Lesion Nematode Pratylenchus Research Articles

Integration of Arbuscular Mycorrhizal and Nematode Antagonistic Fungi for the Biocontrol of Root Lesion Nematode Pratylenchus zeae Graham, 1951 on Sugarcane

To study the integration of two Arbuscular mycorrhizal fungi (AMF) Glomus fasciculatum and G. mosseae and three nematode antagonistic fungi viz., Arthrobotrys oligospora, Purpureocillium lilacinum (= Paecilomyces lilacinus) and Pochonia chlamydosporia on sugarcane cv. 86032 to manage root lesion nematode Pratylenchus zeae, an experiment was conducted under potted condition. Increased shoot and root growth was observed due to either individual or combined inoculations of bioagents than nematode alone control plants. Among the treatments, G. fasciculatum + A. oligospora combination recorded maximum shoot weight followed by G. fasciculatum + P. lilacinum. Reduction in P. zeae population recorded in all the bioagents inoculated plants compared to nematode alone control. The nematode reduction was more when antagonistic fungi were combined with AMF and the nematode reductions in roots was ranged between 50 and 77%. Among the AMF and antagonistic fungi combinations, maximum reduction in nematode population (77%) was recorded with G. fasciculatum + A. oligospora. Compatible association between AMF and other nematode antagonistic fungi observed. There was an increased mycorrhizal colonization recorded in combined treatments of AMF and antagonistic fungi than AMF alone. Integration of AM fungus G. fasciculatum with nematode antagonistic fungus A. oligospora appears to be a potential combination for the control of root lesion nematode P. zeae management in sugarcane.

First report of lesion nematode on new host, Deverra tortuosa, in Mersa Matruh coast, Egypt

Nematological survey was carried out in 2019 on wild plants viz., Aeluropus lagopoides, Ammophila arenaria, Cakile maritime, Deverra tortuosa, Euphorbia paralias, Inula crithmeides, Lotus polyphyllos, Ononis vaginalis, Pancrtium maritimum, Polygonum equisetiforme, Thymelaea hirsuta and Zygophyllum album, colonized the coastal sand dunes habitat of Mersa Matruh, Egypt. Specimens of lesion nematode (Pratylenchus spp.) were collected from rhizosphere soil of Deverra tortuosa Synonym: Pituranthos tortuosus (Desf.) Asch. and Schweinf herb (family: Apiaceae, old Umbelliferae). Lesion nematode was identified based on morphology of females. According to available literature, this is the first report of Pratylenchus on wild plant (Deverra tortuosa) colonized Egypt. More surveys are needed to identify other genera or species of phytonematodes that might occur in Egypt, including weeds, grasses and wild plants in desert areas, also the dissemination of lesion nematode must be explored as well as other plant-feeding nematodes and it is advisable to investigate the nearby cultivated plants.

Natural variation of root lesion nematode antagonism in the biocontrol fungus Clonostachys rosea and identification of biocontrol factors through genome-wide association mapping.

Biological control is a promising approach to reduce plant diseases caused by nematodes to ensure high productivity in agricultural production. Large‐scale analyses of genetic variation in fungal species used for biocontrol can generate knowledge regarding interaction mechanisms that can improve efficacy of biocontrol applications. In this study, we performed a genome‐wide association study (GWAS) for in vitro antagonism against the root lesion nematode Pratylenchus penetrans in 53 previously genome re‐sequenced strains of the biocontrol fungus Clonostachys rosea. Nematode mortality in C. rosea potato dextrose broth (PDB) culture filtrates was highly variable and showed continuous variation (p < .001) between strains, indicating a polygenic inheritance. Twenty‐one strains produced culture filtrates with higher (p ≤ .05) nematode mortality compared with the PDB control treatment, while ten strains lowered (p ≤ .05) the mortality. The difference in in vitro antagonism against P. penetrans correlated with antagonism against the soybean cyst nematode Heterodera glycines, indicating lack of host specificity in C. rosea. An empirical Bayesian multiple hypothesis testing approach identified 279 single nucleotide polymorphism markers significantly (local false sign rate < 10–10) associated with the trait. Genes present in the genomic regions associated with nematicidal activity included several membrane transporters, a chitinase and genes encoding proteins predicted to biosynthesize secondary metabolites. Gene deletion strains of the predicted nonribosomal peptide synthetase genes nps4 and nps5 were generated and showed increased (p ≤ .001) fungal growth and conidiation rates compared to the wild type. Deletion strains also exhibited reduced (p < .001) nematicidal activity and reduced (p ≤ .05) biocontrol efficacy against nematode root disease and against fusarium foot rot on wheat. In summary, we show that the GWAS approach can be used to identify biocontrol factors in C. rosea, specifically the putative nonribosomal peptide synthetases NPS4 and NPS5.

Impacts of Manures and Manure-Based Composts on Root Lesion Nematodes and Verticillium dahliae in Michigan Potatoes.

The interaction of the root lesion nematode Pratylenchus penetrans and the fungal plant pathogen Verticillium dahliae causes potato early die (PED) complex, which induces premature vine senescence and dramatically reduces yield in potatoes. Management of PED is often achieved through the use of soil fumigants and nematicides, but their adverse effects on soil, human and environmental health, and strict regulations worldwide require alternative control tactics. In this study, we investigated the effects of multiple composts and manures on nematode mortality and PED. In lab assays, root lesion nematodes were exposed to poultry manure, layer ash blend, Dairy Doo, or wood ash for 7 days at rates of 0, 0.1, 1, 10, and 20% by volume of product and assessed for nematode survivorship. Additionally, these products were evaluated for volatile fatty acid content to determine if fatty acid content affects nematode control. In a field trial, the composts and manures were evaluated at two different rates, high (11.2 t/ha) or low (2.8 t/ha), and populations of P. penetrans and V. dahliae were quantified. Our results show that a 1% application rate of poultry manure and layer ash blend provided the greatest nematode control in lab assays with 24.5 and 38.2% reduction, respectively, with greater control at higher rates. In the field, plots treated with poultry manure had significantly higher potato yields and significantly fewer nematodes than control plots. Taken together, our results suggest that poultry manure could be a promising amendment to control PED.

Pratylenchus thornei: The Relationship Between Presowing Nematode Density and Yield Loss in Wheat and Barley.

The root lesion nematode Pratylenchus thornei causes economic losses in wheat and barley internationally through both reduced grain yield and grain quality. This study investigated the relationships between the presowing P. thornei density and grain yield and the postharvest nematode densities. Four field experiments were conducted at the same site between 2010 and 2014. A range of presowing P. thornei densities was established in the first year by growing three cereal cultivars that ranged from resistant to susceptible. In the following year, plots were sown with the five same cereal cultivars. A linear relationship was observed between the natural log of the presowing P. thornei density and grain yield across all seasons. The results showed that grain yield losses varied between cultivars and seasons. The importance of season was significant, with this study conducted over several seasons, and it highlighted the variability in yield losses between seasons, which will need further investigation. The greatest yield losses observed were 25 to 28% when the maximum presowing P. thornei densities ranged between 150 and 250 P. thornei g of soil-1. An analysis of the relationship between the presowing and postharvest nematode densities revealed that increased presowing nematode densities resulted in decreased multiplication rates in all seasons and in all cultivars. Nematode multiplication rates also varied between seasons. These results explain why it is difficult to predict nematode levels based on cropping history, and additionally, they highlight the importance of growing resistant cultivars to maintain low levels of P. thornei to minimize risk of yield losses.

Capacidad hospedera de la Chía (Salvia hispanica) a los nematodos Meloidogyne incognita, Meloidogyne graminicola y Pratylenchus sp”, bajo condiciones controladas

Los nematodos Meloidogyne incognita, Meloidogyne graminicola y Pratylenchus sp, son de mucha importancia económica para el Ecuador y en especial para la provincia de Los Ríos donde con frecuencia en el mismo campo se siembra arroz- soya- maíz, difícil de incluir otros cultivos en rotación con fines de manejo de estas tres especies de nematodos. Esta investigación se realizó en la Facultad de Ciencias Agropecuarias de la Universidad Técnica de Babahoyo, ubicada en el kilómetro 7 ½ de la vía Babahoyo-Montalvo. El objetivo fue evaluar la capacidad hospedera de la Chía a los nematodos Meloidogyne incognita, M. graminicola y Pratylenchus sp en condiciones controladas. Para cada especie de nematodos se utilizó 10 macetas llenas con suelo solarizado, en cada una se sembró una planta de chía y se inocularon individualmente con 2500 especímenes de los nematodos mencionados. Las 30 macetas se distribuyeron en un diseño Completamente al Azar. A los 60 días de inoculación se evaluó peso de raíces por planta, número de agallas por planta (Meloidogyne spp.), densidad poblacional de nematodos en suelo y raíces e índice de reproducción de las especies de nematodos investigados. Según los resultados obtenidos, el cultivo de chía silvestre variedad “semilla negra” es altamente susceptible al nematodo agallador de raíces, Meloidogyne incognita, e inmune a M. graminicola. Este cultivo se comportó como hospedero pobre de Pratylenchus sp (población maíz). El índice de reproducción de Meloidogyne incognita en 60 días fue cinco veces superior a la población inicial, y en Pratylenchus sp. fue de 0.3.

An Expansin-Like Candidate Effector Protein from Pratylenchus penetrans Modulates Immune Responses in Nicotiana benthamiana.

The root lesion nematode (RLN) Pratylenchus penetrans is a migratory species that attacks a broad range of crops. After the RLN is initially attracted to host roots by root exudates and compounds, it releases secretions that are critical for successful parasitism. Among those secretions are nematode virulence factors or effectors that facilitate the entry and migration of nematodes through the roots and modulate plant immune defenses. The recognition of the effectors by host resistance proteins leads to effector-triggered immunity and incompatible plant-nematode interactions. Although many candidate effectors of the RLN and other plant-parasitic nematodes have been identified, the detailed mechanisms of their functions and particularly, their host targets remain largely unexplored. In this study, we sequenced and annotated genes encoding expansin-like proteins, which are major candidate effectors of P. penetrans. One of the genes, Pp-EXPB1, which was the most highly expressed during nematode infection in different plant species, was further functionally characterized via transient expression in the model plant Nicotiana benthamiana and global transcriptome profiling of gene expression changes triggered by this candidate effector in plants. As a result of this investigation, the biological roles of Pp-EXPB1 in nematode parasitism were proposed, the putative cellular targets of the proteins were identified, and the molecular mechanisms of plant responses to the nematode-secreted proteins were outlined.

Bacteria isolated from the cuticle of plant-parasitic nematodes attached to and antagonized the root-knot nematode Meloidogyne hapla

Plant-parasitic nematodes are associated with specifically attached soil bacteria. To investigate these bacteria, we employed culture-dependent methods to isolate a representative set of strains from the cuticle of the infective stage (J2) of the root-knot nematode Meloidogyne hapla in different soils. The bacteria with the highest affinity to attach to J2 belonged to the genera Microbacterium, Sphingopyxis, Brevundimonas, Acinetobacter, and Micrococcus as revealed by 16S rRNA gene sequencing. Dynamics of the attachment of two strains showed fast adhesion in less than two hours, and interspecific competition for attachment sites. Isolates from the cuticle of M. hapla J2 attached to the lesion nematode Pratylenchus penetrans, and vice versa, suggesting similar attachment sites on both species. Removal of the surface coat by treatment of J2 with the cationic detergent CTAB reduced bacterial attachment, but did not prevent it. Some of the best attaching bacteria impaired M. hapla performance in vitro by significantly affecting J2 mortality, J2 motility and egg hatch. Most of the tested bacterial attachers significantly reduced the invasion of J2 into tomato roots, suggesting their beneficial role in soil suppressiveness against M. hapla.

Genetic Background of the Resistance against Parasitic Nematodes in Wheat

The state of the art in research on the genes responsible for the resistance of soft wheat Triticum aestivum L. against cereal cyst nematode Heterodera avenae and root lesion nematode Pratylenchus neglectus and the use of these genes in plant breeding programs are described. Most genes responsible for the resistance to these plant pathogens are listed and their chromosomal localization and resistance specificity are described. The sources of resistance genes widely used to control the cereal cyst nematode are presented. The alternative methods for transferring nematode resistance genes into wheat are outlined.

무 뿌리썩이선충에 대한 살선충제의 방제효과 및 무 품질에 미치는 영향

무 뿌리썩이선충에 대한 살선충제의 방제효과 및 무 품질에 미치는 영향

The potential of Citrullus colocynthis oil as a biocide against phytoparasitic nematodes

The high content of nematicidal fatty acids in Citrullus colocynthis seed oil could result in a novel product with a nematicidal potential. In this study, C. colocynthis oil was evaluated for its in vitro activity both against infective juveniles and eggs of the root-knot nematode Meloidogyne incognita and against infective specimens of the lesion nematode Pratylenchus vulnus, as well as against the suppressiveness of M. incognita in an experiment on potted tomatoes. The fatty acid composition of the tested oil was determined by gas chromatography analysis. Linoleic acid methyl ester (44.63%) and oleic acid (26.48%) were the two main fatty acid components, but there were also consistent percentages of erucic acid methyl ester (10.08%), palmitic acid (7.88%), and stearic acid (5.86%). C. colocynthis oil was highly toxic to M. incognita juveniles (>73% mortality) after a 24-h exposure to a 25 μg mL−1 solution, whereas infective specimens of P. vulnus were less sensitive with 46.6% mortality after a 24-h exposure to a 100 μg mL−1 oil solution. The viability of M. incognita eggs was strongly affected by C. colocynthis oil treatments with more than 64% egg mortality resulting from a 72-h immersion in a 250 μg mL−1 oil solution. Soil treatments with C. colocynthis oil resulted in a significant reduction of both M. incognita eggs and gall formation on tomato roots, as well as of nematode density in the soil, in comparison to the non-treated control. Tomato plant growth was not negatively affected by C. colocynthis oil treatments, though a slight increase in plant biomass was recorded at just the highest concentrations of oil. This research demonstrates the nematicidal properties of C. colocynthis oil and, thus, its potential for the formulation of new products that could be applied in the context of organic or integrated management of phytoparasitic nematodes.

A novel species of RNA virus associated with root lesion nematode Pratylenchus penetrans.

The root lesion nematode Pratylenchus penetrans is a migratory species that attacks a broad range of plants. While analysing transcriptomic datasets of P. penetrans, we have identified a full-length genome of an unknown positive-sense single-stranded RNA virus, provisionally named root lesion nematode virus 1 (RLNV1). The 8614-nucleotide genome sequence encodes a single large polyprotein with conserved domains characteristic for the families Picornaviridae, Iflaviridae and Secoviridae of the order Picornavirales. Phylogenetic, BLAST and domain search analyses showed that RLNV1 is a novel species, most closely related to the recently identified sugar beet cyst nematode virus 1 and potato cyst nematode picorna-like virus. In situ hybridization with a DIG-labelled DNA probe confirmed the presence of the virus within the nematodes. A negative-strand-specific RT-PCR assay detected RLNV1 RNA in nematode total RNA samples, thus indicating that viral replication occurs in P. penetrans. To the best of our knowledge, RLNV1 is the first virus identified in Pratylenchus spp.

Identification and characterization of the first pectin methylesterase gene discovered in the root lesion nematode Pratylenchus penetrans.

Similar to other plant-parasitic nematodes, root lesion nematodes possess an array of enzymes that are involved in the degradation of the plant cell wall. Here we report the identification of a gene encoding a cell wall-degrading enzyme, pectin methylesterase PME (EC 3.1.1.11), in the root lesion nematode Pratylenchus penetrans. Both genomic and coding sequences of the gene were cloned for this species, that included the presence of four introns which eliminated a possible contamination from bacteria. Expression of the Pp-pme gene was localized in the esophageal glands of P. penetrans as determined by in situ hybridization. Temporal expression of Pp-pme in planta was validated at early time points of infection. The possible function and activity of the gene were assessed by transient expression of Pp-pme in plants of Nicotiana benthamiana plants via a Potato virus X-based vector. To our knowledge, this is the first report on identification and characterization of a PME gene within the phylum Nematoda.

Occurrence and seasonal variation of the root lesion nematode Pratylenchus neglectuson cereals in Bolu, Turkey

The root lesion nematode Pratylenchus spp. is one of the most important plant-parasitic nematodes causing global cereal yield losses. Effective management of plant-parasitic nematodes depends on reliable management strategies and comprehensive datasets estimating the distribution, abundance, and population change of nematode species. This study reports the occurrence of Pratylenchus neglectus in wheat-growing districts during the 2014/15 and 2015/16 cropping seasons in Bolu, Turkey. Pratylenchus neglectus was identified by both morphological and molecular methods. The nematode was detected in 11.6% of samples collected from five districts. On average, P. neglectus numbered 1556 nematodes/kg soil, while 12% of samples had more than 2500 nematodes/kg soil. P. neglectus population dynamics were evaluated by sowing a susceptible winter wheat variety (Bezostaya) in a naturally infested field near the Çaydurt district of Bolu during the 2014/15 and 2015/16 cropping seasons. There was a positive correlation (P < 0.01) between nematode abundance in roots and surrounding soil temperature. The highest abundance of nematodes in roots occurred during May (average temperature: 22 °C), while the lowest abundance was during December-March (average temperature: 5 °C). The initial population was measured as an average of 60 nematodes/100 g soil. The reproduction rate of P. neglectus ranged from 0.7 to 4.8 individuals.

Bio-Control of the Lesion Nematode Pratylenchus coffeae Using Lixiviate from Banana Rachis (Musa sp.)

The efficiency of lixiviate on the tolerance of plantain to root attacks of Pratylenchus coffeae has been examined. During the growing phase which lasted a month, four different treatments were applied to Banana plants of cultivars CORNE 1 and PITA 3: lix- (no lixiviate), lix100 (100% lixiviate), lix25 (25% lixiviate) and lix5 (5% lixiviate). Then, these plants were inoculated with 500 individuals of P. coffeae to assess the effect of lixiviate treatments against nematodes on both cultivars CORNE 1 and PITA 3. This study showed that 5% lixiviate and 25% lixiviate doses gave better agronomic parameters (mass of root system, the collar circumference, pseudo stem height, leaf area and a number of leaves) evaluated on vivoplants. Cultivars CORNE 1 treated with 25% lixiviate dose and cultivars PITA 3 treated with 5% lixiviate dose, gained tolerance against nematode’s attacks. Otherwise, cultivars PITA 3 were resistant to nematodes after 25% lixiviate dosage because P. coffeae were reduced by 80 % in this treatment. The results presented in this work are encouraging for the development of biological control methods of banana nematodes by lixiviate

Cloning of the defense gene PlchiIII and its potential role in the biocontrol of Pratylenchus coffeae nematodes and Meloidogyne incognita eggs in Musa

Abstract A wide range of crops such as bananas and plantains are devastated by plant parasitic nematodes that affect the root system, leading to impaired plant growth and production. In this scenario, the chitinase gene was isolated from the nematode-resistant cultivar of Pisang lilin. The amplified target gene was cloned into pET28a encoding 323 amino acid residues, which shares a high degree of homology with acidic class III chitinase in Musa acuminata, and the product was transformed into E. coli BL21 strain for protein expression. Using affinity chromatography, the recombinant chitinase was purified as a protein of 29 kDa with an optimal activity at pH 7.0. The purified chitinase was capable of degrading the chitin present in the exoskeleton layer of root lesion nematodes (Pratylenchus coffeae) and in the eggshells of root-knot nematodes (Meloidogyne incognita), as well as significantly influencing its development and mortality. Bioassay was performed under in vitro conditions. In root lesion nematodes, 100% mortality was recorded at concentrations of 0.2 µg/mL and 0.15 µg/mL on the 3rd and 5th days, respectively, whereas the egg-hatching rate was inhibited by 100% at concentrations of 0.2 µg/mL and 0.01 µg/mL on the 1st and 5th days, respectively. The results of this study suggest that the PlchiIII gene can be used as a plant-based microbial agent in the biocontrol of nematodes would help in reducing nematode population and increase the yield of banana.

Resistance to the root lesion nematodes Pratylenchus thornei and P. neglectus in cereals: Improved assessments in the field

The root lesion nematodes (RLN) Pratylenchus thornei and P. neglectus cause yield losses in intolerant field crops, internationally. They both have wide host ranges, invading grass and broadleaf grain crops, pasture species and weeds. Plant resistance, the ability of the plant to prevent nematode reproduction, is the main method of control, but requires accurate information on varietal resistance rankings to plan effective management strategies. This study used a multi environment trial (MET) analysis to examine the effect of cereal varieties (wheat, durum, barley and triticale) on the multiplication of P. thornei and P. neglectus when grown in a range of field environments at high and low pre-sowing nematode densities across a range of growing years. The study measured multiplication of P. thornei (68 varieties) and P. neglectus (62 varieties) in six and seven field experiments, respectively, each with high and low pre-sowing nematode densities, conducted during the years 2011–2014. This study showed genetic variation in the resistance ranking between cereal types and varieties for both P. thornei and P. neglectus. This provides management options to growers and information to breeding programs, which can be used to improve the resistance of future varieties. The consistent rankings across the field experiments and observed high genetic correlation between environments was unexpected given experiments were conducted across a range of years, soil types, geographic locations and different pre-sowing nematode densities. These high correlations suggested that varietal resistance can be determined with small numbers of field experiments, thus reducing the costs and time taken to determine varietal resistance. Finally, it was found that a lower pre-sowing nematode density resulted in a higher nematode multiplication rate compared to the high pre-sowing nematode density. This highlights the need to select resistant varieties to avoid large increases in nematode densities in fields with low nematode densities. This analysis of field experimental data for nematodes is novel and indicates that field data can be used to accurately assess varietal resistance (nematode multiplication) across environments. Therefore, accurate data on varietal resistance that is applicable over wide area can be produced with fewer experiments, resulting in varieties with increased resistance being planted, thus reducing grain yield losses due to root lesion nematodes.

Rhizosphere Microbiomes Modulated by Pre-crops Assisted Plants in Defense Against Plant-Parasitic Nematodes

Plant-parasitic nematodes cause considerable damage to crop plants. The rhizosphere microbiome can affect invasion and reproductive success of plant-parasitic nematodes, thus affecting plant damage. In this study, we investigated how the transplanted rhizosphere microbiome from different crops affect plant-parasitic nematodes on soybean or tomato, and whether the plant’s own microbiome from the rhizosphere protects it better than the microbiome from fallow soil. Soybean plants growing in sterilized substrate were inoculated with the microbiome extracted from the rhizosphere of soybean, maize, or tomato. Controls were inoculated with extracts from bulk soil, or not inoculated. After the microbiome was established, the root lesion nematode Pratylenchus penetrans was added. Root invasion of P. penetrans was significantly reduced on soybean plants inoculated with the microbiome from maize or soybean compared to tomato or bulk soil, or the uninoculated control. In the analogous experiment with tomato plants inoculated with either P. penetrans or the root knot nematode Meloidogyne incognita, the rhizosphere microbiomes of maize and tomato reduced root invasion by P. penetrans and M. incognita compared to microbiomes from soybean or bulk soil. Reproduction of M. incognita on tomato followed the same trend, and it was best suppressed by the tomato rhizosphere microbiome. In split-root experiments with soybean and tomato plants, a systemic effect of the inoculated rhizosphere microbiomes on root invasion of P. penetrans was shown. Furthermore, some transplanted microbiomes slightly enhanced plant growth compared to uninoculated plants. The microbiomes from maize rhizosphere and bulk soil increased the fresh weights of roots and shoots of soybean plants, and microbiomes from soybean rhizosphere and bulk soil increased the fresh weights of roots and shoots of tomato plants. Nematode invasion did not affect plant growth in these short-term experiments. In conclusion, this study highlights the importance of the rhizosphere microbiome in protecting crops against plant-parasitic nematodes. An effect of pre-crops on the rhizosphere microbiome might be harnessed to enhance the resistance of crops towards plant-parasitic nematodes. However, nematode-suppressive effects of a particular microbiome may not necessarily coincide with improvement of plant growth in the absence of plant-parasitic nematodes.

Control of Pratylenchus brachyurus in soybean with Trichoderma spp. and resistance inducers

AbstractTrichoderma spp. is a fungus with nematode control potential; however, its potential to control the root lesion nematode Pratylenchus brachyurus remains poorly studied. Thus, the aim of this study was to select Trichoderma spp. isolates and assess their ability to control P. brachyurus in soybean crops. Different experiments were conducted aiming at selecting isolates, assessing whether they were able to reduce nematode penetration in plants or cause mortality in vitro, and whether they were able to induce resistance in soybean, as well as at studying the possibility of using the selected isolates associated with resistance inducers (acibenzolar‐S‐methyl, Ecolife™ and AgroMos™). The selection experiment found three isolates showing satisfactory results, namely GF422, GF425 and GF427; the GF362 isolate was assessed in the subsequent experiments. These four isolates reduced P. brachyurus penetration in soybean roots and promoted nematode mortality in vitro. Increased total protein and catalase activity were recorded, mainly in the 72‐hr assessments. Overall, the protein production was different between isolates. The best results were found in the combination between the GF362 isolate and the three resistance inducers, between GF427 and Ecolife™, between GF427 and AgroMos™ and between GF422 and Ecolife™.

Serotonin Regulates the Feeding and Reproductive Behaviors of Pratylenchus penetrans.

The success of all plant-parasitic nematodes is dependent on the completion of several complex behaviors. The lesion nematode Pratylenchus penetrans is an economically important parasite of a diverse range of plant hosts. Unlike the cyst and root-knot nematodes, P. penetrans moves both within and outside of the host roots and can feed from both locations. Adult females of P. penetrans require insemination by actively moving males for reproduction and can lay eggs both within and outside of the host roots. We do not have a complete understanding of the molecular basis for these behaviors. One candidate modulator of these behaviors is the neurotransmitter serotonin. Previous research demonstrated an effect of exogenously applied serotonin on the feeding and male mating behaviors of cyst and root-knot nematodes. However, there are no data on the role of exogenous serotonin on lesion nematodes. Similarly, there are no data on the presence and function of endogenous serotonin in any plant-parasitic nematode. Here, we establish that exogenous serotonin applied to P. penetrans regulates both feeding and sex-specific behaviors. Furthermore, using immunohistochemistry and pharmacological assays, our data suggest that P. penetrans utilizes endogenous serotonin to regulate both feeding and sex-specific behaviors.