Meloidogyne Incognita Eggs Research Articles

Combined effect of neem leaf powder and vermicompost in the management of root-knot nematode disease in Celosia argentea

Due to the rising demand for alternative options for root-knot nematode management, Neem (Azadirachta indica) leaf powder and Vermicompost were tested for their efficacy in controlling this disease in Celosia argentea. An experiment, laid out in Completely Randomized Design, was carried out in the screenhouse. It involved the testing of eight treatments which were replicated four times thus making a total of 32 experimental pots. The trial was repeated once to validate results obtained. Plants were inoculated with 5000 Meloidogyne incognita (Mi) eggs. The experimental pots without Mi egg served as the control. Data were collected on plant height, stem girth, number of leaves, branches and flowers, leaf area index, shoot weight, root weight, dry weight, number of galls, final nematode and egg population and subjected to Analysis of Variance. The New Duncan Multiple Range Test was used to separate statistically significant treatment means. Results showed that the amendments used, reduced the infestation of the treated plants whose final Mi nematode population (2360, 2020, 2050, 1720, 1540, 1230) and egg population (2250, 2030, 2120, 1690, 1540, 1230) which were lower (P d” 0.05) than their initial population (5000 eggs) and when compared to the untreated Mi-inoculated (control) plants which had the highest final population (5858 and 5620) that outnumbered the original inoculum. Neem leaf powder and Vermicompost combined at 1% was statistically at par with other treatments in the reduction of the root-knot disease of C. argentea

Biocontrol of the root-knot nematode Meloidogyne incognita with Purporeocillum lilacinum and liquid bio-formulates in tomato (Solanum lycopersicum)

Root-knot nematodes (Meloidogyne spp.) cause great losses in tomato crops. An environmentally friendly for its control is the use of predatory fungi such as Purporeocillum lilacinum, which reduces its population in the soil and mitigates yield losses. Therefore, the objective of the present study was to evaluate the biocontrol efficacy of the strains of the nematophagous fungus Purporeocillum lilacinum and liquid bioformulates on the eggs of the root-knot nematode Meloidogyne incognita, and the formation of galls on the tomato root. Two native strains of Purporeocillum lilacinum H2 and H3 combined with the bioformulated Extract of Beneficial Microorganisms (EPMB®) and the root exudate stimulator Exu-Root® were tested on Meloidogyne incognita eggs and tomato plants. The results obtained indicate that the Purporeocillum lilacinum H2 and H3 strains infected the Meloidogyne incognita eggs, interrupted the development of the embryos and caused their death, which significantly reduced the presence of galls in the root of the plants. In short, the maximum biological performance was presented with the treatments H2+Exu-Root® and H3+EPMB®, which had the lowest number of galls with 19.2 and 20.3 galls per plant respectively, compared to the control that presented 88 galls in the root and the treatments where the fungus was not applied (69-85 galls). Finally, it is concluded that the results demonstrate the potential of the Purporeocillum lilacinum H2 and H3 strains as biocontrol agents against the root-knot nematode Meloidogyne incognita, and that, in combination with EPMB® and Exu-Root®, the efficacy can be increased to reduce its population.

Crude Aqueous Root Extracts of Solanum spp. Show Nematotoxic Activity Against Meloidogyne incognita

Brazilian crops are strongly affected by the root-knot nematode Meloidogyne incognita, which compromises food production and causes serious economic losses around the world. Synthetic nematicides are still some of the main control strategies for this pathogen, despite the high risk to human health and the environment. Therefore, sustainable biotechnology represents a viable alternative for nematode control. Plants of the Solanaceae family are present in several biomes and are a source of secondary metabolites of various chemical classes. In this context, the nematotoxic effect of crude aqueous root extracts (CAREs) of three Solanum species was investigated: Solanum americanum, S. subinerme and S. lycocarpum. CARE showed high nematicidal activity (94.6±9.2% mortality, p ≤ 0.001) against second-stage juveniles (J2) of M. incognita, even after heating to 50 °C. These CAREs also inhibited hatching of juveniles (98.4±0.7% of mortality, p ≤ 0.001) in addition to presenting a mean lethal dose of 336 μg ml-1. No toxic activity was observed against non-target organisms, such as fungi (Trichoderma harzianum and Trichoderma asperellum), yeast (Candida maltosa), nitrogen-fixing bacteria (Bradyrhizobium diazoefficiaens, B. japonicum), two strains of Azospirillum brasilense, AbV 5 and AbV 6 and Bacillus [2538 Ba]. Bioassay performed in a greenhouse demonstrated that CAREs of these species were effective in reducing the number of egg masses and galls (> 85%, p ≤ 0.0001), and did not show a phytotoxic effect on soybean seedlings. Our findings indicate that CAREs from plants of the Solanaceae family, especially S. lycocarpum, demonstrated nematotoxic activity on J2 and inhibited the hatching of Meloidogyne incognita eggs, representing an ecologically appropriate tool to control nematode infection in crops worldwide.

Parasitism of Meloidogyne incognita eggs by Native Fungi of Assam

In the current investigation, four fungi viz., Paecilomyces niphetodes, Acremonium falciforme, Fusarium oxysporium, and F. solani were capable of parasitizing Meloidogyne incognita eggs. The high percentage of egg parasitism was recorded by P. niphetodes. Microscopic examinations showed that the hyphae of P. niphetode, A. falcifrome, F. oxysporum and F. solani were closely attached to the egg surface of the parasitized eggs, made perforations, penetrated, ramified, and completely fed upon the internal content of the eggs. The parasitization of the second stage juvenile that emerged from the eggs by P. niphetodes and A. falciforme was seen. Whereas, A. falcifrome, F. oxysporum, and F. solani established as dormant spores inside or outside of M. incognita eggs.

Nematicidal Activity of Essential Oil from Lavandin (Lavandula × intermedia Emeric ex Loisel.) as Related to Chemical Profile.

Essential oils (EOs) from lavandin are known for a large spectrum of biological properties but poorly and contrastingly documented for their activity against phytoparasitic nematodes. This study investigated the toxicity of EOs from three different lavandin cultivars, Abrialis, Rinaldi Cerioni, and Sumiens, either to juveniles (J2) and eggs of the root-knot nematode Meloidogyne incognita and to infective stages of the lesion nematode Pratylenchus vulnus. The suppressive activity of treatments with EOs from the three lavandin cultivars in soil infested by M. incognita was also investigated in a greenhouse experiment on potted tomato. The compositional profiles of tested EOs were also analyzed by GC-FID and GC-MS. Linalool was the major component of all the three EOs, as accounting for about 66%, 48%, and 40% of total EO from cv Rinaldi Cerioni, Sumiens, and Abrialis, respectively. Linalool acetate was the second most abundant compound in the EOs from cv Abrialis (18.3%) and Sumiens (14.9%), while significant amounts of camphor (11.5%) and 1,8-cineole (12.1%) were detected in cv Rinaldi Cerioni and Sumiens EOs, respectively. The mortality of M. incognita J2 peaked 82.0%, 95.8%, and 89.8% after a 24 h treatment with 100 mg·mL−1 solutions of cv Abrialis, Rinaldi Cerioni, and Sumiens EOs, respectively. Infective specimens of P. vulnus were largely more sensitive than M. incognita J2, as there were peak mortality rates of 65.5%, 67.7%, and 75.7% after 4 h of exposure to Abrialis, Rinaldi Cerioni, and Sumiens EO, respectively. All three lavandin EOs significantly affected also M. incognita egg hatchability, which reduced to 43.6% after a 48 h egg mass exposure to a 100 µg·mL−1 solution of cv Rinaldi Cerioni EO. Soil treatments with the three lavandin EOs strongly reduced, according to a dose–effect relationship, density of M. incognita eggs, and J2 both on tomato roots and in soil, as well as significantly reduced gall formation on tomato roots. Finally, almost all soil treatments with the lavandin EOs also resulted in a positive impact on tomato plant growth.

In Vitro Assessment of N-Phenyl Imides in the Management of Meloidogyne Incognita

Abstract The infestation with root knot nematode Meloidogyne spp. is a key issue in agriculture. Conventional control methods are based on the use of synthetic nematicides, which comes with severe environmental problems. In this study, n-phenyl imide and n-phenyl phthalamic acid were synthesized and reacted independently with Enantia chlorantha crude extract–manganese chloride complex. The effects of the resulting organic compounds were appraised against the root knot nematode Meloidogyne incognita (Kofoid and White 1919) juveniles and eggs in two laboratory experiments. The most active compound was n-phenyl phthalamic acid (PN/TLMA) with 4% egg hatch over a 9-day observation after treatment as against distilled water which recorded 100% egg hatch at 9 days after treatment. n-Phenyl phthalamic acid showed 100% juvenile mortality at 10 days of observation compared to carbofuran dissolved in water (CBFN/water) and carbofuran dissolved in hydroxypropyl-β-cyclodextrin (CBFN/HPCD) while no outstanding (P < 0.05) difference was recorded between the effects of other organic compounds and carbofuran in both solvents. The different rates of treatment applications were not appreciably (P<0.05) dissimilar on percentage juvenile mortality and egg hatch. The nematicidal test results indicated that the synthesized imide compounds with manganese complex moiety are a promising basis for developing new nematicidal compounds with less environmental hazard.

RESPONSE OF SELECTED TREE SEEDLINGS TO ROOT-KNOT NEMATODE (Meloidogyne incognita)

Root-knot nematodes have been implicated in poor growth and death of trees in the nursery and newly established forest plantations. Cultivating resistant tree species is one of the viable methods in the management of nematode pests once they are identified. A pot experiment laid out in completely randomized design was conducted to screen fifteen selected tree seedlings for resistance to Meloidogyne incognita. Each tree seedling was replicated eight times and was grown on a steam-sterilized soil. The seedlings were inoculated each with 7,000 eggs of Meloidogyne incognita at four weeks after planting. Data were collected on plant height and stem girth at 12 weeks after inoculation. At termination, data were also collected on gall index (GI), final nematode population (Pf) and reproductive factor (RF). Data were analyzed using analysis of variance. Resistance or susceptibility status was assigned with Canto-Saenz host designation scheme. There was variability in the growth of the tree seedlings. Simphonia africana had the highest GI, Pf and RF of 3.3, 54,500 and 22.07, respectively and these values were significantly higher than values from other seedlings. Six tree seedlings; Simphonia africana, Theobroma cacao, Gmelina arborea, Piptadeniastrum africana, Chrysophyluum albidium and Parkia biglobosa were found to be susceptible to M. incognita, while six (Tetrapleura tetraptera, Anacardium occidentale, Annonas muricata, Dinium guinensis and Vitex doniana) were found to be resistant and three (Treculia africana, Mangifera indica and Dacryodes edulis) were tolerant. Resistant tree seedlings should be planted in M. incognita-infested plantation and susceptible species should be treated even in

Understanding the Transcriptional Changes During Infection of Meloidogyne incognita Eggs by the Egg-Parasitic Fungus Purpureocillium lilacinum.

The egg-pathogenic fungus Purpureocillium lilacinum parasitizes on nematode eggs, and thus, it is used as a good biocontrol agent against plant root-knot nematodes. However, little is known about the transcriptional response of P. lilacinum while infecting nematode eggs. This study presents the whole transcriptome sequencing of P. lilacinum and transcriptome-wide gene expression analysis of P. lilacinum upon infecting the eggs of Meloidogyne incognita compared to non-infecting controls. A transcriptomic library of P. lilacinum was used as reference gene set and six transcriptomic libraries of the non-infecting control and P. lilacinum infecting M. incognita eggs were constructed, respectively, comprising three biological replicates of each. A total of 1,011 differently expressed genes (DEGs) were identified in the infecting samples, including 553 up-regulated and 458 down-regulated genes compared to the non-infecting control samples. Furthermore, functional enrichment analysis exhibited that these DEGs were primarily involved in oxidative phosphorylation, oxidoreductase activity, and metabolic processes. Fifteen DEGs were randomly selected to verify the RNA sequencing results through quantitative real-time polymerase chain reaction (qPCR). The study focused on P. lilacinum genes that were strongly expressed upon infecting M. incognita eggs. These DEGs were primarily involved in detoxification, parasitic behavior, and nutritional utilization. This study contributes significantly to the understanding of the molecular mechanisms underlying the parasitic action of P. lilacinum on nematode eggs and provides a valuable genetic resource for further research on parasitic behavior of P. lilacinum. Notably, this study examined the transcriptomics of P. lilacinum infecting M. incognita eggs at only one time point. Since there were fungi at different stages of the infection process at that time point, the transcriptional profiles are not precisely examining one specific stage in this process.

Transcriptional reprogramming caused by cold acclimation in Meloidogyne incognita eggs.

Egg hatching in Meloidogyne incognita is a highly regulated developmental event and is strictly correlated with temperature. It has been demonstrated that exposure of M. incognita eggs to low temperature seriously affects their embryonic development. On the other hand, clear evidence has shown that M. incognita is able to overwinter at subzero soil temperatures in certain open fields. Therefore, subtle physiological and genetic adaptations may occur in M. incognita to minimize freezing injuries. A growing body of evidence indicates that cold acclimation plays a large role in an individual organism's ability to cope with freezing-induced cellular damage. Given the decreasing temperatures in late autumn or early winter, we hypothesize that natural cold acclimation occurring during these periods may assist M. incognita in overwintering. Transcriptomic analysis and functional enrichment analyses were used to identify and annotate differentially expressed genes (DEGs) in acclimated eggs. The expression of DEGs involved in signal transduction and protein assembly was subsequently validated by reverse transcription quantitative PCR (RT-qPCR). Relatively long-term preacclimation at 4°C significantly accelerated the hatching of M. incognita eggs that were subjected to freezing at -1°C. Using a transcriptomic approach, we further identified 686 and 460 up- and downregulated transcripts, respectively, in pre-cold-acclimated eggs. Additionally, we used Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology annotations for functional enrichment analyses of the differentially expressed genes (DEGs). The phenomenon in which M. incognita safely overwinters at subzero soil temperatures in certain areas may be attributed to the natural cold acclimation occurring in late autumn. Here, the identification of DEGs between acclimated and nonacclimated eggs will provide us with promising directions for future studies on the mechanisms of M. incognita freezing tolerance.

Relationship between Chemical Composition and Nematicidal Activity of Different Essential Oils.

In this study, the relationship between nematicidal activity and chemical composition of ten essential oils (EOs) from different plant species was investigated both in in vitro assays on juveniles (J2) and eggs of the root-knot nematode Meloidogyne incognita and in experiments on tomato in soil infested by M. incognita. Nematode J2 were exposed for 4, 8 or 24 h to 0.78–100 μg mL−1 concentrations of each EO, whereas 24, 48 or 96 h exposures to 250, 500 and 1000 μg mL−1 solutions were tested on M. incognita egg masses. Treatments with 50, 100 or 200 μg kg soil rates of each EO were applied in the experiment on potted tomato. The highest nematicidal potential resulted for the C. verum EO, as highly toxic to both M. incognita J2 and eggs and strongly suppressive on nematode multiplication on tomato roots. The infestation of M. incognita on tomato roots was also strongly reduced by the EOs from E. citriodora and S. aromaticum, both highly toxic to M. incognita J2 but less active on nematode eggs. Adversely, R. graveolens EO strongly inhibited the egg hatch but was limitedly toxic to the infective J2. Chemical composition of the EOs was determined by GC-FID and GC-MS. The ten EOs showed a very different chemical composition in terms of major phytochemicals, with one or two dominant components totally amounting up to 85%. The structure–activity relationship based on the main phytochemicals identified in the assayed EOs and their nematicidal effects on M. incognita was also discussed. Results from this study confirmed that the selection of suitable EO raw materials can lead to the formulation on new effective nematicidal products.

SUSCEPTIBILITY AND TOLERANCE TO ROOT-KNOT NEMATODES (MELOIDOGYNE INCOGNITA) OF TELFAIRIA OCCIDENTALIS UNDER ORGANIC CONVERSION

Three cultivars of Telfairia occidentalis were assessed for their resistance or otherwise to root-knot nematodes (Meloidogyne spp.) infection on the field. Seeds were extracted from the pods of the selected cultivars and planted on moist sawdust in nursery trays to raise seedlings for transplanting. The experiment was laid out in Randomized Complete Block Design and replicated thrice. Pre-plant soil samples were taken to estimate initial nematode populations. At seven days after transplanting, eggs of Meloidogyne incognita (Mi) were extracted from 60 day-old Celosia argentea and used for inoculation of the three cultivars of T. occidentalis at approximately 5000 eggs/stand. Plants were, thereafter, observed for vine length, vine girth and number of leaves from two weeks till 8 weeks after transplanting. Final soil nematode population and root gall indices were determined at 60-66 days after inoculation. Reproduction factor was determined and used along with the gall indices to rate the cultivars for resistance or susceptibility to Mi. Results showed that cultivars NHTo-020 and NHTo-030 were susceptible to root-knot nematode which implied that plants allowed nematode reproduction and also suffered yield loss while cultivar NHTo-010 was tolerant to nematode infestation meaning that nematode reproduction took place but the plant does not suffer yield loss. There was no significant (P>0.05) difference in the mean vine length and number of leaf irrespective of the inoculum while effect on the vine girth was significantly variable. The inoculated plants gave significantly better vegetative growth than the naturally infested plants which indicated genetic variability in the cultivars.

The root-knot nematode, Meloidogyne incognita, profoundly affects the production of popular biofortified cassava cultivars

Summary Despite being the single largest cassava-producing country, yields in Nigeria remain consistently poor and among the lowest. Regionally, yields are also particularly low across Africa. Pests and pathogens, including plant-parasitic nematodes, play an important role in this current yield deficit. African countries are not only faced with the problem of food security but also that of nutritional deficiency, due to limited micronutrients in the diet. In this study, six biofortified cultivars were evaluated for their response to inoculation with approximately 30 000 root-knot nematode (Meloidogyne incognita) eggs in 30 l pots in Nigeria. All cassava cultivars proved highly susceptible to M. incognita infection after 6 months, with nematode reproduction factor ranging from 7.0 to 44.8. Galling was common on feeder roots and gall index scores were recorded between 4 to 5 (on a scale of 1-5 where 5 ⩽ 100 galls). Meloidogyne incognita infection significantly reduced plant height, stem girth, fresh plant mass, fresh storage root number and storage root weight. Percentage yield loss of between 41.8-88.4% was recorded in M. incognita-infected plants compared with non-infected controls. Although M. incognita reduced storage root weight, it did not necessarily affect the nutritional quality (total carotenoid) or dry weight percentage of the biofortified cassava cultivars. Total carotenoid and dry weight contents of the control cultivar were similar to some of the biofortified cultivars. The high susceptibility of the biofortified cassava cultivars to M. incognita infection indicates that substantial yield losses are likely being experienced by farmers, as this nematode pest is prevalent across sub-Saharan Africa and the tropics.

Effects of Myrothecium verrucaria ZW-2 fermentation filtrates on various plant-parasitic nematodes

This study shows for the first time the effect of the fermentation filtrate of Myrothecium verrucaria, strain ZW-2, on four different species of plant-parasitic nematodes. Our results suggested that the fermentation filtrate of M. verrucaria inhibited hatching of Meloidogyne incognita and Heterodera glycines eggs. The lowest egg hatching rates of H. glycines and M. incognita were 6.3% and 2.0%, respectively, after 15 days of incubation with a fermentation filtrate of M. verrucaria. A 2-week fermentation filtrate had lethal effects on of M. incognita (second stage juveniles), H. glycines and Bursaphelenchus xylophilus. After 72 h of incubation, the following mortality rates were observed: M. incognita J2s, 100%; Hirschmanniella spp., 8.4%; H. glycines J2s, 82.4%; and B. xylophilus, 96.1%. A pot test showed that the mean suppressive rates of H. glycines after one- and two-week fermentation treatments were 78.8% and 91.2%, respectively. There were 0.8 nematodes per tomato root system at seven days after inoculation (DAI) and 4.4 galls and 933.3 eggs per root system at 30 DAI, which were significantly lower than those of the tap water controls (8.0 nematodes, 31.4 galls and 14,622.5 eggs per root system). Our studies confirmed that the fermentation filtrate of strain ZW-2 has nematicidal effects against three plant-parasitic nematodes.

Nematicidal activity of Echinacea species on the root-knot nematode Meloidogyne incognita

Echinacea species are reported for a large content of bioactive compounds, but their effects on phytoparasitic nematodes are still unknown. This study comparatively investigated the in vitro activity of chemically characterized extracts from E. angustifolia, E. pallida and E. purpurea on juveniles and eggs of the root-knot nematode Meloidogyne incognita. Suppressiveness of soil amendments with Echinacea plant biomasses was also investigated against M. incognita on tomato in potting mixes. More than 50% juvenile mortality occurred after a 48-h exposure to a 500 µg mL−1 solution of all Echinacea extracts, as well as more than 50% of M. incognita eggs did not hatch after a 1-week exposure to the same concentration of E. angustifolia extracts. Nematode multiplication on tomato roots was always significantly reduced in soil amended with all Echinacea biomasses, as well as almost all treatments also resulted in a significant tomato growth increase. Polar compounds such as echinacoside and chicoric acid were the main components of the extracts from Echinacea aerial parts, whereas apolar components as alkamides prevailed in root extracts. Data confirmed the potential of the three Echinacea species, mainly E. angustifolia, for the formulation of new formulates for a sustainable nematode management.

In vitro evaluation of some isolated bacteria against the plant parasite nematode Meloidogyne incognita

BackgroundMicrobial cultures are extensively used as environment friendly ways for biological control of parasitic pests, including the root-knot nematodes, alternative to the use of chemical nematicides. The present study was conducted to isolate some lytic rhizobacteria and examine their nematicidal activity against Meloidogyne incognita J2 mortality and egg hatching in in vitro test.ResultsLytic Rhizobacteria were isolated from soil samples adhering to tomato plant roots from different localities at Giza governorate, Egypt. Six bacterial isolates, exhibited high efficacy against root-knot nematodes, were identified based on the analysis of the 16S rRNA gene sequence as Pseudomonas aeruginosa, Paenibacillus polymyxa, Lysinibacillus sphaericus, Bacillus cereus, Bacillus subtilis, and Achromobacter xylosoxidans. These strains showed high production of chitinase, chitosanase, and protease using colloidal chitin and soluble chitosan as carbon sources. Two strains, Paenibacillus polymyxa and Bacillus subtilis, produced the highest levels of chitinase in the media. Except for Pseudomonas aeruginosa, all the bacterial strains produced high levels of chitosanase.ConclusionThe results revealed that high amounts of protease were, however, secreted by Pseudomonas aeruginosa as compared to the other strains. In in vitro tests, all the bacterial culture filtrates potentially displayed nematicidal effect in M. incognita egg hatching and an obvious increase in J2 mortality as compared to control. Paenibacillus polymyxa caused 100% juvenile mortality followed by Bacillus subtilis 97.25%, Bacillus cereus 94%, Achromobacter xylosoxidans 93%, Lysinibacillus sphaericus 92%, and Pseudomonas aeruginosa 84.29% after 48 h of exposure, as compared to control.

ECO-FRIENDLY MANAGEMENT OF ROOT-KNOT NEMATODE AND ROOT ROT DISEASE INFECTING PEPPER PLANTS BY APPLICATION COMPOST AND TEA COMPOST

The present work was conducted to study the efficacy of compost powder and compost extract (tea) in the management of root rot and root-knot nematode disease complex infecting pepper plants under in vitro and in vivo. The inhibitory effect of compost extract concentrations (25%, 50%, 75 and 100%) on Fusarium solani (Mart.) Sacc and Rhizoctonia solani Kuhn were evaluated, the latter was higher sensitive than F. solani by 88.33% and 82.83%, respectively at 100% concentration. The results also, showed that nematicidal effect of unsterilized compost tea (65.98% and 52.3%) was significantly more than sterilized compost tea (54.02% and 45.9%) on the rate of Meloidogyne incognita egg hatching and juvenile mortality, respectively in all tested concentrations. In vivo, the obtained results cleared a decrease in the root rot incidence percentage in disease complex of both compost powder and compost tea extract to 22.1% and 20.1% compared with control treatment. Application of compost powder with the recommended dose, as well as the compost tea extract, led to a significant decrease in gall number (64 and 59 galls/root) compared to the comparative treatment (108 galls/root). This result has led to a significant reduction in egg-masses formation. Furthermore, the obtained results indicated that plant growth parameters significantly increased (plant length, fresh and dry weights) by the application of compost and compost tea extract. In general, application of compost and compost tea extract might be a safe and eco-friendly tool in the sustainable management of disease complex.

Genome-Wide Identification and Characterization of the Cyclophilin Gene Family in the Nematophagous Fungus Purpureocillium lilacinum.

Purpureocillium lilacinum has been widely used as a commercial biocontrol agent for the control of plant parasitic nematodes. Whole genome analysis promotes the identification of functional genes and the exploration of their molecular mechanisms. The Cyclophilin (CYP) gene family belongs to the immunophillin superfamily, and has a conserved cyclophilin-like domain (CLD). CYPs are widely identified in prokaryotes and eukaryotes, and can be divided into single- and multi-domain proteins. In the present study, 10 CYP genes possessing the CLD, named PlCYP1–P10, were identified from the genome of P. lilacinum strain 36-1. Those 10 PlCYPs were predicted to have different cellular localizations in P. lilacinum. Phylogenetic and gene structure analysis revealed the evolutionary differentiation of CYPs between Ascomycotina and Saccharomycotina fungi, but conservation within the Ascomycotina fungi. Motif and gene structure distributions further support the result of phylogenetic analysis. Each PlCYP gene had a specific expression pattern in different development stages of P. lilacinum and its parasitism stage on eggs of Meloidogyne incognita. In addition, the 10 PlCYP genes exhibited different expression abundances in response to abiotic stresses, among which PlCYP4 was highly expressed at a high temperature (35 °C), while PlCYP6 was up-regulated under 5 mM of H2O2 stress. Furthermore, the heterologous expression of PlCYP4 and PlCYP6 in Escherichia coli enhanced the cellular tolerance against a high temperature and H2O2. In summary, our study indicates the potential functions of PlCYPs in virulence and the stress response, and also provides a frame for further analysis of the CYP gene family in Ascomycotina fungi.

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.

Effect of Root-knot Nematode (Meloidogyne incognita) on the Nodulation of Some Varieties of Cowpea (Vigna unguiculata L. Walp)

Abstract Screenhouse and field trials were conducted at the University of Ilorin, Nigeria in 2013 and 2014 to investigate the effect of root knot nematode (Meloidogyne incognita) on the nodulation of five varieties of cowpea (IT89KD-288, IT82D-994, IT93K-452-1, T89K-391 and TT97 568-18). Half of the experimental plants were inoculated with Meloidogyne incognita eggs (n = 1500) while the remaining half served as uninoculated control plants. Data on growth and yield of cowpea, root gall, nodulation, and nematodes population densities in nodules were collected. Other parameters assessed included colour of dissected infected and uninfected nodules, texture of the nodules and varietal performance of the cowpeas. The results of both screenhouse and field trials were consistent in yield and visual observations of texture and colour. The yield of nematode-free varieties was significantly higher than that of M. incognita-infected ones. Infected nodules were dark brown in colour while the healthy ones were pink. For the field trials, nodulation counts in nematode inoculated plants were inversely proportional to the number of galls in their uninoculated counterparts in some varieties. Of all varieties, IT89KD-288 was most resistant to M. incognita. Due to high cost involved in the management of nematodes, especially with synthetic chemicals, variety IT89KD-288 is recommended for use in nematode endemic areas in Nigeria. Further study needs to be done on the histopathology of the infected and uninfected roots and nodules of these cowpea varieties.

An integrative approach for the selection of Pochonia chlamydosporia isolates for biocontrol of potato cyst and root knot nematodes.

The nematophagous fungus Pochonia chlamydosporia , a natural enemy of plant parasitic nematodes (PPN), has been exploited in the development of sustainable management strategies for PPN control. The intrinsic variation among P. chlamydosporia isolates affects biocontrol potential, so sound characterisation is required. Biological, molecular and metabolic analyses can be determinant in the screening and selection of these potential biological control agents. This study aimed to provide integrative characterisation of P. chlamydosporia isolates that can support isolate selection for biological control purposes. Eight Portuguese isolates, associated with Meloidogyne spp., were used as a case study. Isolates were identified and characterised: i) at the biological level through standard bioassays to evaluate their ability for rhizosphere colonisation, to produce chlamydospores, and to parasitise Globodera pallida and Meloidogyne incognita eggs; ii) at the molecular level, examining genetic variation using ERIC-PCR; and iii) at the metabolic level, assessing their metabolic profiles using Biolog FF MicroPlates, with concurrent reads of fungal utilisation of 95 different carbon sources. Molecular data and metabolic characterisation were reduced using Principal Component Analysis and compared with the biological characteristics. Molecular profiles could only be related to isolate geographical origin, but the original substrate (eggs or roots), parasitism of M. incognita eggs and ability for rhizosphere colonisation were correlated with metabolic profiles, indicative of utilisation of specific carbon sources. Meloidogyne egg parasitism and rhizosphere colonisation were related to each other. This integrative characterisation offers novel perspectives on the biology and biocontrol potential of P. chlamydosporia , and, once tested on a broader set of isolates, could be used to assist rapid isolate selection.