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In vitro evaluation of the studied isolate against M. incognita. A-C show parasitization against the nematode, scale bar 50 µm, D Fungal sporulation on water agar plates (×50)
Source publication
Root-knot nematodes (RKNs) of the genus Meloidogyne are agriculturally important pests, causing serious damage to agricultural crops. Biocontrol strategies have gained unprecedented importance to combat RKNs due to their eco-friendly nature. Here, we have developed a repository of fungi selectively isolated using Caenorhabditis elegans as bait. The...
Contexts in source publication
Context 1
... in vitro conditions, Ma_ITCC9014 was found to be effective against M. incognita J2s after 3 days, as compared to control. The results showed that Ma_ITCC9014 caused a significantly high parasitism leading to the death of 97.67 ± 2.08% J2s (Fig. 2) compared to 1.33 ± 0.58% in control. Further to prove Koch's postulates, parasitized nematodes were picked up and the fungus was re-cultured on PDA. Morphological and molecular characterization of the re-isolated fungus confirmed the identity as M. anisopliae Ma_ITCC9014 thus proving the Koch's postulate. Our findings matched with the ...
Context 2
... treatment showed 22.67 ± 0.57 and 24.67 ± 2.1 cm respectively, compared to nematode control 8.33 ± 3.1 and 13.33 ± 3.52 cm, respectively. However, no significant difference was observed between Ma_ITCC9014 and carbofuran treatments. The fresh root weight increased up to 45.2% and 57.3% respectively in Ma_ITCC9014 and carbofuran treatments (Fig. S2). Likewise, no-significant differences were observed in the shoot weight of nematode infected plants receiving carbofuran or Ma_ITCC9014. An earlier report has demonstrated that application of M. anisopliae as soil-drench increased the yield by about 20% ( Bhosle et al. 2006). Similarly, Youssef et al. (2020) showed that different ...
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Purpureocillium lavendulum is a fungus with promising biocontrol applications. Here, transcriptome data acquired during the infection of Caenorhabditis elegans by Purpureocillium lavendulum showed that the transcription of metabolite synthesis genes was significantly up-regulated after 24 and 48 h of the fungus-nematode interaction. Then, the up-re...
Citations
... Therefore, integrated pest management (IPM), which combines various pest control methods, including biopesticides, helps reduce reliance on synthetic pesticides and the development of pesticide resistance in nematodes. Furthermore, nematophagous fungi and bacteria are also promising biocontrol agents that can suppress nematode populations in the soil (Cruz-Martinez et al. 2017;Dlamini et al. 2019;Kassam et al. 2021Kassam et al. , 2022Kassam et al. , 2023a. Nevertheless, currently employed management practices are still inadequate. ...
Key message
The study demonstrates the successful management of Meloidogyne incognita in eggplant using Mi-flp14 RNA interference, showing reduced nematode penetration and reproduction without off-target effects across multiple generations.
Abstract
Root-knot nematode, Meloidogyne incognita, causes huge yield losses worldwide. Neuromotor function in M. incognita governed by 19 neuropeptides is vital for parasitism and parasite biology. The present study establishes the utility of Mi-flp14 for managing M. incognita in eggplant in continuation of our earlier proof of concept in tobacco (US patent US2015/0361445A1). Mi-flp14 hairpin RNA construct was used for generating 19 independent transgenic eggplant events. PCR and Southern hybridization analysis confirmed transgene integration and its orientation, while RT-qPCR and Northern hybridization established the generation of dsRNA and siRNA of Mi-flp14. In vitro and in vivo bio-efficacy analysis of single-copy events against M. incognita showed reduced nematode penetration and development at various intervals that negatively impacted reproduction. Interestingly, M. incognita preferred wild-type plants over the transgenics even when unbiased equal opportunity was provided for the infection. A significant reduction in disease parameters was observed in transgenic plants viz., galls (40–48%), females (40–50%), egg masses (35–40%), eggs/egg mass (50–55%), and derived multiplication factor (60–65%) compared to wild type. A unique demonstration of perturbed expression of Mi-flp14 in partially penetrated juveniles and female nematodes established successful host-mediated RNAi both at the time of penetration even before the nematodes started withdrawing plant nutrients and later stage, respectively. The absence of off-target effects in transgenic plants was supported by the normal growth phenotype of the plants and T-DNA integration loci. Stability in the bio-efficacy against M. incognita across T1- to T4-generation transgenic plants established the utility of silencing Mi-flp14 for nematode management. This study demonstrates the significance of targeting Mi-flp14 in eggplant for nematode management, particularly to address global agricultural challenges posed by M. incognita.
... Crude extracts of M. guizhouense grown on a protein-enriched medium suppressed RKN hatching within 24 h, and caused 100% mortality of juveniles within 48 h post-treatment. Kassam et al. (2022) investigated the efficacy of M. anisopliae strain ITCC9014 against M. incognita under laboratory conditions. This study demonstrated that applying ITCC9014 led up to a 97% parasitism reduction of M. incognita juveniles, within 3 days. ...
Plant-parasitic nematodes (PPN) are one of the most damaging crop pests with broad host ranges and can cause billions of dollars of crop losses, worldwide. Different control measures, including soil organic amendments, green manure, resis
tant varieties, crop rotation, chemical nematicides, and biological control agents, have been evaluated for the management of PPN, all with low to moderate success. Concerns regarding the deleterious effects of synthetic nematicides on non-target soil organisms or the environment are increasing, leading to enhanced interest in alterna tive control strategies. In this chapter we review and discuss potential PPN biological control agents, including fungi, bacteria, nematodes, and nematophagous mites. Relevant case studies focused on the potential of these agents under laboratory, green house, and/or field conditions are highlighted. We also emphasize the factors affecting their efficacy against PPN management, providing suggestions for future work.
... Fungi of the Metarhizium genus, commonly used for their entomopathogenic activity, were shown to be effective in parasitizing the root-knot nematode M. incognita [36]. In particular, M. carneum showed its effectiveness in reducing populations of the potato cyst nematode G. rostochiensis by 33 to 89% under field conditions [20]. ...
The increase in the populations of root-knot nematode Meloidogyne enterolobii in various vegetables such as tomatoes grown under greenhouse conditions as well as increasing restrictions on the use of certain chemical nematicides have led to the search for new, effective management strategies, preferably ones that are sustainable biological alternatives. In this work, two formulations of the nematophagous fungus Metarhizium carneum, one concentrated suspension and one wettable powder, were evaluated under greenhouse conditions to reduce the M. enterolobii infestation in tomato plants. In addition, the effectiveness of the liquid formulation of M. carneum was compared with two biological and three chemical commercial nematicides. The results show that the two M. carneum formulations reduced the M. enterolobii population density by 78 and 66% in relation to the control treatment. In comparison, the liquid formulation of M. carneum and Purpureocillium lilacinum treatments reduced nematode population density by 72 and 43%, respectively, while for metam sodium preplanting applications followed by M. carneum applications during the tomato growth stage, the reduction was 96%. The alternate use of some chemical compounds plus the application of M. carneum as a biocontrol is a good starting strategy for managing M. enterolobii populations. These results confirm that M. carneum is a serious candidate for the short-term commercialization of an environmentally friendly biological nematicide.
... Scientists from India showed the activity of the fungus M. anisopliae against M. incognita, where 97.7% parasitism on J2 juveniles was noted. In addition, the studied isolate reduced the development of meloidoginosis in vivo by 82.3% [39]. We found that the effectiveness of M. anisopliae against the species M. hapla under laboratory conditions was 48.3-70.2%, and under the conditions of a vegetative test was 75.7%. ...
Citation: Nekoval, S.N.; Churikova, A.K.; Chernyakovich, M.N.; Pridannikov, M.V. Primary Screening of Microorganisms against Meloidogyne hapla (Chitwood, 1949) under the Conditions of Laboratory and Vegetative Tests on Tomato. Plants 2023, 12, 3323. https:// Abstract: Highly adapted obligate endoparasites of the root system, root-knot nematodes (Meloidog-yne spp.), cause great damage to agricultural crops. Our research is aimed at the assessment of nematicidal activity and effectiveness of antagonist fungal and bacterial strains against the most common type of root-knot nematode in the south of Russia. By means of molecular genetic identification, it was found that in the south of Russia, the species Meloidogyne hapla Chitwood, 1949 and Meloidogyne incognita (Kofoid and White, 1919) Chitwood, 1949 cause galls on the roots of open-ground and greenhouse tomato. Screening of microbial agents against second-stage juvenile (J2) M. hapla was carried out in the laboratory. At the end of the experiment, two liquid fungal cultures of Paecilomyces lilacinus BK-6 and Metarhizium anisopliae BK-2 were isolated, the nematicidal activity of which reached 100.0 and 70.2%, and exceeded the values of the biological standard (Nemotafagin-Mikopro) by 38.4% and 8.8%. The highest biological efficacy was noted in the liquid cultures of P. lilacinus BK-6, M. anisopliae BK-2, and Arthrobotrys conoides BK-8 when introduced into the soil before planting tomato. The number of formed galls on the roots was lower in comparison with the control by 81.0%, 75.5%, and 74.4%.
... Cucumber [84] Trichoderma asperellum, T. harzianum Cucumber and tomato [36] Lecanicillium muscarium Tomato [85] Trichoderma harzianum [37] Penicillium chrysogenum - [86] Pochonia chlamydosporia Tomato and cucumber [34] Pochonia chlamydosporia Tomato [87] Pochonia chlamydosporia Chickpea [38] Arthrobotrys oligospora, Glomus faciculatum, Purpureocillium lilacinum Cucumber [88] Glomus spp., G. mosseae, G. viscosum, Pochonia chlamydosporia, Trichoderma harzianum Tomato [54] Metarhizium anisopliae [89] Purpureocillium lilacinum M. incognita and M. javanica [90] Arthrobotrys Volutella citrinella - [110] 2.1. Root-Knot Nematodes (RKNs), Meloidogyne spp. ...
... reproduction between 83 and 99%, compared to the single application of molasses, which varied between 49 and 99%. Kassam et al. [89] investigated the effect of the fungus Metarhizium anisopliae ITCC9014 on M. incognita in vitro and reported that 97 ± 2% of juveniles were parasitized after 3 days. Additionally, they noted that M. anisopliae ITCC9014 significantly reduced symptoms 40 days after inoculation, in terms of the total number of galls, females, egg masses, and eggs per egg masses, with no significant differences between the chemical nematicide carbofuran and the fungal treatment [89]. ...
... Kassam et al. [89] investigated the effect of the fungus Metarhizium anisopliae ITCC9014 on M. incognita in vitro and reported that 97 ± 2% of juveniles were parasitized after 3 days. Additionally, they noted that M. anisopliae ITCC9014 significantly reduced symptoms 40 days after inoculation, in terms of the total number of galls, females, egg masses, and eggs per egg masses, with no significant differences between the chemical nematicide carbofuran and the fungal treatment [89]. Lastly, an 82% reduction in the nematode multiplication factor was also observed [89]. ...
Plant-parasitic nematodes (PPNs) are among the most notorious and underrated threats to food security and plant health worldwide, compromising crop yields and causing billions of dollars of losses annually. Chemical control strategies rely heavily on synthetic chemical nematicides to reduce PPN population densities, but their use is being progressively restricted due to environmental and human health concerns, so alternative control methods are urgently needed. Here, we review the potential of bacterial and fungal agents to suppress the most important PPNs, namely Aphelenchoides besseyi, Bursaphelenchus xylophilus, Ditylenchus dipsaci, Globodera spp., Heterodera spp., Meloidogyne spp., Nacobbus aberrans, Pratylenchus spp., Radopholus similis, Rotylenchulus reniformis, and Xiphinema index.
Main conclusion
Integrated management strategies, including novel nematicides and resilient cultivars, offer sustainable solutions to combat root-knot nematodes, crucial for safeguarding global agriculture against persistent threats.
Abstract
Root-knot nematodes (RKN) pose a significant threat to a diverse range of host plants, with their obligatory endoparasitic nature leading to substantial agricultural losses. RKN spend much of their lives inside or in contact by secreting plant cell wall-modifying enzymes resulting in the giant cell development for establishing host-parasite relationships. Additionally, inflicting physical harm to host plants, RKN also contributes to disease complexes creation with fungi and bacteria. This review comprehensively explores the origin, history, distribution, and physiological races of RKN, emphasizing their economic impact on plants through gall formation. Management strategies, ranging from cultural and physical to biological and chemical controls, along with resistance mechanisms and marker-assisted selection, are explored. While recognizing the limitations of traditional nematicides, recent breakthroughs in non-fumigant alternatives like fluensulfone, spirotetramat, and fluopyram offer promising avenues for sustainable RKN management. Despite the success of resistance mechanisms like the Mi gene, challenges persist, prompting the need for integrative approaches to tackle Mi-virulent isolates. In conclusion, the review stresses the importance of innovative and resilient control measures for sustainable agriculture, emphasizing ongoing research to address evolving challenges posed by RKN. The integration of botanicals, resistant cultivars, and biological controls, alongside advancements in non-fumigant nematicides, contributes novel insights to the field, laying the ground work for future research directions to ensure the long-term sustainability of agriculture in the face of persistent RKN threats.
Plant parasitic nematodes (PPNs) are one of the most serious constraints in food security. Among the many biocontrol agents studied for managing PPNs, nematophagous fungi show a high potential. These fungi control/suppress the nematode population either by parasitising or predating/trapping various nematode stages or kill them by secretion of nematotoxic metabolites. With more than 700 species of nematophagous fungi identified with a potential of nematode biocontrol, species such as Purpureocillium (Paecilomyces) lilacinus, Pochonia (Verticillium) chlamydosporia and Trichoderma are exploited as nematode parasitic fungi. Among nematode-trapping fungi, Arthrobotrys oligospora is widely used in nematode management. Along with parasitic and trapping species, Arbuscular mycorrhizal fungi (AMF) also offer an exciting opportunity to be integrated in nematode management programs due to their ability to induce systemic resistance and tolerance, competition for space and nutrients. In this chapter we discuss the mechanisms employed by nematophagous fungi in detail. We suggest that formulations incorporating 2 or more fungi with different modes of action should be commercialised to increase efficiency. Due to the enormous demand and availability of spurious products, strict regulations are necessary, nationally and internationally, to benefit the farming community facing PPNs threats.
Plant parasitic nematodes (PPNs) are distributed worldwide and cause significant losses in agricultural fields. For the sustainable productivity of crops, the management of PPNs is necessary. Various practices, including chemical nematicides, have effectively reduced PPN outbreaks. Various industries manufacture chemical nematicides available in the market, but these chemicals affect non-target organisms also. Various sustainable and non-agrochemical methods have been identified to overcome this effect, resulting in the reduction of PPN outbreaks with a reduced interference in soil health. Using natural enemies of nematodes is the most promising method among all practices, relying on antagonizing microorganisms of soil microhabitats. Some of these microbes act as endoparasites of nematodes that produce toxins to kill their host. Others capture and kill the target organisms. Understanding the mechanism of action of these suppressors provides crucial insights to develop suitable bio-control agents for PPN management.
Key message
This study demonstrates multi-gene silencing approach for simultaneous silencing of several functional genes through a fusion gene strategy for protecting plants against root-knot nematode,Meloidogyne incognita.
The ability of root-knot nematode (RKN), Meloidogyne incognita, to cause extensive yield decline in a wide range of cultivated crops is well-documented. Due to the inadequacies of current management approaches, the alternatively employed contemporary RNA interference (RNAi)-based host-delivered gene silencing (HD-RNAi) strategy targeting different functional effectors/genes has shown substantial potential to combat RKNs. In this direction, we have explored the possibility of simultaneous silencing of four esophageal gland genes, six plant cell-wall modifying enzymes (PCWMEs) and a serine protease gene of M. incognita using the fusion approach. In vitro RNAi showed that combinatorial gene silencing is the most effective in affecting nematode behavior in terms of reduced attraction, penetration, development, and reproduction in tomato and adzuki beans. In addition, qRT-PCR analysis of M. incognita J2s soaked in fusion-dsRNA showed perturbed expression of all the genes comprising the fusion construct confirming successful dsRNA processing which is also supported by increased mRNA abundance of five key-RNAi pathway genes. In addition, hairpin RNA expressing constructs of multi-gene fusion cassettes were developed and used for generation of Nicotiana tabacum transgenic plants. The integration of gene constructs and expression of siRNAs in transgenic events were confirmed by Southern and Northern blot analyses. Besides, bio-efficacy analyses of transgenic events, conferred up to 87% reduction in M. incognita multiplication. Correspondingly, reduced transcript accumulation of the target genes in the M. incognita females extracted from transgenic events confirmed successful gene silencing.
