Bacterial Metabolites of an Entomopathogenic Bacterium, Xenorhabdus nematophila, Inhibit a Catalytic Activity of Phenoloxidase of the Diamondback Moth, Plutella xylostella

Song, Chrisitine Jisso; Seo, Sam-Yeol; Shrestha, Sony; Kim, Yonggyun

doi:10.4014/jmb.1010.10034

Cited by 37 publications

(15 citation statements)

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“…As described by Shi et al . (), the delayed activation of phenoloxidase could be due to the release of Xenorhabdus toxins into the hemocoelic cavity, though, inhibitory effects of symbionts bacteria have been ascertained in other insect species (de Silva et al ., ; Song et al ., ). Even if the efficacy of EPNs is based on the lethal action of symbiotic bacteria in the late phase of infection, results confirmed that, immediately after the entry, parasites must neutralize a complex series of adverse immune reactions performed by the host (Dunphy & Webster, ; Brivio et al ., ; Brivio et al ., ).…”

Section: Discussionmentioning

confidence: 97%

Modulation of immune responses of Rhynchophorus ferrugineus (Insecta: Coleoptera) induced by the entomopathogenic nematode Steinernema carpocapsae (Nematoda: Rhabditida)

et al. 2014

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Aim of this study was to investigate relationships between the red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier) and the entomopathogenic nematode Steinernema carpocapsae (EPN); particularly, the work was focused on the immune response of the insect host in naive larvae and after infection with the EPN. Two main immunological processes have been addressed: the activity and modulation of host prophenoloxidase-phenoloxidase (proPO) system, involved in melanization of not-self and hemocytes recognition processes responsible for not-self encapsulation. Moreover, immune depressive and immune evasive strategies of the parasite have been investigated. Our results suggest that RPW possess an efficient immune system, however in the early phase of infection, S. carpocapsae induces a strong inhibition of the host proPO system. In addition, host cell-mediated mechanisms of encapsulation, are completely avoided by the parasite, the elusive strategies of S. carpocapsae seem to be related to the structure of its body-surface, since induced alterations of the parasite cuticle resulted in the loss of its mimetic properties. S. carpocapsae before the release of its symbiotic bacteria, depress and elude RPW immune defenses, with the aim to arrange a favorable environment for its bacteria responsible of the septicemic death of the insect target.

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Section: Discussionmentioning

confidence: 97%

Modulation of immune responses of Rhynchophorus ferrugineus (Insecta: Coleoptera) induced by the entomopathogenic nematode Steinernema carpocapsae (Nematoda: Rhabditida)

et al. 2014

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“…By contrast, most species of Xenorhabdus can block phenoloxidase activity [24,27,37]. This probably enables them to avoid the effects of prophenoloxidase system activation when the symbiotic nematodes located in the digestive tract of insect larvae inject the bacteria from their gut into the insect hemolymph [16,17].…”

Section: Discussionmentioning

confidence: 99%

Inhibition of Spodoptera frugiperda phenoloxidase activity by the products of the Xenorhabdus rhabduscin gene cluster

et al. 2019

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We evaluated the impact of bacterial rhabduscin synthesis on bacterial virulence and phenoloxidase inhibition in a Spodoptera model. We first showed that the rhabduscin cluster of the entomopathogenic bacterium Xenorhabdus nematophila was not necessary for virulence in the larvae of Spodoptera littoralis and Spodoptera frugiperda . Bacteria with mutations affecting the rhabduscin synthesis cluster (Δ isnAB and Δ GT mutants) were as virulent as the wild-type strain. We then developed an assay for measuring phenoloxidase activity in S . frugiperda and assessed the ability of bacterial culture supernatants to inhibit the insect phenoloxidase. Our findings confirm that the X . nematophila rhabduscin cluster is required for the inhibition of S . frugiperda phenoloxidase activity. The X . nematophila Δ isnAB mutant was unable to inhibit phenoloxidase, whereas Δ GT mutants displayed intermediate levels of phenoloxidase inhibition relative to the wild-type strain. The culture supernatants of Escherichia coli and of two entomopathogenic bacteria, Serratia entomophila and Xenorhabdus poinarii , were unable to inhibit S . frugiperda phenoloxidase activity. Heterologous expression of the X . nematophila rhabduscin cluster in these three strains was sufficient to restore inhibition. Interestingly, we observed pseudogenization of the X . poinarii rhabduscin gene cluster via the insertion of a 120 bp element into the isnA promoter. The inhibition of phenoloxidase activity by X . poinarii culture supernatants was restored by expression of the X . poinarii rhabduscin cluster under the control of an inducible P tet promoter, consistent with recent pseudogenization. This study paves the way for advances in our understanding of the virulence of several entomopathogenic bacteria in non-model insects, such as the new invasive S . frugiperda species in Africa.

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“…and Photorhabdus spp. produce several metabolites, some of which have insecticidal (Bowen et al, 1998;Yang et al, 2006;Nielsen Le-Roux et al, 2012;Castagnola and Stock, 2014), antifungal (Eleftherianos et al, 2007;Houard et al, 2013), antibiotic (Li et al, 1995;Ji et al, 2004;Morales-Soto and Forst, 2011;Song et al, 2011) and antiparasitic activity (Nollmann et al, 2012). So far, however, the only metabolites identified as having nematicidal activity are indole derivatives and hydroxystilbene produced by P. luminescens (Hu et al, 1999) and ammonia by Xenorhabdus spp.…”

Section: Discussionmentioning

confidence: 99%

Effect of the entomopathogenic nematode-bacterial symbiont complex on Meloidogyne hapla and Nacobbus aberrans in short-term greenhouse trials

et al. 2018

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Meloidogyne hapla and Nacobbus aberrans are plant-parasitic nematodes that form galls in the roots of infected plants and cause important economic losses. Entomopathogenic nematodes (EPNs) of the genera Steinernema and Heterorhabditis infect and kill insects via toxins produced by their symbiotic bacteria. EPNs have shown to have an antagonistic effect on different plant-parasitic nematode species in field and greenhouse trials. The aim of the present work was to evaluate, in tomato plants in greenhouse, the effect of the application of three Argentine EPN isolates, their symbiotic bacteria and cell-free supernatants, on a population of M. hapla and two populations of N. aberrans. Sixty days after inoculation, the number of galls and egg masses, the nematode reproduction factor (RF) and plant biomass were calculated. None of the plant-parasitic nematode populations or plant biomass was affected by infective juvenile inoculation of the different EPN isolates. Bacterial action differed among populations; M. hapla was the most susceptible one, with a significant reduction in the number of galls, egg masses and RF caused by the application of the three bacterial strains. The most significant effect was produced by the cell-free supernatants on nematode RF, with reductions of 62-90%, caused by bacterial metabolites. The different inoculation alternatives of the EPN-bacterial symbiont complex tested in the present work (infective juveniles, bacteria and cell-free supernatant) are compared for the first time for plant-parasitic nematode species.

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Bacterial Metabolites of an Entomopathogenic Bacterium, Xenorhabdus nematophila, Inhibit a Catalytic Activity of Phenoloxidase of the Diamondback Moth, Plutella xylostella

Cited by 37 publications

References 0 publications

Modulation of immune responses of Rhynchophorus ferrugineus (Insecta: Coleoptera) induced by the entomopathogenic nematode Steinernema carpocapsae (Nematoda: Rhabditida)

Modulation of immune responses of Rhynchophorus ferrugineus (Insecta: Coleoptera) induced by the entomopathogenic nematode Steinernema carpocapsae (Nematoda: Rhabditida)

Inhibition of Spodoptera frugiperda phenoloxidase activity by the products of the Xenorhabdus rhabduscin gene cluster

Effect of the entomopathogenic nematode-bacterial symbiont complex on Meloidogyne hapla and Nacobbus aberrans in short-term greenhouse trials

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