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1.
Sci Rep ; 14(1): 3733, 2024 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-38355886

RESUMO

The plant-parasitic nematodes are considered as one of the most destructive pests, from which the migratory and sedentary endoparasitic plant parasitic nematodes infect more than 4000 plant species and cause over $100 billion crop losses annually worldwide. These nematodes use multiple strategies to infect their host and to establish a successful parasitism inside the host such as cell-wall degradation enzymes, inhibition of host defense proteins, and molecular mimicry. In the present study, the main parasitism-associated gene families were identified and compared between the migratory and sedentary endoparasitic nematodes. The results showed that the migratory and sedentary endoparasitic nematodes share a core conserved parasitism mechanism established throughout the evolution of parasitism. However, genes involved in pectin degradation and hydrolase activity are rapidly evolving in the migratory endoparasitic nematodes. Additionally, cell-wall degrading enzymes such as GH45 cellulases and pectate lyase and peptidase and peptidase inhibitors were expanded in the migratory endoparasitic nematodes. The molecular mimicry mechanism was another key finding that differs between the endoparasitic and sedentary parasitic nematodes. The PL22 gene family, which is believed to play a significant role in the molecular mechanisms of nematode parasitism, has been found to be present exclusively in migratory endoparasitic nematodes. Phylogenetic analysis has suggested that it was de novo born in these nematodes. This discovery sheds new light on the molecular evolution of these parasites and has significant implications for our understanding of their biology and pathogenicity. This study contributes to our understanding of core parasitism mechanisms conserved throughout the nematodes and provides unique clues on the evolution of parasitism and the direction shaped by the host.


Assuntos
Parasitos , Tylenchida , Tylenchoidea , Animais , Filogenia , Plantas/parasitologia , Doenças das Plantas/genética
2.
Nat Commun ; 15(1): 773, 2024 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-38316773

RESUMO

Using long-read sequencing, we assembled and unzipped the polyploid genomes of Meloidogyne incognita, M. javanica and M. arenaria, three of the most devastating plant-parasitic nematodes. We found the canonical nematode telomeric repeat to be missing in these and other Meloidogyne genomes. In addition, we find no evidence for the enzyme telomerase or for orthologs of C. elegans telomere-associated proteins, suggesting alternative lengthening of telomeres. Instead, analyzing our assembled genomes, we identify species-specific composite repeats enriched mostly at one extremity of contigs. These repeats are G-rich, oriented, and transcribed, similarly to canonical telomeric repeats. We confirm them as telomeric using fluorescent in situ hybridization. These repeats are mostly found at one single end of chromosomes in these species. The discovery of unusual and specific complex telomeric repeats opens a plethora of perspectives and highlights the evolutionary diversity of telomeres despite their central roles in senescence, aging, and chromosome integrity.


Assuntos
Tylenchida , Tylenchoidea , Animais , Caenorhabditis elegans/genética , Hibridização in Situ Fluorescente , Tylenchoidea/genética , Telômero/genética , Poliploidia
3.
BMC Plant Biol ; 24(1): 98, 2024 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-38331735

RESUMO

Pine wilt disease (PWD) is a devastating forest disease caused by the pinewood nematode (PWN), Bursaphelenchus xylophilus, a migratory endoparasite that infects several coniferous species. During the last 20 years, advances have been made for understanding the molecular bases of PWN-host trees interactions. Major advances emerged from transcriptomic and genomic studies, which revealed some unique features related to PWN pathogenicity and constituted fundamental data that allowed the development of postgenomic studies. Here we review the proteomic approaches that were applied to study PWD and integrated the current knowledge on the molecular basis of the PWN pathogenicity. Proteomics has been useful for understanding cellular activities and protein functions involved in PWN-host trees interactions, shedding light into the mechanisms associated with PWN pathogenicity and being promising tools to better clarify host trees PWN resistance/susceptibility.


Assuntos
Pinus , Tylenchida , Animais , Proteômica , Virulência , Pinus/genética , Pinus/parasitologia , Doenças das Plantas/parasitologia
4.
J Agric Food Chem ; 72(3): 1429-1443, 2024 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-38189665

RESUMO

Plant-parasitic nematodes are one of the major threats to crop protection. However, only limited nematicides are currently available and are confronted with a growing resistance problem, which necessitates the development of novel nematicides. In this study, a series of trifluorobutene amide derivatives was synthesized through the strategy of amide bond reversal, and their nematicidal activity against Meloidogyne incognita was evaluated. The bioassay showed that compounds C2, C10, and C18 and some analogues thereof exhibited good nematicidal activity. Among them, the derivatives of compound C2 containing a benzene ring [C26 (R = 2-CH3) and C33 (R = 2-Cl)] exhibited excellent bioactivity against M. incognita in vitro. The LC50/72h values reached 14.13 and 14.71 mg·L-1, respectively. Moreover, analogues of compounds C10 and C18 containing a thiophene ring [C43 (R = 5-CH3), C44 (R = 4-CH3), and C50 (R = 5-Cl)] exhibited significant bioactivity against M. incognita in vivo with inhibition rates of 68.8, 65.5, and 69.8% at 2.5 mg·L-1 in a matrix, respectively. Meanwhile, C44 and C50 also showed excellent control effects against M. incognita in both cups and microplots. The structure-activity relationship (SAR) of synthesized compounds was discussed in detail. Comparative molecular field analysis (CoMFA) was also conducted to develop the SAR profile. The preliminary mode of action investigation showed that compound C33 exhibited strong inhibition on egg hatching, motility, feeding behavior, and growth of Caenorhabditis elegans. At the same time, the impact of active compounds on biochemical indicators related to oxidative stress showed that compound C33 influenced the production of ROS (reactive oxygen species), and the accumulation of lipofuscin and lipids on C. elegans.


Assuntos
Tylenchida , Tylenchoidea , Animais , Amidas/farmacologia , Caenorhabditis elegans , Antinematódeos/química , Relação Estrutura-Atividade
5.
Int J Mol Sci ; 25(2)2024 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-38255917

RESUMO

Rapid and reliable diagnostic methods for plant-parasitic nematodes are critical for facilitating the selection of effective control measures. A diagnostic recombinase polymerase amplification (RPA) assay for Aphelenchoides fragariae using a TwistAmp® Basic Kit (TwistDx, Cambridge, UK) and AmplifyRP® Acceler8® Discovery Kit (Agdia, Elkhart, IN, USA) combined with lateral flow dipsticks (LF) has been developed. In this study, a LF-RPA assay was designed that targets the ITS rRNA gene of A. fragariae. This assay enables the specific detection of A. fragariae from crude nematode extracts without a DNA extraction step, and from DNA extracts of plant tissues infected with this nematode species. The LF-RPA assay showed reliable detection within 18-25 min with a sensitivity of 0.03 nematode per reaction tube for crude nematode extracts or 0.3 nematode per reaction tube using plant DNA extracts from 0.1 g of fresh leaves. The LF-RPA assay was developed and validated with a wide range of nematode and plant samples. Aphelenchoides fragariae was identified from seed samples in California. The LF-RPA assay has great potential for nematode diagnostics in the laboratory with minimal available equipment.


Assuntos
Fragaria , Rabditídios , Tylenchida , Animais , Recombinases , Nucleotidiltransferases , DNA de Plantas , Tylenchida/genética
6.
J Agric Food Chem ; 72(5): 2473-2481, 2024 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-38284538

RESUMO

Bursaphelenchus xylophilus (B. xylophilus) and Meloidogyne are parasitic nematodes that have caused severe ecological and economic damage in pinewood and crops, respectively. Jietacins (jietacin A and B) were found to have excellent biological activity against B. xylophilus. Based on our tremendous demand for chemicals against B. xylophilus, a novel scaffold based on the azo and azoxy groups was designed, and a series of compounds were synthesized. In the bioassay, Ia, IIa, IIc, IId, and IVa exhibited higher activity against B. xylophilus in vitro than avermectin (LC50 = 2.43 µg·mL-1) with LC50 values of 1.37, 1.12, 0.889, 1.56, and 1.10 µg·mL-1, respectively. Meanwhile, Ib, Ic, IIc, and IVa showed good inhibition effects against Meloidogyne in vivo at the concentrations of 80 and 40 µg·mL-1 with inhibition rates of 89.0% and 81.6%, 95.6% and 75.7%, 96.3% and 41.2%, and 86.8% and 78.7%, respectively. In fungicidal activity in vitro, IIb and IVa exhibited excellent effect against Botryosphaeria dothidea with the inhibition of 82.59% and 85.32% at the concentration of 10 µg·mL-1, while the inhibition of Ia was 83.16% against Rhizoctonia solani at the concentration of 12.5 µg·mL-1. Referring to the biological activity against B. xylophilus, a 3D-QASR model was built in which the electron-donating group and small group at the 4-phenylhydrazine were favorable for the activity. In general, the novel azoxy compounds, especially IIc possess great potential for application in the prevention of B. xylophilus.


Assuntos
Pinus , Tylenchida , Tylenchoidea , Animais , Antinematódeos/química , Pinus/parasitologia
7.
Sci Total Environ ; 912: 169531, 2024 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-38145666

RESUMO

The continuous use of chemical pesticides to control nematodes could result in the developing of pesticide-resistant nematodes. Novel nucleic acid pesticides are becoming the focus of pesticide research due to their strong specificity, high efficiency, and environmental friendliness. However, the limited known biochemical targets restrict the development of target pesticides for nematodes. The calcium stress experiments on pine wood nematodes (PWN) showed that 100 mmol/L Ca2+ resulted in longitudinal depression on the PWN body wall, reduced oviposition, and increased corrected mortality. To enrich the biological targets of nematode pesticides, we further investigated the response mechanism of PWN to calcium stress at the molecular level. Differentially expressed gene analysis showed that genes involved in the oxidative phosphorylation (OXPHOS) pathway were significantly enriched. RNA interference results of 6 key genes belonging to four mitochondrial complex I (BXNDUFA2), III (BXQCR8), IV (BXCOX17), V (BXV-ATPaseB, BXV-ATPaseE, BXV-ATPaseε) in non-stressed nematodes showed reduction in PWN oviposition, population size, feeding ability, and pathogenicity. The BXNDUFA2 gene interference had the highest inhibitory impact by decreasing the oviposition from 31.00 eggs to 6.75 eggs and PWN population size from 8.27 × 103 nematodes to 1.64 × 103 nematodes, respectively. Interestingly, RNA interference of these 6 key genes in calcium-stressed nematodes also led to increased mortality and decreased oviposition of PWN. In summary, calcium stress inhibited the reproductive capacity of PWN by down-regulating key genes BXNDUFA2, BXQCR8, BXV-ATPaseB, BXV-ATPaseE, BXV-ATPaseε, and BXCOX17, thereby reducing the pathogenicity. The current results enrich the RNAi targets in PWN and provide a scientific basis for developing novel nucleic nematicides.


Assuntos
Nematoides , Praguicidas , Pinus , Tylenchida , Animais , Virulência , Cálcio , Xylophilus , Fosforilação Oxidativa , Doenças das Plantas , Tylenchida/genética
8.
J Agric Food Chem ; 72(1): 128-139, 2024 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-38154095

RESUMO

To discover new nematicides, a series of novel amide derivatives containing 1,2,4-oxadiazole were designed and synthesized. Several compounds showed excellent nematicidal activity. The LC50 values of compounds A7, A18, and A20-A22 against pine wood nematode (Bursaphelenchus xylophilus), rice stem nematode (Aphelenchoides besseyi), and sweet potato stem nematode (Ditylenchus destructor) were 1.39-3.09 mg/L, which were significantly better than the control nematicide tioxazafen (106, 49.0, and 75.0 mg/L, respectively). Compound A7 had an outstanding inhibitory effect on nematode feeding, reproductive ability, and egg hatching. Compound A7 effectively promoted the oxidative stress of nematodes and caused intestinal damage to nematodes. Compound A7 significantly inhibited the activity of succinate dehydrogenase (SDH) in nematodes, leading to blockage of electron transfer in the respiratory chain and thereby hindering the synthesis of adenosine triphosphate (ATP), which consequently affects the entire oxidative phosphorylation process to finally cause nematode death. Therefore, compound A7 can be used as a potential SDH inhibitor in nematicide applications.


Assuntos
Nematoides , Tylenchida , Animais , Oxidiazóis/farmacologia , Antinematódeos/farmacologia , Reprodução
9.
An Acad Bras Cienc ; 95(4): e20190377, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38055600

RESUMO

Weeds can be hosts of root-knot nematodes of the genus Meloidogyne. The importance of the species Meloidogyne morocciensis parasitizing many crops is recognized, but their reproductive capacity in weeds is not known. The present study hypothesizes the ability of M. morocciensis to parasitize and reproduce in different weed species found in Brazil. The objective was to evaluate the reproduction of M. morocciensis in 36 weed species. The plants were individually inoculated with 5,000 eggs and second stage juveniles and kept in greenhouse for 60 days. The experimental design was completely randomized with twelve replications. The root system of each plant was evaluated for gall index (GI), final nematode population (PF), number of nematode/g of root (NNGR) and reproduction factor (RF). It was verified that M. morocciensis has the capacity to parasite 36 weed species belonging to 16 different botanical families, confirming the hypothesis proposed. From the 36 species evaluated, 77.8% (28) were susceptible (FR ≥ 1.0) to M. morocciensis. The present study is the first to identify different weeds as hosts of M. morocciensis, evidencing its polyphagous habit, indicating species of plants with high capacity to multiply this nematode and that need more attention during the integrated management of these pathogen.


Assuntos
Tylenchida , Tylenchoidea , Humanos , Animais , Brasil , Plantas Daninhas , Reprodução
10.
J Helminthol ; 97: e83, 2023 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-37933560

RESUMO

During a survey on the soil nematodes, a population of the genus Aphelenchoides was collected around the rhizosphere of persimmon in Guilan Province, Iran. The morphological and molecular characters confirmed the new species, namely A. persicus sp. n. The new species is characterized by a female body length (699-1068 µm), lip region offset from the rest of the body by a slight constriction, lateral fields with six incisures, stylet 12-13.5 µm long, with a clear basal swelling, excretory pore ca 1.5 metacorpal length posterior to base of the metacorpus, post uterine sac elongate, about 4-7 times than the vulval body diameter; conical female tail with a single centrally located mucron with tiny projection close to the tail tip, male body length (663-908 µm), and spicule well developed with rounded condylus, blunt conical rostrum, and a hook-like tip of dorsal limb. The new species belongs to the Group 2 category of Aphelenchoides species and was similar to seven known species with six lateral field incisures, including A. allius, A. chinensis, A. meghalayensis, A. nechaleos, A. paranechaleos, A. parasexlineatus, and A. sexlineatus. The molecular phylogeny based on 28S rDNA revealed that the new species stands close to A. hamospiculatus (MN931591; MN931592) and two unidentified Aphelenchoides (KY769057; LC583315). The measurements, line illustrations, LM photographs, and phylogenetic analysis are given for the new species.


Assuntos
Nematoides , Rabditídios , Tylenchida , Animais , Masculino , Feminino , Irã (Geográfico) , Filogenia , Rizosfera
11.
Pestic Biochem Physiol ; 194: 105511, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37532327

RESUMO

Pine wilt disease is a devastating disease of pine caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus. Long-term use of chemical nematicides leads to the development of resistance in nematodes and harms the environment. Evaluations for green environmental protection agents, identified the antibacterial peptide, MaltDef1, from Monochamus alternatus which had nematicidal effect. We studied its nematicidal activity and action against PWN. In this study, the antibacterial peptide S-defensin was synthesized from M. alternatus. The results showed that S-defensin caused mortality to the PWN, causing shrinkage, pore, cell membrane dissolution and muscle atrophy. In addition, PWN reproduction was also affected by S-defensin; it decreased in a concentration dependent manner with increasing treatment concentration. By contrast, reactive oxygen species (ROS) in vivo increased in a concentration-dependent manner. We applied transcriptome to analyze the changes in gene expressions in S-defensin treated PWN, and found that the most significantly enriched pathway was the ERK/MAPK signaling pathway. RNAi was used to validate the functions of four differential genes (Let-23, Let-60, Mek-2 and Lin-1) in this pathway. The results showed that knockdown of these genes significantly decreased the survival rate and reproductive yield of, and also increased ROS in PWN. The antibacterial peptide S-defensin had a significant inhibitory effect on the survival and reproduction of PWN, shown by cell membrane damage and intracellular biological oxidative stress via regulating the ERK/MAPK signaling pathway. This indicates that S-defensin has a target in B. xylophilus, against which new green target pesticides can be developed.


Assuntos
Besouros , Nematoides , Pinus , Tylenchida , Animais , Espécies Reativas de Oxigênio , Doenças das Plantas , Estresse Oxidativo , Antinematódeos/farmacologia , Transdução de Sinais , Reprodução , Tylenchida/genética , Defensinas
12.
Pestic Biochem Physiol ; 194: 105527, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37532336

RESUMO

Bursaphelenchus xylophilus (Pine wood nematode, PWN) has become a worldwide forest disease due to its rapid infection ability, high lethality and difficulty in control. The main means of countering B. xylophilus is currently chemical control, but nematicides can present problems such as environmental pollution and drug resistance. The development of novel environmentally-friendly nematicides has thus become a focus of recent research. In this study, BxUGT3 and BxUGT34, which might be related to detoxification, were investigated by comparing transcriptomic and WGCNA approaches. Three other genes with a similar expression pattern, BxUGT13, BxUGT14, and BxUGT16, were found by gene family analysis. Further bioassays and qPCR assays confirmed that these five genes showed significant changes in transcript levels upon exposure to α-pinene and carvone, demonstrating that they respond to exogenous nematicidal substances. Finally, RNAi and bioassays showed that B. xylophilus with silenced BxUGT16 had increased mortality in the face of α-pinene and carvone stress, suggesting that BxUGT16 plays an important role in detoxification. Taken together, this study used novel molecular research methods, explored the detoxification mechanism of B. xylophilus at a transcriptomic level, and revealed a molecular target for the development of novel biopesticides.


Assuntos
Transcriptoma , Tylenchida , Animais , Xylophilus , Antinematódeos/farmacologia , Tylenchida/genética , Doenças das Plantas
13.
Mol Plant Pathol ; 24(9): 1033-1046, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37448165

RESUMO

Lipase is involved in lipid hydrolysis, which is related to nematodes' energy reserves and stress resistance. However, the role of lipases in Bursaphelenchus xylophilus, a notorious plant-parasitic nematode responsible for severe damage to pine forest ecosystems, remains largely obscure. Here, we characterized a class III lipase as a candidate effector and named it BxLip-3. It was transcriptionally up-regulated in the parasitic stages of B. xylophilus and specifically expressed in the oesophageal gland cells and the intestine. In addition, BxLip-3 suppressed cell death triggered by the pathogen-associated molecular patterns PsXEG1 and BxCDP1 in Nicotiana benthamiana, and its Lipase-3 domain is essential for immunosuppression. Silencing of the BxLip-3 gene resulted in a delay in disease onset and increased the activity of antioxidant enzymes and the expression of pathogenesis-related (PR) genes. Plant chitinases are thought to be PR proteins involved in the defence system against pathogen attack. Using yeast two-hybrid and co-immunoprecipitation assays, we identified two class I chitinases in Pinus thunbergii, PtChia1-3 and PtChia1-4, as targets of BxLip-3. The expression of these two chitinases was up-regulated during B. xylophilus inoculation and inhibited by BxLip-3. Overall, this study illustrated that BxLip-3 is a crucial virulence factor that plays a critical role in the interaction between B. xylophilus and host pine.


Assuntos
Quitinases , Pinus , Tylenchida , Animais , Xylophilus , Ecossistema , Quitinases/genética , Pinus/parasitologia , Tylenchida/genética , Doenças das Plantas/parasitologia
14.
Artigo em Inglês | MEDLINE | ID: mdl-37331545

RESUMO

Pine wilt disease (PWD), caused by Bursaphelenchus xylophilus (pine wood nematodes, PWNs), is a forest disease that seriously threatens the health of Pinus forestry. Glutathione S-transferases (GSTs) play important roles in xenobiotic metabolism, lipophilic compound transport, antioxidative stress reactions, anti-mutagenesis, and antitumor activity. The analysis and investigation of the specific functions of GSTs in the metabolism of toxic substances in nematodes are important for identifying potential target genes to control the spread and transmission of B. xylophilus. In this study, 51 Bx-GSTs were found in the genome of B. xylophilus. Two key Bx-gsts (Bx-gst12 and Bx-gst40) were analyzed when B. xylophilus was exposed to avermectin. The expression of Bx-gst12 and Bx-gst40 was significantly increased when B. xylophilus was exposed to 1.6 and 3.0 mg/mL avermectin solutions. Notably, combined silencing of both Bx-gst12 and Bx-gst40 did not further increase the mortality rates under avermectin exposure. Mortality rates were significantly increased in nematodes treated with dsRNA compared to control nematodes (p < 0.05) after RNAi. The feeding ability of nematodes was also significantly reduced after treatment with dsRNA. These results suggested that Bx-gsts are associated with the detoxification process and feeding behavior of B. xylophilus. Silencing Bx-gsts leads to increased susceptibility to nematicides and reduces the feeding ability of B. xylophilus. Therefore, Bx-gsts will be a new control target of PWNs in the future.


Assuntos
Nematoides , Pinus , Tylenchida , Animais , Xylophilus , Tylenchida/genética , Doenças das Plantas , Nematoides/genética , Pinus/genética , RNA de Cadeia Dupla
15.
BMC Genomics ; 24(1): 296, 2023 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-37264326

RESUMO

BACKGROUND: Plant-parasitic nematodes (PPNs) that cause most damage include root-knot nematodes (RKNs) which are a major impediment to crop production. Root-knot nematodes, like other parasites, secrete proteins which are required for parasite proliferation and survival within the host during the infection process. RESULTS: Here, we used various computational tools to predict and identify classically and non-classically secreted proteins encoded in the Meloidogyne javanica genome. Furthermore, functional annotation analysis was performed using various integrated bioinformatic tools to determine the biological significance of the predicted secretome. In total, 7,458 proteins were identified as secreted ones. A large percentage of this secretome is comprised of small proteins of ≤ 300 aa sequence length. Functional analyses showed that M. javanica secretome comprises cell wall degrading enzymes for facilitating nematode invasion, and migration by disintegrating the complex plant cell wall components. In addition, peptidases and peptidase inhibitors are an important category of M. javanica secretome involved in compatible host-nematode interactions. CONCLUSION: This study identifies the putative secretome encoded in the M. javanica genome. Future experimental validation analyses can greatly benefit from this global analysis of M. javanica secretome. Equally, our analyses will advance knowledge of the interaction between plants and nematodes.


Assuntos
Tylenchida , Tylenchoidea , Animais , Tylenchoidea/genética , Tylenchoidea/metabolismo , Secretoma , Doenças das Plantas/genética , Tylenchida/metabolismo , Proteínas de Helminto/genética , Proteínas de Helminto/metabolismo
16.
Int J Radiat Biol ; 99(12): 1990-1996, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37382942

RESUMO

PURPOSE: Reproduction inhibition of the pine wood nematode (PWN) by electron beam (e-beam) irradiation both in vitro and in vivo was tested to determine if ionizing radiation could control the PWN by reducing survival and preventing reproduction, thus reducing the risk of pine wilt disease (PWD) spread. MATERIALS AND METHODS: E-beam (10 MeV) irradiation treatment at different doses (0-4 kGy) was applied to PWNs in a Petri dish. Treatment of pine wood logs infested with PWNs was performed at 10 kGy. Mortality was determined by comparing the survival rates before and after irradiation treatment. DNA damage by e-beam irradiation (0-10 kGy) in the PWN was determined using the comet assay. RESULTS: E-beam irradiation increased mortality and suppressed reproduction with increasing doses. The lethal dose (LD) values (kGy) were estimated as follows: LD50 = 2.32, LD90 = 5.03, and LD99 = 9.48. E-beam irradiation of pine wood logs significantly suppressed PWN reproduction. Comets of e-beam-irradiated cells showed an increased tail DNA level and moment with an increasing dose. CONCLUSION: This study suggests that e-beam irradiation could be used as an alternative method for the management of pine wood logs infested with PWNs.


Assuntos
Pinus , Tylenchida , Animais , Xylophilus , Elétrons , Tylenchida/genética
17.
Annu Rev Phytopathol ; 61: 209-230, 2023 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-37186900

RESUMO

Plant-parasitic nematodes are one of the most insidious pests limiting agricultural production, parasitizing mostly belowground and occasionally aboveground plant parts. They are an important and underestimated component of the estimated 30% yield loss inflicted on crops globally by biotic constraints. Nematode damage is intensified by interactions with biotic and abiotic factors constraints: soilborne pathogens, soil fertility degradation, reduced soil biodiversity, climate variability, and policies influencing the development of improved management options. This review focuses on the following topics: (a) biotic and abiotic constraints, (b) modification of production systems, (c) agricultural policies, (d) the microbiome, (e) genetic solutions, and (f) remote sensing. Improving integrated nematode management (INM) across all scales of agricultural production and along the Global North-Global South divide, where inequalities influence access to technology, is discussed. The importance of the integration of technological development in INM is critical to improving food security and human well-being in the future.


Assuntos
Tecnologia , Tylenchida , Humanos , Animais , Agricultura , Políticas , Solo
18.
Molecules ; 28(10)2023 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-37241850

RESUMO

Pine wood nematode (PWN), Bursaphelenchus xylophilus, is a major pathogen of pine wilt disease (PWD), which is a devastating disease affecting pine trees. Eco-friendly plant-derived nematicides against PWN have been considered as promising alternatives to control PWD. In this study, the ethyl acetate extracts of Cnidium monnieri fruits and Angelica dahurica roots were confirmed to have significant nematicidal activity against PWN. Through bioassay-guided fractionations, eight nematicidal coumarins against PWN were separately isolated from the ethyl acetate extracts of C. monnieri fruits and A. dahurica roots, and they were identified to be osthol (Compound 1), xanthotoxin (Compound 2), cindimine (Compound 3), isopimpinellin (Compound 4), marmesin (Compound 5), isoimperatorin (Compound 6), imperatorin (Compound 7), and bergapten (Compound 8) by mass and nuclear magnetic resonance (NMR) spectral data analysis. Coumarins 1-8 were all determined to have inhibitory effects on the egg hatching, feeding ability, and reproduction of PWN. Moreover, all eight nematicidal coumarins could inhibit the acetylcholinesterase (AChE) and Ca2+ ATPase of PWN. Cindimine 3 from C. monnieri fruits showed the strongest nematicidal activity against PWN, with an LC50 value of 64 µM at 72 h, and the highest inhibitory effect on PWN vitality. In addition, bioassays on PWN pathogenicity demonstrated that the eight nematicidal coumarins could effectively relieve the wilt symptoms of black pine seedlings infected by PWN. The research identified several potent botanical nematicidal coumarins for use against PWN, which could contribute to the development of greener nematicides for PWD control.


Assuntos
Angelica , Nematoides , Pinus , Tylenchida , Animais , Cnidium , Xylophilus , Acetilcolinesterase/farmacologia , Frutas , Antinematódeos/farmacologia , Antinematódeos/química , Cumarínicos/farmacologia , Doenças das Plantas
19.
Plant Dis ; 107(10): 3148-3154, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37026625

RESUMO

Root-knot nematodes (Meloidogyne spp.) are the most economically damaging group of plant-parasitic nematodes. They are considered to be a major constraint of pepper (Capsicum annuum L.) crops worldwide. In China, Hainan Island is the main producer of pepper, where the climatic conditions and cropping patterns are favorable for infection by Meloidogyne spp. In this study, we conducted a detailed investigation of the occurrence, severity, and population distribution of root-knot nematodes infesting pepper throughout Hainan Island. We also tested the level of resistance to M. enterolobii and M. incognita of the common pepper cultivars in Hainan. Our results showed that root-knot nematodes belonging to M. enterolobii, M. incognita, and M. javanica were found in Hainan, and the dominant population was M. enterolobii, which is the predominant species in the tropical area. Notably, all the pepper cultivars in this study were highly susceptible to M. enterolobii, which is probably a reason for its rapid spread throughout Hainan. The pepper cultivars exhibited different levels of resistance to M. incognita. This study promotes the comprehensive understanding of the root-knot nematode distribution and host resistance level of Meloidogyne in Hainan, which will guide the effective control of root-knot nematodes.


Assuntos
Capsicum , Tylenchida , Tylenchoidea , Animais , Doenças das Plantas/parasitologia , Raízes de Plantas/parasitologia
20.
Plant Dis ; 107(11): 3344-3353, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37115564

RESUMO

The stubby root nematode Paratrichodorus allius is an important plant-parasitic nematode species within the Trichodoridae family. It can directly harm the plants by feeding on the roots or indirectly by transmitting Tobacco rattle virus. These nematodes are mostly diagnosed either by traditional microscopic methods or a polymerase chain reaction (PCR)-based method. Droplet digital PCR (ddPCR) is a novel PCR technique which is sensitive and precise in quantifying DNA templates of the test samples. In this study, we developed a ddPCR assay to detect and quantify P. allius in soil. The specificity and sensitivity of the assay was first determined using P. allius nematode DNA or DNA from sterilized soil artificially inoculated with P. allius, and the assay was used to quantify P. allius populations in field soils. The assay did not detect nematodes other than P. allius, thus showing high specificity. It was able to detect P. allius equivalent to a 0.01 and 0.02 portion of a single nematode in soil DNA and nematode DNA extracts, respectively. Highly linear relationships between DNA copy numbers from ddPCR and serial dilutions of known concentrations were observed with DNA from P. allius nematodes (R2 = 0.9842) and from artificially infested soil (R2 = 0.9464). The P. allius populations from field soils determined by ddPCR were highly correlated with traditional microscopic counts (R2 = 0.7963). To our knowledge, this is the first report of applying ddPCR to detect and quantify stubby root nematode in soil. The results of this study support the potentiality of a ddPCR assay as a new research tool in diagnostics of plant-parasitic nematodes.


Assuntos
Nematoides , Tylenchida , Animais , Solo/parasitologia , Nematoides/genética , Reação em Cadeia da Polimerase/métodos , Plantas , Tylenchida/genética , DNA
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