The successful adaptation of cockroaches is, in part, dependent of the activity of their obligatory endosymbionts, Blattabacterium spp., which are involved in uric acid degradation, nitrogen ...assimilation and nutrient provisioning. Their strategic localization, within bacteriocytes in the proximities of uric acid storage cells (urocytes), highlights their importance in the recycling of nitrogen from urea and ammonia, end-products not secreted by their host insects. In this study, we present the complete genome sequence of two new Blattabacterium spp. from Periplaneta fuliginosa (BPfu) and P. japonica (BPja), and detailed comparison with other Blattabacterium strains from different cockroach species. The genomes of BPfu and BPja show a high degree of stability as showed with for other Blattabacterium representatives, only presenting a 19-kb fragment inversion between BPja and BPfu. In fact, the phylogenomics showed BPja as an ancestor species of BPfu, BPLAN (P. americana) and BBor (Blatta orientalis), in congruence with their host cockroach phylogeny. Their functional profile is similar and closest to the omnivorous strain BBge (Blattella germanica). Interesting, BPja possesses the complete set of enzymes involved sulfate assimilatory pathway only found in BBge and BMda (Mastotermes darwiniensis). The newly sequenced genomes of BPja and BPfu emphasise the remarkable stability of Blattabacterium genomes supported by their long-term coevolution and obligatory lifestyle in their host insect.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Considered an EPPO A2 quarantine pest, Bursaphelenchus xylophilus is the causal agent of the pine wilt disease and the most devastating plant parasitic nematode attacking coniferous trees in the ...world. In the early stages of invasion, this nematode has to manage host defence mechanisms, such as strong oxidative stress. Only successful, virulent nematodes are able to tolerate the basal plant defences, and furthermore migrate and proliferate inside of the host tree. In this work, our main objective was to understand to what extent B. xylophilus catalases are involved in their tolerance to oxidative stress and virulence, using as oxidant agent the reactive oxygen species hydrogen peroxide (H2O2). After 24 hours of exposure, high virulence isolates of B. xylophilus could withstand higher H2O2 concentrations in comparison with low virulence B. xylophilus and B. mucronatus, corroborating our observation of Bxy-ctl-1 and Bxy-ctl-2 catalase up-regulation under the same experimental conditions. Both catalases are expressed throughout the nematode intestine. In addition, transgenic strains of Caenorhabditis elegans overexpressing B. xylophilus catalases were constructed and evaluated for survival under similar conditions as previously. Our results suggest that catalases of high virulence B. xylophilus were crucial for nematode survival under prolonged exposure to in vitro oxidative stress, highlighting their adaptive response, which could contribute to their success in host conditions.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Similar to other plant-parasitic nematodes, root lesion nematodes possess an array of enzymes that are involved in the degradation of the plant cell wall. Here we report the identification of a gene ...encoding a cell wall-degrading enzyme, pectin methylesterase PME (EC 3.1.1.11), in the root lesion nematode Pratylenchus penetrans. Both genomic and coding sequences of the gene were cloned for this species, that included the presence of four introns which eliminated a possible contamination from bacteria. Expression of the Pp-pme gene was localized in the esophageal glands of P. penetrans as determined by in situ hybridization. Temporal expression of Pp-pme in planta was validated at early time points of infection. The possible function and activity of the gene were assessed by transient expression of Pp-pme in plants of Nicotiana benthamiana plants via a Potato virus X-based vector. To our knowledge, this is the first report on identification and characterization of a PME gene within the phylum Nematoda.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Plant-parasitic nematodes (PPNs) are among the most notorious and underrated threats to food security and plant health worldwide, compromising crop yields and causing billions of dollars of losses ...annually. Chemical control strategies rely heavily on synthetic chemical nematicides to reduce PPN population densities, but their use is being progressively restricted due to environmental and human health concerns, so alternative control methods are urgently needed. Here, we review the potential of bacterial and fungal agents to suppress the most important PPNs, namely Aphelenchoides besseyi, Bursaphelenchus xylophilus, Ditylenchus dipsaci, Globodera spp., Heterodera spp., Meloidogyne spp., Nacobbus aberrans, Pratylenchus spp., Radopholus similis, Rotylenchulus reniformis, and Xiphinema index.
A nematological survey was conducted between 2021 and 2022 in banana fields distributed in two major banana-producing regions in the western coast of Syria. As a result, six populations of
Xiphinema
...spp. identified as
X
.
diffusum, X
.
pachtaicum, X
.
simile, X
.
vuittenezi
and
X. zagrosense
were isolated from the rhizosphere of banana plants (
Musa
sp.) and characterized using morphological and molecular data based on two rRNA genes (D2–D3 expansion segments of the 28S, and ITS fragments) and partial region of the cytochrome oxidase I gene (
COI
mtDNA) sequences. Moreover, the molecular identification of the endosymbionts of these populations was also performed using the complete 16S rDNA gene. The phylogenetic relationships of the recovered species of nematodes and respective endosymbionts were reconstructed.
Candidatus
Xiphinematobacter sp. (OR196969; OR196971) and
Ca.
Xiphinematobacter sp. (OR196970) were detected in
X. diffusum
and
X. simile
, respectively, and clustered together with other
Ca.
Xiphinematobacter sp.A and sp.I respectively. To our knowledge, this is the first report of
X. diffusum, X. simile, X. vuittenezi
and
X. zagrosense
parasitizing banana in Syria, extending the geographical distribution of these species within the Mediterranean Basin.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Pine wilt disease (PWD) results from the interaction of three elements: the pathogenic nematode, Bursaphelenchus xylophilus; the insect-vector, Monochamus sp.; and the host tree, mostly Pinus ...species. Bacteria isolated from B. xylophilus may be a fourth element in this complex disease. However, the precise role of bacteria in this interaction is unclear as both plant-beneficial and as plant-pathogenic bacteria may be associated with PWD. Using whole genome sequencing and phenotypic characterization, we were able to investigate in more detail the genetic repertoire of Serratia marcescens PWN146, a bacterium associated with B. xylophilus. We show clear evidence that S. marcescens PWN146 is able to withstand and colonize the plant environment, without having any deleterious effects towards a susceptible host (Pinus thunbergii), B. xylophilus nor to the nematode model C. elegans. This bacterium is able to tolerate growth in presence of xenobiotic/organic compounds, and use phenylacetic acid as carbon source. Furthermore, we present a detailed list of S. marcescens PWN146 potentials to interfere with plant metabolism via hormonal pathways and/or nutritional acquisition, and to be competitive against other bacteria and/or fungi in terms of resource acquisition or production of antimicrobial compounds. Further investigation is required to understand the role of bacteria in PWD. We have now reinforced the theory that B. xylophilus-associated bacteria may have a plant origin.
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BFBNIB, EMUNI, FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UL, UM, UPUK, VKSCE, ZAGLJ
ShK domain-containing proteins are peptides found in different parasitic and venomous organisms. From a previous transcriptomic dataset from
, a plant-parasitic nematode that infects forest tree ...species, we identified 96 transcripts potentially as ShK domain-containing proteins with unknown function in the nematode genome. This study aimed to characterize and explore the functional role of genes encoding ShK domain-containing proteins in
biology. We selected and functionally analyzed nine candidate genes that are putatively specific to
. In situ hybridization revealed expression of one
ShK in the pharyngeal gland cells, suggesting their delivery into host cells. Most of the transcripts are highly expressed during infection and showed a significant upregulation in response to peroxide products compared to the nematode catalase enzymes. We reported, for the first time, the potential involvement of ShK domain genes in oxidative stress, suggesting that these proteins may have an important role in protecting or modulating the reactive oxygen species (ROS) activity of the host plant during parasitism.
Abstract
Pine wilt disease (PWD) has a tremendous impact on worldwide forestlands, both from the environmental and economical viewpoints. Monochamus sp., a xylophagous insect from the Cerambycidae ...family, plays an important role in dissemination of the pinewood nematode, Bursaphelenchus xylophilus, the primary pathogenic agent of PWD. This study investigates, for the first time, the bacterial communities of Monochamus galloprovincialis collected from Portuguese Pinus pinaster trees and B. xylophilus free, using a metagenomics approach. Overall, our results show that natural bacterial communities of M. galloprovincialis are mainly composed by γ-proteobacteria, Firmicutes and Bacteroidetes, which may be a reflection of insects' feeding diet and habitat characteristics. We also report different bacterial communities' composition in the thorax and abdomen of M. galloprovincialis, with high abundance of Serratia sp. in both. Our results encourage further studies in the possible relationship between bacteria from the insect vector and B. xylophilus.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Considered one of the most devastating plant–parasitic nematodes worldwide,
Bursaphelenchus xylophilus
(commonly known as pinewood nematode, PWN) is the causal agent of the pine wilt disease in the ...Eurasian coniferous forests. This migratory parasitic nematode is carried by an insect vector (
Monochamus
spp.) into the host tree (
Pinus
species), where it can feed on parenchymal cells and reproduce massively, resulting in the tree wilting. In declining trees, PWN populations are strongly dependent on fungal communities colonizing the host (predominantly ophiostomatoid fungi known to cause sapwood blue-staining, the blue-stain fungi), which not only influence their development and life cycle but also the number of individuals carried by the insect vector into a new host. Our main aim is to understand if PWN-associated mycobiota plays a key role in the development of PWD, in interaction with the PWN and the insect vector, and to what extent it can be targeted to disrupt the disease cycle. For this purpose, we characterized the fungal communities of
Pinus pinaster
trees infected and non-infected with PWN in three collection sites in Continental Portugal with different PWD temporal incidences. Our results showed that non-infected
P. pinaster
mycoflora is more diverse (in terms of abundance and fungal richness) than PWN-infected pine trees in the most recent PWD foci, as opposed to the fungal communities of long-term PWD history sites. Then, due to their ecological importance for PWN survival, representatives of the main ophiostomatoid fungi isolated (
Ophiostoma, Leptographium
, and
Graphilbum
) were characterized for their adaptative response to temperature, competition in-between taxa, and as food source for PWN. Under the conditions studied,
Leptographium
isolates showed promising results for PWN control. They could outcompete the other species, especially
O. ips
, and significantly reduce the development of PWN populations when compared to
Botrytis cinerea
(routinely used for PWN lab culturing), suggesting this to be a natural antagonist not only for the other blue-stain species but also for the PWN.
The pinewood nematode (PWN),
, is the causal agent of pine wilt disease (PWD) and a quarantine organism in many countries. Managing PWD involves strict regulations and heavy contingency plans, and ...present climate change scenarios predict a spread of the disease. The urgent need for sustainable management strategies has led to an increasing interest in promising biocontrol agents capable of suppressing the PWN, like endoparasitic nematophagous fungi of the
genus. Here, we review different aspects of the biology and ecology of these nematophagous fungi and provide future prospects.
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