Meloidogyne Javanica Research Articles

SlWRKY16 and SlWRKY31 of tomato, negative regulators of plant defense, involved in susceptibility activation following root-knot nematode Meloidogyne javanica infection

The involvement of WRKY transcription factors in plant-nematode interactions, and in particular, how these WRKYs participate in regulating the complex morphological and physiological changes occurring after nematode infection, are the topic of active research. We characterized the functional role of the unstudied tomato WRKY genes SlWRKY16 and SlWRKY31 in regulating tomato roots’ response to infection by the root-knot nematode Meloidogyne javanica. Using promoter–GUS reporter gene fusions and qRT-PCR, we show that both SlWRKYs are predominantly expressed during the first half of the parasitic life stages, when feeding-site induction and construction occur. Expression of SlWRKY16 increased sharply 15 days after inoculation, whereas SlWRKY31 was already induced earlier, but reached its maximum expression at this time. Both genes were downregulated at the mature female stage. To determine biological function, we produced transgenic lines overexpressing SlWRKY16 and SlWRKY31 in tomato hairy roots. Overexpression of both genes resulted in enhanced M. javanica infection, reflected by increased galling occurrence and reproduction. Expression profiling of marker genes responsive to defense-associated phytohormones indicated reductions in salicylic acid defense-related PR-1 and jasmonic acid defense-related PI in inoculated roots overexpressing SlWRK16 and SlWRKY31, respectively. Our results suggest that SlWRKY16 and SlWRKY31 function as negative regulators of plant immunity induced upon nematode infection.

Assaying the effects of some essential oils on Root-knot Nematode [Meloidogyne javanica (Treub 1885) Chitwood 1949] in the laboratory

Nematodes are man’s faceless enemy whose activities encourage hunger and poverty. This study was conducted to determine the efficacy of selected plant oil extract in the control of root knot Nematode [Meloidogyne javanica] in the laboratory. The experimental design used was Complete Randomized Design (CRD) with fourteen treatments, replicated three times. Egg hatch inhibition test on M. javanica eggs and juvenile mortality test were separately performed by exposing the eggs and juveniles to different dosage of the essential oils. Neem seed oil statistically proved effective in inhibiting egg hatch followed closely by Garlic clove oil and then Moringa seed oil. All the essential oil treatments were more effective than carbofuran treatment. The surfactant Sodium Lauryl Sulphate was shown to have nematicidal properties as it also recorded zero egg hatching at all the doses applied. The second stage juveniles of M. javanica recorded a higher mortality rate (100%), when they were treated with Neem seed oil, closely followed by Garlic clove oil and then Moringa seed oil. All Surfactant treatments caused 100% juveniles’ mortality. The higher the doses of the essential oils, the higher the juvenile mortality rate. Neem seed oil at all the dosage proved effective in controlling Meloidogyne javanica causing high rate of juvenile mortality and suppressing M. javanica egg hatch. The nematicidal characteristics exhibited by the essential oils might be due to the phytochemicals present in the oils.

Effective combination of arugula vermicompost, chitin and inhibitory bacteria for suppression of the root-knot nematode Meloidogyne javanica and explanation of their beneficial properties based on microbial analysis.

Root-knot nematodes (Meloidogyne spp.) are dangerous parasites of many crops worldwide. The threat of chemical nematicides has led to increasing interest in studying the inhibitory effects of organic amendments and bacteria on plant-parasitic nematodes, but their combination has been less studied. One laboratory and four glasshouse experiments were conducted to study the effect on M. javanica of animal manure, common vermicompost, shrimp shells, chitosan, compost and vermicompost from castor bean, chinaberry and arugula, and the combination of arugula vermicompost with some bacteria, isolated from vermicompost or earthworms. The extract of arugula compost and vermicompost, common vermicompost and composts from castor bean and chinaberry reduced nematode egg hatch by 12-32% and caused 13-40% mortality of second-stage juveniles in vitro. Soil amendments with the combination vermicompost of arugula + Pseudomonas. resinovorans + Sphingobacterium daejeonense + chitosan significantly increased the yield of infected tomato plants and reduced nematode reproduction factor by 63.1-76.6%. Comparison of chemical properties showed that arugula vermicompost had lower pH, EC, and C/N ratio than arugula compost. Metagenomics analysis showed that Bacillus, Geodermatophilus, Thermomonas, Lewinella, Pseudolabrys and Erythrobacter were the major bacterial genera in the vermicompost of arugula. Metagenomics analysis confirmed the presence of chitinolytic, detoxifying and PGPR bacteria in the vermicompost of arugula. The combination of arugula vermicompost + chitosan + P. resinovorans + S. daejeonense could be an environmentally friendly approach to control M. javanica.

Potential of cavalcade, Centrosema pascuorum, leaves for controlling Meloidogyne javanica and quantification of active phytochemicals

Summary The legume cavalcade, Centrosema pascuorum, is used extensively as a cover crop and as a component of conservation agriculture systems. It is also an attractive rotation or cover crop for the management of root-knot nematodes (RKN; Meloidogyne spp.) as it is a non-host. RKN are persistent pests that are well known to be difficult to control. However, the mechanisms governing the non-host status of cavalcade is unknown. The current study established that cavalcade leaves are toxic to RKN as either aqueous extracts or soil amendments. Bioassays conducted using Meloidogyne javanica showed that a 90% concentration of aqueous extract derived from 1-month-old cavalcade leaves (89 mg crude extract ml−1) suppressed nematode hatch (82.9%) and killed infective second-stage juveniles of M. javanica (85.3%). Soil amendments with 1% (w/w) of 1-month-old cavalcade leaves (0.99 mg crude extract g−1 soil) also provided effective control of M. javanica in the glasshouse on okra. One-month-old leaves appeared more effective than 2- or 3-month-old leaves. The soil amendments had no adverse phytotoxic effect on okra seed germination. Our study demonstrates the potential for using cavalcade leaves or extracts to manage RKN. This may be due to the nematicidal activity of the various compounds in the leaves, such as flavonoids, phenols and terpenoids, which should be further assessed.

Sustainable Management of Root- Knot Nematode (Meloidogyne javanica) on Brinjal

Brinjal (Solanum melongena) is an important Solanaceae family vegetable, which is grown all around the world. It is affected by various fungal, bacterial, viral, nematode diseases but it is a major host for root-knot nematode, Meloidogyne javanica. Hence, for effective management of root-knot nematode experiment was conducted in field condition using the culture filtrate (3gm/kg soil) of bio-agents (viz., Trichoderma viride, Trichoderma harzianum, Purpureocillium lilacinum, Pochonia chlamydosporia and Pseudomonas fluorescens). The findings of the experiments revealed that, when compared to the control, all of the tested bio-agents considerably improved plant development characteristics and decreased nematode populations. Among the tested bio-agents T. viride was found most effective treatment with improve plant growth characters as well as in reducing nematode population over other treatment in field condition.

Management of Root-Knot Nematode on Okra through Bio-Agents

A pot study was conducted to assess the efficacy of various fungal and bacterial antagonists as seed coating treatments against Meloidogyne javanica, a root-knot nematode that infects okra plants. The seeds of okra cv. Pusa Sawani were subjected to treatments with Trichoderma viride, Purpureocillium lilacinum, and Pseudomonas fluorescens at a rate of 2 g/kg seed. As a comparison, Carbosulfan 3G was used as a control, applied at a rate of 3g/kg soil. The treated seeds were then planted in soil infested with two second-stage juveniles of the root -knot nematode per gram of soil. After 45 days of sowing, it was observed that the okra plants exhibited enhanced growth, while the population of root-knot nematodes was significantly reduced in all treatment groups compared to the untreated control. Among the different bio agents tested, Purpureocillium lilacinum exhibited the best treatment followed by Trichoderma viride and Pseudomonas fluorescens for increase plant growth characters as well as reduced nematode reproduction.

Impact of the Interaction between Meloidogyne javanica and Fusarium oxysporum on the Okra Plantation

The development of diseases in cultivated crops depends on the complex interrelationship between the host, pathogen, and prevailing environmental conditions. The interaction between the root knot nematode Meloidogyne javanica and the fungus Fusarium oxysporum was studied for the okra cultivar Pusa Sawani. Sequential and simultaneous inoculation of the nematode and fungus was performed to observe the disease severity in the plants due to the individual and interactive effects of the tested nematode and fungus. The results indicated that plant growth was adversely affected in all cases where the plant was inoculated with M. javanica and F. oxysporum, compared to the uninoculated control. The study clearly showed that nematodes act as predisposing factors in the spread of secondary fungal pathogens.

Attractive response of Meloidogyne javanica varies among non-host plants, while all of them reduce the nematode population when intercropped with host plants

Attractive response of Meloidogyne javanica varies among non-host plants, while all of them reduce the nematode population when intercropped with host plants

Differential response of some nematode-resistant and susceptible tomato genotypes to Meloidogyne javanica infection

Differential response of some nematode-resistant and susceptible tomato genotypes to Meloidogyne javanica infection

Anaerobic soil disinfestation with ethanol or sucrose reduces the viability of Meloidogyne javanica and Stromatinia cepivora

Anaerobic soil disinfestation (ASD) is an ecological alternative to chemical soil fumigation. However, little is known about the potential of this technique for the management of Meloidogyne javanica and Stromatinia cepivora. To test the hypothesis that ASD reduces the viability of these two pathogens, we assessed ethanol (5%, v:v) and sucrose (5%, m:v) as carbon sources for ASD, for an incubation period of three weeks. Twenty kilograms of soil naturally infested with M. javanica (82 ± 43 J2 100 cm-3 soil) were placed into a plastic container. Polyester traps, each with 15 S. cepivora sclerotia, were buried at 10 and 20 cm depth per container. ASD with diluted ethanol or sucrose (5% v:v or m:v) was compared to the untreated control (UTC), chemical fumigant metam sodium (MS), and soil saturation with water. In comparison to the UTC, ASD using ethanol reduced the numbers of J2 in soil and the galls in tomato roots by more than 93%, a degree of suppression similar to that achieved when using MS. The viability of sclerotia of S. cepivora was reduced by ASD using ethanol or sucrose from 38.12 to 58.1% compared to the UTC. ASD for three weeks using ethanol or sucrose (5%) reduces the viability of M. javanica and S. cepivora in the microcosm.

Divergent Responses of Tomato Cultivars with Resistance to Tomato Yellow Leaf Curl Virus as Infected by Meloidogyne javanica

Commercial tomatoes are usually complex F1 hybrids with multiple resistances genes from different wild Solanum species. The response of tomato cultivars with resistance to root-knot nematodes (RKN) and Tomato yellow leaf curl virus (TYLCV) as infected by Meloidogyne javanica was determined in a controlled environment and field conditions. Four treatments were tested, viz. tomato cultivars with (i) RKN resistance alone; (ii) combination of RKN and TYLCV resistance (RKN + TYLCV); (iii) TYLCV resistance alone; and (iv) control (susceptible to the nematode and virus). The RKN-resistant plants effectively suppressed nematode infection and reproduction both in a controlled environment and in field conditions. The RKN + TYLC-resistant plants were less effective (p < 0.001) than the RKN plants in a controlled environment, and their resistance levels were significantly reduced in the field. Nonetheless, the RKN + TYLCV plants supported lower (p < 0.001) nematode infection and reproduction than the susceptible control plants. The TYLCV-resistant plants reduced (p < 0.001) nematode infection and reproduction compared to the susceptible control in a controlled environment and in field conditions. The divergent response of tomato cultivars with resistance to TYLCV via infection by M. javanica can be attributed to the genetic background of the cultivars.

A real time PCR assay to detect and quantify root-knot nematodes from soil extracts.

Root-knot nematodes cause forking and stubbing of the growing carrot root tip, decreasing market value and reducing yield by up to 45%. Since crop damage by these nematodes depends on their initial population densities at planting, pre-plant detection of potentially low nematode numbers is critical for predicting future yield loss. The aim of this study was to overcome some of the drawbacks of the labor and time-intensive process of root-knot nematode identification and quantification by developing and field testing a real time PCR (qPCR) assay. Primers were designed targeting the root-knot nematode Meloidogyne incognita species complex, which includes M. incognita as well as the closely related Meloidogyne javanica and Meloidogyne arenaria. The qPCR assay successfully detected each species and showed little amplification for non-target nematode groups except for the sister group Meloidogyne enterolobii, which is not known to occur in California. Predicted nematode densities related well with microscopic counts of nematodes from prepared solutions, as well as from solutions extracted from field soil. In a greenhouse experiment, the qPCR assay distinguished between low, medium and high levels of M. incognita infection and qPCR predicted densities at planting were negatively related in linear models with final carrot fresh weight, length and diameter. These results suggest that qPCR assays could be a valuable diagnostic tool to predict nematode infections and prevent crop losses.

Investigating the Effects of Alltech Crop Science (ACS) Products on Plant Defence against Root-Knot Nematode Infestation.

Two formulations of Alltech Crop Science products (ACS), a proprietary blend of fermentation products and plant extracts with micronutrients (ACS5075), and a microbial based product (ACS3048), were tested to understand (1) their impact on the tomato plant immune response and (2) whether they are priming a resistance response in plants against root knot nematodes (RKN). Research findings reported previously indicate that tomato plants pre-treated with ACS5075 and ACS3048 were found less sensitive to Meloidogyne javanica infection. In the current study, the expression of six defence-related genes (PR-1, PR-3, PR-5T, ACO, CAT and JERF 3), relative to a housekeeping gene, were monitored via RT-PCR. Results suggest that the treatment with ACS5075 enhanced ACO and PR-1 gene expression levels, both post- treatment and post-infection with M. javanica. Reduced M. javanica infestation that was reported in the previous study could be attributed to the increased expression of these genes in the ACS5075-treated plants. Tomato plants treated with ACS3048, but without RKN infection, also demonstrated higher levels of ACO and PR-1 gene expression. Subsequently, 2D-gel electrophoresis was performed to study the differential protein expression in leaf tissues of treated tomato plants in an effort to elucidate a possible mechanism of action for these products. Protein spot 1 was identified as 'disease resistance protein RPP13-like', protein spot 2 as 'phosphatidylinositol 4-phosphate 5-kinase 2', spot 3 as 'protein SABRE like' and protein spot 4 as 'uncharacterized protein'. Overall research findings indicate that the ACS products could be used as plant immunity-boosting agents, as they play a significant role in the expression of certain genes and proteins associated with plant defence.

Reproduction factor of Meloidogyne javanica, M. incognita and Pratylenchus brachyurus in sorghum, millet and sunflower varieties

The use of agricultural species resistant to root-knotting and root-wounding nematodes, in crop rotation systems, keeps the nematode population at low levels, reducing losses and enabling the planting of more susceptible species. In this study, the resistance of sorghum, millet and sunflower genotypes to root-knot nematodes Meloidogyne javanica, M. incognita and Pratylenchus brachyurus was evaluated. The tests were conducted in a greenhouse and the genotypes sown in plastic pots containing 2 L of sterilized substrate and inoculated with 1,600 nematode eggs and juveniles per pot, arranged in a completely randomized design with nine replications. The evaluation of nematode reproduction was performed by counting the number of juveniles/adults per root system and soil, calculating the Reproduction Factor (FR = Pf/Pi). According to the results, all sorghum, millet and sunflower genotypes behaved as resistant to the reproduction of M. javanica, M. incognita and P. brachyurus. Commercial resistant genotypes are indicated for use in rotation of areas infested by these nematodes.

Efficacy of moringa (Moringa oleifera) formulations on suppression of root-knot nematodes (Meloidogyne javanica) and growth of eggplant (Solanum melongena)

Eggplant (Solanum melongena L.) is one of the premier vegetables and is widely cultivated. One of the most important reasons for reduced yield of eggplant is root-knot (Meloidogyne species) nematode. So, it is important to control this pest; therefore, an investigation was conducted in 2022 at the Aquaculture Research Unit lab to evaluate the effectiveness of moringa (Moringa oleifera Lam.) application in controlling root-knot nematode in eggplant. During this study, Meloidogyne javanica (Treub) was identified from the rhizosphere soil samples. Fresh leaf extracts of moringa, including positive control (fenamiphos), were investigated in vivo for efficacy against M. javanica in root and soil. Seedlings of eggplant were inoculated with 3000 eggs and second-stage juveniles (J2) of M. javanica in pot trials, with treatments comprising fresh leaf extracts of moringa (M. oleifera) in a series of concentrations. Fifty-six days after inoculation, the Phyto nematicide had reduced eggs and J2 in soil by 62-89%, gall number by 58-87%, and gall index by 35-87%. The best treatment was moringa (80 ppm) which was significantly superior to moringa (40 ppm) and moringa (60 ppm) (P less than 0.05). However, fenamiphos had no significant difference (P greater than 0.05). The results showed that moringa (80 ppm) was the best treatment for controlling root-knot nematode in eggplant.

In silico secretome analyses of the polyphagous root-knot nematode Meloidogyne javanica: a resource for studying M. javanica secreted proteins

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

Biochar from grape pomace, a waste of vitivinicultural origin, is effective for root-knot nematode control

Root-knot nematodes (RKNs) are obligate endoparasites that feed on their host plants to complete its life cycle, representing a major threat to agriculture and economy worldwide. The development of new management strategies becomes essential as effective chemical nematicides are progressively being restricted. Hence, we analysed grape pomace-derived biochars, pyrolysed at 350 °C (BC350) and 700 °C (BC700), focusing on their potential for RKN control. The thermal treatment of grape pomace caused an increase in the concentration of carbon and plant macro- and micronutrients, which were largely present in a water-soluble form. Synchrotron radiation-based Fourier transform infrared microspectroscopy data showed a general loss of carboxylic functional groups during pyrolysis, partially contributing to the alkalinisation of both biochars, mostly in BC700. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis revealed a highly porous structure filled with different crystals composed of elements such as K, Ca, Mg, P, Si or Al, which could be a suitable environment for the growth of microorganisms. Biochar-derived aqueous extracts showed phytotoxicity to tomato seedlings at high concentrations, and disappeared upon dilution, but no toxic effect was observed on the nematode’s infective stage. However, the infective and reproductive traits of a Meloidogyne javanica population in tomato were significantly reduced (i.e. egg masses and eggs per plant) in washed-biochar-treated soil in pots (0.75%; BC350W). Therefore, the large amount of grape waste generated after wine production can be transformed into a valuable product such as biochar, effective for RKNs control, thus reducing the waste management problem and contributing to a circular economy.Graphical abstract

Selection of cowpea (Vigna unguiculata [L.] Walp) accessions resistant to root‐knot nematode

AbstractCowpea, Vigna unguiculata, is a legume adapted to regions with a tropical climate and limited water resources, and it has become a basic food source and income generator. Root‐knot nematodes (Meloidogyne spp.) cause substantial damage to the root system, resulting in yield losses. Genetic resistance is one of the most efficient management methods. The objective of this study was to generate information on genetic resistance to Meloidogyne incognita and Meloidogyne javanica of Brazilian cowpea genotypes. For this, 18 accessions of cowpea from the collection of Embrapa Meio‐Norte and six control accessions of cowpea were tested in completely randomized design with six replications, evaluated 60 days after inoculation, and carried out twice in time. To assess root penetration of nematodes and root gall formation in NIL‐CB3‐isoline, which allows reproduction but limits gall formation, nematodes inside the roots were stained with acid fuchsin, after inoculation with 5000 J2, with estimates at 72 h time‐points up to 28 days. None of the 18 accessions from Embrapa showed resistance to M. javanica, but accessions MNC06‐895‐1, MNC04‐14, MNC06‐909‐6, 98, MNCO4‐907‐35, and Am60‐15 showed resistance to M. incognita. There was a reduction in the number and size of galls in the NIL‐CB3 egg isoline, and an increase in formation of males, which are not important for parasitism. Given the importance and prospects for expansion of the cowpea crop throughout Brazil, the results of this study contribute to the knowledge on the reaction of Brazilian cowpea genotypes to the root‐knot nematode.

Plant disease management with amelioration of systemic resistance in soybean by endophytic fungi associated with GC-MS metabolic profiling of Chaetomium sp.,

Plants exhibit beneficial associations between fungal endophytes and roots for better growth, disease suppression, and stress tolerance. Considerable information is now available about the beneficial role of fungal endophytes. In this study, endophytic fungi Chaetomium sp., Curvularia chonburiensis, C. specifera, C. hawaiiensis, Rhizoctonia solani, Fusarium solani, Talaromyces assiutensis and T. trachyspermus isolated and evaluated for nematocidal activity against a root-knot nematode Meloidogyne javanica. The culture filtrates of endophytic fungi were prepared and used to check their efficacy against root knot nematodes. The culture filtrates of endophytic fungi were applied to pot and field experiments using soybean as host plants. In vitro study of these endophytic fungal culture filtrates showed strong nematocidal activity by killing juveniles of M. javanica to a certain degree, while Chaetomium sp., and Talaromyces assiutensis showed 100% mortality rate after 48 h. The application of Cephalosporium sp., Chaetomium sp., Talaromyces trachyspermus and T. assiutensis suppressed root rotting fungi of soybean in both screen house and field plots experiments. Significance of fungal isolates was further confirmed by repeated experiments. Endophytic fungi also showed positive impacts on the host plants by increasing the rate of their growth and improving their tolerance level to biotic stress which was evident by the production of increased amounts of resistance markers like salicylic acid and polyphenol contents with subsequent improvement of the antioxidant status. The n-hexane fraction of the culture filtrate of Chaetomium sp., were subjected to GC-MS analysis for the identification of compounds and some new compounds have been reported for the first time from this fungus. The results will facilitate a better understanding of host plant and fungal interaction and are likely to assist in the screening and utilization of beneficial microbes.

Glucosinolate-extracts from residues of conventional and organic cultivated broccoli leaves (Brassica oleracea var. italica) as potential industrially-scalable efficient biopesticides against fungi, oomycetes and plant parasitic nematodes

This study aimed to standarize a protocol for obtaining a bioactive extract from broccoli (Brassica oleracea var. italica) crop residues, that is suitable for application on an industrial scale and effective in reducing plant disease incidence. For this purpose, the influence of several extraction factors in the glucosinolate (GSL) content was studied with leaves collected from two conventional broccoli fields and two organic broccoli fields. The analysis showed that lyophilization had no influence on the GSL content. Storage of plant material under two different temperatures (− 20ºC and − 80ºC) had no influence on the GSLs content of the extracts. Phytotoxicity of the extracts was studied with six different plant seeds, and also cytotoxicity was determined with human liver cells in vitro. The extracts were phytotoxic at dilutions above 10%, while cell toxicity was low. Extracts concentrations of 0.1%, 1% and 2% were tested in vitro against eight plant pathogenic fungi and two oomycetes in solid and in liquid media. The extracts reduced the growth of several plant pathogenic fungi at 2% dilution by up to 38.37% against Alternaria alternata and up to 46.55% against Sclerotinia sclerotiorum. When combined with myrosinase enzyme the effect of the extracts was enhanced, reaching inhibition values of 67.06% against A. alternata in solid medium and 68.52% against Rhizoctonia solani in liquid medium. In contrast, the same extracts increased the growth of the plant pathogenic oomycetes Pythium ultimum and Phytophthora cactorum. The effect of the same extracts in the free leaving larvae, J2s, of the plant-parasitic nematode (PPN) Meloidogyne javanica was not obvious. Minor significant differences were obtained but with no clear dose-response in nematode mortality, and no inhibition of eggs hatching was observed. These results show the industrial potential of using broccoli residues to obtain extracts with biopesticide activity against plant pathogenic fungi.