Institute of Phytopathology and Applied Zoology

Gießen, Germany

Institute of Phytopathology and Applied Zoology

Gießen, Germany
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Baumgardt K.,Institute of Microbiology and Molecular Biology | Baumgardt K.,University Pierre and Marie Curie | Melior H.,Institute of Microbiology and Molecular Biology | Madhugiri R.,Institute of Microbiology and Molecular Biology | And 5 more authors.
Microbiology (United Kingdom) | Year: 2017

The ribonucleases (RNases) E and J play major roles in E. coli and Bacillus subtilis, respectively, and co-exist in Sinorhizobium meliloti. We analysed S. meliloti 2011 mutants with mini-Tn5 insertions in the corresponding genes rne and rnj and found many overlapping effects. We observed similar changes in mRNA levels, including lower mRNA levels of the motility and chemotaxis related genes flaA, flgB and cheR and higher levels of ndvA (important for glucan export). The acyl-homoserine lactone (AHL) levels were also higher during exponential growth in both RNase mutants, despite no increase in the expression of the sinI AHL synthase gene. Furthermore, several RNAs from both mutants migrated aberrantly in denaturing gels at 300 V but not under stronger denaturing conditions at 1300 V. The similarities between the two mutants could be explained by increased levels of the key methyl donor S-adenosylmethionine (SAM), since this may result in faster AHL synthesis leading to higher AHL accumulation as well as in uncontrolled methylation of macromolecules including RNA, which may strengthen RNA secondary structures. Indeed, we found that in both mutants the N6-methyladenosine content was increased almost threefold and the SAM level was increased at least sevenfold. Complementation by induced ectopic expression of the respective RNase restored the AHL and SAM levels in each of the mutants. In summary, our data show that both RNase E and RNase J are needed for SAM homeostasis in S. meliloti. © 2017 The Authors.

Dubovskiy I.M.,Russian Academy of Sciences | Whitten M.M.A.,University of Swansea | Kryukov V.Y.,Russian Academy of Sciences | Yaroslavtseva O.N.,Russian Academy of Sciences | And 7 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2013

A 'dark morph' melanic strain of the greater wax moth, Galleria mellonella, was studied for its atypical, heightened resistance to infection with the entomo-pathogenic fungus, Beauveria bassiana. We show that these insects exhibit multiple intraspecific immunity and physiological traits that distinguish them from a non-melanic, fungus-susceptible morph. The melanic and non-melanic morphs were geographical variants that had evolved different, independent defence strategies. Melanic morphs exhibit a thickened cuticle, higher basal expression of immunity- and stress-management-related genes, higher numbers of circulating haemocytes, upregulated cuticle phenoloxidase (PO) activity concomitant with conidial invasion, andanenhanced capacitytoencap-sulate fungal particles. These insects prioritize specific augmentations to those frontline defences that are most likely to encounter invading pathogens or to sustain damage. Other immune responses that target late-stage infection, such as haemolymph lysozyme and PO activities, do not contribute to fungal tolerance. The net effect is increased larval survival times, retarded cuticular fungal penetration and a lower propensity to develop haemolymph infections when challenged naturally (topically) and by injection. In the absence of fungal infection, however, the heavy defence investments made by melanic insects result in a lower biomass, decreased longevity and lower fecundity in comparison with their non-melanic counterparts. Although melanism is clearly correlated with increased fungal resistance, the costly mechanisms enabling this protective trait constitute more than just a colour change. © 2013 The Author(s) Published by the Royal Society. All rights reserved.

Reitz M.U.,University of Warwick | Pai S.,Institute of Phytopathology and Applied Zoology | Imani J.,Institute of Phytopathology and Applied Zoology | Schafer P.,University of Warwick
Plant Signaling and Behavior | Year: 2013

Tubby-like proteins (TLPs) have been associated with hormone signaling and responses to abiotic and biotic stress in plants. Recently, Arabidopsis thaliana TLP3 was found to translocate from the plasma membrane of cells in response to distinct abiotic stresses, thereby activating cellular signaling. In addition, several AtTLPs were demonstrated to be necessary for normal colonization of roots by the mutualistic fungus Piriformospora indica. Here, we present evidence for the involvement of another two AtTLPs in this interaction. Furthermore, we show that plasma membrane targeting of TLPs might be conserved in other plant species, although we did not find it for all members of the protein family. Finally, the position of a GFP-tag influences the localization of AtTLP3, which needs to be considered when working with TLPs. © 2013 Landes Bioscience.

Tang X.,Max Planck Institute for Chemical Ecology | Freitak D.,Max Planck Institute for Chemical Ecology | Freitak D.,Institute of Phytopathology and Applied Zoology | Vogel H.,Max Planck Institute for Chemical Ecology | And 7 more authors.
PLoS ONE | Year: 2012

Background: The gut of most insects harbours nonpathogenic microorganisms. Recent work suggests that gut microbiota not only provide nutrients, but also involve in the development and maintenance of the host immune system. However, the complexity, dynamics and types of interactions between the insect hosts and their gut microbiota are far from being well understood. Methods/Principal Findings: To determine the composition of the gut microbiota of two lepidopteran pests, Spodoptera littoralis and Helicoverpa armigera, we applied cultivation-independent techniques based on 16S rRNA gene sequencing and microarray. The two insect species were very similar regarding high abundant bacterial families. Different bacteria colonize different niches within the gut. A core community, consisting of Enterococci, Lactobacilli, Clostridia, etc. was revealed in the insect larvae. These bacteria are constantly present in the digestion tract at relatively high frequency despite that developmental stage and diet had a great impact on shaping the bacterial communities. Some low-abundant species might become dominant upon loading external disturbances; the core community, however, did not change significantly. Clearly the insect gut selects for particular bacterial phylotypes. Conclusions: Because of their importance as agricultural pests, phytophagous Lepidopterans are widely used as experimental models in ecological and physiological studies. Our results demonstrated that a core microbial community exists in the insect gut, which may contribute to the host physiology. Host physiology and food, nevertheless, significantly influence some fringe bacterial species in the gut. The gut microbiota might also serve as a reservoir of microorganisms for ever-changing environments. Understanding these interactions might pave the way for developing novel pest control strategies. © 2012 Tang et al.

Achatz B.,Institute of Phytopathology and Applied Zoology | Kogel K.-H.,Institute of Phytopathology and Applied Zoology | Franken P.,Leibniz Institute of Vegetable and Ornamental Crops | Waller F.,Institute of Phytopathology and Applied Zoology
Plant Signaling and Behavior | Year: 2010

Root colonization by the basidiomycete fungus Piriformospora indica induces host plant tolerance against abiotic and biotic stress, and enhances growth and yield. As P. indica has a broad host range, it has been established as a model system to study beneficial plant-microbe interactions. Moreover, its properties led to the assumption that P. indica shows potential for application in crop plant production. Therefore, possible mechanisms of P. indica improving host plant yield were tested in outdoor experiments: Induction of higher grain yield in barley was independent of elevated pathogen levels and independent of different phosphate fertilization levels. In contrast to the arbuscular mycorrhiza fungus Glomus mosseae total phosphate contents of host plant roots and shoots were not significantly affected by P. indica. Analysis of plant development and yield parameters indicated that positive effects of P. indica on grain yield are due to accelerated growth of barley plants early in development. © 2010 Landes Bioscience.

Schenk S.T.,Institute of Phytopathology and Applied Zoology | Stein E.,Institute of Phytopathology and Applied Zoology | Kogel K.-H.,Institute of Phytopathology and Applied Zoology | Schikora A.,Institute of Phytopathology and Applied Zoology
Plant Signaling and Behavior | Year: 2012

N-acyl-homoserine lactones (AHLs) play an important role in the communication within the rhizosphere; they serve as a chemical base for interactions within and between different species of Gram-negative bacteria. Not only bacteria, also plants perceive and react to AHLs with diverse responses. Here we describe a negative correlation between the length of AHLs' lipid chains and the observed growth promotion in Arabidopsis thaliana. Moreover, we speculate on a positive correlation between the reinforcement of defense mechanisms and the length of the lipid moieties. Observation presented here may be of great importance for understanding of the complex interplay between plants and their environment, as well as for agronomic applications. © 2012 Landes Bioscience.

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