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1.
Molecules ; 24(20)2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31600927

RESUMO

Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle, is a serious forest pest, causing enormous economic losses in pine trees in Korea, China, Japan, and countries in Western Europe. To prevent pine wilt disease (PWD), trunk injection with nematicide is performed in Korea. Although these nematicidal agents are quite efficient, the development of new nematicidal agents is needed to prevent pesticide resistance and reduce pest management costs. The aim of this study was to investigate nematicidal activities of pure naphthoquinones (NTQs)-1,4-NTQ, juglone, and plumbagin-against B. xylophilus via in vitro and semi-in vivo assays to identify new candidate agents for trunk injection. Estimated LC50 values (48 h exposure) were 100.0 ppm, 57.0 ppm, and 104.0 ppm for 1,4-NTQ, juglone, and plumbagin, respectively. In the semi-in vivo assay on pine bolt of the Japanese black pine, Pinus thunbergii, the population of inoculated B. xylophilus was significantly decreased at two weeks after treatment with juglone when compared with the effects of treatment with 1,4-NTQ and plumbagin. We also observed that naphthoquinones could generate reactive oxygen species, which presumably indicated that naphthoquinones caused significant oxidative stress in B. xylophilus. The findings of this study suggest the nematicidal potential of naphthoquinones and their possible use in further in vivo assays to test their nematicidal efficacy against B. xylophilus when injected through trunk injection.


Assuntos
Antinematódeos/farmacologia , Naftoquinonas/farmacologia , Tylenchida/efeitos dos fármacos , Animais , Antinematódeos/química , Relação Dose-Resposta a Droga , Estrutura Molecular , Naftoquinonas/química , Testes de Sensibilidade Parasitária , Pinus/metabolismo , Pinus/parasitologia , Espécies Reativas de Oxigênio
2.
J Agric Food Chem ; 67(17): 4782-4792, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30973721

RESUMO

Polyketides represent an important class of biologically active and structurally diverse compounds found in nature. They are biosynthesized from acyl CoA precursors by polyketide synthases (PKSs). The use of combinatorial biosynthesis to form hybrid PKSs is considered to be an excellent approach for the development of novel polyketides. Here, 10 new 16-membered macrolide compounds were isolated from the broth of the genetically engineered strain Streptomyces avermitilis TM24, in which the PKS gene aveA3 was seamlessly replaced by the milbemycin PKS gene milA3. Their structures were elucidated on the basis of NMR and MS spectroscopic analyses. The acaricidal and nematicidal activities of them against Tetranychus cinnabarinus and Bursaphelenchus xylophilus were tested. The results indicated that compound 1 had potent acaricidal activity against adult mites with an LC50 value of 0.0022 mg L-1, while compounds 5 and 7 possessed potent nematicidal activity with LC50 values of 4.56 and 4.30 mg L-1, respectively.


Assuntos
Acaricidas/farmacologia , Antinematódeos/farmacologia , Proteínas de Bactérias/genética , Macrolídeos/farmacologia , Streptomyces/química , Streptomyces/genética , Acaricidas/química , Acaricidas/isolamento & purificação , Acaricidas/metabolismo , Animais , Antinematódeos/química , Antinematódeos/isolamento & purificação , Antinematódeos/metabolismo , Proteínas de Bactérias/metabolismo , Feminino , Engenharia Genética , Macrolídeos/química , Macrolídeos/isolamento & purificação , Macrolídeos/metabolismo , Masculino , Estrutura Molecular , Streptomyces/metabolismo , Tetranychidae/efeitos dos fármacos , Tylenchida/efeitos dos fármacos
3.
Acta Biochim Biophys Sin (Shanghai) ; 51(3): 254-262, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30668628

RESUMO

Pine wilt disease (PWD) caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus, is a devastating disease for Pinus spp. The virulence and resilience of PWN are closely linked to the spread and development of PWD. Numerous studies have shown that autophagy has important physiological and pathological functions in eukaryotes. But little is known about the relationships between autophagy and PWNs' virulence and resistance. In this study, through observation under the microscope and recording, we found the induction of autophagy by rapamycin could dramatically improve movement ability of PWNs with different virulence, and the highly virulent AMA3 isolate moved more than the low virulent YW4 isolate when autophagy was over-induced. High concentrations of rapamycin substantially improved the feeding and reproduction of AMA3 but not YW4. Conserved domains of autophagy genes BxATG3, BxATG4, and BxATG7 were first cloned from PWNs by reverse transcription-polymerase chain reaction (RT-PCR). Expression profiling of these three autophagy genes under biotic and abiotic stresses in PWNs with different virulence was determined by quantitative RT-PCR. The results revealed the expression levels of these three autophagy genes in PWNs with different virulence were increased significantly when nematodes were subject to high and low temperatures, oxidative stress, and defensive responses of pine trees. The expression levels of autophagy genes under biotic and abiotic stresses in AMA3 were higher than those in YW4, and different genes showed different performance. Our study clarified that autophagy was closely related to virulence and resistance of PWN, and the ability of a highly virulent isolate to regulate autophagy activity under stresses was stronger than that of a low virulent isolate.


Assuntos
Autofagia/genética , Pinus/parasitologia , Doenças das Plantas/parasitologia , Sirolimo/farmacologia , Estresse Fisiológico , Tylenchida/efeitos dos fármacos , Animais , Estresse Oxidativo , Temperatura , Tylenchida/genética , Tylenchida/patogenicidade , Tylenchida/fisiologia , Virulência
4.
Pest Manag Sci ; 75(6): 1734-1742, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30525290

RESUMO

BACKGROUND: Nacobbus aberrans (Tylenchida: Pratylenchidae) is one of the main plant-parasitic nematodes species that affects crops in Mexico, generating substantial economic losses. Traditionally, the control of the nematodes is carried out using chemical products; however, research efforts are presently focused on the search for new methods for the control of this pest. Natural products derived from plants are an alternative for the control of populations of plant-parasitic nematodes. The genus Heterotheca (Asteraceae) is characterized by containing sesquiterpenes with cadinane skeleton, and some species of this genus exert nematicidal activity. RESULTS: We determined the effects of selected Heterotheca inuloides plant metabolites and some semisynthetic derivatives on the hatching of eggs isolated from the gelatinous matrix and infective second-stage juveniles (J2) of the false root-knot nematode N. aberrans using an in vitro experimental model. Among the evaluated compounds, nematodes were more susceptible to hydroxylated and quinone compounds, whereas the remaining compounds showed moderate or no activity. The presence of the hydroxyl group is essential for nematicidal potential, with changes at the hydroxyl group modifying the nematicidal activity. CONCLUSION: Flowers of Heterotheca inuloides contain bioactive compounds that showed nematicidal activity against N. aberrans. Here we report the nematicidal activities of cadinenes isolated from the flowers of H. inuloides and their semisynthetic derivatives against the false root-knot nematode N. aberrans. © 2018 Society of Chemical Industry.


Assuntos
Antinematódeos/toxicidade , Asteraceae/metabolismo , Asteraceae/parasitologia , Produtos Biológicos/toxicidade , Sesquiterpenos/toxicidade , Tylenchida/efeitos dos fármacos , Animais , Antinematódeos/metabolismo , Produtos Biológicos/metabolismo , Flores/metabolismo , Oviposição/efeitos dos fármacos , Tylenchida/crescimento & desenvolvimento , Tylenchida/fisiologia
5.
Appl Environ Microbiol ; 84(23)2018 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-30242007

RESUMO

Resistance of fungi to predation is thought to be mediated by toxic metabolites and proteins. Many of these fungal defense effectors are highly abundant in the fruiting body and not produced in the vegetative mycelium. The defense function of fruiting body-specific proteins, however, including cytoplasmically localized lectins and antinutritional proteins such as biotin-binding proteins, is mainly based on toxicity assays using bacteria as a heterologous expression system, with bacterivorous/omnivorous model organisms as predators. Here, we present an ecologically more relevant experimental setup to assess the toxicity of potential fungal defense proteins towards the fungivorous, stylet-feeding nematodes Aphelenchus avenae and Bursaphelenchus okinawaensis As a heterologous expression host, we exploited the filamentous fungus Ashbya gossypii Using this new system, we assessed the toxicity of six previously characterized, cytoplasmically localized, potential defense proteins from fruiting bodies of different fungal phyla against the two fungivorous nematodes. We found that all of the tested proteins were toxic against both nematodes, albeit to various degrees. The toxicity of these proteins against both fungivorous and bacterivorous nematodes suggests that their targets have been conserved between the different feeding groups of nematodes and that bacterivorous nematodes are valid model organisms to assess the nematotoxicity of potential fungal defense proteins.IMPORTANCE Our results support the hypothesis that cytoplasmic proteins abundant in fungal fruiting bodies are involved in fungal resistance against predation. The toxicity of these proteins toward stylet-feeding nematodes, which are also capable of feeding on plants, and the abundance of these proteins in edible mushrooms, may open possible avenues for biological crop protection against parasitic nematodes, e.g., by expression of these proteins in crops.


Assuntos
Proteínas Fúngicas/toxicidade , Fungos/química , Tylenchida/efeitos dos fármacos , Animais , Comportamento Alimentar/efeitos dos fármacos , Carpóforos/química , Tylenchida/fisiologia
6.
Fitoterapia ; 128: 20-25, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29723562

RESUMO

Five new amide alkaloids (1-3, 5-6) were isolated from the seeds of Clausena lansium together with one new natural product (4) and four known analogues (7-10). The structures of the new amide alkaloids were elucidated based on a comprehensive spectroscopic data analysis including 1D and 2D NMR as well as HRESIMS, and by comparison with the literature. The bioactivity results showed that compound 8 expressed potent nematicidal activity against Panagrellus redivevus, with IC50 value of 0.12 mM, while compounds 3 and 5 presented moderate nematicidal activity with IC50 values of 2.75 and 3.93 mM, respectively (abamectin as the positive control with IC50 value of 1.05 mM).


Assuntos
Alcaloides/isolamento & purificação , Amidas/isolamento & purificação , Anti-Helmínticos/isolamento & purificação , Clausena/química , Sementes/química , Alcaloides/farmacologia , Amidas/farmacologia , Animais , Anti-Helmínticos/farmacologia , Estrutura Molecular , Tylenchida/efeitos dos fármacos
7.
Appl Microbiol Biotechnol ; 102(5): 2155-2165, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29372299

RESUMO

Avermectin produced by Streptomyces avermitilis is an anti-nematodal agent against the pine wood nematode Bursaphelenchus xylophilus. However, its potential usage is limited by its poor water solubility. For this reason, continuous efforts are underway to produce new derivatives that are more water soluble. Here, the enzymatic glycosylation of avermectin was catalyzed by uridine diphosphate (UDP)-glycosyltransferase from Bacillus licheniformis with various UDP sugars. As a result, the following four avermectin B1a glycosides were produced: avermectin B1a 4″-ß-D-glucoside, avermectin B1a 4″-ß-D-galactoside, avermectin B1a 4″-ß-L-fucoside, and avermectin B1a 4″-ß-2-deoxy-D-glucoside. The avermectin B1a glycosides were structurally analyzed based on HR-ESI MS and 1D and 2D nuclear magnetic resonance spectra, and the anti-nematodal effect of avermectin B1a 4″-ß-D-glucoside was found to exhibit the highest activity (IC50 = 0.23 µM), which was approximately 32 times greater than that of avermectin B1a (IC50 = 7.30 µM), followed by avermectin B1a 4″-ß-2-deoxy-D-glucoside (IC50 = 0.69 µM), avermectin B1a 4″-ß-L-fucoside (IC50 = 0.89 µM), and avermectin B1a 4″-ß-D-galactoside (IC50 = 1.07 µM). These results show that glycosylation of avermectin B1a effectively enhances its in vitro anti-nematodal activity and that avermectin glycosides can be further applied for treating infestations of the pine wood nematode B. xylophilus.


Assuntos
Anti-Helmínticos/farmacologia , Bacillus licheniformis/enzimologia , Proteínas de Bactérias/metabolismo , Glicosídeos/farmacologia , Glicosiltransferases/metabolismo , Ivermectina/análogos & derivados , Pinus/parasitologia , Doenças das Plantas/parasitologia , Tylenchida/efeitos dos fármacos , Animais , Anti-Helmínticos/química , Anti-Helmínticos/metabolismo , Bacillus licheniformis/metabolismo , Proteínas de Bactérias/química , Glicosídeos/química , Glicosídeos/metabolismo , Glicosiltransferases/química , Ivermectina/química , Ivermectina/metabolismo , Ivermectina/farmacologia , Doenças das Plantas/prevenção & controle , Tylenchida/fisiologia
8.
BMC Genomics ; 18(1): 927, 2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-29191166

RESUMO

BACKGROUND: Xenorhabdus innexi is a bacterial symbiont of Steinernema scapterisci nematodes, which is a cricket-specialist parasite and together the nematode and bacteria infect and kill crickets. Curiously, X. innexi expresses a potent extracellular mosquitocidal toxin activity in culture supernatants. We sequenced a draft genome of X. innexi and compared it to the genomes of related pathogens to elucidate the nature of specialization. RESULTS: Using green fluorescent protein-expressing X. innexi we confirm previous reports using culture-dependent techniques that X. innexi colonizes its nematode host at low levels (~3-8 cells per nematode), relative to other Xenorhabdus-Steinernema associations. We found that compared to the well-characterized entomopathogenic nematode symbiont X. nematophila, X. innexi fails to suppress the insect phenoloxidase immune pathway and is attenuated for virulence and reproduction in the Lepidoptera Galleria mellonella and Manduca sexta, as well as the dipteran Drosophila melanogaster. To assess if, compared to other Xenorhabdus spp., X. innexi has a reduced capacity to synthesize virulence determinants, we obtained and analyzed a draft genome sequence. We found no evidence for several hallmarks of Xenorhabdus spp. toxicity, including Tc and Mcf toxins. Similar to other Xenorhabdus genomes, we found numerous loci predicted to encode non-ribosomal peptide/polyketide synthetases. Anti-SMASH predictions of these loci revealed one, related to the fcl locus that encodes fabclavines and zmn locus that encodes zeamines, as a likely candidate to encode the X. innexi mosquitocidal toxin biosynthetic machinery, which we designated Xlt. In support of this hypothesis, two mutants each with an insertion in an Xlt biosynthesis gene cluster lacked the mosquitocidal compound based on HPLC/MS analysis and neither produced toxin to the levels of the wild type parent. CONCLUSIONS: The X. innexi genome will be a valuable resource in identifying loci encoding new metabolites of interest, but also in future comparative studies of nematode-bacterial symbiosis and niche partitioning among bacterial pathogens.


Assuntos
Toxinas Bacterianas/metabolismo , Interações Hospedeiro-Patógeno , Tylenchida/microbiologia , Tylenchida/fisiologia , Xenorhabdus/patogenicidade , Aedes , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Drosophila melanogaster/efeitos dos fármacos , Drosophila melanogaster/imunologia , Drosophila melanogaster/microbiologia , Genoma Bacteriano , Proteínas de Fluorescência Verde/metabolismo , Lepidópteros/efeitos dos fármacos , Lepidópteros/imunologia , Lepidópteros/microbiologia , Masculino , Filogenia , Locos de Características Quantitativas , Simbiose , Tylenchida/efeitos dos fármacos , Tylenchida/imunologia , Virulência , Fatores de Virulência/genética , Fatores de Virulência/metabolismo , Xenorhabdus/classificação , Xenorhabdus/genética , Xenorhabdus/fisiologia
9.
Pestic Biochem Physiol ; 143: 147-153, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29183585

RESUMO

Bursaphelenchus xylophilus causes pine wilt disease (PWD), which severely damages pine species. The plant volatile trans­2-hexenal has strong activity against nematodes, although the precise mechanism of this inhibitory action remains unclear. In this paper, the fumigant effects of the LC10 and LC30 of trans­2-hexenal on B. xylophilus were demonstrated. The trans­2-hexenal treatments significantly inhibited the dispersal ability of nematodes. The results also indicated that trans­2-hexenal affects the metabolism of nutrients and the activity of digestive enzymes. Among detoxifying enzymes, after treatment with trans­2-hexenal, glutathione S-transferase activity increased significantly and general esterase activity decreased significantly. Based on these results, trans­2-hexenal disturbs the normal physiological and biochemical activities of this nematode. These results provide valuable insight into the nematicidal mechanisms of trans­2-hexenal.


Assuntos
Aldeídos/toxicidade , Antinematódeos/toxicidade , Tylenchida/efeitos dos fármacos , Animais , Esterases/metabolismo , Glutationa Transferase/metabolismo , Lipase/metabolismo , Peptídeo Hidrolases/metabolismo , Pinus/parasitologia , Caules de Planta/parasitologia , Trealase/metabolismo , Tylenchida/metabolismo , Tylenchida/fisiologia
10.
Molecules ; 22(9)2017 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-28927023

RESUMO

Among 98 3-acyltetramic acid analogues, compounds 1c, 2c, 2f and 2g, showed >90% nematicidal activity against the pine wood nematode Bursaphelenchus xylophilus at a 10 µg/mL concentration. The nematicidal activities of compounds 1d, 1h, and 2k were a little lower at 88.0%, 85.8%, and 57.2% at a 10 µg/mL concentration, respectively. The nematicidal activity of emamection benzoate, widely used in Korea for the prevention of pine wilt disease, was 32.3% at a 10 µg/mL concentration. Other 3-acyltetramic acid analogues showed less than 30% nematicidal activity. A structure-activity relationship study indicated that the chain length of the C-acyl substituent was very important for high nematicidal activity. All active compounds had C13H27 or C11H23 acyl substituents, in two closely related groups with the common physicochemical properties of a polar surface area 57.6A², PSA (polar surface area) 7.8-8.6% and ClogP (calculated partition coefficient) 5.1-5.9 and a polar surface area 75-84A², PSA 11.1-11.6% and ClogP 4.7-5.1, respectively. Our study indicates that active 3-acyltetramic acid analogues could have potential as lead compounds for developing novel pine wood nematode control agents.


Assuntos
Antinematódeos/química , Pirrolidinonas/química , Tylenchida/efeitos dos fármacos , Animais , Antinematódeos/farmacologia , Estrutura Molecular , Pinus , Pirrolidinonas/farmacologia , Relação Estrutura-Atividade , Propriedades de Superfície
11.
Pestic Biochem Physiol ; 135: 64-68, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28043333

RESUMO

The ethanol extract of Punica granatum L. rind was tested to show significant nematicidal activity against pine wood nematode. Three nematicidal compounds were obtained from the ethanol extract by bioassay-guided fractionation and identified as punicalagin 1, punicalin 2, and corilagin 3 by mass and nuclear magnetic resonance spectral data analysis. Punicalagin 1 was most active against PWN among the purified compounds with the LC50 value of 307.08µM in 72h. According to the enzyme assays in vitro, punicalagin 1 could inhibit the activity of acetylcholinesterase, amylase and cellulase from PWN with IC50 value of 0.60mM, 0.96mM and 1.24mM, respectively. The morphological structures of PWNs treated by punicalagin 1 were greatly changed. These physiological effects of punicalagin 1 on PWN may helpful to elucidate its nematicidal mechanism.


Assuntos
Antinematódeos/toxicidade , Taninos Hidrolisáveis/toxicidade , Lythraceae , Extratos Vegetais/toxicidade , Tylenchida/efeitos dos fármacos , Acetilcolinesterase/metabolismo , Amilases/antagonistas & inibidores , Animais , Antinematódeos/química , Celulase/antagonistas & inibidores , Inibidores da Colinesterase/química , Inibidores da Colinesterase/toxicidade , Glucosídeos/análise , Glucosídeos/toxicidade , Taninos Hidrolisáveis/análise , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Extratos Vegetais/química , Tylenchida/enzimologia , Tylenchida/ultraestrutura
12.
Pest Manag Sci ; 73(5): 888-895, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-27414986

RESUMO

BACKGROUND: Bursaphelenchus xylophilus is a serious quarantined pest that causes severe damage and major economic losses to pine forests. Because of the adverse effects of some traditional nematicides on humans and the environment, the search for new plant toxicants against these nematodes has intensified. Nematicidal activity of trans-2-hexenal, which is a six-carbon aldehyde present in many plants, was tested against the nematode. RESULTS: trans-2-Hexenal showed significant efficacy against B. xylophilus in a dose range of 349.5-699 g m-3 by fumigation of pinewood logs. Additionally, it had significant nematicidal activity against different life stages of B. xylophilus in an in vitro test, with second-stage larvae (L2s) being the most sensitive, with an LC50 value of 9.87 µg mL-1 at 48 h. Egg hatch was also significantly inhibited. Further studies revealed that trans-2-hexenal inhibited the reproductive activity of B. xylophilus, with negative effects on reproduction rate and egg numbers. Moreover, trans-2-hexenal reduced the body length of B. xylophilus. Respiratory rate and thrashing behaviour of B. xylophilus also decreased following treatment with this compound. CONCLUSION: trans-2-Hexenal had significant nematicidal activity against B. xylophilus, providing a basis for elucidation of the mode of action of trans-2-hexenal against plant-parasitic nematodes in future studies. © 2016 Society of Chemical Industry.


Assuntos
Aldeídos/farmacologia , Comportamento Animal/efeitos dos fármacos , Tylenchida/efeitos dos fármacos , Tylenchida/fisiologia , Animais , Feminino , Fumigação , Locomoção/efeitos dos fármacos , Masculino , Oviposição/efeitos dos fármacos , Pinus/parasitologia , Reprodução/efeitos dos fármacos , Respiração/efeitos dos fármacos , Tylenchida/crescimento & desenvolvimento , Tylenchida/metabolismo
13.
Pest Manag Sci ; 73(7): 1446-1452, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27862932

RESUMO

BACKGROUND: The nematode Bursaphelenchus xylophilus and its insect vectors from the Monochamus genus are major global quarantine pests of timber products. Owing to the phase-out of methyl bromide for plant quarantine and preshipment treatments, an alternative fumigant is essential. Based on preliminary laboratory studies on the efficacy of ethanedinitrile (C2 N2 ) to B. xylophilus and Monochamus alternatus, three quarantine trials were conducted at three dosages and three temperatures. Potential for inhalation exposure was assessed by monitoring atmospheric C2 N2 in relation to the threshold limit value. RESULTS: Concentration × time products (Ct) of 398.6, 547.2 and 595.9 g h m-3 were obtained for each trial. A 100% mortality of B. xylophilus and M. alternatus larvae at 23 ± 4 °C and 10 ± 4 °C occurred with a load factor of pine logs of 46% and at 3 ± 1 °C with a load factor of 30%. During all fumigations, atmospheric levels of C2 N2 20 m downwind were below the TLV. During aeration, levels 10 and 5 m downwind were below the TLV after 0.4 and 1 h respectively. CONCLUSION: For the purpose of quarantine or phytosanitary treatment, specific doses of C2 N2 at the trial temperatures could control B. xylophilus and M. alternatus larvae without significant inhalation risk to workers. © 2016 Society of Chemical Industry.


Assuntos
Besouros/efeitos dos fármacos , Fumigação/métodos , Nitrilos/farmacologia , Tylenchida/efeitos dos fármacos , Animais , Antinematódeos/farmacologia , Insetos Vetores/efeitos dos fármacos , Larva/efeitos dos fármacos , Pinus/parasitologia , Temperatura , Madeira
14.
Molecules ; 21(10)2016 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-27669203

RESUMO

During a screening program for new agrochemicals from Chinese medicinal herbs, the ethanol extract of Notopterygium incisum rhizomes was found to possess strong nematicidal activity against the two species of nematodes, Bursaphelenchus xylophilus and Meloidogyne incognita. Based on bioactivity-guided fractionation, the four constituents were isolated from the ethanol extract and identified as columbianetin, falcarindiol, falcarinol, and isoimperatorin. Among the four isolated constituents, two acetylenic compounds, falcarindiol and falcarinol (2.20-12.60 µg/mL and 1.06-4.96 µg/mL, respectively) exhibited stronger nematicidal activity than two furanocoumarins, columbianetin, and isoimperatorin (21.83-103.44 µg/mL and 17.21-30.91 µg/mL, respectively) against the two species of nematodes, B. xylophilus and M. incognita. The four isolated constituents also displayed phototoxic activity against the nematodes. The results indicate that the ethanol extract of N. incisum and its four isolated constituents have potential for development into natural nematicides for control of plant-parasitic nematodes.


Assuntos
Apiaceae/química , Extratos Vegetais/farmacologia , Tylenchida/efeitos dos fármacos , Tylenchoidea/efeitos dos fármacos , Animais , Di-Inos/química , Medicamentos de Ervas Chinesas/farmacologia , Álcoois Graxos/química , Furocumarinas/química , Extratos Vegetais/química , Rizoma/química , Tylenchida/patogenicidade , Tylenchoidea/patogenicidade
15.
Phytopathology ; 106(12): 1563-1571, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27452899

RESUMO

Plant-parasitic nematodes cause substantial damage to agricultural crops worldwide. Long-term management of these pests requires novel strategies to reduce infection of host plants. Disruption of nematode chemotaxis to root systems has been proposed as a potential management approach, and novel assays are needed to test the chemotactic behavior of nematodes against a wide range of synthetic chemicals and root exudates. Two microfluidic chips were developed that measure the attraction or repulsion of nematodes to chemicals ("chemical chip") and young plant roots ("root chip"). The chip designs allowed for chemical concentration gradients to be maintained up to 24 h, the nematodes to remain physically separate from the chemical reservoirs, and for images of nematode populations to be captured using either a microscope or a flatbed scanner. In the experiments using the chemical chips, seven ionic solutions were tested on second-stage juveniles (J2s) of Meloidogyne incognita and Heterodera glycines. Results were consistent with previous reports of repellency of M. incognita to a majority of the ionic solutions, including NH4NO3, KNO3, KCl, MgCl2, and CaCl2. H. glycines was found to be attracted to both NH4NO3 and KNO3, which has not been reported previously. A software program was written to aid in monitoring the location of nematodes at regular time intervals using the root chip. In experiments with the root chip, H. glycines J2s were attracted to roots of 3-day-old, susceptible (cultivar Williams 82) soybean seedlings, and attraction of H. glycines to susceptible soybean was similar across the length of the root. Attraction to resistant (cultivar Jack) soybean seedlings relative to the water only control was inconsistent across runs, and H. glycines J2s were not preferentially attracted to the roots of resistant or susceptible cultivars when both were placed on opposite sides of the same root chip. The chips developed allow for direct tests of plant-parasitic nematode chemotaxis to chemicals and roots with minimal human intervention.


Assuntos
Fatores Biológicos/farmacologia , Doenças das Plantas/prevenção & controle , Soja/parasitologia , Tylenchoidea/efeitos dos fármacos , Animais , Doenças das Plantas/parasitologia , Raízes de Plantas/parasitologia , Tylenchida/efeitos dos fármacos
16.
Microb Ecol ; 72(3): 669-81, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27461253

RESUMO

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.


Assuntos
Endófitos , Estilo de Vida , Infecções Oportunistas , Pinus/microbiologia , Serratia marcescens/isolamento & purificação , Serratia marcescens/fisiologia , Serratia marcescens/patogenicidade , Tylenchida/microbiologia , Animais , Anti-Infecciosos , Antinematódeos/farmacologia , Sequência de Bases , Classificação , Besouros/microbiologia , DNA Bacteriano , Genes Bacterianos , Interações Hospedeiro-Parasita/fisiologia , Insetos Vetores/microbiologia , Microscopia Confocal , Microscopia Eletrônica de Varredura , Anotação de Sequência Molecular , Nematoides/patogenicidade , Filogenia , Pinus/parasitologia , Doenças das Plantas/microbiologia , Serratia marcescens/genética , Árvores/microbiologia , Árvores/parasitologia , Tylenchida/efeitos dos fármacos , Tylenchida/patogenicidade
17.
Nat Prod Res ; 30(17): 1969-73, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26479900

RESUMO

The ethanol extract of the Ficus carica L. leaves was tested to show strong nematicidal activity against pine wood nematode (PWN), Bursaphelenchus xylophilus, causing 90.93% corrected mortality within 72 h at 1.0 mg/mL. From the ethyl acetate soluble fraction of the F. carica L. leaves extract, the main nematicidal constituents were obtained by bioassay-guided isolation and identified as linear furocoumarins bergapten (1) and psoralen (2) by mass and NMR spectral data analysis. Bergapten and psoralen had significant nematicidal activity against PWN with the LC50 values of 97.08 aKSnd 115.03  µ g/mL within 72 h, respectively. The two furocoumarins could inhibit the activities of amylase, cellulase and acetylcholinesterase (AchE) from PWN. The morphologies of PWNs changed much after they were treated by bergapten and psoralen. The physiological effects of bergapten and psoralen on PWN might provide helpful clues to elucidate their nematicidal mechanisms.


Assuntos
Antinematódeos/farmacologia , Ficus/química , Nematoides/efeitos dos fármacos , 5-Metoxipsoraleno , Amilases/antagonistas & inibidores , Animais , Antinematódeos/química , Antinematódeos/isolamento & purificação , Celulase/antagonistas & inibidores , Inibidores da Colinesterase/isolamento & purificação , Inibidores da Colinesterase/farmacologia , Ficusina/isolamento & purificação , Ficusina/farmacologia , Furocumarinas/química , Furocumarinas/isolamento & purificação , Furocumarinas/farmacologia , Metoxaleno/análogos & derivados , Metoxaleno/isolamento & purificação , Metoxaleno/farmacologia , Folhas de Planta/química , Tylenchida/efeitos dos fármacos
18.
J Basic Microbiol ; 55(10): 1239-44, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26058971

RESUMO

A strain SMrs28 was isolated from the rhizosphere soil of a toxic plant Stellera chamaejasme and identified as Bacillus sp. on the basis of morphological and partial 16S rRNA gene sequence analysis. The crude extract of SMrs28 fermentation broth showed strong nematocidal activities in preliminary test. To define the active nematocidal metabolites of SMrs28, a novel compound (1), 4-oxabicyclo[3.2.2]nona-1(7), 5,8-triene, along with five known compounds (2-6), were isolated from the strain by various column chromatographic techniques and characterized on the basis of spectroscopic analysis. Results of the in vitro nematicidal tests showed that the metabolites presented different levels of activity at certain exposure conditions. Compounds (1-3) displayed LC50 values of 904.12, 451.26, 232.98 µg/ml and 1594.0, 366.62, 206.38 µg/ml against Bursaphelenchus xylophilus and Ditylenchus destructor at 72 h, respectively. This is the first report of the nematicidal activity of the compounds as constituents of Bacillus sp.. Our findings help to find potential chemical structures to develop nematicides from microbial source for the management of nematode-infected plant diseases.


Assuntos
Antinematódeos/isolamento & purificação , Antinematódeos/farmacologia , Bacillus/química , Bacillus/metabolismo , Animais , Fermentação , Estrutura Molecular , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controle , RNA Ribossômico 16S , Rizosfera , Análise de Sequência de RNA , Microbiologia do Solo , Tylenchida/efeitos dos fármacos , Tylenchoidea/efeitos dos fármacos
19.
Appl Environ Microbiol ; 81(16): 5326-34, 2015 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-26025902

RESUMO

Avermectin (AVM) and ivermectin (IVM) are potent pesticides and acaricides which have been widely used during the past 30 years. As insect resistance to AVM and IVM is greatly increasing, alternatives are urgently needed. Here, we report two novel AVM derivatives, tenvermectin A (TVM A) and TVM B, which are considered a potential new generation of agricultural and veterinary drugs. The molecules of the TVMs were designed based on structure and pharmacological property comparisons among AVM, IVM, and milbemycin (MBM). To produce TVMs, a genetically engineered strain, MHJ1011, was constructed from Streptomyces avermitilis G8-17, an AVM industrial strain. In MHJ1011, the native aveA1 gene was seamlessly replaced with milA1 from Streptomyces hygroscopicus. The total titer of the two TVMs produced by MHJ1011 reached 3,400 mg/liter. Insecticidal tests proved that TVM had enhanced activities against Tetranychus cinnabarinus and Bursaphelenchus xylophilus, as desired. This study provides a typical example of exploration for novel active compounds through a new method of polyketide synthase (PKS) reassembly for gene replacement. The results of the insecticidal tests may be of use in elucidating the structure-activity relationship of AVMs and MBMs.


Assuntos
Acaricidas/metabolismo , Anti-Helmínticos/metabolismo , Ivermectina/análogos & derivados , Engenharia Metabólica , Streptomyces/genética , Streptomyces/metabolismo , Acaricidas/química , Animais , Anti-Helmínticos/química , Ivermectina/química , Ivermectina/metabolismo , Estrutura Molecular , Testes de Sensibilidade Parasitária , Análise de Sobrevida , Tetranychidae/efeitos dos fármacos , Tylenchida/efeitos dos fármacos
20.
Mol Plant Microbe Interact ; 28(4): 398-407, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25423264

RESUMO

The root-knot nematode (RKN) is one of the most devastating parasitic nematodes of plants. Although some secondary metabolites released by the host plant play roles as defense substances against parasitic nematodes, the mechanism underlying the induction of such defense responses is not fully understood. We found that sclareol, a natural diterpene known as an antimicrobial and defense-related molecule, inhibited RKN penetration of tomato and Arabidopsis roots. Sclareol induced genes related to ethylene (ET) biosynthesis and signaling and phenylpropanoid metabolism in Arabidopsis roots. In roots of ein2-1, an ET-insensitive mutant line, both sclareol-induced inhibition of RKN penetration and sclareol-induced enhancement of lignin accumulation were abolished. A mutant defective in lignin accumulation did not exhibit such inhibition. Sclareol also activated MPK3 and MPK6, Arabidopsis mitogen-activated protein kinases whose activation is required for triggering ET biosynthesis. Sclareol-induced inhibition of RKN penetration was exhibited by mutants of neither MPK3 nor MPK6. Treatment with a biosynthetic precursor of ET was insufficient compared with sclareol treatment to inhibit RKN penetration, suggesting the existence of an ET-independent signaling pathway leading to RKN resistance. These results suggested that sclareol induced resistance to RKN penetration partially through ET-dependent accumulation of lignin in roots.


Assuntos
Resistência à Doença/efeitos dos fármacos , Diterpenos/farmacologia , Doenças das Plantas/parasitologia , Raízes de Plantas/metabolismo , Raízes de Plantas/parasitologia , Tylenchida/efeitos dos fármacos , Animais , Arabidopsis/efeitos dos fármacos , Etilenos/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Lignina/metabolismo , Lycopersicon esculentum/efeitos dos fármacos
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