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1.
BMC Plant Biol ; 21(1): 402, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34470613

RESUMO

BACKGROUND: Plant-parasitic nematodes and herbivorous insects have a significant negative impact on global crop production. A successful approach to protect crops from these pests is the in planta expression of nematotoxic or entomotoxic proteins such as crystal proteins from Bacillus thuringiensis (Bt) or plant lectins. However, the efficacy of this approach is threatened by emergence of resistance in nematode and insect populations to these proteins. To solve this problem, novel nematotoxic and entomotoxic proteins are needed. During the last two decades, several cytoplasmic lectins from mushrooms with nematicidal and insecticidal activity have been characterized. In this study, we tested the potential of Marasmius oreades agglutinin (MOA) to furnish Arabidopsis plants with resistance towards three economically important crop pests: the two plant-parasitic nematodes Heterodera schachtii and Meloidogyne incognita and the herbivorous diamondback moth Plutella xylostella. RESULTS: The expression of MOA does not affect plant growth under axenic conditions which is an essential parameter in the engineering of genetically modified crops. The transgenic Arabidopsis lines showed nearly complete resistance to H. schachtii, in that the number of female and male nematodes per cm root was reduced by 86-91 % and 43-93 % compared to WT, respectively. M. incognita proved to be less susceptible to the MOA protein in that 18-25 % and 26-35 % less galls and nematode egg masses, respectively, were observed in the transgenic lines. Larvae of the herbivorous P. xylostella foraging on MOA-expression lines showed a lower relative mass gain (22-38 %) and survival rate (15-24 %) than those feeding on WT plants. CONCLUSIONS: The results of our in planta experiments reveal a robust nematicidal and insecticidal activity of the fungal lectin MOA against important agricultural pests which may be exploited for crop protection.


Assuntos
Aglutininas/farmacologia , Arabidopsis/parasitologia , Herbivoria , Marasmius/química , Nematoides/fisiologia , Aglutininas/química , Animais , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Mariposas/fisiologia , Doenças das Plantas/prevenção & controle , Plantas Geneticamente Modificadas
2.
Curr Opin Insect Sci ; 44: 72-81, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33866041

RESUMO

Entomopathogenic nematodes (EPNs) are obligate parasites that infect a broad range of insect species. Host-seeking is a crucial step for EPN infection success and survival. Yet, the identity and ecological functions of chemicals involved in host-seeking by EPNs remain overlooked. In this review, we report known CO2, plant-derived and insect-derived cues shaping EPN host-seeking and recognition. Despite species-specific response to environmental cues, we highlight a hierarchical integration of chemicals by EPNs. We further emphasize the impact of EPN selection pressure, age, and experience on their responsiveness to infochemicals. Finally, we feature that EPN chemical ecology can translate into powerful sustainable strategies to control insect herbivores in agriculture.


Assuntos
Comportamento de Busca por Hospedeiro/fisiologia , Insetos/química , Nematoides/fisiologia , Compostos Orgânicos Voláteis , Animais , Dióxido de Carbono , Sinais (Psicologia) , Ecossistema , Controle Biológico de Vetores , Microbiologia do Solo , Especificidade da Espécie
3.
Microbiol Res ; 248: 126755, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33845302

RESUMO

Plants interact with enormous biotic and abiotic components within ecosystem. For instance, microbes, insects, herbivores, animals, nematodes etc. In general, these interactions are studied independently with plants, that condenses only specific information about the interaction. However, the limitation to study the cross-interactions masks the collaborative role of organisms within ecosystem. Beneficial microbes are most prominent organisms that are needed to be studied due to their bidirectional nature towards plants. Fascinatingly, Plant-Parasitic Nematodes (PPNs) have been profoundly observed to cause mass destruction of agricultural crops worldwide. The huge demand for agriculture for present-day population requires optimization of production potential by curbing the damage caused by PPNs. Chemical nematicides combats their proliferation, but their extended usage has abruptly affected flora, fauna and human populations. Because of consistent pressing issues in regard to environment, the use of biocontrol agents are most favourable alternatives for managing agriculture. However, this association is somehow, tug of war, and understanding of plant-nematode-microbial relation would enable the agriculturists to monitor the overall development of plants along with limiting the use of agrochemicals. Soil microbes are contemporary bio-nematicides emerging in the market, that stimulates the plant growth and impedes PPNs populations. They form natural enemies and trap nematodes, henceforth, it is crucial to understand these interactions for ecological and biotechnological perspectives for commercial use. Moreover, acquiring the diversity of their relationship and molecular-based mechanisms, outlines their cascade of signaling events to serve as biotechnological ecosystem engineers. The omics based mechanisms encompassing hormone gene regulatory pathways and elicitors released by microbes are able to modulate pathogenesis-related (PR) genes within plants. This is achieved via Induced Systemic Resistance (ISR) or acquired systemic channels. Taking into account all these validations, the present review mainly advocates the relationship among microbes and nematodes in plants. It is believed that this review will boost zest and zeal within researchers to effectively understand the plant-nematodes-microbes relations and their ecological perspectives.


Assuntos
Fenômenos Fisiológicos Bacterianos , Nematoides/fisiologia , Doenças das Plantas/parasitologia , Animais , Bactérias/genética , Bactérias/isolamento & purificação , Ecossistema , Controle Biológico de Vetores , Doenças das Plantas/prevenção & controle , Solo/parasitologia
4.
PLoS One ; 16(4): e0246723, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33857148

RESUMO

Dispersal is an important life-history trait. In marine meiofauna, and particularly in nematodes, dispersal is generally considered to be mainly passive, i.e. through transport with water currents and bedload transport. Because nematodes have no larval dispersal stage and have a poor swimming ability, their per capita dispersal capacity is expected to be limited. Nevertheless, many marine nematode genera and even species have near-cosmopolitan distributions, and at much smaller spatial scales, can rapidly colonise new habitat patches. Here we demonstrate that certain marine nematodes, like the morphospecies Litoditis marina, can live inside macroalgal structures such as receptacula and-to a lesser extent-floating bladders, which may allow them to raft over large distances with drifting macroalgae. We also demonstrate for the first time that these nematodes can colonize new habitat patches, such as newly deposited macroalgal wrack in the intertidal, not only through seawater but also through air. Our experimental set-up demonstrates that this aerial transport is probably the result of hitchhiking on vectors such as insects, which visit, and move between, the patches of deposited algae. Transport by wind, which has been observed for terrestrial nematodes and freshwater zooplankton, could not be demonstrated. These results can be important for our understanding of both large-scale geographic distribution patterns and of the small-scale colonization dynamics of habitat patches by marine nematodes.


Assuntos
Distribuição Animal/fisiologia , Nematoides/metabolismo , Alga Marinha/metabolismo , Animais , Biodiversidade , Ecossistema , Estuários , Água Doce , Larva/metabolismo , Nematoides/fisiologia , Plantas , Água do Mar , Alga Marinha/fisiologia , Vento
5.
Aquat Toxicol ; 235: 105827, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33882407

RESUMO

Toxicity tests using the model organism Caenorhabditis elegans have shown that exposure to small microplastics such as polystyrene (PS) beads lead to high body burdens and dietary restrictions that in turn inhibit reproduction. Pharyngeal pumping is the key mechanism of C. elegans for governing the uptake of food and other particles and can be easily monitored by determining the pumping rates. In this study, pharyngeal pumping of C. elegans was examined in response to increasing quantities of food bacteria (E. coli: 106-1010 cells ml-1) and synthetic particles (107-109 beads ml-1) of similar size (1 µm). While the average pumping rate of C. elegans exposed to E. coli depended on the density of the bacterial cells, this was not the case for the synthetic beads. At 107 items ml-1, bacterial cells and synthetic beads triggered a basic stimulation of the pumping rate, independent of the nutritional value of the particle. At quantities >107 items ml-1, however, the nutritional value was essential to maximize the pumping rate, as it was upregulated only by E. coli cells, which can be chemosensorially recognized by C. elegans. Given the unselective uptake of all particles in the size range of bacteria, restricting the pumping rates for particles with low nutritional value to a basic rate, prevents the nematodes from wasting energy by high-frequency pumping, but still allows a food-quality screening at low food levels.


Assuntos
Caenorhabditis elegans/fisiologia , Microplásticos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Bactérias , Escherichia coli/fisiologia , Comportamento Alimentar/efeitos dos fármacos , Alimentos , Nematoides/fisiologia , Plásticos , Poliestirenos/análise
6.
Am Nat ; 197(2): E40-E54, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33523790

RESUMO

AbstractParasitic worms with complex life cycles have several developmental stages, with each stage creating opportunities to infect additional host species. Using a data set for 973 species of trophically transmitted acanthocephalans, cestodes, and nematodes, we confirmed that worms with longer life cycles (i.e., more successive hosts) infect a greater diversity of host species and taxa (after controlling for study effort). Generalism at the stage level was highest for middle life stages, the second and third intermediate hosts of long life cycles. By simulating life cycles in real food webs, we found that middle stages had more potential host species to infect, suggesting that opportunity constrains generalism. However, parasites usually infected fewer host species than expected from simulated cycles, suggesting that generalism has costs. There was no trade-off in generalism from one stage to the next, but worms spent less time growing and developing in stages where they infected more taxonomically diverse hosts. Our results demonstrate that life-cycle complexity favors high generalism and that host use across life stages is determined by both ecological opportunity and life-history trade-offs.


Assuntos
Acantocéfalos/fisiologia , Cestoides/fisiologia , Especificidade de Hospedeiro , Interações Hospedeiro-Parasita , Nematoides/fisiologia , Animais , Cadeia Alimentar , Estágios do Ciclo de Vida
7.
Sci Rep ; 11(1): 1268, 2021 01 14.
Artigo em Inglês | MEDLINE | ID: mdl-33446737

RESUMO

Higher volumes of conventional and novel chemical insecticides are applied by farmers to control resistant strains of armyworm (Spodoperta litura) in Pakistan without knowing their risks to the environment and to public health. Ten reduced-risk insecticides were tested for their compatibility with two entomopathogenic nematodes (EPNs); Heterorhabditis indica and Steinernema carpocapsae against S. litura. The insecticide emamectin benzoate was highly toxic (LC50 = 2.97 mg/l) against 3rd instar S. litura larvae when applied alone whereas, novaluron and methoxyfenozide were the least toxic (LC50 = 29.56 mg/l and 21.06 mg/l), respectively. All the insecticides proved harmless against the two EPNs even 96 h after treatment. Indoxacarb, flubendiamide and spinetoram produced the greatest mortalities (72-76%) of S. litura larvae after 72 h when applied in mixtures with H. indica. Lowest mortalities (44.00 ± 3.74% and 48.00 ± 2.89) were observed for mixtures of H. indica with methoxyfenozide and chlorfenapyr, respectively. The positive control treatments with both EPNs (S. carpocapsae and H. indica) produced > 50% mortality 96 h after treatment. For insecticide mixtures with S. carpocapsae, only indoxacarb produced 90% mortality of larvae, whereas, indoxacarb, flubendiamide, emamectin benzoate, and spinetoram produced 90-92% mortality of larvae when applied in mixtures with H. indica. Additive interactions (Chi-square < 3.84) of EPN mixtures with reduced volumes of reduced-risk insecticides suggest opportunities to develop more environmentally favorable pest management programs for S. litura.


Assuntos
Inseticidas/toxicidade , Nematoides/efeitos dos fármacos , Spodoptera/efeitos dos fármacos , Animais , Desinfetantes/toxicidade , Nematoides/fisiologia , Controle de Pragas , Spodoptera/fisiologia , Testes de Toxicidade
8.
J Chem Ecol ; 47(2): 139-152, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33475939

RESUMO

Hitchhikers (phoretic organisms) need vehicles to disperse out of unsuitable habitats. Therefore, finding vehicles with the right functional attributes is essential for phoretic organisms. To locate these vehicles, phoretic organisms employ cues within modalities, ranging from visual to chemical senses. However, how hitchhikers discriminate between individual vehicles has rarely been investigated. Using a phoretic nematode community associated with an obligate fig-fig wasp pollination mutualism, we had earlier established that hitchhiking nematodes make decisions based on vehicle species identity and number of conspecific hitchhikers already present on the vehicle. Here we investigate if hitchhikers can differentiate between physiological states of vehicles. We asked whether phoretic nematodes choose between live or dead vehicles present in a chemically crowded environment and we investigated the basis for any discrimination. We conducted two-choice and single-choice behavioral assays using single nematodes and found that plant- and animal-parasitic nematodes preferred live over dead vehicles and used volatiles as a sensory cue to make this decision. However, in single-choice assays, animal-parasitic nematodes were also attracted towards naturally dead or freeze-killed wasps. The volatile profile of the wasps was dominated by terpenes and spiroketals. We examined the volatile blend emitted by the different wasp physiological states and determined a set of volatiles that the phoretic nematodes might use to discriminate between these states which is likely coupled with respired CO2. We determined that CO2 levels emitted by single wasps are sufficient to attract nematodes, demonstrating the high sensitivity of nematodes to this metabolic product.


Assuntos
Comportamento Animal , Dióxido de Carbono/fisiologia , Nematoides/fisiologia , Compostos Orgânicos Voláteis , Vespas/química , Animais , Ecossistema , Feminino , Ficus , Masculino
9.
Parasitol Res ; 120(3): 993-1001, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33409644

RESUMO

Understanding the processes responsible for structuring communities has been a challenge in ecology, and parasite communities are an excellent system to address this issue. The use of different diversity metrics can help us to understand the determinants of the structure of parasite communities, and in this sense, functional diversity indexes make it possible to measure the variability of organism traits in communities. In this study, we investigate how host body size and habitat use influence the functional diversity of nematode parasite infracommunities. We collected and examined 213 individuals of 11 species of anurans in an area of the Brazilian Atlantic Forest, calculated Rao's quadratic entropy as a measure of functional diversity of parasite infracommunities, and tested if this index was related to host body size and habitat use with an analysis of covariance (ANCOVA). Anuran species varied in body size (from 1.80 to 10.35 cm) and habit use (arboreal, terrestrial, and semiaquatic), and in the functional diversity of parasite infracommunities (Rao's quadratic entropy ranged from 0 to 0.196). We observed that anurans with larger body size and terrestrial habit showed significantly greater functional diversity of parasites. We conclude that anuran characteristics drive the functional diversity of nematode parasite communities, and highlight the importance of using different diversity metrics to understand the determinants in the host-parasite interaction.


Assuntos
Anuros/fisiologia , Anuros/parasitologia , Biodiversidade , Nematoides/isolamento & purificação , Animais , Tamanho Corporal , Brasil , Ecossistema , Interações Hospedeiro-Parasita , Nematoides/classificação , Nematoides/genética , Nematoides/fisiologia
10.
Parasitol Res ; 120(3): 773-783, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33501585

RESUMO

Macrocyclic lactones are frequently used dewormers in livestock farms around the world. Due to their wide spectrum of action against nematodes and arthropods and their practicality of application at very low doses, their use has become massive since their discovery. These compounds are eliminated in a large percentage in the feces of animals, causing adverse effects on coprophilic fauna. Several research groups around the world have been devoted to evaluating these effects on this fauna. The aim of this review is to register the adverse effects of the concentrations in which macrocyclic lactones are eliminated in the feces of domestic animals and the importance of the coprophilic and edaphilous fauna on the degradation of the feces of the animals. The documented data shows that the use of macrocyclic lactones has a high toxicological risk for the different species that colonize the dung, thus causing an adverse effect on its disintegration and its subsequent incorporation into the soil. Even so, more studies at the regional level and their standardization are necessary to make the comparison between different areas possible.


Assuntos
Lactonas/farmacologia , Animais , Antiparasitários/química , Antiparasitários/farmacologia , Antiparasitários/toxicidade , Artrópodes/efeitos dos fármacos , Artrópodes/fisiologia , Fezes/parasitologia , Lactonas/química , Lactonas/toxicidade , Nematoides/efeitos dos fármacos , Nematoides/fisiologia , Solo/parasitologia , Poluentes do Solo/química , Poluentes do Solo/toxicidade
11.
Exp Cell Res ; 399(2): 112474, 2021 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-33434530

RESUMO

The aging proteostasis decline manifests in a failure of aging cells and organisms to properly respond to proteotoxic challenges. This proteostasis collapse has long been considered a hallmark of aging in nematodes, and has recently been shown to occur also in human cells upon entry to senescence, opening the way to exploring the phenomenon in the broader context of human aging. Cellular senescence is part of the normal human physiology of aging, with senescent cell accumulation as a prominent feature of aged tissues. Being highly resistant to cell death, senescent cells, as they accumulate, become pro-inflammatory and promote disease. Here we discuss the causes of human senescence proteostasis decline, in view of the current literature on nematodes, on the one hand, and senescence, on the other hand. We review two major aspects of the phenomenon: (1) the decline in transcriptional activation of stress-response pathways, and (2) impairments in proteasome function. We further outline potential underlying mechanisms of transcriptional proteostasis decline, focusing on reduced chromatin dynamics and compromised nuclear integrity. Finally, we discuss potential strategies for reinforcing proteostasis as a means to improve organismal health and address the relationship to senolytics.


Assuntos
Envelhecimento/metabolismo , Proteostase/fisiologia , Envelhecimento/genética , Animais , Senescência Celular/fisiologia , Regulação para Baixo , Resposta ao Choque Térmico/fisiologia , Humanos , Nematoides/fisiologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteostase/genética , Estresse Fisiológico/fisiologia , Ativação Transcricional/fisiologia
12.
Arch Insect Biochem Physiol ; 106(2): e21758, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33145828

RESUMO

Stress enhances the concentration of reactive oxygen species (ROS) in animal plasma. Increased ROS alter various physiological functions, such as development and the immune response, but excessive increases could be harmful. In this study, we tested the hypothesis that abnormally increased plasma ROS levels are associated with animal death. Injection of the nematode Caenorhabditis elegans into insect larvae caused high mortality in Galleria mellonella, and the plasma ROS concentration was four times higher than M9 buffer-injected larvae. There was no difference in plasma antioxidant activity after nematode injection. However, coinjecting nematodes with an antioxidant (ascorbic acid or N-acetylcysteine) suppressed increases in ROS concentrations by the nematodes and increases in the number of nematodes in the larvae, which increased G. mellonella survival. These results suggest that the abnormal elevation of ROS associated with the stress caused by nematode propagation is lethal for G. mellonella.


Assuntos
Interações Hospedeiro-Parasita , Mariposas/parasitologia , Nematoides/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Animais , Larva/crescimento & desenvolvimento , Larva/parasitologia , Mariposas/crescimento & desenvolvimento , Plasma/parasitologia
13.
Parasitol Int ; 80: 102185, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32919082

RESUMO

Data regarding helminth communities can provide insights into health, feeding interactions, behaviour and evolution of their host organisms. Penguins (Spheniscidae) are important components of marine food webs and tracking their helminth communities can be indicative of ecosystem health. New Zealand is home to 5 of the world's 19 penguin species and little is known about their gastrointestinal helminths. Here, we provide the first study on the gastrointestinal helminths of little blue penguins from south-eastern South Island, New Zealand. The helminth community consisted of two species of tapeworm; Tetrabothrius lutzi and Tetrabothrius sp.; three nematode species, Contracaecum eudyptulae, Capillaria sp. and Stegophorus macronectes; two acanthocephalans, Andracantha sigma and Bolbosoma balaenae; and one trematode, Galactosomum otepotiense. The most prevalent parasites were T. lutzi, A. sigma, and C. eudyptulae. This work includes three new host records and five new geographic records. This is the first report of B. balaenae occurring in a host other than a marine mammal. This study adds to our knowledge about the helminth community of New Zealand little blue penguins, and includes new genetic data on helminth species, providing a baseline against which future studies may be compared.


Assuntos
Doenças das Aves/epidemiologia , Helmintíase Animal/epidemiologia , Enteropatias Parasitárias/epidemiologia , Spheniscidae , Acantocéfalos/fisiologia , Animais , Doenças das Aves/parasitologia , Cestoides/fisiologia , Feminino , Helmintíase Animal/parasitologia , Enteropatias Parasitárias/parasitologia , Masculino , Nematoides/fisiologia , Nova Zelândia/epidemiologia , Prevalência , Trematódeos/fisiologia
14.
Sci Rep ; 10(1): 21316, 2020 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-33277609

RESUMO

Entomopathogenic nematodes (EPNs) have been extensively studied as potential biological control agents against root-feeding crop pests. Maize roots under rootworm attack have been shown to release volatile organic compounds, such as (E)-ß-caryophyllene (Eßc) that guide EPNs toward the damaging larvae. As yet, it is unknown how belowground ecosystems engineers, such as earthworms, affect the biological control capacity of EPNs by altering the root Eßc-mediated tritrophic interactions. We here asked whether and how, the presence of endogeic earthworms affects the ability of EPNs to find root-feeding larvae of the beetle Diabrotica balteata. First, we performed a field mesocosm experiment with two diverse cropping systems, and revealed that the presence of earthworms increased the EPN infection potential of larvae near maize roots. Subsequently, using climate-controlled, olfactometer-based bioassays, we confirmed that EPNs response to Eßc alone (released from dispensers) was two-fold higher in earthworm-worked soil than in earthworm-free soil. Together our results indicate that endogeic earthworms, through burrowing and casting activities, not only change soil properties in a way that improves soil fertility but may also enhance the biocontrol potential of EPNs against root feeding pests. For an ecologically-sound pest reduction in crop fields, we advocate agricultural practices that favour earthworm community structure and diversity.


Assuntos
Besouros , Nematoides/fisiologia , Oligoquetos/fisiologia , Controle Biológico de Vetores , Zea mays , Animais , Ecossistema , Larva , Olfatometria , Raízes de Plantas
15.
Nat Commun ; 11(1): 6406, 2020 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-33335105

RESUMO

Body size is a key life-history trait that influences community assembly by affecting how ecological processes operate at the organism level. However, the extent to which the relative influences of ecological processes mediate the assembly of differentially sized soil organisms is still unknown. Here, we investigate the community assembly of differentially sized soil microorganisms and microfauna using a continental-scale sampling effort combined with a global-scale meta-analysis. Our results reveal a general relationship between organism body size and the stochastic-deterministic balance operating on community assembly. The smallest microorganisms (bacteria) are relatively more influenced by dispersal-based stochastic processes, while larger ones (fungi, protists and nematodes) are more structured by selection-based deterministic processes. This study elucidates a significant and consistent relationship between an organism life-history trait and how distinct ecological processes operate in mediating their respective community assemblages, thus providing a better understanding of the mechanisms supporting soil biodiversity.


Assuntos
Nematoides/anatomia & histologia , Microbiologia do Solo , Animais , Bactérias , Biodiversidade , Ecossistema , Fungos , Traços de História de Vida , Nematoides/fisiologia , Solo/química
16.
PLoS One ; 15(11): e0241546, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33151992

RESUMO

Here we present and analyze the complete genome of Alcaligenes faecalis strain Mc250 (Mc250), a bacterium isolated from the roots of Mimosa calodendron, an endemic plant growing in ferruginous rupestrian grasslands in Minas Gerais State, Brazil. The genome has 4,159,911 bp and 3,719 predicted protein-coding genes, in a single chromosome. Comparison of the Mc250 genome with 36 other Alcaligenes faecalis genomes revealed that there is considerable gene content variation among these strains, with the core genome representing only 39% of the protein-coding gene repertoire of Mc250. Mc250 encodes a complete denitrification pathway, a network of pathways associated with phenolic compounds degradation, and genes associated with HCN and siderophores synthesis; we also found a repertoire of genes associated with metal internalization and metabolism, sulfate/sulfonate and cysteine metabolism, oxidative stress and DNA repair. These findings reveal the genomic basis for the adaptation of this bacterium to the harsh environmental conditions from where it was isolated. Gene clusters associated with ectoine, terpene, resorcinol, and emulsan biosynthesis that can confer some competitive advantage were also found. Experimental results showed that Mc250 was able to reduce (~60%) the virulence phenotype of the plant pathogen Xanthomonas citri subsp. citri when co-inoculated in Citrus sinensis, and was able to eradicate 98% of juveniles and stabilize the hatching rate of eggs to 4% in two species of agricultural nematodes. These results reveal biotechnological potential for the Mc250 strain and warrant its further investigation as a biocontrol and plant growth-promoting bacterium.


Assuntos
Alcaligenes faecalis/genética , Citrus/microbiologia , Genoma Bacteriano , Sequenciamento Completo do Genoma , Alcaligenes faecalis/efeitos dos fármacos , Animais , Antibacterianos/farmacologia , Sequência de Bases , Citrus/parasitologia , DNA Circular/genética , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Resistência Microbiana a Medicamentos/genética , Ilhas Genômicas/genética , Ferro/metabolismo , Metais Pesados/toxicidade , Mimosa/microbiologia , Nematoides/fisiologia , Fenóis/metabolismo , Filogenia
17.
PLoS One ; 15(11): e0241777, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33147264

RESUMO

Decomposition of vertebrate remains is a dynamic process that creates localized soil enrichment zones. A growing body of literature has documented effects of vertebrate decomposition on soil pH, electrical conductivity, oxygen levels, nitrogen and carbon speciation, microbial biomass, and microbial successional patterns. However, relatively few studies have examined the microfaunal members of the soil food web that function as secondary consumers, specifically nematodes. Nematodes are often used as indicators of enrichment in other systems, and initial observations from vertebrate decomposition zones have indicated there is an effect on nematode communities. Our goal was to catalog decomposition-induced nematode succession and changes to alpha, beta, and functional diversity, and identify potential indicator taxa associated with decomposition progression. Six adult beaver (Castor canadensis) carcasses were allowed to decompose in a forest ecosystem for one year. During this period soil temperature, moisture, and electrical conductivity were monitored. Soils samples were taken at two depths in order to assess nematode community dynamics: 30-cm cores and 1-cm interface samples. Nematode abundance, alpha, beta, and functional diversity all responded to soil enrichment at the onset of active decay, and impacts persisted through skeletonization. After one year, nematode abundances and alpha diversity had recovered to original levels, however both community membership and functional diversity remained significantly altered. We identified seven indicator taxa that marked major transitions in decomposition progression. Enrichment of Rhabditidae (B1) and Diplogasteridae (B1) coupled with depletion in Filenchus (F2) characterized active and advanced decay prior to skeletonization in both cores and interface soils. Enrichment of Acrobeloides (B2), Aphelenchoides (F2), Tylencholaimidae (F4) and Seinura (P2) occurred during a narrow period in mid-skeletonization (day 153). Our study has revealed soil nematode successional patterns during vertebrate decomposition and has identified organisms that may function as indicator taxa for certain periods during decomposition.


Assuntos
Nematoides/fisiologia , Solo/parasitologia , Animais , Biodiversidade , Florestas , Nematoides/crescimento & desenvolvimento , Roedores/fisiologia , Solo/química , Temperatura
18.
Aquat Toxicol ; 228: 105632, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33010638

RESUMO

An experiment was carried out using microcosms to evaluate the impact of the fluoroquinolone antibiotic on nematode trophic groups structure and bacterial abundance. Sediment samples were experimentally enriched with four increasing doses of ciprofloxacin [D1 (50 ppm), D2 (100 ppm), D3 (200 ppm) and D4 (500 ppm)] and compared to non-enriched sediments (used as control). Ciprofloxacin changed the trophic composition of nematodes taxa where the relative abundance of microvores (M), epigrowth feeders (EF) and ciliate consumers (CF), raised in a control microcosm, was highly affected and significantly decreased in response to the increasing doses. Nevertheless, the abundance of deposit feeders (DF), optional predators (FP) and exclusive predators (Pr) showed a significant increase. Results from the multivariate analysis showed a clear impact of this antibiotic on nematode trophic assemblages. Microcosms treated with the three highest doses [D2, D3 and D4] were different from the control. The exceptions were those treated with the lowest dose, D1, and which were grouped with the control. The SIMPER analysis results showed that the average dissimilarity continuously increased in the treated microcosms compared to the control. Furthermore, our results have shown that ciprofloxacin also leads to a significant decrease in bacterial density with the highest dose, which could explain the results obtained for nematode trophic groups distribution. Thus, the bacteriophages nematodes only use bacteria as a nutrition source and the lack or presence in small quantity of this food could induce a decrease in their abundance as well as changing of nematodes groups repartition. Our work demonstrates that the nematode responses were dependent on sediment enrichment with ciprofloxacin and opens new perspectives on the potential impact of antibiotics on functional nematode diversity.


Assuntos
Antibacterianos/toxicidade , Organismos Aquáticos/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Ciprofloxacina/toxicidade , Ecossistema , Sedimentos Geológicos/química , Nematoides/fisiologia , Animais , Bactérias/efeitos dos fármacos , Análise por Conglomerados , Geografia , Sedimentos Geológicos/microbiologia , Região do Mediterrâneo , Análise Multivariada , Nematoides/efeitos dos fármacos , Densidade Demográfica , Análise de Componente Principal , Poluentes Químicos da Água/toxicidade
19.
Microbiome ; 8(1): 142, 2020 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-33008469

RESUMO

BACKGROUND: The soil mycobiome is composed of a complex and diverse fungal community, which includes functionally diverse species ranging from plant pathogens to mutualists. Among the latter are arbuscular mycorrhizal fungi (AMF) that provide phosphorous (P) to plants. While plant hosts and abiotic parameters are known to structure AMF communities, it remains largely unknown how higher trophic level organisms, including protists and nematodes, affect AMF abundance and community composition. RESULTS: Here, we explored the connections between AMF, fungivorous protists and nematodes that could partly reflect trophic interactions, and linked those to rhizosphere P dynamics and plant performance in a long-term manure application setting. Our results revealed that manure addition increased AMF biomass and the density of fungivorous nematodes, and tailored the community structures of AMF, fungivorous protists, and nematodes. We detected a higher abundance of AMF digested by the dominant fungivorous nematodes Aphelenchoides and Aphelenchus in high manure treatments compared to no manure and low manure treatments. Structural equation modeling combined with network analysis suggested that predation by fungivorous protists and nematodes stimulated AMF biomass and modified the AMF community composition. The mycorrhizal-fungivore interactions catalyzed AMF colonization and expression levels of the P transporter gene ZMPht1;6 in maize roots, which resulted in enhanced plant productivity. CONCLUSIONS: Our study highlights the importance of predation as a key element in shaping the composition and enhancing the biomass of AMF, leading to increased plant performance. As such, we clarify novel biological mechanism of the complex interactions between AMF, fungivorous protists, and nematodes in driving P absorption and plant performance. Video Abstract.


Assuntos
Comportamento Alimentar , Micobioma/fisiologia , Micorrizas/fisiologia , Nematoides/fisiologia , Simbiose , Zea mays/microbiologia , Zea mays/fisiologia , Animais , Biomassa , Esterco , Nematoides/isolamento & purificação , Microbiologia do Solo
20.
PLoS Pathog ; 16(10): e1008884, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-33007049

RESUMO

Plant parasitic nematodes are microscopic pathogens that invade plant roots and cause extensive damage to crops. We have used a chemical biology approach to define mechanisms underpinning their parasitic behaviour: We discovered that reserpine, a plant alkaloid that inhibits the vesicular monoamine transporter (VMAT), potently impairs the ability of the potato cyst nematode Globodera pallida to enter the host plant root. We show this is due to an inhibition of serotonergic signalling that is essential for activation of the stylet which is used to access the host root. Prompted by this we identified core molecular components of G. pallida serotonin signalling encompassing the target of reserpine, VMAT; the synthetic enzyme for serotonin, tryptophan hydroxylase; the G protein coupled receptor SER-7 and the serotonin-gated chloride channel MOD-1. We cloned each of these molecular components and confirmed their functional identity by complementation of the corresponding C. elegans mutant thus mapping out serotonergic signalling in G. pallida. Complementary approaches testing the effect of chemical inhibitors of each of these signalling elements on discrete sub-behaviours required for parasitism and root invasion reinforce the critical role of serotonin. Thus, targeting the serotonin signalling pathway presents a promising new route to control plant parasitic nematodes.


Assuntos
Proteção de Cultivos/métodos , Interações Hospedeiro-Patógeno , Nematoides/fisiologia , Doenças das Plantas/parasitologia , Serotonina/metabolismo , Transdução de Sinais , Solanum tuberosum/metabolismo , Animais , Solanum tuberosum/parasitologia
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