Meloidogyne Research Articles

The root-knot nematode effector MiEFF12 targets the host ER quality control system to suppress immune responses and allow parasitism.

Root-knot nematodes (RKNs) are microscopic parasitic worms able to infest the roots of thousands of plant species, causing massive crop yield losses worldwide. They evade the plant's immune system and manipulate plant cell physiology and metabolism to transform a few root cells into giant cells, which serve as feeding sites for the nematode. RKN parasitism is facilitated by the secretion in planta of effector molecules, mostly proteins that hijack host cellular processes. We describe here a conserved RKN-specific effector, effector 12 (EFF12), that is synthesized exclusively in the oesophageal glands of the nematode, and we demonstrate its function in parasitism. In the plant, MiEFF12 localizes to the endoplasmic reticulum (ER). A combination of RNA-sequencing analysis and immunity-suppression bioassays revealed the contribution of MiEFF12 to the modulation of host immunity. Yeast two-hybrid, split luciferase and co-immunoprecipitation approaches identified an essential component of the ER quality control system, the Solanum lycopersicum plant bap-like (PBL), and basic leucine zipper 60 (BZIP60) proteins as host targets of MiEFF12. Finally, silencing the PBL genes in Nicotiana benthamiana decreased susceptibility to Meloidogyne incognita infection. Our results suggest that EFF12 manipulates PBL function to modify plant immune responses to allow parasitism.

A QTL on Maize Chromosome 5 is Associated with Root-Knot Nematode Resistance.

This study provides the first report of a quantitative trait locus (QTL) in maize (Zea mays) for resistance to the southern root-knot nematode (SRKN) (Meloidogyne incognita). The SRKN can feed on the roots of maize in the U.S. Southern Coastal Plain region and can cause yield losses of 30% or greater in heavily infested fields. Increases in SRKN density in the soil may reduce the yield for subsequently planted susceptible crops. The use of maize hybrids with resistance to SRKN could prevent an increase in SRKN density, yet no genetic regions have been identified that confer host resistance. In this study, a B73 (susceptible) x Ky21 (resistant) S5 recombinant inbred line (RIL) population was phenotyped for total number of eggs (TE) and root weight. This population has been previously genotyped using single nucleotide polymorphisms (SNPs). By utilizing the SNP data with the phenotype data, a single QTL was identified on chromosome 5 that explained 15% of the phenotypic variation (PV) for the number of eggs and 11% of the PV for the number of eggs per g of root (EGR). Plants that were homozygous for the Ky21 allele for the most associated marker PZA03172.3 had fewer eggs and fewer EGR than the plants that were homozygous or heterozygous for the B73 allele. Thus, the first QTL for SRKN resistance in maize has been identified and could be incorporated into maize hybrids.

Efficacy of nematicides, Tricuran-P (Trichoderma harzianum T-22) and chicken manure on cucumber root-knot nematode populations, plant growth and soil enzyme activities

Efficacy of nematicides, Tricuran-P (Trichoderma harzianum T-22) and chicken manure on cucumber root-knot nematode populations, plant growth and soil enzyme activities

Effectiveness of bionematicide from Purpureocillium lilacinum in controlling root-knot nematodes (Meloidogyne spp.)

This research aimed to study the efficacy of the fungus Purpureocillium lilacinum as a bionematicide to control root-knot nematodes (RKN). Two steps of experiments were carried out in this study. The first experiment involved the application of various levels of bionematicide doses to control RKN on tomato plants. The second experiment tested the application of bionematicide (both as a single application and in combination with bromelain compost) to control RKN on guava cv. Kristal. A carbofuran nematicide was applied following the company’s recommendation in this second experiment for comparison. The results of the first trial showed that the application of P. lilacinum bionematicide at doses ranging from 20–40 g per plant or 7–13 g per kg of soil was effective in reducing the J-2 RKN population in the soil and roots, as well as mitigating damage to plant roots. In the second experiment, it was shown that the application of P. lilacinum bionematicide, either alone or mixed with bromelain compost, was more effective than the application of carbofuran nematicide in reducing the J-2 RKN population in the soil and roots, as well as in minimizing root damage to guava seedlings. Additionally, the application of bionematicides mixed with compost proved more effective than their single application in reducing plant root damage. Furthermore, apart from being able to control nematode populations and plant damage, P. lilacinum bionematicide could stimulate plant growth.

Volatile organic compounds released from entomopathogenic nematode-infected insect cadavers for the biocontrol of Meloidogyne incognita.

Root-knot nematodes (RKNs), Meloidogyne spp., are one of the most destructive polyphagous plant-parasitic nematodes. They pose a serious threat to global food security and are difficult to control. Entomopathogenic nematodes (EPNs) show promise in controlling RKNs. However, it remains unclear whether the volatile organic compounds (VOCs) emitted from EPN-infected cadavers can control RKNs. We investigated the fumigation activity of VOCs released from cadavers infected by five different species of EPNs on RKNs in Petri dishes, and found that VOCs released from Steinernema feltiae (SN strain) and S. carpocapsae (All strain) infected cadavers had a significant lethal effect on second-stage juveniles (J2s) of Meloidogyne incognita. The VOCs released from the cadavers infected with S. feltiae were analyzed using SPME-GC/MS. Dimethyl disulfide (DMDS), tetradecane, pentadecane, and butylated hydroxytoluene (BHT), were selected for a validation experiment with pure compounds. The DMDS compound had significant nematicidal activity and repelled J2s. DMDS also inhibited egg hatching and the invasion of tomato roots by J2s. In a pot experiment, the addition of S. feltiae-infected cadavers and cadavers wrapped with a 400-mesh nylon net also significantly reduced the population of RKNs in tomato roots after 7 days. The number of root knots and eggs was reduced by 58% and 74.34%, respectively, compared to the control. These results suggested that the VOCs emitted by the EPN-infected cadavers affected various developmental stages of M. incognita and thus have the potential to be used in controlling RKNs through multiple methods. © 2024 Society of Chemical Industry.

Unraveling the enigma of root-knot nematodes: from origins to advanced management strategies in agriculture.

Integrated management strategies, including novel nematicides and resilient cultivars, offer sustainable solutions to combat root-knot nematodes, crucial for safeguarding global agriculture against persistent threats. Root-knot nematodes (RKN) pose a significant threat to a diverse range of host plants, with their obligatory endoparasitic nature leading to substantial agricultural losses. RKN spend much of their lives inside or in contact by secreting plant cell wall-modifying enzymes resulting in the giant cell development for establishing host-parasite relationships. Additionally, inflicting physical harm to host plants, RKN also contributes to disease complexes creation with fungi and bacteria. This review comprehensively explores the origin, history, distribution, and physiological races of RKN, emphasizing their economic impact on plants through gall formation. Management strategies, ranging from cultural and physical to biological and chemical controls, along with resistance mechanisms and marker-assisted selection, are explored. While recognizing the limitations of traditional nematicides, recent breakthroughs in non-fumigant alternatives like fluensulfone, spirotetramat, and fluopyram offer promising avenues for sustainable RKN management. Despite the success of resistance mechanisms like the Mi gene, challenges persist, prompting the need for integrative approaches to tackle Mi-virulent isolates. In conclusion, the review stresses the importance of innovative and resilient control measures for sustainable agriculture, emphasizing ongoing research to address evolving challenges posed by RKN. The integration of botanicals, resistant cultivars, and biological controls, alongside advancements in non-fumigant nematicides, contributes novel insights to the field, laying the ground work for future research directions to ensure the long-term sustainability of agriculture in the face of persistent RKN threats.

Harnessing Walnut-Based Zinc Oxide Nanoparticles: A Sustainable Approach to Combat the Disease Complex of Meloidogyne arenaria and Macrophomina phaseolina in Cowpea.

Zinc oxide nanoparticles (ZnO NPs) exhibit diverse applications, including antimicrobial, UV-blocking, and catalytic properties, due to their unique structure and properties. This study focused on the characterization of zinc oxide nanoparticles (ZnO NPs) synthesized from Juglans regia leaves and their application in mitigating the impact of simultaneous infection by Meloidogyne arenaria (root-knot nematode) and Macrophomina phaseolina (root-rot fungus) in cowpea plants. The characterization of ZnO NPs was carried out through various analytical techniques, including UV-visible spectrophotometry, Powder-XRD analysis, FT-IR spectroscopy, and SEM-EDX analysis. The study confirmed the successful synthesis of ZnO NPs with a hexagonal wurtzite structure and exceptional purity. Under in vitro conditions, ZnO NPs exhibited significant nematicidal and antifungal activities. The mortality of M. arenaria juveniles increased with rising ZnO NP concentrations, and a similar trend was observed in the inhibition of M. phaseolina mycelial growth. SEM studies revealed physical damage to nematodes and structural distortions in fungal hyphae due to ZnO NP treatment. In infected cowpea plants, ZnO NPs significantly improved plant growth parameters, including plant length, fresh mass, and dry mass, especially at higher concentrations. Leghemoglobin content and the number of root nodules also increased after ZnO NP treatment. Additionally, ZnO NPs reduced gall formation and egg mass production by M. arenaria nematodes and effectively inhibited the growth of M. phaseolina in the roots. Furthermore, histochemical analyses demonstrated a reduction in oxidative stress, as indicated by decreased levels of reactive oxygen species (ROS) and lipid peroxidation in ZnO NP-treated plants. These findings highlight the potential of green-synthesized ZnO NPs as an eco-friendly and effective solution to manage disease complex in cowpea caused by simultaneous nematode and fungal infections.

New management systems for northern root-knot nematode (Meloidogyne hapla Chitwood Tylenchida: Heteroderidae) in daylily (Hemerocallis spp.) ornamental plant production fields

Michigan has the third largest floriculture industry in the United States, with the production of daylily (Hemerocallis spp.) a top commodity. Daylily is one of the most economically important ornamental plants, yet their production is plagued by plant-parasitic nematodes, especially the northern root-knot nematode, Meloidogyne hapla. Seven treatments in combination with a high-carbon, cow manure compost were selected for a three-year field trial at a commercial nursery in Zeeland, MI to discern the best M. hapla management strategies in daylily field production for its entire production cycle. Treatments included the compost manure by itself, Indemnify as a soil drench and as a pre-plant dip both together and separately, AzaGuard, TerraClean 5.0, and an untreated control. Additionally, a similar multi-year greenhouse trial was conducted and included a new treatment: Majestene 304. Results showed that the high-carbon, cow manure compost + Indemnify as a soil drench by itself and in combination as a pre-plant dip were the most effective treatments in reducing M. hapla population levels; in the greenhouse experiment, Indemnify reduced population levels by 83%. Majestene 304 provided the next best control of M. hapla, yet it had the highest gall ratings; the compost by itself was not effective, having higher M. hapla populations than the control in both experiments. Lastly, both trials emphasize the importance of applying these management strategies every year for the best M. hapla management. These results give the ornamental plant industry new, effective management systems to control M. hapla in ornamental plant field production.

Host-induced RNA interference targeting the neuromotor gene FMRFamide-like peptide-14 (Mi-flp14) perturbs Meloidogyne incognita parasitic success in eggplant.

The study demonstrates the successful management of Meloidogyne incognita in eggplant using Mi-flp14 RNA interference, showing reduced nematode penetration and reproduction without off-target effects across multiple generations. Root-knot nematode, Meloidogyne incognita, causes huge yield losses worldwide. Neuromotor function in M. incognita governed by 19 neuropeptides is vital for parasitism and parasite biology. The present study establishes the utility of Mi-flp14 for managing M. incognita in eggplant in continuation of our earlier proof of concept in tobacco (US patent US2015/0361445A1). Mi-flp14 hairpin RNA construct was used for generating 19 independent transgenic eggplant events. PCR and Southern hybridization analysis confirmed transgene integration and its orientation, while RT-qPCR and Northern hybridization established the generation of dsRNA and siRNA of Mi-flp14. In vitro and in vivo bio-efficacy analysis of single-copy events against M. incognita showed reduced nematode penetration and development at various intervals that negatively impacted reproduction. Interestingly, M. incognita preferred wild-type plants over the transgenics even when unbiased equal opportunity was provided for the infection. A significant reduction in disease parameters was observed in transgenic plants viz., galls (40-48%), females (40-50%), egg masses (35-40%), eggs/egg mass (50-55%), and derived multiplication factor (60-65%) compared to wild type. A unique demonstration of perturbed expression of Mi-flp14 in partially penetrated juveniles and female nematodes established successful host-mediated RNAi both at the time of penetration even before the nematodes started withdrawing plant nutrients and later stage, respectively. The absence of off-target effects in transgenic plants was supported by the normal growth phenotype of the plants and T-DNA integration loci. Stability in the bio-efficacy against M. incognita across T1- to T4-generation transgenic plants established the utility of silencing Mi-flp14 for nematode management. This study demonstrates the significance of targeting Mi-flp14 in eggplant for nematode management, particularly to address global agricultural challenges posed by M. incognita.

Host Status and Response Differences of Flat-Leaf and Curly-Leaf Parsley to Meloidogyne hapla, M. chitwoodi, M. fallax, and M. incognita Infestation.

Leaf parsley growth and productivity are often affected by pathogen infection. Root-knot nematodes of the genus Meloiogyne are common pathogens reported on leaf parsley. The response of leaf parsley to Meloidogyne species in tropical and subtropical regions is quite known, while in temperate regions, comparable information is still scarce. In this study, we evaluated the host status and response of three flat-leaf (Laica, Laura, Gigante d'Italia) and three curly-leaf (Grüne Perle, Orfeo, Sombre) parsley cultivars to Meloidogyne species from temperate regions, i.e., M. hapla, M. chitwoodi, and M. fallax, as well as to the southern root-knot nematode M. incognita. Evaluation was based on measuring plant biomass and nematode reproduction nine weeks after nematode inoculation. Our results showed that all four Meloidogyne species did not cause the reduction in leaf parsley growth under the given experimental conditions. Regarding the host status of leaf parsley cultivars for Meloidogyne, results were variable. All six parsley cultivars were found to be good hosts for M. hapla. Regarding M. chitwoodi, the host status could not be clarified properly; however, each cultivar allowed nematode reproduction at least in one experiment. For M. fallax, flat-leaf parsley turned out to be less susceptible than curly-leaf parsley; and for M. incognita, Orfeo, Laura, and Laica were classified as good hosts, Grüne Perle and Sombre as poor hosts, and Gigante d'Italia as a non-host. Amongst all tested cultivars, Gigante d'Italia was found to be the least susceptible cultivar due to its poor host status for M. chitwoodi and non-host status for M. fallax and M. incognita. Infection with M. hapla, M. chitwoodi, and M. incognita, but not with M. fallax, resulted in distinct gall formation on the roots of all six leaf parsley cultivars.

Nitrated fly ash inhibits root-knot nematode and alleviates biotic stress in beetroot: A novel approach towards soil friendly nematode management

Due to the toxic effects of chemical pesticides on the beneficial soil microbiome, alternative ecofriendly tactics are required for sustainable disease management in crops. To find a cost-effective and comparatively safe management practice, we investigated a novel approach by evaluating the waste fly ash modified as nitrated fly ash to control a notorious pest, Meloidogyne enterolobii, which causes considerable losses to beetroot through root-knot disease. Molecular characterization through SSU rRNA confirmed the identification of the pathogen M. enterolobii, which significantly hampers plant growth, pigment content, and yield of beetroot plants. However, applying optimum nitrated fly ash (15 % fly ash + 150 kg/ha N) significantly reduced disease severity significantly and substantially improved the plant biomass, biochemical attributes, and yield of beetroot plants. Furthermore, scanning electron microscopy revealed a significant improvement in nematode stress-induced stomatal closure with the application of nitrated fly ash at 15 % fly ash +150 kg/ha nitrogen amendment to the soil. The nematicidal activities of fly ash were also confirmed through in vitro experiments combined with cell viability methods. Our results suggest that exploiting nitrated fly ash at optimum concentrations can be a promising approach to manage this waste product and control root-knot nematodes (RKNs) in an eco-friendly manner.

Response of mint varieties from Central Europe (Mentha spp.) to Meloidogyne infestation

Mentha is a cosmopolitan genus of medicinal and aromatic plants, which is characterised by the essential oils in its leaves and its therapeutic and aromatic qualities. Mint species are usually cultivated as a perennial crop and therefore susceptible for various pests and diseases. Root-knot nematodes of the genus Meloidogyne are one of the pathogens that can reproduce on mint and cause plant growth reduction. To better understand the pathogenicity of Meloidogyne on mint we studied whether an increasing number of Meloidogyne affects plant growth and essential oil content in the leaves. For our greenhouse experiments, we selected peppermint (Mentha x piperita ˈMultimenthaˈ) as the major mint variety cultivated in Central Europe and the root-knot nematode M. hapla that can pose a major threat in temporal regions. In addition, we evaluated the pathogenicity and reproduction of M. chitwoodi, M. fallax and M. incognita on peppermint and other commonly grown mint varieties in Central Europe, i.e. Mentha x piperita ˈFränkische Blaueˈ, apple mint (M. rotundifolia) and spearmint (M. spicata). None of the studied root-knot nematode species had a negative impact on plant growth of peppermint ˈMultimenthaˈ. However, high densities of M. hapla caused a reduction in the essential oil content. In conclusion, peppermint ˈMultimenthaˈ turned out to be a good host for M. hapla, but a non-host for M. chitwoodi, M. fallax and M. incognita. Plant growth of all four mint varieties was not affected by M. hapla infestation. In addition, peppermint ˈMultimenthaˈ and spearmint were more susceptible to M. hapla than apple mint and peppermint ˈFränkische Blaueˈ.

Antifeedant, antifungal and nematicidal compounds from the endophyte Stemphylium solani isolated from wormwood

The continuous search for natural product-based biopesticides from fungi isolated from untapped sources is an effective tool. In this study, we studied a pre-selected fungal endophyte, isolate Aa22, from the medicinal plant Artemisia absinthium, along with the antifungal, insect antifeedant and nematicidal compounds present in the extract. The endophyte Aa22 was identified as Stemphylium solani by molecular analysis. The antifungal activity was tested by broth microdilution against Fusarium solani, F. oxysporum, F. moniliforme and Botrytis cinerea, the insect antifeedant by choice bioassays against Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi and the in vitro mortality against the root-knot nematode Meloiydogyne javanica. The structures of bioactive compounds were determined on the basis of 1D and 2D NMR spectroscopy and mass spectrometry. The ethyl acetate extract obtained from the solid rice fermentation showed mycelial growth inhibition of fungal pathogens (EC50 0.08–0.31 mg/mL), was antifeedant to M. persicae (99%) and nematicidal (68% mortality). A bioguided fractionation led to the isolation of the new compound stempholone A (1), and the known stempholone B (2) and stemphol (3). These compounds exhibited antifeedant (EC50 0.50 mg/mL), antifungal (EC50 0.02–0.43 mg/L) and nematicidal (MLD 0.5 mg/mL) activities. The extract activities can be explained by 3 (antifungal), 1–3 (antifeedant) and 1 (nematicidal). Phytotoxicity tests on Lolium perenne and Lactuca sativa showed that the extract and 1 increased L. sativa root growth (121–130%) and 1 reduced L. perenne growth (48–49%). These results highlight the potential of the endophytic fungi Aa22 as biotechnological source of natural product-based biopesticides.

Isolation, characterization, and predatory activity of nematode-trapping fungus, Arthrobotrys oligospora PSGSS01

A research study was undertaken to find a fungus that could effectively trap and kill Meloidogyne spp., which are root-knot nematodes that cause significant crop loss worldwide. Soil samples were collected and processed appropriately for the isolation of nematode-trapping fungi. After a primary screening, a potential nematode-trapping fungus, Arthrobotrys oligospora (Orbilia oligospora) PSGSS01 was selected for further investigation. Its growth was tested under various conditions, including different media types, temperatures, and pH levels. Its predatory activity on Meloidogyne incognita was also assessed in vitro. The fungus exhibited septate double-celled conidiospores, trapping hyphae, and radiating and sparse mycelium. Optimal conditions for growth were found to be at 25 °C and a pH of 4.0 and 5.0 on corn meal agar. The best temperature and pH for conidiospore germination were 25°C − 37°C and 5.0, respectively. The isolate could trap 94% of second-stage juveniles of M. incognita, and 92% juvenile mortality was recorded in 120 h at 28°C. Therefore, the study concluded that the isolate A. oligospora (Orbilia oligospora) PSGSS01 could be used as a biological control agent against root-knot nematodes.

Simulation and application assessment of the efficacy of fosthiazate-loaded microcapsules against root-knot nematode.

Although microencapsulation technology is an effective pesticide formulation method, the correlation between the release properties of microcapsules and pesticide concentrations in soil and their efficacy has not been thoroughly investigated. Here, the effects of the release properties of the nematicide Fosthiazate (FTZ) from microcapsules on their efficacy against the nematode Meloidogyne incognita were examined using experimental and mathematical approaches. Gradual release of FTZ from both polyurea microcapsules (PU-MC) and melamine-formaldehyde microcapsules (MF-MC) was observed over 30 days in the release test, and each release curve was completely distinct. In the biological test, the efficacy of both microcapsules against M. incognita 42 days after the application was 8-15% higher than that of the non-encapsulated FTZ at a concentration of 2.0 mg FTZ kg-1 soil. Soil degradation experiments suggested that the microcapsules worked effectively to protect the FTZ from degradation, which resulted in higher efficacy at a later stage. A simulation study to predict the concentration of FTZ outside the microcapsule found that the timing of supplying FTZ was important and suggested that the mixture of non-encapsulated FTZ (non-MC) and MF-MC showed enhanced efficiency for the entire cultivation period in the biological test; the efficacy against nematodes was also confirmed by the measurement of nematode density using the Bearman funnel method. The release properties of FTZ from microcapsules are critical for their effective application against M. incognita, and the established simulation study is a useful step in designing suitable release properties under complex soil conditions. © 2024 Society of Chemical Industry.

Identification of Combined Resistance to Meloidogyne enterolobii and M. incognita in Sweet Potato Genotypes

Root-knot nematodes, genus Meloidogyne, are the most damaging nematodes of sweet potato, causing yield reduction and aesthetic damage of the marketable product. Several sweet potato cultivars currently grown in the Unites States have intermediate-to-high resistance to Meloidogyne incognita; however, many of these cultivars are susceptible to M. enterolobii. Therefore, the response of 69 sweet potato genotypes to M. enterolobii and M. incognita was evaluated under greenhouse conditions to identify potential sources of resistance. The cultivars ‘Beauregard’ and ‘Jewel’ were used as controls. Results showed that sweet potato genotypes were either highly resistant or highly susceptible to M. enterolobii, whereas they showed a wide-spectrum response to M. incognita, ranging from highly susceptible to highly resistant. Twenty-six genotypes were resistant to M. enterolobii and 11 genotypes were resistant to M. incognita. Combined resistance to M. enterolobii and M. incognita was observed in three sweet potato genotypes. Selected genotypes from this study will be used to incorporate the observed resistance into a commercially viable sweet potato cultivar.

CRISPR/Cas9-induced knockout of an amino acid permease gene (AAP6) reduced Arabidopsis thaliana susceptibility to Meloidogyne incognita

BackgroundPlant-parasitic root-knot nematode (Meloidogyne incognita) causes global yield loss in agri- and horticultural crops. Nematode management options rely on chemical method. However, only a handful of nematicides are commercially available. Resistance breeding efforts are not sustainable because R gene sources are limited and nematodes have developed resistance-breaking populations against the commercially available Mi-1.2 gene-expressing tomatoes. RNAi crops that manage nematode infection are yet to be commercialized because of the regulatory hurdles associated with transgenic crops. The deployment of the CRISPR/Cas9 system to improve nematode tolerance (by knocking out the susceptibility factors) in plants has emerged as a feasible alternative lately.ResultsIn the present study, a M. incognita-responsive susceptibility (S) gene, amino acid permease (AAP6), was characterized from the model plant Arabidodpsis thaliana by generating the AtAAP6 overexpression line, followed by performing the GUS reporter assay by fusing the promoter of AtAAP6 with the β-glucuronidase (GUS) gene. Upon challenge inoculation with M. incognita, overexpression lines supported greater nematode multiplication, and AtAAP6 expression was inducible to the early stage of nematode infection. Next, using CRISPR/Cas9, AtAAP6 was selectively knocked out without incurring any growth penalty in the host plant. The ‘Cas9-free’ homozygous T3 line was challenge inoculated with M. incognita, and CRISPR-edited A. thaliana plants exhibited considerably reduced susceptibility to nematode infection compared to the non-edited plants. Additionally, host defense response genes were unaltered between edited and non-edited plants, implicating the direct role of AtAAP6 towards nematode susceptibility.ConclusionThe present findings enrich the existing literature on CRISPR/Cas9 research in plant-nematode interactions, which is quite limited currently while compared with the other plant-pathogen interaction systems.

Bio-Efficacy of Bacillus Species in the Management of Root-Knot Nematode Pest of Pepper

Bio-Efficacy of Bacillus Species in the Management of Root-Knot Nematode Pest of Pepper

Unraveling the Roles of Neuropeptides in the Chemosensation of the Root-Knot Nematode Meloidogyne javanica.

The identification of novel drug targets in plant-parasitic nematodes (PPNs) is imperative due to the loss of traditional nematicides and a lack of replacements. Chemosensation, which is pivotal for PPNs in locating host roots, has become a focus in nematode behavioral research. However, its underlying molecular basis is still indistinct in such a diverse group of PPNs. To characterize genes participating in chemosensation in the Javanese root-knot nematode Meloidogyne javanica, RNA-sequencing of the second-stage juveniles (J2s) treated with tomato root exudate (TRE) for 1 h and 6 h was performed. Genes related to chemosensation in M. javanica mainly responded to TRE treatment at 1 h. Moreover, a gene ontology (GO) analysis underscored the significance of the neuropeptide G protein-coupled receptor signaling pathway. Consequently, the repertoire of putative neuropeptides in M. javanica, including FMRFamide-like peptides (FLPs), insulin-like peptides (ILPs), and neuropeptide-like peptides (NLPs), were outlined based on a homology analysis. The gene Mjflp-14a, harboring two neuropeptides, was significantly up-regulated at 1 h TRE treatment. Through peptide synthesis and J2 treatment, one of the two neuropeptides (MjFLP-14-2) was proven to influence the J2 chemotaxis towards tomato root tips. Overall, our study reinforces the potential of nematode neuropeptides as novel targets and tools for root-knot nematode control.

Inoculation of Fava Bean Plants (Vicia faba L.) with a PGPR Combination Suppresses the Impact of Root-Knot Nematode and Promotes Plant Growth

Inoculation of Fava Bean Plants (Vicia faba L.) with a PGPR Combination Suppresses the Impact of Root-Knot Nematode and Promotes Plant Growth