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  • 1
    UID:
    gbv_1727826450
    Format: XV, 134 Seiten , Diagramme, Illustrationen
    Content: Recently crops encounter an increased number of individual and combined abiotic and biotic stress, which severely affect their growth and yield. Plants are associated with a large number of microorganisms including beneficial as well as pathogenic microorganisms. The interaction of plants with beneficial microorganisms can exert a substantial impact on plant growth and health and their potential can be utilized in sustainable plant production systems. Currently, climate change will increase the impact of stress on crops which will more likely be exposed to combined abiotic and biotic stress. At present, knowledge on how abiotic and biotic stress and the combination of both stresses affect the plant performance and the microbiome is limited. Soil-borne pathogens are responsible for relevant economic losses and are difficult to control. The root bacterial endophytes have shown potential in alleviating stress on plants and improving crop yield and quality. This raises the question how individual abiotic stress like salinity (ionic) and drought (osmotic) and the combination with biotic stress (Verticillium dahliae or Fusarium oxysporum) affects the root microbiota and thus the performance of the plant. Therefore, the goal of this thesis was to improve the understanding of the impact of individual and combined biotic and abiotic stress especially the endophytic root microbiota and thus plant performance. The work is focused on the economically important horticultural crop tomato. [...]
    Note: Dissertation Universität Potsdam 2020
    Language: English
    Subjects: Agriculture, Forestry, Horticulture, Fishery, Domestic Science
    RVK:
    Keywords: Stressreaktion ; Tomate ; Endophyten ; Hochschulschrift
    Author information: Franken, Philipp 1960-
    Author information: Gulati, Sneha 1989-
    Author information: Börnke, Frederik 1971-
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  • 2
  • 3
    UID:
    b3kat_BV008379256
    Format: 86 S. , graph. Darst.
    Note: Köln, Univ., Diss.
    Language: German
    Keywords: Mais ; Anthocyane ; Biosynthese ; Genregulation ; Mais ; Anthocyane ; Biosynthese ; Hochschulschrift
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  • 4
    UID:
    gbv_1667959689
    Format: viii, 135 Seiten , Illustrationen, Diagramme
    Content: Um das Immunsystem der Pflanze zu manipulieren translozieren gram-negative pathogene Bakterien Typ-III Effektorproteine (T3E) über ein Typ-III Sekretionssystem (T3SS) in die pflanzliche Wirtszelle. Dort lokalisieren T3Es in verschiedenen subzellulären Kompartimenten, wo sie Zielproteine modifizieren und so die Infektion begünstigen. HopZ1a, ein T3E des Pflanzenpathogens Pseudomonas syringae pv. syringae, ist eine Acetyltransferase und lokalisiert über ein Myristolierungsmotiv an der Plasmamembran der Wirtszelle. Obwohl gezeigt wurde, dass HopZ1a die frühe Signalweiterleitung an der Plasmamembran stört, wurde bisher kein mit der Plasmamembran assoziiertes Zielprotein für diesen T3E identifiziert. Um bisher unbekannte HopZ1a-Zieleproteine zu identifizieren wurde im Vorfeld dieser Arbeit eine Hefe-Zwei-Hybrid-Durchmusterung mit einer cDNA-Bibliothek aus Tabak durchgeführt, wobei ein nicht näher charakterisiertes Remorin als Interaktor gefunden wurde. Bei dem Remorin handelt es sich um einen Vertreter der Gruppe 4 der Remorin-Familie,…
    Note: Dissertation Universität Potsdam 2019
    Language: German
    Keywords: Abwehrreaktion ; Phytopathogene Bakterien ; Hochschulschrift
    Author information: Börnke, Frederik 1971-
    Author information: Albers, Philip
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  • 5
    UID:
    edochu_18452_22240
    Format: 1 Online-Ressource (6 Seiten)
    Content: Silencing of SlSUT2 expression in tomato plants leads to a dwarfed phenotype, reduced pollen vitality and reduces pollen germination rate. Male sterility of flowers, together with a dwarfed growth behavior is reminiscent to brassinosteroid defective mutant plants. Therefore we aimed to rescue the SlSUT2 silencing phenotype by local brassinosteroid application. The phenotypical effects of SlSUT2 down-regulation could partially be rescued by epi-brassinolide treatment suggesting that SlSUT2 interconnects sucrose partitioning with brassinosteroid signaling. We previously showed that SlSUT2 silenced plants show increased mycorrhization and, this effect was explained by a putative sucrose retrieval function of SlSUT2 at the periarbuscular membrane. More recently, we reported that the symbiotic interaction between Solanaceous hosts and AM fungi is directly affected by watering the roots with epi-brassinolide. Here we show that the SlSUT2 effects on mycorrhiza are not only based on the putative sucrose retrieval function of SlSUT2 at the periarbuscular membrane. Our analyses argue that brassinosteroids as well as SlSUT2 per se can impact the arbuscular morphology/architecture and thereby affect the efficiency of nutrient exchange between both symbionts and the mycorrhizal growth benefit for the plant.
    Content: Peer Reviewed
    Note: This article was supported by the Open Access Publication Fund of Humboldt-Universität zu Berlin.
    In: Austin, Tex. : Landes Bioscience, 15,2
    Language: English
    URL: Volltext  (kostenfrei)
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  • 6
    UID:
    edochu_18452_25003
    Format: 1 Online-Ressource (17 Seiten)
    Content: Endophytic fungi that colonize the plant root live in an environment with relative high concentrations of different sugars. Analyses of genome sequences indicate that such endophytes can secrete carbohydrate-related enzymes to compete for these sugars with the surrounding plant cells. We hypothesized that typical plant sugars can be used as carbon source by root endophytes and that these sugars also serve as signals to induce the expression and secretion of glycolytic enzymes. The plant-growth-promoting endophytes Serendipita indica and Serendipita herbamans were selected to first determine which sugars promote their growth and biomass formation. Secondly, particular sugars were added to liquid cultures of the fungi to induce intracellular and extracellular enzymatic activities which were measured in mycelia and culture supernatants. The results showed that both fungi cannot feed on melibiose and lactose, but instead use glucose, fructose, sucrose, mannose, arabinose, galactose and xylose as carbohydrate sources. These sugars regulated the cytoplasmic activity of glycolytic enzymes and also their secretion. The levels of induction or repression depended on the type of sugars added to the cultures and differed between the two fungi. Since no conventional signal peptide could be detected in most of the genome sequences encoding the glycolytic enzymes, a non-conventional protein secretory pathway is assumed. The results of the study suggest that root endophytic fungi translocate glycolytic activities into the root, and this process is regulated by the availability of particular plant sugars.
    Content: Peer Reviewed
    In: Basel : MDPI, 10,2
    Language: English
    URL: Volltext  (kostenfrei)
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  • 7
    UID:
    edochu_18452_25643
    Format: 1 Online-Ressource (14 Seiten)
    Content: Dark septate endophytes (DSEs) represent a diverse group of root-endophytic fungi that have been isolated from plant roots in many different natural and anthropogenic ecosystems. Melanin is widespread in eukaryotic organisms and possesses various functions such as protecting human skin from UV radiation, affecting the virulence of pathogens, and playing a role in development and physiology of insects. Melanin is a distinctive feature of the cell walls of DSEs and has been thought to protect these fungi from abiotic stress. Melanin in DSEs is assumed to be synthesized via the 1,8-dihydroxynaphthalene (DHN) pathway. Its function in alleviation of salt stress is not yet known. The aims of this study were: (i) investigating the growth responses of three DSEs (Periconia macrospinosa, Cadophora sp., and Leptodontidium sp.) to salt stress, (ii) analyzing melanin production under salt stress and, (iii) testing the role of melanin in salt stress tolerance of DSEs. The study shows that the three DSE species can tolerate high salt concentrations. Melanin content increased in the hyphae of all DSEs at 100 mM salt, but decreased at 500 mM. This was not reflected in the RNA accumulation of the gene encoding scytalone dehydratase which is involved in melanin biosynthesis. The application of tricyclazole, a DHN-melanin biosynthesis inhibitor, did not affect either salt stress tolerance or the accumulation of sodium in the hyphae. In addition, melanin biosynthesis mutants of Leptodontidium sp. did not show decreased growth performance compared to the wild-type, especially not at high salt concentrations. This indicates that DSEs can live under salt stress and withstand these conditions regardless of melanin accumulation.
    Content: Peer Reviewed
    In: Lausanne : Frontiers Media, 11
    Language: English
    URL: Volltext  (kostenfrei)
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  • 8
    UID:
    edochu_18452_21881
    Format: 1 Online-Ressource (11 Seiten)
    Content: Arbuscular mycorrhizal fungi (AMF) proliferate in soils and are known to affect soil structure. Although their contribution to structure is extensively investigated, the consequences of those processes for soil water extractability and transport has, so far, gained surprisingly little attention. Therefore we asked, whether AMF can affect water retention and unsaturated hydraulic conductivity under exclusion of root ingrowth, in order to minimize plant driven effects. We carried out experiments with tomato inoculated with Rhizoglomus irregulare in a soil substrate with sand and vermiculite that created variation in colonization by mixed pots with wild type (WT) plants and mycorrhiza resistant (RMC) mutants. Sampling cores were introduced and used to assess substrate moisture retention dynamics and modeling of substrate water retention and hydraulic conductivity. AMF reduced the saturated water content and total porosity, but maintained air filled porosity in soil spheres that excluded root ingrowth. The water content between field capacity and the permanent wilting point (6–1500 kPa) was only reduced in mycorrhizal substrates that contained at least one RMC mutant. Plant available water contents correlated positively with soil protein contents. Soil protein contents were highest in pots that possessed the strongest hyphal colonization, but not significantly affected. Substrate conductivity increased up to 50% in colonized substrates in the physiologically important water potential range between 6 and 10 kPa. The improvements in hydraulic conductivity are restricted to substrates where at least one WT plant was available for the fungus, indicating a necessity of a functional symbiosis for this effect. We conclude that functional mycorrhiza alleviates the resistance to water movement through the substrate in substrate areas outside of the root zone.
    Content: Peer Reviewed
    In: Lausanne : Frontiers Media S.A., 9
    Language: English
    URL: Volltext  (kostenfrei)
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  • 9
    UID:
    edochu_18452_21614
    Format: 1 Online-Ressource (13 Seiten)
    Content: Arbuscular mycorrhizal (AM) fungi confer heavy metal tolerance to plants, but this characteristic differs between different AM fungal strains. We tested the hypotheses if acclimatization of an AM fungus to Zn stress is possible and if this leads also to higher Zn tolerance of mycorrhizal plants. The AM fungus Rhizophagus irregularis was acclimatized in root organ cultures (Daucus carota L.) to Zn resulting in an acclimatized (Acc+) strain. The non-acclimatized (Acc-) strain remained untreated. Fungal development and RNA accumulation of a set of stress-related genes were analyzed in root organ cultures and the capacity of conferring Zn tolerance to maize plants was investigated in pot cultures. Development of Acc+ strain was significantly higher than Acc- strain, when strains were grown in Zn-enriched root organ cultures, whereas the growth of the Acc+ strain was reduced on normal medium probably due to a higher Zn demand compared to the Acc- strain. RNA accumulation analyses revealed different expression patterns of genes encoding glutathione S-transferase (RiGST), superoxide dismutase (RiSOD) and glutaredoxin (RiGRX) between the two strains. Plants inoculated with the Acc+ strain showed higher biomass and lower Zn content than those inoculated with the Acc- strain. The results showed that R. irregularis can be acclimatized to increased amounts of Zn. This acclimatization leads not only to improved fungal development in Zn-stress conditions, but also to an increase of mycorrhiza-induced Zn tolerance of colonized plants.
    Content: Peer Reviewed
    In: Lausanne : Frontiers Media S.A., 9
    Language: English
    URL: Volltext  (kostenfrei)
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  • 10
    UID:
    edochu_18452_21882
    Format: 1 Online-Ressource (6 Seiten)
    Content: Arbuscular mycorrhizal (AM) fungi have become an attractive target as biostimulants in agriculture due to their known contributions to plant nutrient uptake and abiotic stress tolerance. However, inoculation with AM fungi can result in depressed, unchanged, or stimulated plant growth, which limits security of application in crop production systems. Crop production comprises high diversity and variability in atmospheric conditions, substrates, plant species, and more. In this review, we emphasize that we need integrative approaches for studying mycorrhizal symbioses in order to increase the predictability of growth outcomes and security of implementation of AM fungi into crop production. We briefly review known mechanisms of AM on nutrient uptake and drought tolerance of plants, on soil structure and soil hydraulic properties. We carve out that an important factor for both nutrient availability and drought tolerance is yet not well understood; the AM effects on soil hydraulic properties. We gave special emphasis to circular references between atmospheric conditions, soil hydraulic properties and plant nutrient and water uptake. We stress that interdisciplinary approaches are needed that account for a variability of atmospheric conditions and, how this would match to mycorrhizal functions and demands in a way that increased plant nutrient and water uptake can be effectively used for physiological processes and ultimately growth. Only with integrated analyses under a wide range of growing conditions, we will be able to make profound decisions whether or not to use AM in particular crop production systems or can adjust culture conditions in ways that AM plants thrive.
    Content: Peer Reviewed
    In: Lausanne : Frontiers Media S.A., 9
    Language: English
    URL: Volltext  (kostenfrei)
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