Root-knot Nematode Meloidogyne Javanica Research Articles

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

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

The other side of the coin: systemic effects of Serendipita indica root colonization on development of sedentary plant–parasitic nematodes in Arabidopsis thaliana

Main conclusionUpon systemic S. indica colonization in split-root system cyst and root-knot nematodes benefit from endophyte-triggered carbon allocation and altered defense responses what significantly facilitates their development in A. thaliana.Serendipita indica is an endophytic fungus that establishes mutualistic relationships with different plants including Arabidopsis thaliana. It enhances host’s growth and resistance to different abiotic and biotic stresses such as infestation by the cyst nematode Heterodera schachtii (CN). In this work, we show that S. indica also triggers similar direct reduction in development of the root-knot nematode Meloidogyne javanica (RKN) in A. thaliana. Further, to mimick the natural situation occurring frequently in soil where roots are unequally colonized by endophytes we used an in vitro split-root system with one half of A. thaliana root inoculated with S. indica and the other half infected with CN or RKN, respectively. Interestingly, in contrast to direct effects, systemic effects led to an increase in number of both nematodes. To elucidate this phenomenon, we focused on sugar metabolism and defense responses in systemic non-colonized roots of plants colonized by S. indica. We analyzed the expression of several SUSs and INVs as well as defense-related genes and measured sugar pools. The results show a significant downregulation of PDF1.2 as well as slightly increased sucrose levels in the non-colonized half of the root in three-chamber dish. Thus, we speculate that, in contrast to direct effects, both nematode species benefit from endophyte-triggered carbon allocation and altered defense responses in the systemic part of the root, which promotes their development. With this work, we highlight the complexity of this multilayered tripartite relationship and deliver new insights into sugar metabolism and plant defense responses during S. indica–nematode–plant interaction.

Effect on Hatching and Mortality of Root-knot Nematode (Meloidogyne javanica) by Bio-agents

Investigations were carried out in vitro condition to evaluate the antagonistic effect of fungal and bacterial bio-agents. For effective management of root-knot nematode experiment was conducted in laboratory condition using the culture filtrate (5, 10 and 20 percent concentrate) of bio-agents (viz., Trichoderma viride, Trichoderma harzianum, Purpureocillium lilacinum, Pochonia chlamydosporia and Pseudomonas fluorescens). Experimental results showed that all the tested bio-agents significantly reduced the percent hatched juveniles and increased the percent mortality of juveniles. Among the tested bio-agents T. viride was found most effective treatment with minimum percent hatched juveniles and maximum percent mortality on eggs and juveniles of Meloidogyne javanica.

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.

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.

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.

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.

Nematicidal Potential of Thymol against Meloidogyne javanica (Treub) Chitwood.

Root-knot nematodes (RKN; Meloidogyne spp.) are obligatory endoparasites with worldwide distribution which cause severe damage to agricultural crops. The present study aimed to define the nematicidal activity of thymol on different life stages of the root-knot nematode Meloidogyne javanica (Treub) Chitwood, at concentrations of 37.5-1000 μL/L. This study is the first to report the effect of thymol on egg differentiation and also its vapor and sublethal concentration activities. A mortality of greater than 90% of M. javanica second-stage juveniles (J2s) occurred after 96 h of exposure at a concentration of 500 μL/L. At this concentration, thymol inhibited 59.7% of nematode hatching. In addition, the use of thymol at sublethal concentrations reduced the number of females per gram in tomato roots in a pot test, as well as inhibiting egg differentiation. On the contrary, no nematostatic effects were observed in paralysis bioassays. The results presented here indicate that the use of thymol may show its potential as a source of a new sustainable nematicidal product.

Discerning host plant resistance sources in common bean (Phaseolus vulgaris) against root-knot nematode (Meloidogyne javanica) infection

From this study we could conclude that, resistant cultivars are the single effective solution to the management of root-knot nematode population to avoid crop losses. Also, it is essential to use resistant cultivars in situations where nematodes are present and when control is advantageous to yields. However, the reported moderately resistant cultivars, viz. Gujarat Rajmash, Amber (IPR 96-4) and HUR15 belong to secondary gene pool with cross-compatibility to cultivated common bean. Therefore, it may be further used in the pre- breeding programme for developing resistant common bean cultivars against root knot nematodes.

Improvement the activities of plant growth-promoting rhizobacteria in root-knot nematode Meloidogyne javanica and tomato plant growth in Wasit Province

This study had been conducted to detect the existence and dispersal of bacteria in the agricultural area in Wasit province and the role of them in controlling root knote nematode .Two genera of bacteria Azotobacter and Pseudomonas were isolated from six locations in Wasit province which were Alsiwarah , Alnuamania , Alahrar , Alhay , Alkut and Algardhia with five isolates of Azotobacter and eight isolates of Pseudomonas . The infectivity study of five Azotobacter isolates revealed that there is a significant differences between the isolates comparing with the control in reduction eggs hatching and the more effective isolates was Azotobacter sp1 ( Az1) with inhibition percentage 95.05% followed by the isolate Azotobacter sp2 (Az2 ) 84.32%. while the study of eight Pseudomonas isolates revealed that the more effective isolates was Ps eudomonas fluorescens2 ( Ps2) ) with inhibition percentage 90.16% and the lowest percentage recorded in the case of the isolate P. fluorescens6 ( Ps6) which was 55.76% . The infectivity study of four selective bacterial isolates (Az1, Az2, Ps1 , Ps2 ) with the fungus Glomus against nematode revealed the highest percentage of reduction in root galling recorded when the tomato plants inoculated with the fungus and the two bacterial isolates( Az1) , ( Ps2) and the number of galls were 3 galls/gm roots comparing with the control 10.6 galls/gm roots and the percentage of reduction 71.69 follwed by the treatment with the fungus and the two bacterial isolates( Az1) , ( Ps1) 68.86 %. The result also revealed that the combination between Glomus and bacterial isolates induced plant growth and increased the criteria of growth parameters. The result also revealed G lomus alone achieved percentage of reduction in root galling recorded when47.16% and the number of galls were 5.6 galls/gm roots comparing with the control 10.6 galls/gm roots.

Biological control of Root-knot nematode (Meloidogyne javanica) by potential antagonism of endophytic fungi isolated from Taify roses

ObjectivesPlant-parasitic nematodes are a serious threat to global agricultural production worldwide. To avoid synthetic chemistries toxicity there is a dire need of the hour to develop innovative nematode control strategies. Biological control using the antagonistic fungi of the plants is considered very economical and environment friendly. MethodsEfficacy of different fungal filtrate concentrations was estimated towards the mortality and clutching of Meloidogyne javanica. To determine the antagonistic potential of Penicillium citrinum (MN518391), time of disclosure was assessed in the laboratory with the result “exposure to 8% filtrate for a clock (24 hrs.), expressively reduced the viable juveniles and hatched eggs. ResultsExposition to aforementioned filtrate of P. citrinum for a clock (24 hrs.) revealed that juvenile body turned into straight stature leading to reduction in viability of nematodes. Contrary to it most of nematodes exhibited bent body when exposed to Aspergillusniger (MK713445), or (MN513383) its filtrates. Among the various isolated antagonistic fungi, GC–MS analysis revealed 22 unique compounds e.g., quinazoline and its derivatives as the most prevalent and squalene as least occurring possess significant nematicidal properties against the rootknot nematodes. ConclusionHence, using antagonistic fungus from the described plans as BCAs in agriculture against plant-parasitic nematodes is a viable long-term biocontrol technique and provide future avenues in this area of research.

Effects of Arugula Vermicompost on the Root-Knot Nematode (Meloidogyne javanica) and the Promotion of Resistance Genes in Tomato Plants.

Root-knot nematodes are the most important plant-parasitic nematodes worldwide. Many efforts have been made to find non-chemical, risk-free, and environmentally friendly methods for nematode control. In this study, the effects of compost and vermicompost of arugula (Eruca sativa) on Meloidogyne javanica were investigated in three glasshouse experiments. In addition, the expression of the defense-related genes nonexpressor of pathogenesis-related 1 (NPR1) and lipoxygenase 1 (LOX1) was detected in tomato plants treated with vermicompost of arugula at 0, 2, 7, and 14 days after nematode inoculation. The result showed that the vermicompost of arugula significantly reduced the reproduction factor of the nematode by 54.4% to 70.5% in the three experiments and increased the dry weight of shoots of infected tomato plants. Gene expression analysis showed that LOX1 expression increased on the second and seventh day after nematode inoculation, while NPR1 expression decreased. The vermicompost of arugula showed stronger nematode inhibitory potential than the vermicompost of animal manure. The vermicompost of arugula is superior to arugula compost in suppressing the activity of M. javaniva and reducing its impact. It manipulates the expression of resistance genes and could induce systemic resistance against root-knot nematodes.

Valorization of the Hydrolate Byproduct from the Industrial Extraction of Purple Alium sativum Essential Oil as a Source of Nematicidal Products.

The hydrolate byproduct resulting from the industrial essential oil extraction of Spanish purple garlic has been studied against the root-knot nematode Meloidogyne javanica by in vitro and in vivo bioassays. The essential oil, the hydrolate and its organic fraction caused high mortality of juveniles, suppressed egg hatch, and reduced nematode infection and reproduction on tomato plants. The nematicidal compounds of garlic oil, diallyl disulfide and diallyl trisulfide, were the major components of the hydrolate organic fraction. These findings have important implications for the development of new nematode control products based on garlic hydrolate compounds and highlight the recovery of waste from essential oils extraction, promoting a circular economy.

Use of Leaf Extract and Powder of Ipomoea asarifolia for Control of Root-Knot Nematode (Meloidogyne javanica) on Okra in Jalingo Nigeria

As the unseen enemy, nematodes have caused untold damage to crops and farmers’ income across the world. A study was conducted in 2019 and 2020 to determine the effect of leaf extract and powder of Ipomoea asarifolia (Desr.) Roem. & Schult. On root-knot nematode (Meloidogyne javanica) (Treub, 1885) on okra in the laboratory and pot experiment. Juvenile mortality and egg hatch inhibition tests were conducted in the laboratory. Result of the juvenile mortality test showed that the crude extract (100 % extract) cause the highest mortality (95.33 %) of juveniles while the same crude extract inhibited the hatching of more M. javanica eggs (89.67 %) than the dilutions and control. For the pot experiment, results show that the 60 g powder treatment gave the least galling index (1.0), nematode population (146.96), reproduction factor (0.25) and the highest yield (1568.3 Kg/ha) in 2019. The same trend was observed in 2020. Based on these findings, I. asarifolia leaf extract and powder (60 g) have the potential to put in check the menace posed by M. javanica on okra.

Effect of Compost Along with Bio Agents on Root Knot Nematode (Meloidogyne spp.) in Okra (Abelmoschus esculentus L., Walp)

Okra [Abelmoschus esculentus L., Moench] a native of South-Africa and commonly known as ‘Bhindi’ is an annual malvaceous vegetable crop, especially grown in tropical and subtropical climates. It is also called “perfect villager’s vegetable”. Root-knot nematodes are considered among the top five major plant pathogens and the first among the ten most important genera of plant parasitic nematodes in the world. Amongst nematodes, root-knot nematode (Meloidogyne incognita and Meloidogyne javanica) causes severe damage to okra. Trichoderma viride, Pseudomonas fluorescene and Rhizobium were tested under field conditions during Rabi 2020-2021 for their efficacy against the Root knot nematode and growth & nematode population.

Plant growth-promoting rhizobacteria - Bacillus cereus KMT-5 and B. megaterium KMT-8 effectively suppressed Meloidogyne javanica infection

Root-knot nematodes are the most ecologically and economically damaging pests, causing significant crop losses worldwide. The management of root-knot nematodes via biological means is an effective and ecofriendly strategy being followed nowadays. This study aimed to isolate, identify, characterize plant growth-promoting rhizospheric bacteria (PGPR) KMT-5 and KMT-8 and evaluate against root-knot nematode Meloidogyne javanica under laboratory, greenhouse as well as field conditions. The bacterial strains KMT-5 and KMT-8 were identified based on 16S rRNA gene sequence analysis as Bacillus cereus (accession no. MT626659) and B. megaterium (accession no. MT626661), respectively. Both the strains showed various plant growth promoting attributes such as phytohormone production, ammonia excretion, and hydrogen cyanide production. In vitro experiments on culture filtrates of both the strains against M. javanica eggs and juveniles (J2)11J2: Second stage juveniles. resulted in up to 96% hatching inhibition and nearly 85–89% mortality of juveniles. The nematode populations were significantly suppressed (up to 93%) in greenhouse experiments (2018 and 2021). A massive decline in the number of eggs and galls was observed compared to control. Both the strains significantly improved the plant growth and yield of brinjal and tomato crops compared to control as well as carbofuran treatment. A similar trend was followed during field trials on brinjal and cucumber in nematode-infected farmer's fields. Field nematode population went down up to 56% in KMT-5 and 68% in KMT-8 treated plots. A notable enhancement in brinjal and cucumber yield was also observed. The results were again significantly better than the carbofuran treatment. Therefore, the plant growth-promoting bacterial isolates KMT-5 and KMT-8 can act as potential biological control agents against root-knot nematodes and could be considered eco-friendly substitutes to synthetic nematicides.

Effective and Promising Strategy in Management of Tomato Root-Knot Nematodes by Trichoderma harzianum and Arbuscular Mycorrhizae

The ecosystem is considerably affected due to the extensive use of chemical pesticides and fertilizers. As an alternative strategy, this study aimed to assess the biocontrol potential of the bioagents arbuscular mycorrhizal fungi and plant growth-promoting Trichoderma harzianum MZ025966 against tomato root-knot nematodes (Meloidogyne javanica). T. harzianum showed a great potentiality to produce indole acetic acid (IAA) (12.11 ± 2.12 μg/mL) and exhibited a noticeable activity of ammonification. Furthermore, T. harzianum revealed protease and lipase enzymatic activity of 28.36 ± 2.82 U/mL and 12.30 ± 0.31 U/mL, respectively, which may illustrate the control mechanism of nematode eggs and juveniles. As in mycorrhizal and/or T. harzianum inoculated tomato plants, the penetration rates of nematodes, as well as the number of juveniles, females, egg mass, and galls were significantly reduced. The lowest number of juveniles was observed in the case of either single mycorrhizal inoculation (45%) or in combination with T. harzianum (55%). The enzymatic activity of glutathione peroxidase and catalase was enhanced in tomato plants inoculated with the bioagents to overcome the negative impact of nematode parasitism. Our results proved that the application of biocontrol agents not only reduced the nematode population and penetration rate but also improved the plant growth, increased the nutritional elemental content and stimulated the plant’s systematic resistance.

Screening of the hatching control of root-knot nematodes using extract concentrations from oat genotypes

Even though oats (Avena spp.) have the capacity to produce numerous compounds with the potential to act antagonistically against plant pathogens, studies on the genotypic effect of this crop focusing on their nematicidal activity are limited. The objective of this study was to verify the effect of the aqueous extracts prepared with the biomass of oat genotypes, on the hatching of second-stage juveniles of root-knot nematodes (Meloidogyne javanica and Meloidogyne incognita). The bioassays were carried out in a completely randomized design with four replications. Eighteen extracts were evaluated, consisting of a combination of six oat genotypes Agro Quaraí, Agro Esteio, Embrapa 139, AF 12202, UPFPS Farroupilha, and AF 1345 Ucraniana, and three extract concentrations (5 %, 10 %, and 20 % w/v). Three additional treatments were added to the study (distilled water, chemical nematicides abamectin, and imidacloprid + thiodicarb). The treatments and the suspension containing nematode eggs were placed in Petri dishes and incubated in a growth chamber for ten days. At the 5 % and 10 % w/v concentration levels, a genotype effect was observed in the hatching of juveniles for both nematode species. For the control of M. javanica the extracts of Embrapa 139 had a better performance, while the extracts of Agro Quaraí and AF1345 Ucraniana performed better when under the control of M. incognita. Thus, oat biomass formation might have the ability to suppress the nematode population in the soil, and could therefore, be used for the management of root-knot nematodes.

Infection and Egg Development of the Root-Knot Nematode Meloidogyne javanica on Oleander Nerium oleander

Adel, R.M. and F.K. Aljuboori. 2022. Infection and Egg Development of the Root-Knot Nematode Meloidogyne javanica on Oleander Nerium oleander. Arab Journal of Plant Protection, 40(4): 293-298. https://doi.org/10.22268/AJPP40.4.293298 The identification and first record of Nerium oleander infection with root-knot nematode M. javanica was confirmed by the PCR test using the pair of species-specific primers (Fjav and Rjav). Symptoms of the Oleander root-knot disease are similar to those caused by these nematodes on other flowering plants. The results of the study described the stages of embryo development inside the egg and until hatching under laboratory conditions. The difference in egg shape index ranged from 35.8 to 87.9, whereas the dominant egg shape index was between 44.5 and 48.8. Keywords: Nerium oleander, eggs, embryo development, root knot nematode, Meloidogyne javanica

Effectiveness of Silver Nanoparticles Botanically and Chemically Synthesized as well as Chitosan against Root-Knot Nematode Meloidogyne javanica in Vitro

Effectiveness of Silver Nanoparticles Botanically and Chemically Synthesized as well as Chitosan against Root-Knot Nematode Meloidogyne javanica in Vitro