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Root-knot nematode Meloidogyne incognita is among the biotic factors which has greatly affected both the yield and the quality of the tomato crop. The egg parasitic nematode, Purpureocillium lilacinum (Pl) is considered as one of the most promising agents in controlling and overcoming this plant pathogen. The nematicidal effect of the native isolate Pl AUMC 10149 on second stage juvenile’s survival and egg hatching of M. incognita at different times of exposure was tested in vitro. The obtained data showed that Pl gave a maximum percentage of J2 mortality (97.6%) and egg hatching inhibition (79.8%) after 72 hours of exposure. The potentiality of Pl as well as Bio-Nematon to control M. incognita infecting tomato was conducted using different times of application in vivo. Nine treatments with five replicates were used for such bioagents compared with the nematicide Oxamyl. Each seedling was inoculated with 1000 J2s of nematode/pot and 10 mL of Pl (1x1010 CFU/mL) or Bio-Nematon spore suspension (1x108 CFU/mL) 10mL/pot. The results indicated that the most effective treatments in reducing nematode population, number of galls and egg masses of M. incognita in plant roots was performed with treatment by Pl pre-planting and post-infection with Pl (Rf 1.9) giving a significant enhancement in plant length (64.9%), fresh weight (72.52%) and shoot dry weight (163.41%) without negatively impacting environment. Therefore, the present study confirmed that using P. lilacinum AUMC 10149 can be used as a practical supplement to environmentally friendly disease management of root-knot nematodes in Egypt. Resumo O nematoide-das-galhas Meloidogyne incognita está entre os fatores bióticos que afetaram enormemente a produção e a qualidade da cultura do tomate. O nematoide parasita de ovos, Purpureocillium lilacinum (Pl), é considerado um dos mais promissores agentes no controle e superação desse fitopatógeno. O efeito nematicida do isolado nativo Pl AUMC 10149 na sobrevivência de juvenis de segundo estágio e na eclosão dos ovos de M. incognita em diferentes momentos de exposição foi testado in vitro. Os dados obtidos mostraram que o Pl deu um percentual máximo de mortalidade de J2 (97.6%) e inibição da eclosão dos ovos (79.8%) após 72 horas de exposição. A potencialidade de Pl e de Bio-Nematon para controlar M. incognita infectando tomate foi conduzida em diferentes tempos de aplicação in vivo. Nove tratamentos com cinco repetições foram usados para tais bioagentes em comparação com o nematicida Oxamyl. Cada muda foi inoculada com 1.000 J2s de nematoide / vaso e 10 mL de Pl (1×1010 CFU/mL). Ou suspensão de esporos Bio-Nematon (1×108 CFU/mL) 10mL/pot. Os resultados indicaram que os tratamentos mais eficazes na redução da população de nematoides, número de galhas e desovas de M. incognita nas raízes das plantas foram realizados com Pl pré-plantio e pós-infecção com Pl (Rf 1.9), dando um aumento significativo no comprimento da planta (64.9%), massa fresca (72.52%) e massa seca da parte aérea (163.41%) sem impactar negativamente o meio ambiente. Portanto, o presente estudo confirmou que o uso de P. lilacinum AUMC 10149 pode ser usado como um suplemento prático para o manejo ecologicamente correto de nematoides-das-galhas no Egito.

Root-knot nematodes (Meloidogyne spp.) are obligate plant parasites that cause severe economic losses to agricultural crops worldwide. Because of serious health and environmental concerns related to the use of chemical nematicides, the development of efficient alternatives is of great importance. Biological control through exploiting the potential of rhizosphere microorganisms is currently accepted as an important approach for pest management in sustainable agriculture. In our research, during screening of rhizosphere bacteria against the root-knot nematodes Meloidogyne incognita, Ochrobactrum pseudogrignonense strain NC1 from the rhizosphere of healthy tomatoes showed strong nematode inhibition. A volatile nematicidal assay showed that the cell-free fermentation filtrate in the first-row wells of 12-well tissue culture plates caused M. incognita juvenile mortality in the second-row wells. Gas chromatography-mass spectrometry analysis revealed that dimethyl disulfide (DMDS) and benzaldehyde were the main volatile compounds produced by strain NC1. The nematicidal activity of these compounds indicated that the lethal concentration 50 against the M. incognita juveniles in the second-row wells and the fourth-row wells were 23.4 μmol/ml and 30.7 μmol/ml for DMDS and 4.7 μmol/ml and 15.2 μmol/ml for benzaldehyde, respectively. A greenhouse trial using O. pseudogrignonense strain NC1 provided management efficiencies of root-knot nematodes of 88 to 100% compared with the untreated control. This study demonstrated that nematode-induced root-gall suppression mediated by the bacterial volatiles DMDS and benzaldehyde presents a new opportunity for root-knot nematode management.

Nemours effective management tactics were used to reduce world crop losses caused by plant-parasitic nematodes. Nowadays the metallic nanoparticles are easily developed with desired size and shape. Nanoparticles (NPs) technology becomes a recognized need for researchers. Ecofriendly and biosafe SiNPs are developed from microorganisms. Recently, silicon nanoparticles (SiNPs) have gained novel pesticide properties against numerous agricultural pests. This study assessed the biosynthesis of SiNPs from Fusarium oxysporum SM5. The obtained SiNPs were spherical with a size of 45 nm and a negative charge of −25.65. The nematocidal effect of SiNPs against egg hatching and second-stage juveniles (J2) of root-knot nematode (RKN) (Meloidogyne incognita) was evaluated on eggplant,Solanum melongena L. plants. In vitro, all tested SiNPs concentrations significantly (p ≤ 0.05) inhibited the percentage of egg hatching at a different time of exposure than control. Meanwhile, after 72 h, the percent mortality of J2 ranged from 87.00 % to 98.50 %, with SiNPs (100 and 200 ppm). The combination between SiNPs and the half-recommended doses (0.5 RD) of commercial nematicides namely, fenamiphos (Femax 40 % EC)R, nemathorin (Fosthiazate 10 % WG) R, and fosthiazate (krenkel 75 % EC) R confirmed the increase of egg hatching inhibition and J2 mortality after exposure to SiNPs (100 ppm) mixed with 0.5 RD of synthetic nematicides. The findings suggest that the combination between SiNPs, and 0.5 RD of nematicides reduced nematode reproduction, gall formation, egg masses on roots and final population of J2 in the soil. Therefore, improving the plant growth parameters by reducing the M. incognita population.

Meloidogyne incognita, the southern root-knot nematode (RKN), is the most predominant plant-parasitic nematode species of tomato and causes significant yield loss. The Mi-1.2 gene confers resistance in tomatoes to M. incognita; however, virulent RKN populations capable of parasitizing resistant tomato cultivars have been reported from different regions in the world. Four naturally occurring virulent populations of M. incognita were found in vegetable fields from four counties in Georgia with no history of tomato cultivation of the Mi gene. Two consecutive greenhouse trials showed that all four virulent RKN populations reproduced on tomato cultivars, including Amelia, Skyway, and Myrtle, with the Mi-1 gene, while an avirulent population of M. incognita race 3 was unable to overcome host resistance. Virulent RKN populations varied in reproduction among resistant cultivars, with Ma6 population having the greatest reproduction potential. No difference in penetration potential of the virulent (Ma6) and avirulent populations was found on susceptible and resistant tomato cultivars. However, virulent Ma6 population females were successful at egg-laying, whereas avirulent female development was arrested in the resistant cultivars. The virulent Ma6 population also induced feeding sites in the roots of resistant cultivars, whereas the avirulent population did not. To our knowledge, this is the first report of resistance-breaking populations of M. incognita in Georgia and the second state in the United States after California.

Cucumber (Cucumis sativus L.) is an economically important vegetable crop in China. Southern root-knot nematode (Meloidogyne incognita) is a significant obstacle in cucumber production, causing severe root damage and yield losses. Moreover, resistance development to fosthiazate, and poor mobility of abamectin, have led to failure to control this nematode. It is of great interest to growers and the vegetable industry to explore novel nonfumigant nematicides that can provide adequate control in an environmentally friendly manner. Fluopimomide (FM), a new chemical having a similar structure to fluopyram, was shown to exhibit toxic effects on fungi and nematodes. The efficacy of FM to reduce infection of M. incognita in cucumber was evaluated under greenhouse and field conditions. In the greenhouse, FM at all test rates resulted in a 22.5 to 39.6% and 31.3 to 55.0% reduction in the population density of M. incognita in the soil at 30 and 60 days after treatment (DAT), respectively, compared with the nontreated control. FM at 500 and 750 g ha−1 reduced (P < 0.05) root galling, meanwhile increasing plant height compared with the nontreated control at 30 and 60 DAT. In the field trials, FM at 500 and 750 g ha−1 decreased the population density of M. incognita and root galling 57.2 to 69.9% compared with the untreated control, while enhancing cucumber yield in two consecutive years. Furthermore, FM at 500 g ha−1 combined with fosthiazate was the most effective treatment showing a synergistic effect on reducing population densities of M. incognita, which was significantly greater than either FM or fosthiazate by themselves. In summary, FM has considerable potential for managing M. incognita on cucumber.

BACKGROUND The combination of biocontrol agents is a desirable strategy to improve control efficacy against the root-knot nematode (RKN) Meloidogyne incognita under field conditions. However, strains compatibility is generally tested in vitro and incompatible combinations are normally not further examined in experiments in planta. Therefore, there is virtually no information on the performance of incompatible strains. In this study, we evaluated two Bacillus strains previously described as incompatible in vitro for effects on plant growth and suppression of M. incognita, pathogenic fungi and nematophagous fungi. RESULTS Strains BMH and INV were shown to be closely related to Bacillus velezensis. These strains, when applied individually, reduced the number of galls and eggs of M. incognita by more than 90% in tomato roots. When BMH and INV were combined (BMH + INV), RKN suppression and tomato shoot weight were lower compared to single-strain applications. Additionally, metabolites in cell-free supernatants and volatile organic compounds (VOCs) from strains BMH and INV had strong effects against the plant pathogens M. incognita, Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsiii, but not against three species of nematophagous fungi. Although strain INV and the combination BMH + INV emitted fewer VOCs than strain BMH, they were still capable of killing second-stage juveniles of M. incognita. CONCLUSIONS Bacillus strains BMH and INV inhibited M. incognita and fungal pathogens, and promoted tomato growth. However, strain INV emitted fewer VOCs and the combination BMH + INV did not enhance the activity of the biocontrol strains against the RKN or their capacity to promote plant growth.

Various kinds of biotic and abiotic environmental stresses impose threat on growth and yield of crops. Amongst biotic stresses, Root knot nematode (RKN), especially Meloidogyne incognita act as one of the main constraints with wide range of hosts, that ultimately results in huge global losses in terms of yield and productivity. Nowadays, different soil micro biota has achieved importance as bio-control agents against RKNs. In this aspect, the present study was designed to assess the nematicidal potential of metabolites produced by Streptomyces sp. strain MR-14 against M. incognita in order to regulate its pathogenicity in plants. The current study revealed that metabolites present in crude extract showed 83% of mortality in juveniles of M. incognita. The work was further carried out in 7 days old M. incognita infested Solanum lycopersicum seedlings. The seedlings that were pre-treated with the metabolites in the form of crude extract and supernatant showed significant reduction in gall formation. Furthermore, treated seedlings showed enhanced photosynthetic activities as well as antioxidative defence mechanism. The microscopic studies were also assessed to screen the effect of microbial strain on the glutathione tagging and cell viability. The studies confirmed the potential of Streptomyces sp. strain MR-14 as biocontrol agent that not only promoted the plant growth but also improved the biochemical responses of the infected plants.

International audience

Ginger (genus Zingiber) is widely used as a spice and a medicinal herb worldwide and is the major ingredient of traditional local drinks such as jamu in Southeast Asia. Because ginger is frequently consumed, there is an increasing interest in organic ginger production without the use of synthetic agrochemicals. Recent studies have reported that certain kinds of entomopathogenic fungi (EPF) can establish endophytic- or mycorrhiza-like relationships with plants, thereby promoting plant growth and health, in addition to their typical role in crop protection as biological control agents. In this study, we explored the possibility of non-entomopathogenic effects of EPF Beauveria bassiana and Cordyceps fumosorosea on ginger plants (Zingiber officinale) via antagonism with Fusarium oxysporum or the parasitic nematode Meloidogyne incognita. The two EPF negatively affected the growth of F. oxysporum and survival of M. incognita in vitro. The application of EPF did not have any negative effect on the growth of ginger plants. Soil chemical properties were not different between the plots with or without EPF application, while the diversity of soil bacteria was observed to increase on application of EPF. At least C. fumosorosea appeared to persist in soil during the period of ginger cultivation. Thus, these EPF are potentially useful tools for producing chemical-free ginger.

Brinjal (Solanum melongena L.) is an important vegetable worldwide and its production is hampered by the infestation of root-knot nematodes (Meloidogyne spp.). In an attempt to identify the Meloidogyne species involved in causing root-knot disease of brinjal by using molecular tools, plants showing knots/galls were collected from 22 brinjal growing locations that belong to different agro-ecological zones in Bangladesh. Nematode populations were maintained in a susceptible brinjal variety by inoculating with egg-masses developed on different varieties of brinjal roots collected from different locations. For molecular identification, DNA was extracted directly from galls developed in the roots of the inoculated plants. Randomly selected three galls from each location were crushed together in order to get DNA from mixed species of root-knot nematodes. Sequence Specific Amplified Region (SCAR) primers specific for Meloidogyne incognita, M. javanica or M. arenaria were used for PCR amplification. For 18 of the 22 locations, M. javanica was identified. At two locations M. incognita was found as a mixed population with M. javanica. M. arenaria was not found. PCR products were sequenced bi-directionally and their analysis revealed genetic variation among the populations. M. javanica was the predominant root-knot nematode species of brinjal in Bangladesh. Intra-specific variation of the SCAR suggested six phylogenetic groups of M. javanica. They showed significant differences in reproduction on brinjal and in their effect on root and shoot weight, while differences in hatching dynamics over five weeks were not significant. This population-dependent aggressiveness of the dominant root-knot nematode M. javanica on brinjal in Bangladesh should be considered for a more efficient management.

We reported an NBS-LRR gene, PsoRPM3, is highly expressed following RKN infection, initiating an HR response that promotes plant resistance. Meloidogyne spp. are root-knot nematodes (RKNs) that cause substantial economic losses worldwide. Screening for resistant tree resources and identifying plant resistance genes is currently the most effective way to prevent RKN infestations. Here, we cloned a novel TIR-NB-LRR-type resistance gene, PsoRPM3, from Xinjiang wild myrobalan plum (Prunus sogdiana Vassilcz.) and demonstrated that its protein product localized to the nucleus. In response to Meloidogyne incognita infection, PsoRPM3 gene expression levels were significantly higher in resistant myrobalan plum plants compared to susceptible plants. We investigated this difference, discovering that the − 309 to − 19 bp region of the susceptible PsoRPM3 promoter was highly methylated. Indeed, heterologous expression of PsoRPM3 significantly enhanced the resistance of susceptible tobacco plants to M. incognita. Moreover, transient expression of PsoRPM3 induced a hypersensitive response in tobacco, whereas RNAi-mediated silencing of PsoRPM3 in transgenic tobacco reduced this hypersensitive response. Several hypersensitive response marker genes were considerably up-regulated in resistant myrobalan plum plants when compared with susceptible counterparts inoculated with M. incognita. PsoPR1a (a SA marker gene), PsoPR2 (a JA marker gene), and PsoACS6 (an ET signaling marker gene) were all more highly expressed in resistant than in susceptible plants. Together, these results support a model in which PsoRPM3 is highly expressed following RKN infection, initiating an HR response that promotes plant resistance through activated salicylic acid, jasmonic acid, and ethylene signaling pathways.

The relevance of studying resilience is among other things conditioned by faster evolution of social objects, increase in general uncertainty, lack of stability, complexity and ambiguity of the dynamics of their state, which, in their turn, lead to an increase in the requirements for adaptation mechanisms of an individual and social groups (families, collectives, sports teams, managerial or project teams); the importance of an individual’s socio-psychological and psychological resources is increasing. Not all spontaneously formed adaptation mechanisms of individual and group subjects are developed in a timely manner, correspond to life situations or change optimally in accordance with changes in the purposes and requirements of the environment. The purpose of the study is to investigate human resilience under conditions of uncertainty; the subjects of the study are social and psychological mechanisms and resources of human resilience; the research methods are historical and theoretical analysis and analysis of the empirical research results. The hypothesis is that maintaining resilience of an individual and social groups through the development of prosocial behavior mechanisms according to the specific model (prototype) is the first stage. Subsequent stages of resilience development presuppose formation of adaptation mechanisms initiated and supported by the evolution of the subject’s “internal conditions”. It is stated that the two states of a person are considered within the boundaries of historically formed paradigms: “below the norm” and “within the norm” of social, psychological and physical functioning. Its characteristics are described by such concepts as “improvement”, “positive adaptation”, “preservation”, “optimal state”, etc. Resilience is viewed as the person’s achievement and maintenance of “social homeostasis” with an orientation towards pro-social behavior models of others and reproduction of such models. Individual’s advancement to a higher level of social functioning and his/her positive professional evolution are often associated with repeated changes and complications of the social conditions of social environment (medium), with the growth in its “resistance”; they remain understudied and retain a kind of “terra incognita” status. One of the possible and probable approaches that contribute to overcoming the binary thinking of the historically established paradigm can be the use of a new methodology, i.e. construction of system triads (that recreate social objects’ integrity) and linear triads that restore the sequences of social objects’ syntheses when they are integrated into systems of a greater generality.

International audience; Root-knot nematodes, Meloidogyne spp., secrete effectors to modulate plant immune responses and establish a parasitic relationship with host plants. However, the functions and plant targets of C-type lectin (CTL)-like effectors of Meloidogyne incognita remain unknown. Here, we characterized a CTL-like effector of M. incognita, MiCTL1a, and identified its target and role in nematode parasitism. In situ hybridization demonstrated the expression of MiCTL1 in the subventral glands; and in planta, immunolocalization showed its secretion during M. incognita parasitism. Virus-induced gene silencing of the MiCTL1 reduced the infection ability of M. incognita in Nicotiana benthamiana. The ectopic expression in Arabidopsis not only increased susceptibility to M. incognita but also promoted root growth. Yeast two-hybrid and co-immunoprecipitation assays revealed that MiCTL1a interacts with Arabidopsis catalases, which play essential roles in hydrogen peroxide homeostasis. Knockout or overexpression of catalases showed either increased or reduced susceptibility to M. incognita, respectively. Moreover, MiCTL1a not only reduced catalase activity in vitro and in planta but also modulated stress-related gene expressions in Arabidopsis. Our data suggest that MiCTL1a interacts with plant catalases and interferes with catalase activity, allowing M. incognita to establish a parasitic relationship with its host by fine-tuning responses mediated by reactive oxygen species.

Summary Cover crops can be a useful tool for managing plant-parasitic nematodes provided they are poor or non-hosts for the target nematode species. A glasshouse experiment was done to determine the host status of four common cover crops in Florida, sunn hemp, cowpea, sorghum sudangrass and sunflower, to pure populations of four common tropical root-knot nematode (RKN) species Meloidogyne javanica (Mj), M. incognita (Mi), M. enterolobii (Me) and M. arenaria (Ma). Tomato was included as a susceptible control. Eight weeks after nematode inoculation (WAI), tomato showed the highest root gall damage for all tested RKN species, with gall indices (GI) between 7 (Ma) and 8.5 (Me) and reproduction factor (RF) ranging from 20 (Ma) to 50 (Mj). No visible root galls were observed for any of the RKN species on sunn hemp and sorghum sudangrass at 8 WAI. However, Mj and Mi were able to reproduce slightly on sorghum sudangrass (RF = 0.02 and 0.79, respectively). Sunflower and cowpea were infected by all four tested RKN species, but host suitability varied. Sunflower root galling ranged from 1.1 (Me) to 4.5 (Mj) and RF = 3.2 (Me) to 28.7 (Mj), while cowpea root galling ranged from 0.6 (Mi) to 5.1 (Me) and RF = 0.8 (Mi) to 67.3 (Mj). Sunn hemp and, to a lesser extent, sorghum sudangrass were poor hosts to all four tested RKN species. Sunflower was a good host to all RKN species, but root gall damage and RF were lowest for Me. Cowpea was a good host to Mj, Me and Ma, but a poor host to Mi. Our results confirm and stress the importance of RKN species identification when selecting cover crops as an RKN management strategy.

Biological control using rhizosphere bacteria, Pseudomonas spp. and Serratia spp. is a prospective alternative technique to overcome plant parasitic nematodes infection. So, the current study was conducted in vitro on five egg-masses, 100 free eggs and 100 infective juveniles (IJs) of Meloidogyne incognita as well as greenhouse treatments on Luffa aegyptiaca L. to evaluate the nematicidal potential of six strains belong to Pseudomonas spp. and Serratia spp. as compared to oxamyl. Results showed that the inhibitory effect and juvenile mortality varied according to bacteria species, strains and exposure time. All the tested bacteria significantly (P ≤ 0.05) inhibited egg hatching and increased juvenile mortality in vitro. After 3 days of treatment, Pseudomonas spp. were more effective against eggs (48.31to 55.15%) and IJs (20.98 to 25.30%) than Serratia spp. (44.55 to 49.75% with eggs) and (19.06 to 21.61% with IJs), respectively. In the pot experiment, Luffa aegyptiaca L. treated with Serratia spp. and Pseudomonas spp. displayed significantly higher (P ≤ 0.05) levels of growth (as indicated by root length, fresh roots weight and fresh shoots weight) compared to control plants and significantly (P ≤ 0.05) suppressed galling (number of galls) and reproduction (as indicated by number of egg-masses on roots and number of eggs and juveniles in pot soil). Meanwhile, among the treated plants, Serratia spp. and Pseudomonas spp. gave the best results in shoot weight of pots infected by eggs of M. incognita than those infected with IJs as compared with positive control. While, oxamyl treatment gave the best results in pots infected by eggs and IJs. The lowest galling (gall index), number of eggs and juveniles in soil was observed in the treatment with mixture of Serratia spp. and Pseudomonas spp. as well as, enhanced growth of sponge gourd more than application each of them alone. Pots treated with oxamyl overwhelmed those treated with mixture of Serratia spp. and Pseudomonas spp.

The impact of root infection by the nematode Meloidogyne incognita on leaf anti-herbivore defenses and plant resistance to the caterpillar Spodoptera exigua is modulated by the nematode infection cycle., Studies on plant-mediated interactions between root parasitic nematodes and aboveground herbivores are rapidly increasing. However, outcomes for the interacting organisms vary, and the mechanisms involved remain ambiguous. We hypothesized that the impact of root infection by the root-knot nematode Meloidogyne incognita on the performance of the aboveground caterpillar Spodoptera exigua is modulated by the nematode’s infection cycle. We challenged root-knot nematode-infected tomato plants with caterpillars when the nematode’s infection cycle was at the invasion, galling, and reproduction stages. We found that M. incognita root infection enhanced S. exigua performance during the galling stage, while it did not affect the caterpillar’s performance at the invasion and reproduction stages. Molecular and chemical analyses performed at the different stages of the nematode infection cycle revealed that M. incognita root infection systemically affected the jasmonic acid-, salicylic acid-, and abscisic acid-related responses, as well as the changes in the leaf metabolome triggered during S. exigua feeding. The M. incognita-induced leaf responses varied over the nematode’s root infection cycle. These findings suggest that specific leaf responses triggered systemically by the nematode at its different life-cycle stages underlie the differential impact of M. incognita on plant resistance against the caterpillar S. exigua.

The nematode species Meloidogyne incognita infects a large variety of cultivated crops and is one of nature’s most notorious pests. One cultivated plant which is prone to M. incognita infestation is the tomato. Knowing that in A. thaliana the PIN auxin efflux transporters distribution is being altered upon early invasion by M. incognita, the PIN1 allocation patterns in the giant cells of tomato plants after 15 and 25 days of infection were investigated. PIN1 was absent from the giant cells’ membrane in both assessment timings examined, indicating the maintenance of a local auxin maxima, which was also supported by IAA immunodetection. PIN1 distribution pattern could be attributed on either the nematodes nutritional needs throughout its life cycle or due to the tomato plants differential responses upon M. incognita infection.

Roots can recruit beneficial microorganisms to suppress plant pathogens. However, conventional and organic practices differently shape the soil microbiome and consequently the root protection. Here, we investigated the suppressive activity of soil microbiome against the root-knot nematode (RKN) Meloidogyne incognita in horticultural areas under organic or conventional practices and the microbiome profiles in non-inoculated (RKN-absent) and inoculated (RKN-present) rhizospheres. Soils were collected from neighboring areas under long-term conventional or organic practices, but physicochemically similar. After a set of bio-tests in autoclaved and non-autoclaved soils, we concluded that the soil suppressiveness was of biological origin. However, plant growth, RKN suppression and defense induction were higher in organic soils. Also, RKN was highly suppressed when the organic soil microbiome was transferred to infested substrates. We used Illumina MiSeq platform to determine bacterial and fungal profiles in organic and conventional tomato rhizospheres, inoculated or not with M. incognita. Our data suggest that despite the higher bacterial abundance in the conventional RKN-absent rhizosphere, the organic RKN-present rhizosphere recruited more efficiently antagonistic bacteria and fungi. Microbiome α-diversity increased in the organic RKN-present rhizosphere. Antagonistic bacterial genera Pseudomonas, Serratia, Bradyrhizobium, Burkholderia and Azospirillum and fungal genera Beauveria, Clonostachys, Metarhizium, Purpureocillium and Arthrobotrys were highly abundant only in the organic RKN-present rhizosphere. This work suggests the organic and conventional practices interfere in the rhizosphere microbiome composition and consequently in the suppression of RKN, where organic practices intensified the assembly of bacterial and fungal antagonists in the presence of M. incognita.

We appraised the use of zinc oxide nanoparticles, (ZnO-NPs) and zinc oxide bulk (ZnO-bulk) or zinc acetate, as a natural nematocide, alone or in combination with oxamyl in vitro and in vivo trials in order to improve systems for root-knot nematode (RKNs) control in banana plants. Especially, ZnO-NPs were biosynthesized from the alga, Ulva fasciata. In general, all applications of ZnO-NPs were more effective to control RKNs than ZnO-bulk as well oxamyl alone (chemical control). In in vitro conditions, ZnO-NPs with oxamyl showed 98.91% second stage juveniles2 (J2s) mortality of Meloidogyne incognita after 72 h, while 72.86% mortality was observed at the same NPs treatment without oxamyl at the same exposure time. The same treatment was the most significantly effective in diminution of J2s community (82.77%) in soil and galls number (81.87%) in roots under in vivo conditions. In contrast, the highest weight and height of the shoot was observed in Zn-bulk treatment in combination with oxamyl as well oxamyl only (nematocides check). Scanning electron microscopy (SEM) reports displayed the distributions and accumulations of ZnO-NPs on the nematode (J2s) body under direct exposure, which might be the reason of NP-mediated toxicity and disruption for M. incognita.

Biochar is a vital carbon complex and can improve plant growth and suppress of soil-borne pathogens. Root-knot nematode, Meloidogyne incognita is identified as one of the most demoralizing pests blighting roots of many crops and lead to notable decrease in their productivities. So, the present study was carried out with a hypothesis that the application of biochar from various feed-stocks may cause significant enhancements in the tolerance of eggplant for M. incognita infection. Two types of biochars were manufactured by the slow pyrolysis process of rice straw and peanut residues. A pot experiment was conducted to explore the effects of rice straw biochar (RSB) and peanut residues biochar (PRB) on M. incognita and the growth and yield performances of eggplant in loamy soil. Eight treatments were achieved in the current experiment, resulted from the combination between RSB and PRB at four applied rates [zero =no addition, 5.25, 10.5 and 21 g/pot, which were equated to 0, 5, 10 and 20 t/ha, respectively]. Treatments were arranged in a randomized complete block design (RCBD) and with five replicates. The individual incorporation of RSB and PRB at rates of 5.25, 10.5, and 21 g/pot exhibited significant enhancements in growth parameters (length, fresh and dry weight of shoots and roots), and productivity of eggplant. Application of RSB or PRS at 21 g/pot caused superior impacts in enhancing the fresh fruit yield of eggplant (946 and 1012 g/pot). Soil pH increased after applications of RSB and PRB from 5.85 in the control treatment to 6.12-6.39 and 6.28-6.75, respectively. Both RSB and PRB revealed variable degrees in lessening numbers of egg masses and galls/root system and J2/250 g soil of M. incognita and this caused marked improvements in eggplant growth parameters in comparison to the control. The use of high doses of RSB and PRB was responsible for larger efficiency in declining the above-mentioned M. incognita parameters than their low rates. The largest declines in galls/ root system (80 and 93%), egg-masses/ root system (90 and 96%), egg/egg-mass (76 and 90%) and J2/250g soil (83 and 92%) at 50 and 90 days after transplanting (DAT) were shown after application of PRB at a rate of 21 g/pot. This study indicated that RSB and PRB can be used as effective materials in dropping the harmful effects of M. incognita and also can be recommended as eco-friendly alternatives to synthetic pesticides with marked nematicidal activity to control M. incognita infection.

Meloidogyne incognita causes large-scale losses of agricultural crops worldwide. The natural metabolite furfural acetone has been reported to attract and kill M. incognita, but whether the attractant and nematicidal activities of furfural acetone on M. incognita function simultaneously in the same system, especially in three-dimensional spaces or in soil, is still unknown. Here, we used 23% Pluronic F-127 gel and a soil simulation device to demonstrate that furfural acetone has a significant attract-and-kill effect on M. incognita in both three-dimensional model systems. At 24 h, the chemotaxis index and the corrected mortality of nematodes exposed to 60 mg/ml of furfural acetone in 23% Pluronic F-127 gel were as high as 0.82 and 74.44%, respectively. Soil simulation experiments in moist sand showed that at 48 h, the chemotaxis index and the corrected mortality of the nematode toward furfural acetone reached 0.63 and 82.12%, respectively, and the effect persisted in the presence of tomato plants. In choice experiments, nematodes selected furfural acetone over plant roots and were subsequently killed. In pot studies, furfural acetone had a control rate of 82.80% against M. incognita. Collectively, these results provide compelling evidence for further investigation of furfural acetone as a novel nematode control agent.