Il permettra de valider le choix et la méthode d’application de l’ALB retenu.
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est sequencing from embryogenic Cyclamen persicum cell cultures identifies a high proportion of transcripts homologous to plant genes involved in somatic embryogenesis
Journal of Plant Growth Regulation, 2005Co-Authors: Stefan A Rensing, Daniel Lang, Eik Schumann, Ralf Reski, Annette HoheAbstract:To learn more about the process of somatic embryogenesis in the economically important ornamental plant Cyclamen persicum, we initiated an expressed sequence tag (EST) project. A normalized cDNA library was constructed from embryogenic cell material in different developmental stages, and clones were subsequently sequenced from the 5′ end. A total of 2083 filtered EST with an average length of 499 bases were analyzed in this study and submitted to the international sequence databases. By computational analyses, the Cyclamen transcripts were annotated and checked against plant genes previously described to be involved in somatic embryogenesis. Approximately one third of those genes were covered by the Cyclamen EST analyzed in this study. A high proportion of homologs to genes involved in somatic embryogenesis in the model system Daucus carota (carrot) were found in the Cyclamen EST collection. Of special interest are transcripts encoding gibberellin oxidases and somatic embryogenesis receptor-like kinases (SERK), both of which were confirmed to be important for development of embryos from somatic carrot cells. In addition, the set of candidate genes was expanded by using gene ontology (GO) annotations as well as by comparison with EST that were shown to be upregulated during Glycine max (soybean) somatic embryogenesis in a microarray approach. Our computational biology approach disclosed a set of around 90 candidate genes that now can be tested in the wet lab for their influence on somatic embryogenesis in Cyclamen. The annotated Cyclamen transcripts are available via http://www.Cyclamen-est.de.
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co2 accumulation in bioreactor suspension cultures of Cyclamen persicum mill and its effect on cell growth and regeneration of somatic embryos
Plant Cell Reports, 1999Co-Authors: Annette Hohe, Traud Winkelmann, Hansgeorg SchwenkelAbstract:CO2 accumulation in different culture systems containing embryogenic cell suspension cultures of Cyclamen (Cyclamen persicum Mill.) was analyzed. In bioreactors equipped with a bubble-free or a bubble aeration system, CO2 mole fractions in the gas phase of more than 10% were determined whereas in Erlenmeyer flasks, CO2 mole fractions were below 2%. CO2 accumulation in bioreactors was severely growth inhibiting in comparison to the flasks. By removing CO2 in the aeration gas of a bubble-free aerated bioreactor, cell growth comparable to that in flasks was achieved. The regeneration ability of cell suspensions after being cultured in bioreactors with CO2 accumulation was better than those after culture in bioreactors without CO2 accumulation or in flasks.
