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Introduction: The management of root-knot nematodes has predominantly been based on use of chemicals, which are detrimental to the environment and human health. Biological control provides alternative management. This study evaluated the potential of using Pleurotus ostreatus , an edible mushroom species to control Meloidogyne spp. in eggplants. Methods: In vitro , the mortality of juveniles (J2) of Meloidogyne spp. were assessed i) P. ostreatus - water suspension with actively growing mycelia, and ii) different dilutions of P. ostreatus PDB broth culture filtrates. In the screen house nematicidal potential of P. ostreatus was tested on eggplants using artificially inoculated soils in a screen house. To attain this, juveniles (J2) of Meloidogyne spp. were inoculated at the base of plants in pots containing P. ostreatus colonized millet grains mixed in 3 kg of soil. The galling index (GI) (scale of 0 to 5), root growth and nematode populations in the different treatments were assessed. Results and discussion: Mortality of nematodes in the P. ostreatus - water suspension significantly increased with time, reaching over 88% at 48 h and 95% at 72 h. Mortality in undiluted filtrate was consistently significantly higher than the diluted filtrates and control without P. ostreatus. Mortality in the undiluted filtrate increased to 95% at 48 h. When 50 g of P. ostreatus -millet culture was mixed with 3 kg autoclaved pot soil, a GI of 0.95 was observed, dropping to 0.70 when the inoculum was doubled to 100 g. For the treatment without P. ostreatus , a high GI of 2.4 was scored. A significant difference in eggplant root growth and nematode population at (p = 0.02) was found across the treatments. The findings from this study for both in-vitro and pot assay suggest that P. ostreatus and its substrate are potential biological control agents for plant parasitic nematodes in eggplants. [ABSTRACT FROM AUTHOR]

Summary Tomato is one of the most economically important vegetable crops in the world and has been seriously affected by the devastating agricultural pest root‐knot nematodes (RKNs). Current understanding of tomato resistance to RKNs is quite limited. VQ motif‐containing family proteins are plant‐specific regulators; however, whether and how tomato VQs regulate resistance to RKNs is unknown. Here, we found that SlVQ15 recruited SlWRKY30IIc to coordinately control tomato defence against the RKN Meloidogyne incognita without affecting plant growth and productivity. The jasmonate (JA)‐ZIM domain (JAZ) repressors of the phytohormone JAs signalling associated and interfered with the interaction of SlVQ15 and SlWRKY30IIc. In turn, SlWRKY30IIc bound to SlJAZs promoters and cooperated with SlVQ15 to repress their expression, whereas this inhibitory effect was antagonized by SlJAZ5, forming a feedback regulatory mechanism. Moreover, SlWRKY30IIc expression was directly regulated by SlMYC2, a SlJAZ‐interacting negative regulator of resistance to RKNs. In conclusion, our findings revealed that a regulatory circuit of SlVQ15‐SlWRKY30IIc and the JA pathway fine‐tunes tomato defence against the RKN M. incognita, and provided candidate genes and clues with great potential for crop improvement. [ABSTRACT FROM AUTHOR]

Background: Climate change threatens sub-Saharan Africa's agricultural production, causing abiotic and biotic stressors. The study of plant responses to joint stressors is crucial for understanding molecular processes and identifying resilient crops for global food security. This study aimed to explore the shared and tailored responses of okra plants (cv. ''Meya'), at the biochemical and molecular levels, subjected to combined stresses of drought and Meloidogyne incognita infection. Design: The study involved 240 okra plants in a completely randomized design, with six treatments replicated 20 times. Okra plants were adequately irrigated at the end of every 10-days water deficit that lasted for 66 days (D). Also, the plants were infected with M. incognita for 66 days and irrigated at 2-days intervals (R). The stresses were done independently, in sequential combination (D before R and R before D) and concurrently (R and D). All biochemical and antioxidant enzyme assays were carried out following standard procedures. Results: Significant reductions in leaf relative water content were recorded in all stressed plants, especially in leaves of plants under individual drought stress (D) (41.6%) and plants stressed with root-knot nematode infection before drought stress (RBD) (41.4%). Malondialdehyde contents in leaf tissues from plants in D, nematode-only stress (RKN), drought stress before root-knot nematode infection (DBR), RBD, and concurrent drought-nematode stress (RAD) significantly increased by 320.2%, 152.9%, 186.5%, 283.7%, and 109.6%, respectively. Plants in D exhibited the highest superoxide dismutase activities in leaf (147.1% increase) and root (105.8% increase) tissues. Catalase (CAT) activities were significantly increased only in leaves of plants in D (90.8%) and RBD (88.9%), while only roots of plants in D exhibited a substantially higher CAT activity (139.3% increase) in comparison to controlled plants. Okra plants over-expressed NCED3 and under-expressed Me3 genes in leaf tissues. The NCED3 gene was overexpressed in roots from all treatments, while CYP707A3 was under-expressed only in roots of plants in RBD and RKN. CYP707A3 and NCED3 were grouped as closely related genes, while members of the Me3 genes were clustered into a separate group. Conclusion: The biochemical and molecular responses observed in okra plants (cv. ''Meya') subjected to combined stresses of drought and Meloidogyne incognita infection provide valuable insights into enhancing crop resilience under multifaceted stress conditions, particularly relevant for agricultural practices in sub-Saharan Africa facing increasing climatic challenges. [ABSTRACT FROM AUTHOR]

The southern root-knot nematode, Meloidogyne incognita, is a highly serious plant parasitic nematode species that causes significant economic losses in various crops, including cucumber (Cucumis sativus L.). Currently, there are no commercial cultivars available with resistance to M. incognita in cucumber. However, the African horned melon (Cucumis metuliferus Naud.), a semi-wild relative of cucumber, has shown high resistance to M. incognita. In this study, we constructed an ultrahigh-density genetic linkage bin-map using low-coverage sequences from an F2 population generated through the cross between C. metuliferus inbred lines CM3 and CM27. Finally, we identified a QTL (quantitative trait locus, QTL3.1) with a LOD (logarithm of the odds) score of 3.84, explaining 8.4% of the resistance variation. Subsequently, by combining the results of qPCR (quantitative PCR) and VIGS (virus-induced gene silencing), we identified two genes, EVM0025394 and EVM0006042, that are potentially involved in the resistance to M. incognita in CM3. The identification of QTLs and candidate genes in this study serve as a basis for further functional analysis and lay the groundwork for harnessing this resistance trait. [ABSTRACT FROM AUTHOR]

Bacillus species are among the most studied and commercially exploited biocontrol agents of plant‐parasitic nematodes. These antagonists may control nematodes by producing toxic or repellent substances, inducing systemic resistance in plants and disrupting nematode chemotaxis. Understanding the mechanism of action of antagonists increases the likelihood of success for microbiological nematicides under field conditions. Therefore, the objective of this work was to elucidate the mechanisms of action of Bacillus amyloliquefaciens strain BaNCT02 against Meloidogyne incognita. We assessed the potential of this strain for forming biofilm in roots and producing volatile and non‐volatile toxic substances. BaNCT02 did not induce systemic resistance in tomato plants against M. incognita. Scanning electron microscopy and chemotaxis analyses revealed that the bacteria form a biofilm on soybean roots and 67% of second‐stage juveniles of M. incognita are repelled by common bean roots treated with the antagonist. Additionally, BaNCT02 produces substances with toxic effects against eggs and juveniles of M. incognita, including volatile organic compounds such as 2‐undecanone and 2‐heptanone, as well as non‐volatile metabolites like proteases and chitinases. The suppressive effect of these substances on hatching and mortality of juveniles varied from approximately 70% to more than 90%. We concluded that B. amyloliquefaciens BaNCT02 forms a biofilm on root surfaces and produces volatile and non‐volatile metabolites with nematicidal and repellent effects against M. incognita. [ABSTRACT FROM AUTHOR]

A crude hexane extract of seed kernel was processed into fatty acid methyl esters (FAME) using methanolic-sulfuric acid. Herbal mixtures (seed extracts of A. squamosa and essential oils of Cymbopogon nardus (citronella) and Pelargonium graveolens (geranium)) were evaluated against root knot nematode (Meloidogyne spp). The mortality of J2s of M. incognita in hexane and methanol extracts (AHE+AME) of A. squamosa with geranium oil (GO) ranged from 50.75-89.75% to 71.50-99.00% at 31.25 to 1000 μgmL-1 in 24 to 96 hours. The number of galls after CO+AHE+AME treatment was 4.0 ± 0.0 and 5.67 ± 0.58 galls/seedling and were recorded at 1000 and 500 μgmL-1 treatments on 30 days after inoculation, compared to carbofuran (3.0 ± 0.0 and 4.3 ± 0.6 galls/seedling) at 1000 and 500 μgmL-1 and velum prime (3.6 ± 0.6 and 4.6 ± 0.6 galls/seedling) at 1000 and 500 μgmL-1. The maximum shoot length of brinjal seedlings was recorded in CO+AHE+AME treatment compared to carbofuran (47.3 ± 0.6cm) and velum prime (48.7 ± 0.6 cm) at 1000 μg mL-1 in soil drenching application. Methanol and hexane extracts (AHE+AME) obtained from Annona squamosa seeds were investigated for their nematicidal properties. M. graminicola in direct-seeded rice at the nursery level and M. incognita in brinjal (eggplant) were controlled for up to sixty days when treated with these mixtures. [ABSTRACT FROM AUTHOR]

Root-knot nematodes induce the formation of feeding sites within the host roots and the relocation of auxin into galls results in abnormal lateral root growth. Here, we analyzed the changes in cucumber root architecture under Meloidogyne incognita stress and the distribution of auxin in these morphological and molecular root changes. The number of root tips significantly decreased, and regression analysis showed a positive relationship between the size of root galls and the numbers of nematodes in galls compared with the lateral roots on galls, emphasizing the effect of nematode parasitism on root development. Data generated via a promoter-reporter system using the transgenic hairy root system first characterized the auxin distribution during nematode parasitism in cucumber. Using DR5:GUS staining of root galls, we further detected the expression of CsPIN1 and CsAUX1, which regulate polar auxin transport. The results showed that both CsPIN1 and CsAUX1 were induced in galls, and the relative expression of the two genes significantly increased at 21 DAI. The TIBA treatment, which can disrupt polar auxin transport inhibited the numbers of cucumber root tips and total length following increasing concentration gradients. Moreover, the numbers of galls were significantly affected by TIBA treatment, which showed the vital role of auxin during nematode parasitism. Our findings suggest that the transportation of auxin plays an important role during gall formation and induces cucumber lateral root development within nematode feeding sites. [ABSTRACT FROM AUTHOR]

Papaya trees showing disease symptoms caused by root-knot nematodes (Meloidogyne spp.) were detected in a tropical fruit farm in Vero Beach, FL, USA. Roots were severely galled containing a high population density of root-knot nematode eggs. The nematode species causing damage was identified as M. incognita based on the morphometrics of body, stylet, and tail length of the second-stage juveniles, and morphological characteristics of female perineal patterns. Molecular analyses using both species-specific and universal primers also confirmed the species identity. A pathogenicity test confirmed M. incognita reproduction on papaya by producing nematode females and egg masses within the root galls. This report documents the first confirmed detection of M. incognita in papaya in Florida, USA, providing detailed information on the nematode's morphology characteristics and DNA sequence data. [ABSTRACT FROM AUTHOR]

BACKGROUND: Root‐knot nematodes (RKNs), Meloidogyne spp., are one of the most destructive polyphagous plant‐parasitic nematodes. They pose a serious threat to global food security and are difficult to control. Entomopathogenic nematodes (EPNs) show promise in controlling RKNs. However, it remains unclear whether the volatile organic compounds (VOCs) emitted from EPN‐infected cadavers can control RKNs. RESULTS: We investigated the fumigation activity of VOCs released from cadavers infected by five different species of EPNs on RKNs in Petri dishes, and found that VOCs released from Steinernema feltiae (SN strain) and S. carpocapsae (All strain) infected cadavers had a significant lethal effect on second‐stage juveniles (J2s) of Meloidogyne incognita. The VOCs released from the cadavers infected with S. feltiae were analyzed using SPME‐GC/MS. Dimethyl disulfide (DMDS), tetradecane, pentadecane, and butylated hydroxytoluene (BHT), were selected for a validation experiment with pure compounds. The DMDS compound had significant nematicidal activity and repelled J2s. DMDS also inhibited egg hatching and the invasion of tomato roots by J2s. In a pot experiment, the addition of S. feltiae‐infected cadavers and cadavers wrapped with a 400‐mesh nylon net also significantly reduced the population of RKNs in tomato roots after 7 days. The number of root knots and eggs was reduced by 58% and 74.34%, respectively, compared to the control. CONCLUSION: These results suggested that the VOCs emitted by the EPN‐infected cadavers affected various developmental stages of M. incognita and thus have the potential to be used in controlling RKNs through multiple methods. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Although microencapsulation technology is an effective pesticide formulation method, the correlation between the release properties of microcapsules and pesticide concentrations in soil and their efficacy has not been thoroughly investigated. Here, the effects of the release properties of the nematicide Fosthiazate (FTZ) from microcapsules on their efficacy against the nematode Meloidogyne incognita were examined using experimental and mathematical approaches. RESULTS: Gradual release of FTZ from both polyurea microcapsules (PU‐MC) and melamine‐formaldehyde microcapsules (MF‐MC) was observed over 30 days in the release test, and each release curve was completely distinct. In the biological test, the efficacy of both microcapsules against M. incognita 42 days after the application was 8–15% higher than that of the non‐encapsulated FTZ at a concentration of 2.0 mg FTZ kg−1 soil. Soil degradation experiments suggested that the microcapsules worked effectively to protect the FTZ from degradation, which resulted in higher efficacy at a later stage. A simulation study to predict the concentration of FTZ outside the microcapsule found that the timing of supplying FTZ was important and suggested that the mixture of non‐encapsulated FTZ (non‐MC) and MF‐MC showed enhanced efficiency for the entire cultivation period in the biological test; the efficacy against nematodes was also confirmed by the measurement of nematode density using the Bearman funnel method. CONCLUSION: The release properties of FTZ from microcapsules are critical for their effective application against M. incognita, and the established simulation study is a useful step in designing suitable release properties under complex soil conditions. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: Abamectin (ABA) is considered a powerful insecticidal and anthelmintic agent. It is an intracellular product of Streptomyces avermitilis; is synthesized through complicated pathways and can then be extracted from mycelial by methanol extraction. ABA serves as a biological control substance against the root-knot nematode Meloidogyne incognita. This investigation is intended to reach a new strain of S. avermitilis capable of producing ABA effectively. Results: Among the sixty actinobacterial isolates, Streptomyces St.53 isolate was chosen for its superior nematicidal effectiveness. The mycelial-methanol extract of isolate St.53 exhibited a maximum in vitro mortality of 100% in one day. In the greenhouse experiment, the mycelial-methanol extract demonstrated, for the second-stage juveniles (J2s), 75.69% nematode reduction and 0.84 reproduction rate (Rr) while for the second-stage juveniles (J2s), the culture suspension demonstrated 75.38% nematode reduction and 0.80 reproduction rate (Rr). Molecular identification for St.53 was performed using 16 S rRNA gene analysis and recorded in NCBI Genbank as S. avermitilis MICNEMA2022 with accession number (OP108264.1). LC-MS was utilized to detect and identify abamectin in extracts while HPLC analysis was carried out for quantitative determination. Both abamectin B1a and abamectin B1b were produced and detected at retention times of 4.572 and 3.890 min respectively. Conclusion: Streptomyces avermitilis MICNEMA2022 proved to be an effective source for producing abamectin as a biorational agent for integrated nematode management. [ABSTRACT FROM AUTHOR]

Summary: Purpureocillium lilacinum is a potent biocontrol agent against Meloidogyne spp. and various other plant-parasitic nematodes in crops. However, existing commercial formulations of P. lilacinum suffer from drawbacks like short shelf life and inconsistent performance in different environmental conditions. To address these issues, a new nano-formulation of P. lilacinum was developed and tested against Meloidogyne incognita infecting tomatoes. Initially, edible oil-based emulsions were prepared using probe ultrasonication, with 40 formulations screened and 14 selected for further testing. Seven of these emulsions remained stable at room temperature (28 ± 4°C) for 8 weeks, with stability assessed based on particle size, zeta potential, and particle shape using particle size analysis and transmission electron microscopy (TEM). Among these, NE 8 (comprising 10 ml of 1% carboxyl methyl cellulose (CMC), 1.25 ml of Tween 80 and 5 ml of sunflower oil) exhibited superior characteristics, with an average particle size of 226.6 nm, a zeta potential of −54.80 mV, and a spherical morphology under TEM examination. The P. lilacinum nanoemulsion formulation was produced by homogenising NE 8 emulsion and spores at a 1:1 ratio, ensuring efficient spore dispersion and encapsulation without loss of viability. In vitro tests demonstrated 100% immobility of M. incognita second-stage juveniles (J2) and 100% parasitism of eggs at a concentration of 5.0 ml l−1. Under glasshouse conditions, soil drenching with the nano-formulation at concentrations ranging from 0.5 to 5.0 ml l−1 resulted in enhanced tomato growth and significant suppression of M. incognita populations in soil and roots, with increased egg mass parasitism. Bio-safety tests confirmed that P. lilacinum nano-formulation at concentrations of 0.25 ml l−1 and 5.0 ml l−1 had no harmful effects on the earthworm Eudrilus eugeniae. [ABSTRACT FROM AUTHOR]

Plants produce reactive oxygen species (ROS) upon infection, which typically trigger defence mechanisms and impede pathogen proliferation. Root‐knot nematodes (RKNs, Meloidogyne spp.) represent highly detrimental pathogens capable of parasitizing a broad spectrum of crops, resulting in substantial annual agricultural losses. The involvement of ROS in RKN parasitism is well acknowledged. In this study, we identified a novel effector from Meloidogyne incognita, named CATLe, that contains a conserved catalase domain, exhibiting potential functions in regulating host ROS levels. Phylogenetic analysis revealed that CATLe is conserved across RKNs. Temporal and spatial expression assays showed that the CATLe gene was specifically up‐regulated at the early infection stages and accumulated in the subventral oesophageal gland cells of M. incognita. Immunolocalization demonstrated that CATLe was secreted into the giant cells of the host plant during M. incognita parasitism. Transient expression of CATLe significantly dampened the flg22‐induced ROS production in Nicotiana benthamiana. In planta assays confirmed that M. incognita can exploit CATLe to manipulate host ROS levels by directly degrading H2O2. Additionally, interfering with expression of the CATLe gene through double‐stranded RNA soaking and host‐induced gene silencing significantly attenuated M. incognita parasitism, highlighting the important role of CATLe. Taken together, our results suggest that RKNs can directly degrade ROS products using a functional catalase, thereby manipulating host ROS levels and facilitating parasitism. [ABSTRACT FROM AUTHOR]

Rhizome rot poses a significant threat to ginger cultivation, caused by a complex interaction of pathogens such as Pythium aphanidermatum, Fusarium oxysporum, Ralstonia solanacearum, Sclerotium rolfsii and Meloidogyne incognita. The pathogens were individually inoculated at 75, 105 and 135 days after planting (DAP), as well as in various combinations, to evaluate disease severity and symptom development. Results revealed that R. solanacearum exhibited the highest disease severity and fastest symptom development across all stages of inoculation, followed by P. aphanidermatum, F. oxysporum, S. rolfsii and M. incognita. The combined inoculation of pathogens significantly increased disease incidence and rhizome rot compared to individual inoculations, indicating synergistic interactions among the pathogens. Sequential inoculation experiments demonstrated that pre‐infection by M. incognita exacerbated disease severity, highlighting the role of nematodes in predisposing plants to secondary infections. [ABSTRACT FROM AUTHOR]

Streptomyces saraceticus strain 31 (SS31) exhibits antagonistic activities against a variety of phytopathogenic bacteria, fungi and nematodes. In our effort to integrate SS31 into an effective pest management programme for controlling plant pathogens, we assessed the toxicities of 74 pesticides commonly employed in agricultural production on SS31 using paper disc assays. Most of the test insecticides, acaricides, nematicides and plant growth regulators showed no antagonistic effects towards SS31. However, all six tested herbicides, glyphosate, paraquat, glufosinate‐ammonium, quizalofop‐ethyl, pendimthalin and butralin exerted strong inhibitory effects on SS31. Among the 42 tested fungicides, half of them, including acid amides, strobilurins, carbamates, antibiotics and morphine displayed no detrimental effects on SS31. Notably, copper‐based fungicides demonstrated high toxicity to SS31. Although chlorothalonil and thiophanate methyl + streptomycin displayed inhibitory effects on SS31, applying these pesticides with SS31 in pot tests resulted in a lower Meloidogyne incognita galling index compared with the mock control under greenhouse conditions. Additionally, applying SS31 with carbofuran or ethoprop effectively controlled M. incognita. These findings can provide strategies to refine application timing and enhance the beneficial effects of SS31. [ABSTRACT FROM AUTHOR]

Sweetpotato (Ipomoea batatas L.) is susceptible to infection by the root knot nematode (RKN) Meloidogyne incognita, which results in significant reductions in the yield of this important tuber crop worldwide. Previously, transcriptome analysis revealed differential gene expression between the roots of RKN-susceptible and -resistant sweetpotato cultivars after RKN infection, raising the possibility of identifying the genes involved in protection against RKN infection. A number of trait-specific and/or response-specific genes were also identified, including RKN infection-responsive aquaporin protein encoded by the nodulin-26-like intrinsic protein (NIP) gene. Therefore, in this study, we investigated the role of NIP genes in the defense response to RKN infection in susceptible and resistant sweetpotato cultivars. A comparison of the nucleotide sequences of sweetpotato with those of its closely related species, morning glory, revealed a group of NIP genes that could be categorized into four different ortholog groups. These four groups contained several unique genes that showed changes in expression in sweetpotato roots after RKN infection. These results indicate that NIP genes could have a potential role in protecting sweetpotato roots from RKN infection. [ABSTRACT FROM AUTHOR]

Meloidogyne incognita is among the most detrimental parasitic nematodes with a wide host range causing huge economic losses annually. Biological control of M. incognita has emerged as a promising alternative in sustainable agriculture. In our previous study, Bacillus velezensis TA-1 effectively controlled M. incognita in vitro and in the field trials through direct nematocidal activities. However, it remains poorly understood for the underlying mechanisms including whether TA-1 could induce host resistance against M. incognita. In the present study, the effects of TA-1 induced resistance against M. incognita in tomato were determined. Results showed that TA-1 colonized tomato roots, with 1.23 × 108 colony forming units (CFU)/g root tissues attached within 36 h, significantly reduced the number of galls in the local and systemic root systems in the split-root experiments by 44.0% and 28.1%, respectively. The bacteria also increased the basic defense responses of tomato plants, such as lignin accumulation and hydrogen peroxide (H2O2) content, which was associated with the enhanced activities of enzymes related to plant defense [e.g. phenylalanine ammonia-lyase (PAL), peroxidase (POD) and polyphenol oxidase (PPO)]. Moreover, TA-1 enhanced the expressions of tomato defense response genes in the salicylic acid (PR1a and PR-P6) and jasmonic acid (PI II and MC) pathways and induced resistance against M. incognita. These results suggested that TA-1 could effectively control M. incognita through induction of tomato resistance, therefore it could be used as a promising biocontrol agent to be incorporated in the integrated management programs in tomato production. [ABSTRACT FROM AUTHOR]

Nematodes from the genus Meloidogyne are extremely harmful to agricultural crops due to their wide geographic distribution, variety of hosts, and strong reproductive capacity. The most used phytonematoid control method is the application of nematicides, which can also affect human health and the environment. Selenol ester derivatives have pharmaceutical applications, but little is known about their biological activities. We examined whether six selenol ester derivatives were nematicidal and ovicidal to the nematodes Caenorhabditis elegans and Meloidogyne incognita, and determined their toxicity to non-target organisms. The compound Se-p-methyl phenylselenobenzoate (2e) exhibited the lowest nematicidal and ovicidal Lethal concentration (LC50) to C. elegans (4.42 and 0.56 mg/L, respectively) and M. incognita (4.6 and 2.77 mg/L, respectively), which were similar or lower than the LC50 values for the control treatment with fluensulfone in C. elegans (4.07 and 6.05 mg/L, respectively) and M. incognita (43.07 and 49.63 mg/L, respectively). Compound 2e efficiently controlled the phytoparasite in greenhouse and reduced the number of galls and eggs present in tomato roots. Compared with the negative control, compound 2e was not toxic to other organisms such as Chlorella vulgaris algae, Galleria mellonella and Aedes aegypti larvae, and the aquatic protozoan Tetrahymena pyriformis. Our findings indicate that the selenol ester derivatives are potent and effective nematicides with no toxicity to the non-target organisms tested. [ABSTRACT FROM AUTHOR]

The root‐knot nematode (RKN; Meloidogyne incognita Kofoid & White) and reniform nematode (RN; Rotylenchulus reniformis Linford & Oliveira) are serious pathogens of upland cotton (Gossypium hirsutum L.) that significantly affect yield and fiber quality annually. Here, we describe two upland cotton germplasm lines that have combined resistance to RKN and RN while maintaining good yield and fiber quality traits. Upland germplasm lines MS‐4857 (Reg. no. GP‐1147, PI 704481) and MS‐4878 (Reg. no. GP‐1148, PI 704482) are F6 recombinant inbred lines from a cross between M240 RNR (RKN resistant) and MT2468 Ren1 (moderately RN resistant). These lines are highly resistant to RKN and show ∼30% fewer RN eggs g−1 root than the MT2468 Ren1 parent due to significantly improved root system development compared with MT2468 Ren1. Yield and fiber quality traits are equivalent or superior to the parental lines. The upland‐derived RN resistance in these lines provides a valuable alternative source of resistance to cotton breeding programs, especially in combination with high‐level RKN resistance. Core Ideas: Root‐knot (RKN) and reniform nematode (RN) are serious cotton pathogens.Combining resistance to multiple nematode species is important to the cotton community.MS‐4857 and MS‐4878 are highly resistant to RKN and moderately resistant to RN.MS‐4857 and MS‐4878 RN resistance is improved over the parent lines.The upland‐derived RN resistance provides an alternative to currently deployed RN resistance QTL. [ABSTRACT FROM AUTHOR]

The nematicidal efficacy of liquid formulation of Pochonia chlamydosporia, Bacillus subtilis, Purpureocillium lilacinum, Trichoderma viride and vermiculite formulation of Rhizophagus intraradices were challenged against Meloidogyne incognita under glasshouse conditions. The in vivo experiment were piloted to test the potential of these biological agents by soil drenching of liquid formulation @ 1 ml/pot or soil application of vermiculite formulation @ 1g/pot/dose. Their effect was compared with the granular application of Carbofuran @ 1g/pot/dose. All the liquid bioformulations investigated were capable of enhancing plant growth and lowering the pathogenicity and parasitic success of M. incognita in carrots. The soil drenching of P. chlamydosporia caused a significant reduction of galls in the root (51%), nematode population in the root (43.6%), egg mass in the root (65.3%) and infective juvenile population in soil (51.8%) over other treatments and Carbofuran. [ABSTRACT FROM AUTHOR]

Identification of Meloidogyne species is difficult using classical techniques alone, as some species have similar characteristics. Meloidogyne incognita is a plant-parasitic nematode that is one of the four most common species worldwide and has numerous hosts, including tomato (Solanum lycopersicum L.). This nematode is regarded as the most significant contributing factor to the reduction in tomato yield. Therefore, the present investigation was conducted in 2024 at the University of Limpopo to identify M. incognita. The COI mtDNA was sequenced and amplified from female nematodes, following which the blast result showed that the South African population exhibited a high similarity (100% identity) to those populations studied in China (MH743221 and MH743220). Utilizing the Maximum Likelihood method for phylogenetic analysis, it was demonstrated that our population and the other populations of M. incognita form a robust clade (87% bootstrap values). [ABSTRACT FROM AUTHOR]

Plants produce reactive oxygen species (ROS) upon infection, which typically trigger defence mechanisms and impede pathogen proliferation. Root‐knot nematodes (RKNs, Meloidogyne spp.) represent highly detrimental pathogens capable of parasitizing a broad spectrum of crops, resulting in substantial annual agricultural losses. The involvement of ROS in RKN parasitism is well acknowledged. In this study, we identified a novel effector from Meloidogyne incognita, named CATLe, that contains a conserved catalase domain, exhibiting potential functions in regulating host ROS levels. Phylogenetic analysis revealed that CATLe is conserved across RKNs. Temporal and spatial expression assays showed that the CATLe gene was specifically up‐regulated at the early infection stages and accumulated in the subventral oesophageal gland cells of M. incognita. Immunolocalization demonstrated that CATLe was secreted into the giant cells of the host plant during M. incognita parasitism. Transient expression of CATLe significantly dampened the flg22‐induced ROS production in Nicotiana benthamiana. In planta assays confirmed that M. incognita can exploit CATLe to manipulate host ROS levels by directly degrading H2O2. Additionally, interfering with expression of the CATLe gene through double‐stranded RNA soaking and host‐induced gene silencing significantly attenuated M. incognita parasitism, highlighting the important role of CATLe. Taken together, our results suggest that RKNs can directly degrade ROS products using a functional catalase, thereby manipulating host ROS levels and facilitating parasitism. [ABSTRACT FROM AUTHOR]

Meloidogyne spp. are the most devastating plant‐parasitic nematodes affecting tomato worldwide. Although resistant cultivars and rootstocks are used, selection for virulence occurs in the pathogen. Consequently, using other resistance sources, such as Solanumtorvum, could improve resistance durability. Several experiments in microplots and plastic greenhouses were carried out to determine the potential use of S. torvum as a tomato rootstock to protect against M. incognita and M. javanica. In microplots, the relationship between nematode density at transplanting (Pi) and multiplication rate did not differ between Meloidogyne species in either ungrafted or grafted tomato. However, maximum multiplication rate and maximum density on grafted tomato were 1.27% and 2.93% those on ungrafted, respectively. The grafted tomato plants yielded between 2.9 and 7.5 more times than the ungrafted plants at Pi ≥ 100 eggs + J2s per 100 cm3 of soil, but no differences were observed in plastic greenhouse where a large amount of scion‐rooting occurred. In microplots, the quality of the tomato fruits of ungrafted and grafted plants was affected by the Pi. In parallel, some pot experiments were conducted on S. torvum and susceptible eggplant to determine the putative selection for nematode virulence to S. torvum and the nematode fitness cost. These showed that the nematode subpopulations infected and reproduced less on S. torvum than on eggplant. However, the female fertility was only reduced after development of three or four subpopulations on S. torvum. Finally, a histopathological study showed that nematode infection and development in S. torvum was delayed compared to eggplant. [ABSTRACT FROM AUTHOR]

Tomato is the most important horticultural crop, and India is its second largest producer; however, the plant‐pathogenic nematode Meloidogyne incognita is a serious pest of tomato, causing detrimental losses in its production. This study is focused on the use of multistress‐tolerant Pseudomonas aeruginosa SSVP3 to control this devastating nematode and attempts to decipher the roles of its metabolites and volatile organic compounds (VOCs) during this interaction. The supernatant of P. aeruginosa SSVP3 caused 58% mortality in M. incognita J2 juveniles. The major nematicidal metabolites, identified using liquid chromatography‐mass spectrometry, were pyocyanin, pyoluteorin, pyochelin, benthocyanin and phenazines. The VOCs secreted by P. aeruginosa SSVP3, which were identified via gas chromatography–mass spectrometry (HS‐SPME‐GC–MS) in a mixture, caused 98% mortality in M. incognita J2 juveniles. In a pot experiment, seedling root treatment with P. aeruginosa SSVP3 activated the induced systemic response in tomato plants to M. incognita by increasing the activity of defence and antioxidant enzymes as well as the proline and phenolic contents. The malondialdehyde content in P. aeruginosa SSVP3‐treated plants decreased as compared to those in the other treatment groups. The number of galls formed and the number of endoparasitic stages of M. incognita in the untreated nematode control plants were much greater (19 and 35) than those in the P. aeruginosa SSVP3‐treated (0.33 and 1) and chemically treated groups (0.67 and 1.33). These results indicate that P. aeruginosa and its secreted metabolites and VOCs have a high potential for controlling nematodes. [ABSTRACT FROM AUTHOR]

Eggs represent a crucial life stage for Meloidogyne incognita, and viable eggs are frequently employed in nematode research. The common issue currently encountered with established technologies is that higher concentrations of sodium hypochlorite (NaOCl) result in irreversible damage to M. incognita eggs. Therefore, developing a novel method to avoid such a problem is highly important. In this study, the fresh roots of infected cucumber plants were prestored in plastic bags at 28 °C, after which M. incognita egg masses were collected from these root samples. Egg masses from roots prestored for more than 48 h could be efficiently disassociated with a low concentration (0.3%) of NaOCl in a short period of time (2 min), representing an innovative new method. Moreover, the hatchability of the harvested M. incognita eggs was maximized in this work. Additionally, if the treatment time was extended beyond 5 min, 0.3% NaOCl affected larval hatching irreversibly. Overall, these findings indicate that prestorage of infected roots in plastic bags enables the application of lower concentrations of NaOCl in M. incognita egg extraction. [ABSTRACT FROM AUTHOR]

Meloidogyne incognita (root-knot nematode) is one of the most destructive pests of crops worldwide. Injudicious use of synthetic nematicides has led to environmental toxicity, development of resistance, and disruption of ecological balance, necessitating the need for safer and effective alternatives. Essential oil from Mentha spicata (Spearmint) has been reported to have nematicidal activity but the activity of its polar constituents is unexplored against the nematodes, infesting agricultural crops. Six compounds, stigmasterol (1), β-sitosterol-3-O-β-D-glucoside (2), 3β,13β-dihydroxy-urs-11-en-28-oic acid (3), 5,6-dihydroxy-7,8,4′-trimethoxyflavone (4), 5,6,4′-trihydroxy-7,8,3′-trimethoxyflavone (5), and 5,6,4′-trihydroxy-7,8-dimethoxyflavone (6), were isolated from methanolic extract of Mentha spicata (spearmint) and identified by NMR (1D & 2D) spectral analysis. Compound 3 was identified for the first time from genus Mentha. In vitro nematicidal activity of pure compounds (2 and 4–6) was carried out against Meloidogyne incognita, and results showed significant mortality (LC50 values ranging between 62.64 and 74.19 ppm after 96 h). Molecular docking study revealed the favourable binding of the test compounds with acetylcholinesterase enzyme, facilitated by H-bond, electrostatic interactions, and hydrophobic interactions. The binding energy of the tested compounds with the target protein was found highest in 5 (− 10.0 kcal/mol) and 6(− 9.9 kcal/mol) followed by 2 (− 9.2 kcal/mol) and 4 (− 8.9 kcal/mol). The minimum binding energy was recorded in carbofuran (−7.5 kcal/mol), a positive control, and was also corroborated with in vitro nematicidal activity. This study showed the potent nematicidal activity of compounds (2 and 4–6), which can be further used for the development of nematicides against M. incognita in agriculture. [ABSTRACT FROM AUTHOR]

Brazil is the largest coffee-producing nation in the world. Over 50% of the national production comes from the Minas Gerais state, with relevant contribution of the region covered by the Cerrado biome. Given the threat posed by root-knot nematodes (RKN, Meloidogyne spp.) to coffee production, we collected plant and soil samples from infested plantations across 16 counties and identified the species of this pathogen. Based on the female perineal patterns, male morphology, esterase phenotypes and SCAR markers, the species found were Meloidogyne exigua, Meloidogyne paranaensis, Meloidogyne incognita and Meloidogyne arenaria. The most prevalent species was M. exigua, occurring in 83.8% of the sampled sites, followed by M. paranaensis (19%) and M. incognita (4.9%). Mixed populations of RKN were observed in 7.7% of the sites, with the highest prevalence of M. exigua + M. paranaensis and M. paranaensis + M. incognita, followed by M. exigua + M. incognita. Meloidogyne arenaria was found in one site, in a mixed population with M. paranaensis + M. exigua. Strategies to prevent the spread of these nematodes to non-infested areas are highly recommended, particularly focusing on the most aggressive species such as M. paranaensis and M. incognita. [ABSTRACT FROM AUTHOR]

The availability of high‐throughput sequencing technologies increased our understanding of different genomes. However, the genomes of all living organisms still have many unidentified coding sequences. The increased number of missing small open reading frames (sORFs) is due to the length threshold used in most gene identification tools, which is true in the genic and, more importantly and surprisingly, in the intergenic regions. Scanning the cucumber genome intergenic regions revealed 420 723 sORF. We excluded 3850 sORF with similarities to annotated cucumber proteins. To propose the functionality of the remaining 416 873 sORF, we calculated their codon adaptation index (CAI). We found 398 937 novel sORF (nsORF) with CAI ≥ 0.7 that were further used for downstream analysis. Searching against the Rfam database revealed 109 nsORFs similar to multiple RNA families. Using SignalP‐5.0 and NLS, identified 11 592 signal peptides. Five predicted proteins interacting with Meloidogyne incognita and Powdery mildew proteins were selected using published transcriptome data of host‐pathogen interactions. Gene ontology enrichment interpreted the function of those proteins, illustrating that nsORFs' expression could contribute to the cucumber's response to biotic and abiotic stresses. This research highlights the importance of previously overlooked nsORFs in the cucumber genome and provides novel insights into their potential functions. Summary Statment: We identified small open reading frames× (sORF) in the intergenic regions of the cucumber genome. Analysing genomics, transcriptomics, and proteomics data revealed the possible expression of sORF. Five predicted proteins in cucumber interact with proteins in Meloidogyne incognita and Powdery mildew. [ABSTRACT FROM AUTHOR]

WRKY transcription factors (TFs) can participate in plant biological stress responses and play important roles. SlWRKY80 was found to be differentially expressed in the Mi-1- and Mi-3-resistant tomato lines by RNA-seq and may serve as a key node for disease resistance regulation. This study used RNAi to determine whether SlWRKY80 silencing could influence the sensitivity of 'M82' (mi-1/mi-1)-susceptible lines to M. incognita. Further overexpression of this gene revealed a significant increase in tomato disease resistance, ranging from highly susceptible to susceptible, combined with the identification of growth (plant height, stem diameter, and leaf area) and physiological (soluble sugars and proteins; root activity) indicators, clarifying the role of SlWRKY80 as a positive regulatory factor in tomato defense against M. incognita. Based on this phenomenon, a preliminary exploration of its metabolic signals revealed that SlWRKY80 stimulates different degrees of signaling, such as salicylic acid (SA), jasmonic acid (JA), and ethylene (ETH), and may synergistically regulate reactive oxygen species (ROS) accumulation and scavenging enzyme activity, hindering the formation of feeding sites and ultimately leading to the reduction of root gall growth. To our knowledge, SlWRKY80 has an extremely high utilization value for improving tomato resistance to root-knot nematodes and breeding. [ABSTRACT FROM AUTHOR]

The sustainable management of large amounts of fly ash (FA) is a concern for researchers, and we aim to determine the FA application in plant development and nematicidal activity in the current study. A pot study is therefore performed to assess the effects of adding different, FA-concentrations to soil (w/w) on the infection of chickpea plants with the root-knot nematode Meloidogyne incognita. Sequence characteristic amplified region (SCAR) and internal transcribed spacer (ITS) region-based-markers were used to molecularly confirm M. incognita. With better plant growth and chickpea yield performance, FA enhanced the nutritious components of the soil. When compared with untreated, uninoculated control (UUC) plants, the inoculation of M. incognita dramatically reduced chickpea plant growth, yield biomass, and metabolism. The findings showed that the potential of FA to lessen the root-knot nematode illness in respect of galls, egg-masses, and reproductive attributes may be used to explain the mitigating effect of FA. Fascinatingly, compared with the untreated, inoculated control (UIC) plants, the FA treatment, primarily at 20%, considerably (p ≤ 0.05) boosted plant growth, yield biomass, and pigment content. Additionally, when the amounts of FA rose, the activity of antioxidants like superoxide dismutase-SOD, catalase-CAT, and peroxidase-POX as well as osmo-protectants like proline gradually increased. Therefore, our findings imply that 20% FA can be successfully applied as a potential strategy to increase biomass yield and plant growth while simultaneously reducing M. incognita infection in chickpea plants. [ABSTRACT FROM AUTHOR]

The root-knot nematode (RKN), Meloidogyne incognita, poses significant challenges for many important crops. Identified distinctive bacterial proteases have emerged as potential nematicides. In this study, the nprE from Bacillus subtilis 168 encoded the neutral metalloprotease, effectively enhancing it through a site-directed mutation. The enzyme-specific activity of pro118, secreted by the modified strain BS118, reached 215.4 U mg-1. It was twice that of pro168 produced by the wild-type strain BS168, which recorded an enzyme-specific activity of 101.6 U mg-1. The protease, pro118, caused the highest mortality in M. incognita juveniles, J2S (91.3% to 84.5%) after 48 h of in vitro treatment. Furthermore, when simultaneously applying pro118 with the nematode infection, it notably decreased the number of J2S, root galls, and egg masses/root systems by 19.5%, 18.8%, and 26.2%, respectively, compared with its application one week after the nematode infection. This consistent trend also manifested in the plant shoot length and fresh weight enrichment, which showed an increase of 9.7% and 14.7% in the first treatment versus the second. In conclusion, the study asserts that applying neutral metalloprotease as a bioagent to biocontrol M. incognita is a promising approach for mitigating the impact of this agricultural pest. [ABSTRACT FROM AUTHOR]

• MgONPs were synthesized through green approach using trichoderma fungus. • Myco-synthesized NPs exhibited strong nematicidal activity. • Soil application of NPs improved plant growth under nematode infection. • Soil application of NPs reduced nematode population and development. Meloidogyne incognita is believed to be the most devastating pest causing severe damage to crops, and hence, innovative and effective means of controlling the nematode is the need of the day. The focus of the current study is to devise an effective and innovative myco-fabrication of MgO nanoparticles (NPs) along with melatonin for efficient management of M. incognita infecting tomatoes. Fungal extracts were used to synthesize the myco-fabricated NPs through a green synthesis pathway and were verified using different spectroscopic means. The nanoparticles exhibited appreciable nematicidal potential, such as drastic egg hatch inhibition and juvenile mortality under in vitro assays. Evaluation of NPs and melatonin in planta, alone or combined form, was investigated on tomato plants already inoculated with M. incognita. The alterations in the nematode population on roots of plants as well as in soil, growth parameters, and biochemical attributes of plants were recorded. A significant reduction in nematode population was revealed on the application of melatonin and myco-fabricated nanoparticles, hence exhibiting an improvement in the plant's biochemical (glutathione, phenolic, flavonoid, and antioxidant enzymes) and growth parameters. A synergistic impact was shown on the combined application of the treatments. Furthermore, an enhancement in the expression as well as activities of antioxidant enzymes was also observed. Increased resistance of plants against nematodes resulted in connection with the improved antioxidant status of plants due to this combined treatment. The significantly improved growth of plants under M. incognita stress conditions reveals the potential of the proposed treatments having synergistic interaction to manage phyto-parasitic nematodes effectively. This presents innovative means of agricultural biotechnologies that have the potential to contribute to the efficient management of nematodes infecting plants. [ABSTRACT FROM AUTHOR]

Radish is an important root vegetable that is widely grown in Asia. The root-knot nematode (RKN) Meloidogyne incognita seriously affects the growth and development of radish root and causes poor appearance quality. However, the molecular mechanism of radish response to RKNs remains poorly understood. In this study, a total of 220 lncRNAs, 1144 mRNAs, 20 miRNAs and 153 proteins were differential expressed between the RKN-infected and WT samples. Correlation analysis of all DEPs compared with all DGEs showed that 8 mRNAs-DEPs showed a changed abundance. The results showed that 18 DEmiRNAs have 167 target DEGs in 220 miRNA-target modules and 29 DElncRNAs were predicted as putative targets of 16 DEmiRNAs in 37 miRNA-target modules. In all, 6 DGEs in the ABA pathway and 2 DGEs in the JA pathway were identified under RKN infection, respectively. The four regulatory networks of lncRNA-miRNA-mRNA were constructed in response to RKN infection. qRT-PCR analysis found that the expression pattern of 6 DElncRNAs, 6 DEmRNAs, 6 DEmiRNAs and 6 DEPs were consistent with sequencing results. These results provide a theoretical basis for studying the molecular mechanism of radish in response to M. incognita and breeding resistant varieties to this nematode. [ABSTRACT FROM AUTHOR]

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Background: The interplay between root-knot nematode (RKN) parasitism and the complex web of host-associated microbiota has been recognized as pivotal for effective management of the pest. However, studies assessing this relationship have focussed on the bacterial and fungal communities, neglecting the unicellular eukaryotic members. Here, we employed amplicon sequencing analysis of the bacterial 16S rRNA, fungal ITS and eukaryotic 18S rRNA genes, and comprehensively examined how the microbiome composition, diversity and networking developed with time in the rhizospheres and roots of RKN-inoculated and non-inoculated tomato plants. Results: As expected, infection with the RKN Meloidogyne incognita decreased plant growth. At individual timepoints, we found distinct bacterial, fungal and eukaryote community structures in the RKN-inoculated and non-inoculated rhizospheres and roots, and RKN inoculation affected several taxa in the root-associated microbiome differentially. Correlation analysis revealed several bacterial and fungal and few protist taxa that correlated negatively or positively with M. incognita. Moreover, network analysis using bacterial, fungal and eukaryotic data revealed more dynamic networks with higher robustness to disturbances in the RKN-inoculated than in the non-inoculated rhizospheres/roots. Hub taxa displayed a noticeable successional pattern that coincided with different phases of M. incognita parasitism. We found that fungal hubs had strong negative correlations with bacteria and eukaryotes, while positive correlations characterized hub members within individual kingdoms. Conclusion: Our results reveal dynamic tomato-associated microbiomes that develop along different trajectories in plants suffering M. incognita infestation and non-infested plants. Overall, the results identify stronger associations between RKN and bacterial and fungal taxa than between eukaryotic taxa and RKN, suggesting that fungal and bacterial communities could play a larger role in the regulation of RKN. The study identifies several putative RKN-antagonistic bacterial and fungal taxa and confirms the antagonistic potential previously identified in other taxa. [ABSTRACT FROM AUTHOR]

Background and aims: Root-knot nematodes (RKN; Meloidogyne spp.) are among the highly prevalent and significantly detrimental pathogens that cause severe economic and yield losses in crops. Currently, control of RKN primarily relies on the application of chemical nematicides but it has environmental and public health concerns, which open new doors for alternative methods in the form of biological control. Methods: In this study, we investigated the nematicidal and attractive activities of an endophytic strain WF01 against Meloidogyne incognita in concentration-dependent experiments. The active nematicidal metabolite was extracted in the WF01 crude extract through the Sephadex column, and its structure was identified by nuclear magnetic resonance and mass spectrometry data. Results: The strain WF01 was identified as Aspergillus tubingensis based on morphological and molecular characteristics. The nematicidal and attractive metabolite of A. tubingensis WF01 was identified as oxalic acid (OA), which showed solid nematicidal activity against M. incognita, having LC50 of 27.48 μg ml–1. The Nsy-1 of AWC and Odr-7 of AWA were the primary neuron genes for Caenorhabditis elegans to detect OA. Under greenhouse, WF01 broth and 200 μg ml–1 OA could effectively suppress the disease caused by M. incognita on tomatoes respectively with control efficiency (CE) of 62.5% and 70.83%, and promote plant growth. In the field, WF01-WP and 8% OA-WP formulations showed moderate CEs of 51.25%–61.47% against RKN in tomato and tobacco. The combined application of WF01 and OA resulted in excellent CEs of 66.83% and 69.34% toward RKN in tomato and tobacco, respectively. Furthermore, the application of WF01 broth or OA significantly suppressed the infection of J2s in tomatoes by upregulating the expression levels of the genes (PAL, C4H, HCT, and F5H) related to lignin synthesis, and strengthened root lignification. Conclusion: Altogether, our results demonstrated that A. tubingensis WF01 exhibited multiple weapons to control RKN mediated by producing OA to lure and kill RKN in a concentration-dependent manner and strengthen root lignification. This fungus could serve as an environmental bio-nematicide for managing the diseases caused by RKN. [ABSTRACT FROM AUTHOR]

This paper mainly reveals the dhynamic occurrence rule of root-knot nematode in the vegetable soil of Chifeng protected area, and provides a theoretical basis for the control of southern root-knot nematode disease in this area. The dynamic change of root-knot nematode quantity in the soil of Chifeng protected land was monitored for 10 years. The dynamic change law of the lateral and vertical distribution of root-knot nematode in the soil from 2013 to 2014 was investigated. The dynamic occurrence law of the southern root-knot nematode under different years and agronomic measures was expounded. The results showed that the lateral distribution of southern root-knot nematodes in greenhouse soil was as follows: the northern and central nematodes were the most abundant, while the southern nematodes were the least abundant. The vertical distribution of nematodes was as follows; the southern root-knot nematodes distributed most in the 4-15 cm soil layer, and less in the 15-25 cm soil layer. During the 10 years of monitoring sites, the occurrence rule of southern root-knot nematodes was as follows: about 6 generations occurred every year in greenhouses of monitoring sites, and each crop occurred about 3 generations. In terms of quantity, the maximum number of root-knot nematodes appeared around May and November every year, and the number of overwinter stubble was greater than that of autumn stubble. The distribution and dynamic occurrence of southern root-knot nematode in soil were studied, which can provide theoretical guidance for the prevention and control of root-knot nematode disease in Chifeng area. [ABSTRACT FROM AUTHOR]

Considering the stricter European regulations for chemical pesticides (e.g. abolishment of the use of chemical soil fumigation products, such as methyl bromide), the need for more sustainable plant protection products is strongly increasing. In this research, Product X, an innovative mixture of bio-nematicidal compounds was developed and evaluated for efficacy. Product X showed a direct nematicidal effect against the root-knot nematode Meloidogyne incognita. In pot trials with tomato plants infected with M. incognita, Product X treatment lead to a significant reduction in nematode-induced gall formation. mRNA-sequencing indicated alterations in phytohormone levels and ROSmetabolism in tomato roots upon treatment with Product X, which was subsequently biochemically validated. Increased levels of abscisic acid and peroxidase activity seem to be the main factors in the response of tomato plants to Product X. Long-term administration of Product X did not yield negative effects on tomato growth or yield. In conclusion, Product X provides a new interesting mix of bio-active compounds in the combat against rootknot nematodes. [ABSTRACT FROM AUTHOR]

Background: Meloidogyne incognita is one of the most important plant-parasitic nematodes and causes tremendous losses to the agricultural economy. Light is an important living factor for plants and pathogenic organisms, and sufficient light promotes root-knot nematode infection, but the underlying mechanism is still unclear. Results: Expression level and genetic analyses revealed that the photoreceptor genes PHY, CRY, and PHOT have a negative impact on nematode infection. Interestingly, ELONGATED HYPOCOTYL5 (HY5), a downstream gene involved in the regulation of light signaling, is associated with photoreceptor-mediated negative regulation of root-knot nematode resistance. ChIP and yeast one-hybrid assays supported that HY5 participates in plant-to-root-knot nematode responses by directly binding to the SWEET negative regulatory factors involved in root-knot nematode resistance. Conclusions: This study elucidates the important role of light signaling pathways in plant resistance to nematodes, providing a new perspective for RKN resistance research. [ABSTRACT FROM AUTHOR]

Counting nematodes is a labor-intensive and time-consuming task, yet it is a pivotal step in various quantitative nematological studies; preparation of initial population densities and final population densities in pot, micro-plot and field trials for different objectives related to management including sampling and location of nematode infestation foci. Nematologists have long battled with the complexities of nematode counting, leading to several research initiatives aimed at automating this process. However, these research endeavors have primarily focused on identifying single-class objects within individual images. To enhance the practicality of this technology, there’s a pressing need for an algorithm that cannot only detect but also classify multiple classes of objects concurrently. This study endeavors to tackle this challenge by developing a user-friendly Graphical User Interface (GUI) that comprises multiple deep learning algorithms, allowing simultaneous recognition and categorization of nematode eggs and second stage juveniles of Meloidogyne spp. In total of 650 images for eggs and 1339 images for juveniles were generated using two distinct imaging systems, resulting in 8655 eggs and 4742 Meloidogyne juveniles annotated using bounding box and segmentation, respectively. The deep-learning models were developed by leveraging the Convolutional Neural Networks (CNNs) machine learning architecture known as YOLOv8x. Our results showed that the models correctly identified eggs as eggs and Meloidogyne juveniles as Meloidogyne juveniles in 94% and 93% of instances, respectively. The model demonstrated higher than 0.70 coefficient correlation between model predictions and observations on unseen images. Our study has showcased the potential utility of these models in practical applications for the future. The GUI is made freely available to the public through the author’s GitHub repository (https://github.com/bresilla/ nematode_counting). While this study currently focuses on one genus, there are plans to expand the GUI’s capabilities to include other economically significant genera of plant parasitic nematodes. Achieving these objectives, including enhancing the models’ accuracy on different imaging systems, may necessitate collaboration among multiple nematology teams and laboratories, rather than being the work of a single entity. With the increasing interest among nematologists in harnessing machine learning, the authors are confident in the potential development of a universal automated nematode counting system accessible to all. This paper aims to serve as a framework and catalyst for initiating global collaboration toward this important goal. [ABSTRACT FROM AUTHOR]

Root knot nematode (RKN), Meloidogyne incognita, is considered a major soil-borne pathogen that can cause severe yield losses for vegetables and diverse crops. Usually, reducing of M. incognita damage is mainly relies on the application of nematicides and good agricultural practices. However, the use of synthetic nematicides is restricted due to concerns about their impact on the environment and human health. As a result, the use of alternative strategies is becoming necessary to combat RKN resistance. This study evaluates the antagonistic impact of the root mutualistic fungus Piriformospora indica on M. incognita. It also assesses its influence on the nutritional status, photo-synthesis, antioxidant enzyme activity, endogenous abscisic acid (ABA) levels, and selected ABA related-responsive genes in cucumber plants. Roots of cucumber seedlings were inoculated with P. indica and the second-stage juveniles (1000 J2 per plant). The results demonstrated that P. indica significantly reduced M. incognita invasion in roots, resulting in a 24% reduction in root galling and 42.6% decline in final population. Inoculating plants with both P. indica and RKN increased performance of root fresh and dry weight, as well as improved photochemical efficiency of PSII (Fv/Fm), photosystem II efficiency (PSII), catalase (CAT), peroxidase (POD), and superoxide dis-mutase (SOD). Furthermore, P. indica colonization, either alone or in combination with M. incognita, significantly improved number of fruits per plant, average fruit weight, the plant's marketable yield, and leaf nutrient content (N, P, K and Mg), Moreover, there was an increase in IAA content combined with a decrease in ABA content in roots of dual inoculation plants, if compared to M. incognita infested plants. The highest ABA content was recorded in the root of RKN-cucumber plants. The decline in ABA content due to P. indica treatment was consistent with the modulation of ABA pathway genes, specifically PP2C, PYL1, RK2,1, and RK2,2. The mixed of P. indica and M. incognita led to a decrease in the expression of PP2C, PLY1, RK2,1, and RK2,2 in comparison to the control group. These results indicate that P. indica application could help reduce the negative effects of RKN on important crops. [ABSTRACT FROM AUTHOR]

Meloidogyne enterolobii is regarded as one of the most severe and threatening pathogens worldwide. Guava production in India is quenched by the invasion of root-knot nematode, Meloidogyne enterolobii. Bacterial bio-control agents confer resistance against nematodes by producing various bioactive molecules. Exploiting these biomolecules will lead to the development of novel nematicidal formulations for managing plant parasitic nematodes. Considering this, our present investigation was focused on the isolation and identification of endophytic bacterial communities from wild guava Psidium eugeniaefolia. Amongst various endophytes, Bacillus subtilis GEB-1 exhibited a 90% reduction in the population of M. enterolobii. Cell-free supernatant extracts of B. subtilis GEB-1 revealed the presence of seventeen unique biomolecules. Attempts were made to dock these biomolecules against major protein targets of M. enterolobii such as E3 ubiquitin ligase, Neurotransmitter-gated ion-channel, G protein-coupled receptor kinase, Peptidase M12B domain-containing protein, Hyaluronidase through molecular docking techniques. The results of in-silico studies revealed that all seventeen biomolecules had a significant impact on protein targets of M. enterolobii. Among other bacterial metabolites, 2-heptanone and 2,3-butanediol were found to have a greater binding affinity with protein targets of M. enterolobii. Furthermore, the in-vitro evaluation of 2-heptanone and 2,3-butanediol at different concentrations confirmed their nematicidal activity against eggs and second-stage juveniles of M. enterolobii. Hence our present study revealed that bacterial metabolites, 2 heptanone, and 2,3-butanediol can be explored as novel nematicidal molecules against guava root-knot nematodes, M. enterolobii. [ABSTRACT FROM AUTHOR]

The use of arbuscular mycorrhizal fungi (AMF) offers promising benefits to agriculture in the Amazon regions, where soils are characteristically acidic and nutrient-poor. The purpose of this research was to investigate the potential effects of two recently described species of AMF (Nanoglomus plukenetiae and Rhizoglomus variabile) native to the Peruvian Amazon for improving the plant growth of Plukenetia volubilis (inka nut or sacha inchi) and protecting the roots against soil pathogens. Two assays were simultaneously conducted under greenhouse conditions in Peru. The first focused on evaluating the biofertilizer effect of AMF inoculation, while the second examined the bioprotective effect against the root knot nematode, Meloidogyne incognita. Overall, the results showed that AMF inoculation of P. volubilis seedlings positively improved their development, particularly their biomass, height, and the leaf nutrient contents. When seedlings were exposed to M. incognita, plant growth was also noticeably higher for AMF-inoculated plants than those without AMF inoculation. Nematode reproduction was significantly suppressed by the presence of AMF, in particular R. variabile, and especially when inoculated prior to nematode exposure. The dual AMF inoculation did not necessarily lead to improved crop growth but notably improved P and K leaf contents. The findings provide strong justification for the development of products based on AMF as agro-inputs to catalyze nutrient use and uptake and protect crops against pests and diseases, especially those that are locally adapted to local crops and cropping conditions. [ABSTRACT FROM AUTHOR]

Root‐knot nematodes, particularly, Meloidogyne incognita, are among the most destructive endoparasitic nematodes, infecting a diverse range of plant hosts. Nematode‐trapping fungi are known for their potential application as biological control agents against plant parasitic nematodes. In the present study, the nematode‐trapping fungus Arthrobotrys thaumasia was isolated from the rhizosphere soil of tomato plants in the West Mediterranean Region of Türkiye. Two hundred and twenty‐three tomato plant rhizosphere soil samples yielded six nematode‐trapping fungal isolates, giving an occurrence frequency of 2.69%. Using morphology and molecular marker sequences (ITS and β‐tubulin loci), the species of the fungi was confirmed to be A. thaumasia. In vitro, A. thaumasia reduced second‐stage juveniles of M. incognita by 77.5% (isolate I‐Y4‐2) and 72.5% (isolate B‐G5‐1). This is the first report on the isolation and characterization of the nematode‐trapping fungus A. thaumasia from Türkiye. Two isolates of A. thaumasia (I‐Y4‐2 and B‐G5‐1) appear to be promising biological control agents that may be utilized for controlling M. incognita‐caused root‐knot diseases. [ABSTRACT FROM AUTHOR]

The aim of the present study was to determine the prevalence and severity of root-knot nematodes in peach orchards in the Pothwar Region of Pakistan. Thirty-seven peach orchards were surveyed in the region and root and soil samples were collected from 10 randomly selected plants in each orchard for analysis. In the region, an overall incidence rate of 19.8% and a prevalence rate of 65.7% of root-knot nematodes were observed. The district Attock exhibited the highest prevalence rate of 71.43% and incidence rate of 34.29%. Conversely, the district Islamabad displayed the lowest prevalence rate of 50.5% and incidence rate of 10%. The surveys encountered five distinct peach varieties, and Early Grand had the highest prevalence (85.71%) of root-knot nematodes while Local Aroo showed the lowest (50%). Florida Gold and Aroo-5 were not infested with root-knot nematodes. In the region, peach trees were found to be infected by two types of root-knot nematodes, namely, Meloidogyne incognita and M. javanica., which was more prevalent than M. incognita, and it dominated all districts, except for Attock, where M. incognita was dominant. M. incognita was not present in Islamabad district. The occurrence of M. incognita and M. javanica as single populations were observed in 26.09 and 43.48% of orchards, respectively, while mixed populations were found in 30.43% of peach orchards. The overall galling index of the root-knot nematodes was 1.33, with the highest index in Attock and the lowest in Islamabad districts. Among the different peach cultivars, the Early Grand cultivar exhibited the maximum galling index, whereas no galling index was observed in the Florida Gold and Aroo-5 cultivars. It is recommended that stringent control strategies should be adopted to prevent the spread of nematodes to new plantations and to eradicate them from established orchards. [ABSTRACT FROM AUTHOR]

This study provides the first report of a quantitative trail locus (QTL) in maize (Zea mays) for resistance to the southern root-knot nematode (SRKN) (Meloidogyne incognita). The SRKN can feed on the roots of maize in the U.S. Southern Coastal Plain region and can cause yield losses of 30% or more in heavily infested fields. Increases in SRKN density in the soil may reduce the yield for subsequently planted susceptible crops. The use of maize hybrids with resistance to SRKN could prevent an increase in SRKN density, yet no genetic regions have been identified that confer host resistance. In this study, a B73 (susceptible) x Ky21 (resistant) S5 recombinant inbred line (R1L) population was phenotyped for total number of eggs (TE) and root weight. This population had been genotyped using single-nucleotide polymorphisms (SNPs). By utilizing the SNP data with the phenotype data, a single QTL was identified on chromosome 5 that explained 15% of the phenotypic variation (PV) for the number of eggs and 11 % of the P V for the number of eggs per gram of root (EGR). Plants that were homozygous for the Ky2l allele for the most associated marker PZA03172.3 had fewer eggs and fewer EGR than the plants that were homozygous or heterozygous for the B73 allele. Thus, the first QTL for SRKN resistance in maize has been identified and could be incorporated into maize hybrids. [ABSTRACT FROM AUTHOR]

Bacillus volatiles to control fungus and root-knot nematodes are a topic of great interest among researchers due to their safe and environmentally friendly nature. Bacillus megaterium GIUBAM-2020 showed high nematicidal activity against Meloidogyne incognita, with 92% mortality compared with control and antifungal activity against Fusarium oxysporum by producing a 3 cm in vitro mycelial inhibition zone. Pure volatiles produced by Bacillus. megaterium GIUBAM-2020 was identified through gas chromatography and mass spectrometry (GC–MS). Among fourteen volatile organic compounds (VOCs), only one volatile compound, i.e., 2-(Ethyl-imidazol-yl) acetic acid hydrochlorid, showed strong nematicidal and antifungal activity with a mortality rate of 95% at 0.3 ng/mL after 72 h and 100% inhibition zone of fungus at 1.5 µg/mL, respectively. The VOCs-induced severe oxidative stress in nematodes, which caused rapid death. Moreover, in the presence of Bacillus megaterium GIUBAM-2020 the disease index decreased in tomato seedlings as compared to single application of F. oxysporum and M. incognita. Moreover, genes responsible for plant growth promotion SlCKX1, SlIAA1, Sipin6 and Exp18 showed an upsurge in expression, in tomato plants treated with bacterial antagonistic and challenged with the disease complex of Fusarium oxysporum and Meloidogyne incognita. Furthermore, the defence-related genes (PR1, PR5) in infested tomato plants were upregulated after treatment with Bacillus megaterium GIUBAM-2020. These findings suggest Bacillus megaterium GIUBAM-2020 possesses excellent biocontrol potential against Meloidogyne incognita and Fusarium oxysporum, by upregulating the key genes involved in plant growth promotion, and the defense mechanism. Therefore, it is concluded Bacillus megaterium GIUBAM-2020 efficiently controls Meloidogyne incognita and Fusarium oxysporum-infested tomato plants wilt disease complex. [ABSTRACT FROM AUTHOR]

Leaf parsley growth and productivity are often affected by pathogen infection. Root-knot nematodes of the genus Meloiogyne are common pathogens reported on leaf parsley. The response of leaf parsley to Meloidogyne species in tropical and subtropical regions is quite known, while in temperate regions, comparable information is still scarce. In this study, we evaluated the host status and response of three flat-leaf (Laica, Laura, Gigante d'Italia) and three curly-leaf (Grüne Perle, Orfeo, Sombre) parsley cultivars to Meloidogyne species from temperate regions, i.e., M. hapla, M. chitwoodi, and M. fallax, as well as to the southern root-knot nematode M. incognita. Evaluation was based on measuring plant biomass and nematode reproduction nine weeks after nematode inoculation. Our results showed that all four Meloidogyne species did not cause the reduction in leaf parsley growth under the given experimental conditions. Regarding the host status of leaf parsley cultivars for Meloidogyne, results were variable. All six parsley cultivars were found to be good hosts for M. hapla. Regarding M. chitwoodi, the host status could not be clarified properly; however, each cultivar allowed nematode reproduction at least in one experiment. For M. fallax, flat-leaf parsley turned out to be less susceptible than curly-leaf parsley; and for M. incognita, Orfeo, Laura, and Laica were classified as good hosts, Grüne Perle and Sombre as poor hosts, and Gigante d'Italia as a non-host. Amongst all tested cultivars, Gigante d'Italia was found to be the least susceptible cultivar due to its poor host status for M. chitwoodi and non-host status for M. fallax and M. incognita. Infection with M. hapla, M. chitwoodi, and M. incognita, but not with M. fallax, resulted in distinct gall formation on the roots of all six leaf parsley cultivars. [ABSTRACT FROM AUTHOR]

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Understanding the transcriptional regulatory characteristics throughout the embryogenesis of plant-parasitic nematodes is crucial for elucidating their developmental processes' uniqueness. However, a challenge arises due to the lack of suitable technical methods for synchronizing the age of plant-parasitic nematodes embryo, it is difficult to collect detailed transcriptome data at each stage of embryonic development. Here, we recorded the 11 embryonic developmental time-points of endophytic nematode Meloidogyne incognita (isolated from Wuhan, China), Heterodera glycines (isolated from Wuhan, China), and Ditylenchus destructor (isolated from Jinan, China) species, and constructed transcriptome datasets of single embryos of these three species utilizing low-input smart-seq2 technology. The datasets encompassed 11 complete embryonic development stages, including Zygote, 2-cell, 4-cell, 8-cell, 24–44 cell, 64–78 cell, Comma, 1.5-fold, 2-fold, Moving, and L1, each stage generated four to five replicates, resulting in a total of 162 high-resolution transcriptome libraries. This high-resolution cross-species dataset serves as a crucial resource for comprehending the embryonic developmental properties of plant-parasitic nematodes and for identifying functional regulatory genes during embryogenesis. [ABSTRACT FROM AUTHOR]