Plant-parasitic Nematodes Research Articles

Development and Validation of a Resistance Management Model for the Soybean Cyst Nematode, Heterodera glycines.

Plant-parasitic nematodes are a key yield-limiting pest of crops around the world. Deployment of plant resistance genes are an important management tactic for many economically important plant-parasitic nematodes. The selection for virulence in nematode populations is a major threat to the effectiveness of resistance gene-based management. Little research has gone into resistance management modelling despite the importance of both plant-parasitic nematodes and resistance genes for their management. In this paper, we report on a cyst nematode resistance management model created to explore the factors which are most important for determining the durability of resistance genes to this important family of plant-parasitic nematodes. The relative dominance of virulence expression, the level of inbreeding, and the number of generations per cropping season were the most important factors in predicting resistance gene durability. Aspects of cyst nematode biology that reduce the number of generations per season for a portion of the population had a much smaller effect on the durability of resistance genes. These factors included delayed hatching within a season and early dormancy. The accuracy and utility of the model was tested using the soybean cyst nematode (SCN) rhg1-mediated resistance system. The model accurately predicted the rate at which virulence to the rhg1b resistance gene developed in Iowa over a two-decade period. The model suggested resistance gene pyramids as the most durable management solution for SCN with multiple possible avenues to obtain acceptable efficacy and durability.

Employing Plant Parasitic Nematodes as an Indicator for Assessing Advancements in Landfill Remediation

This research concentrated on the soil nematode communities inhabiting a reclaimed municipal waste landfill situated in Giedlarowa, southeastern Poland. The landfill, which was layered with natural soil in 2008 and cultivated with grass, served as the primary focus of the study. Samples for analysis were taken four times (October 2020 (Pf1), March 2021 (Pf2), October 2021 (Pf3), and March 2022 (Pf4)), with each time comprising three repetitions. The analysis was conducted employing microscopic examination, which enabled the identification of up to five trophic groups and species of plant-parasitic nematodes. During the assessment of nematode activity in the initial and subsequent growing seasons, it was found that Pratylenchus crenatus emerged as the predominant species among herbivorous nematodes in the plant-parasitic nematode (PPNs) community. Criconemoides informis, another nematode species, held a significant rank as well; their population during the third growing season formed the most substantial group among the PPN organisms dwelling in the soil. Nevertheless, interesting results were also obtained by populations of nematodes of the genus Hemicyclophora and Loofia, which were characterized by high densities. The analyzed soil environment showcased a C:N ratio spanning from 0.69 to 3.13. Furthermore, the soil samples exhibited variations in phosphorus content (P2O5), ranging from 4.02 mg/100 g to 10.09 mg/100 g. Criconemoides informis, Longidorus attenuates, Mesocriconema spp., and Bitylenchus maximus exhibited a positive correlation with soil mineral levels of calcium (Ca) and magnesium (Mg).

Effect of the Biostimulants of Microbiological Origin on the Entomopathogenic and Plant Parasitic Nematodes from Miscanthus × Giganteus Plantations

Abstract This study aimed to evaluate the effect of biostimulants derived from Streptomyces avermitilis metabolites on entomopathogenic nematodes: Steinernema carpocapsae, Steinernema feltiae, and Heterorhabditis bacteriophora, obtained from the soil of several Miscanthus × giganteus plantations in 2020–2023. The nematodes were isolated, identified, and cultured using live insects (the greater wax moth Galleria mellonella). Three preparations containing biostimulants – Charkor, Stimpo, and Regoplant, were tested for compatibility with entomopathogenic and plant parasitic nematodes. Their effect on nematode survival was evaluated using the Petri dish test. The study showed that the effect of biostimulants on the survival of nematodes depended on the concentration of aversectin contained in the evaluated preparations. Stimpo and Regoplant had an adverse effect on plant parasitic nematodes. The highest G. mellonella mortality was observed at the higher dose of Charkor (0.4%), and the lowest at the lower dose of Regoplant (1.22%). The study showed that the virulence of the nematodes decreased after 48 hours of incubation in Regoplant and Stimpo solutions containing aversectin. The degree of interaction between nematodes depended on the nematode species, trophic preferences, and the concentration of active ingredients in the preparations. This conclusion is crucial for the selection of appropriate types of entomopathogenic nematodes and the application rate of plant parasitic nematodes in the assessment of their short- and long-term spread, persistence, and recycling in field conditions.

Phytoparasitic Nematodes of Musa spp. with Emphasis on Sources of Genetic Resistance: A Systematic Review.

Bananas are a staple food that considerably contributes to both food security and income generation, especially in countries of Africa, Asia, and Central and South America. The banana plant (Musa spp.) is affected by various pathogens, of main concern being the plant-parasitic nematodes associated with the rhizosphere, the most important of which are Radopholus similis (burrowing nematode), Helicotylenchus sp. (spiral nematode), Pratylenchus sp. (root lesion nematode), and Meloidogyne sp. (gall nematode). Infected plants reduce their ability to absorb water and nutrients, which can lead to delayed flowering, fewer bunches, and lower fruit mass. Obtaining nematode-resistant banana cultivars through genetic improvement is an effective and sustainable option compared with chemical control with nematicides. Here, we provide the first systematic review of existing banana sources of resistance to nematodes to aid the management and control of nematodes in banana and plantain crops. Articles selected from different databases were evaluated, and searches were conducted using pre-established inclusion and exclusion criteria. We found 69 studies dealing with genetic improvement for nematode resistance in banana cultivation. Our findings revealed that sources of resistance are currently under investigation to combat the diseases caused by different nematode species in banana plants.

Computational analysis of 16D10 effector peptides from root-knot nematodes and their interaction with Mi resistance (R) protein through molecular docking

Plant-parasitic nematodes, especially root-knot nematodes (RKNs), pose significant threats to global agriculture, affecting both the quantity and quality of crop yields. Central to the parasitism strategy of RKNs is the deployment of effector proteins, such as the 16D10 peptide, which interact with host plant resistance mechanisms. This study focuses on the computational analysis and molecular docking of 16D10 effector peptides derived from major RKN species (M. incognita, M. arenaria, M. hapla, M. javanica, and M. chitwoodi) to explore their interaction with the Mi resistance protein in tomatoes. Initial bioinformatics assessments included sequence retrieval, multiple sequence alignment, and phylogenetic analysis, utilizing tools such as CLUSTALW and the MEME Suite. Notably, our phylogenetic analysis revealed a close evolutionary relationship between M. incognita and M. chitwoodi, contrasting with other RKN species based on both DNA and protein data. Subsequent, in silico 3D modeling and docking studies, conducted using Chem-Sketch and MOE software, provided insights into the structural basis of the interaction between 16D10 peptides and the Mi protein. Our findings indicate that these interactions could play a crucial role in the modulation of plant defense mechanisms, potentially leading to effector-triggered susceptibility (ETS). This study not only enhances our understanding of nematode-host interactions but also aids in the development of novel strategies for managing RKN infections in economically important crops.

Screening of indigenous entomopathogenic fungal isolates on plant parasitic nematodes in China

Screening of indigenous entomopathogenic fungal isolates on plant parasitic nematodes in China

Nematode community structure in sugarcane fields under continuous vinasse fertigation

Sugarcane vinasse is a residue from ethanol production, which has high content of nutrients and organic matter, improving chemical, physical and biological changes in the soil. This study evaluated nematode community structure, food web, metabolic footprint, and soil quality in sugarcane fields under continuous vinasse fertigation. Soil samples were collected from four sugarcane fields in Pernambuco State, Brazil, under continuous vinasse fertigation for nematode identification at the genus (plant parasites) and family (free-living) level, physical and chemical analyses of the soil. Nine genera of plant-parasitic nematodes and five families of free-living nematodes were identified in sugarcane fields. Plant-parasitic nematodes were dominant, except in the field with five years of continuous vinasse application. The genera Mesocriconema, Meloidogyne, Helicotylenchus and Pratylenchus were frequent in all fields. Predators and fungivores nematodes were few abundant, although, according to the soil food web, all sugarcane fields were low to moderately disturbed environments. A positive correlation was observed between the microbial respiration and Rhabdtidae in fields with five years of vinasse application, and between the electrical conductivity of the soil and Meloidogyne in fields without vinasse application. We highlight those alterations in the structure and composition of the nematode community, and soil characteristics that can occur due to vinasse fertigation in sugarcane fields.

Control of the plant-parasitic nematode Meloidogyne incognita in soil and on tomato roots by Clonostachys rosea.

Clonostachys rosea is a well-known mycoparasite that has recently been investigated as a bio-based alternative to chemical nematicides for the control of plant-parasitic nematodes. In the search for a promising biocontrol agent, the ability of the C. rosea strain PHP1701 to control the southern root-knot nematode Meloidogyne incognita was tested. Control of M. incognita in vitro and in soil by C. rosea strain PHP1701 was significant and concentration dependent. Small pot greenhouse trials confirmed a significant reduction in tomato root galling compared to the untreated control. In a large greenhouse trial, the control effect was confirmed in early and mid-season. Tomato yield was higher when the strain PHP1701 was applied compared to the untreated M. incognita-infected control. However, the yield of non-M. incognita-infected tomato plants was not reached. A similar reduction in root galling was also observed in a field trial. The results highlight the potential of this fungal strain as a promising biocontrol agent for root-knot nematode control in greenhouses, especially as part of an integrated pest management approach. We recommend the use of C. rosea strain PHP1701 for short-season crops and/or to reduce M. incognita populations on fallow land before planting the next crop.

Joint Impacts of Meloidogyne incognita and Soil Nutrition on Solanum lycopersicum var. cerasiforme.

Strategies for plant nutrient resource allocation under Meloidogyne spp. infection and different soil nutrient conditions are not well established. In response, the objectives of this research are to determine if increased vegetative growth of Solanum lycopersicon var. cerasiforme (cherry tomato) under high nutrition enhances resistance to M. incognita and whether adaptive strategies for growth, reproduction, and nutrient uptake by cherry tomato infected with M. incognita alter nutrient availability. The study was conducted under greenhouse conditions using high, medium, and low soil nutrient regimes. The research results indicate that the total biomass of cherry tomato was less in the presence of M. incognita infection under all three nutrient conditions, compared with plants grown in the absence of this nematode. However, the increase in the root/shoot ratio indicates that cherry tomato allocated more resources to belowground organs. Under the combined impacts of M. incognita infection and low or medium soil nutrition, the nitrogen content in root system tissues and the phosphorus content in shoot system tissues were increased to meet the nutrient requirements of galled root tissue and plant fruit production. It is suggested that plants increase the allocation of reproductive resources to fruits by improving phosphorus transportation to the aboveground reproductive tissues under low and medium nutrient conditions. Overall, the study highlights a significant impact of soil nutrient levels on the growth and resource allocation associated with M. incognita-infected cherry tomato. In response, soil nutrient management is another practice for reducing the impacts of plant-parasitic nematodes on crop production.

Silencing Ditylenchus destructor cathepsin L-like cysteine protease has negative pleiotropic effect on nematode ontogenesis

Ditylenchus destructor is a migratory plant-parasitic nematode that severely harms many agriculturally important crops. The control of this pest is difficult, thus efficient strategies for its management in agricultural production are urgently required. Cathepsin L-like cysteine protease (CPL) is one important protease that has been shown to participate in various physiological and pathological processes. Here we decided to characterize the CPL gene (Dd-cpl-1) from D. destructor. Analysis of Dd-cpl-1 gene showed that Dd-cpl-1 gene contains a signal peptide, an I29 inhibitor domain with ERFNIN and GNFD motifs, and a peptidase C1 domain with four conserved active residues, showing evolutionary conservation with other nematode CPLs. RT-qPCR revealed that Dd-cpl-1 gene displayed high expression in third-stage juveniles (J3s) and female adults. In situ hybridization analysis demonstrated that Dd-cpl-1 was expressed in the digestive system and reproductive organs. Silencing Dd-cpl-1 in 1-cell stage eggs of D. destructor by RNAi resulted in a severely delay in development or even in abortive morphogenesis during embryogenesis. The RNAi-mediated silencing of Dd-cpl-1 in J2s and J3s resulted in a developmental arrest phenotype in J3 stage. In addition, silencing Dd-cpl-1 gene expression in female adults led to a 57.43% decrease in egg production. Finally, Dd-cpl-1 RNAi-treated nematodes showed a significant reduction in host colonization and infection. Overall, our results indicate that Dd-CPL-1 plays multiple roles in D. destructor ontogenesis and could serve as a new potential target for controlling D. destructor.

Biosecurity risks to human food supply associated with plant-parasitic nematodes.

Biosecurity in agriculture is essential for preventing the introduction and spread of plant-parasitic nematodes (PPNs) which threaten global food security by reducing crop yields and facilitating disease spread. These risks are exacerbated by increased global trade and climate change, which may alter PPN distribution and activity, increasing their impact on agricultural systems. Addressing these challenges is vital to maintaining the integrity of the food supply chain. This review highlights significant advancements in managing PPN-related biosecurity risks within the food supply chain, particularly considering climate change's evolving influence. It discusses the PPN modes of transmission, factors increasing the risk of infestation, the impact of PPNs on food safety and security, and traditional and emerging approaches for detecting and managing these pests. Literature suggests that implementing advanced biosecurity measures could decrease PPN infestation rates by up to 70%, substantially reducing crop yield losses and bolstering food security. Notably, the adoption of modern detection and management techniques, (molecular diagnostics and integrated pest management) and emerging geospatial surveillance and analysis systems (spectral imaging, change-detection analysis) has shown greater effectiveness than traditional methods. These innovations offer promising avenues for enhancing crop health and securing the food supply chain against environmental shifts. The integration of these strategies is crucial, demonstrating the potential to transform biosecurity practices and sustain agricultural productivity in the face of changing climatic conditions. This analysis emphasizes the importance of adopting advanced measures to protect crop health and ensure food supply chain resilience, providing valuable insights for stakeholders across the agricultural sector.

Nanonematicides: production, mechanisms, efficacy, opportunities and challenges

Summary Classical methods of using many toxic chemical pesticides for managing plant-parasitic nematodes (PPN) on key crops are inappropriate and have unfavourable consequences on human health and the environment. By contrast, nanotechnology can provide a wide range of alternative applications with additional merits based on nanoparticle (NP) pesticides. Three major categories, i.e., physical, chemical and biological methods, have been generally used for synthesis of nanonematicides. The merits and demerits of these methods are highlighted. The biological method generally involves easy, fast, scalable, cheap and environmentally safe techniques. As nanonematicides can reduce the non-selective use of classical nematicides with their high pollution and unhealthy levels, mechanisms underlying PPN population suppression by these nanonematicides are presented to help in their further optimisation. Nanonematicides are guiding a radical change in their efficacy against PPN, but more attention should be given to secure their clean production and application with cost-effective methods.

Morphological and molecular characterization of Heterodera ripae, a new record cyst nematode in the rhizosphere soil of Fagopyrum esculentum

Numerous plant parasitic nematodes (PPNs) have the potential to inflict considerable damage on agricultural crops. Through a comprehensive survey aimed at identifying PPNs affecting crops, cyst nematodes were isolated from the rhizosphere soil of buckwheat (Fagopyrum esculentum). Employing both molecular and morphological techniques, this cyst nematode was conclusively identified as Heterodera ripae. Notably, this represents the first documented occurrence of this particular cyst nematode species within the rhizosphere soil of F. esculentum.

Identification of Meloidogyne Species on Traditional Chinese Medicine Plants in the Qinling Mountain Area of China and Their Aggressiveness to Different Medicinal Herbs.

Root-knot nematodes (Meloidogyne spp.) are plant-parasitic nematodes that cause serious damage worldwide. There are many species of traditional Chinese medicine (TCM) plants, but only a few have been reported to be infected by Meloidogyne species. From 2020 to 2022, a survey was conducted in the Qinling mountain area, which is the main production region of TCM plants in China. Obvious galling symptoms were observed on the root systems of 15 species of TCM plants. Females were collected from diverse diseased TCM plants and subsequently identified at morphological and molecular levels. Among the 20 diseased root samples collected, Meloidogyne hapla populations were identified in 12 samples (60%), and M. incognita populations were identified in eight samples (40%). Among the 15 species of diseased TCM plants, eight species, namely, Scutellaria baicalensis, Leonurus japonicus, Dioscorea zingiberensis, Cornus officinalis, Viola philippica, Achyranthes bidentata, Senecio scandens, and Plantago depressa, were reported to be infected by Meloidogyne species for the first time. The host status of five species of TCM plants for two M. hapla isolates and one M. incognita isolate from TCM plants in this study was then evaluated. Differences in TCM plants' response to nematode infection were apparent when susceptibility was evaluated by the egg counts per gram of fresh root and the reproduction factor of the nematodes. Among the five species of TCM plants tested, Salvia miltiorrhiza and Gynostemma pentaphyllum were the most susceptible, while S. baicalensis and V. philippica were not considered suitable hosts for M. hapla or M. incognita.

Prevalence of Plant-Parasitic Nematodes in Horticultural Fields of Assam Agricultural University: Jorhat Campus, India

A random survey of the horticultural crops was conducted to assess the nematode community structure in the Experimental field of Department of Horticulture, AAU, Jorhat during Rabi and Kharif season, 2022-2023. Soil and root samples, representing 200 locations were examined. Analysis of 200 soil and root samples collected from the root rhizosphere of different vegetable, fruit and ornamental crops showed the presence of root-knot nematode(Meloidogyne incognita), reniform nematode (Rotylenchulus reniformis), root-lesion nematode (Pratylenchus spp.), lance nematode (Hoplolaimus spp.), spiral nematode (Helicotylenchus spp.), stunt nematode (Tylenchorhynchus spp.) along with Criconema spp., Xiphinema spp, Longidorus spp., free-living nematodes, mycophagous nematodes and predatory nematodes. Among all the isolated plant-parasitic nematodes, root-knot nematode (Meloidogyne incognita) was found to be more abundant with prominence value of 136.7, 81.3 and 76.3 in vegetable crops, fruit crops and ornamental crops, followed by Helicotylenchus spp. and Rotylenchulus reniformis. The prominence value of reniform nematode (Rotylenchulus reniformis) was found to be 90.5, 54.1 and 54.1 in vegetable crops, fruit crops and ornamental plants respectively.

FARManalytics – A bio-economic model to optimize the economic value of sustainable soil management on arable farms

Soil quality is an important determinant of agricultural productivity and environmental quality. Despite its importance, few economic models incorporate sustainable soil management. The objective of this study is to develop and illustrate FARManalytics: a bio-economic model to gain quantitative insight in the economic value of sustainable soil management. First, we defined a comprehensive set of chemical, physical and biological soil quality indicators and quantitative rules on how these indicators respond to farmers’ production management over time. Second, we introduce an economic calculation framework that enables accurate calculation of the contribution of different production management decisions towards farm income using Activity-Based-Costing. The set of soil quality indicators and economic calculations serve as the basis for the bio-economic model FARManalytics, which consists of two modules: (1) the PMcalculator, a module that calculates the impact of current production management on soil quality and farm economics and (2) the PMoptimizer, a module that uses Mixed-Integer-Linear-Programming to maximize farm incomewithin predefined soil quality indicator constraints. The decision variables are the crop rotation, cover crops, manure & fertilizer application and crop residue management. We illustrate the added value of the model by applying it to an extensive and intensive farm type, both on clay and sandy soil. These farm types are derived from the Farm Accountancy Data Network (FADN) in the Netherlands. FARManalytics demonstrates that it is possible to increase farm income with up to €940 ha−1 year−1 on clay soil and up to €683 ha−1 year−1 on sandy soil, while meeting all soil quality targets except subsoil compaction vulnerability. The latter was among the most limiting soil quality indicators for the farm types in this study, together with soil organic matter input, wind erosion vulnerability and plant-parasitic nematodes. FARManalytics integrates the impact of production management decisions on soil quality and economics at farm level. Combined with representative farm types, the bio-economic modeling approach of FARManalytics can provide useful information for policy support. FARManalytics can also be tailored to provide decision support for individual farms, based on data that is commonly available on arable farms at low cost.

Redox signalling in plant-nematode interactions: Insights into molecular crosstalk and defense mechanisms.

Plant-parasitic nematodes, specifically cyst nematodes (CNs) and root-knot nematodes (RKNs), pose significant threats to global agriculture, leading to substantial crop losses. Both CNs and RKNs induce permanent feeding sites in the root of their host plants, which then serve as their only source of nutrients throughout their lifecycle. Plants deploy reactive oxygen species (ROS) as a primary defense mechanism against nematode invasion. Notably, both CNs and RKNs have evolved sophisticated strategies to manipulate the host's redox environment to their advantage, with each employing distinct tactics to combat ROS. In this review, we have focused on the role of ROS and its scavenging network in interactions between host plants and CNs and RKNs. Overall, this review emphasizes the complex interplay between plant defense mechanism, redox signallingand nematode survival tactics, suggesting potential avenues for developing innovative nematode management strategies in agriculture.

VND Genes Redundantly Regulate Cell Wall Thickening during Parasitic Nematode Infection.

Plant parasitic root-knot nematodes are major agricultural pests worldwide, as they infect plant roots and cause substantial damages to crop plants. Root-knot nematodes induce specialized feeding cells known as giant cells (GCs) in the root vasculature, which serve as nutrient reservoirs for the infecting nematodes. Here, we show that the cell walls of GCs thicken to form pitted patterns that superficially resemble metaxylem cells. Interestingly, VASCULAR-RELATED NAC-DOMAIN1 (VND1) was found to be upregulated, while the xylem-type programmed cell death marker XYLEM CYSTEINE PEPTIDASE 1 was downregulated upon nematode infection. The vnd2 and vnd3 mutants showed reduced secondary cell wall pore size, while the vnd1 vnd2 vnd3 triple mutant produced significantly fewer nematode egg masses when compared with the wild type. These results suggest that the GC development pathway likely shares common signaling modules with the metaxylem differentiation pathway and VND1, VND2, and VND3 redundantly regulate plant-nematode interaction through secondary cell wall formation.

Parasitic Nematodes of Sugarcane: A Major Productivity Impediment and Grand Challenges in Management.

Sugarcane is an important cash crop grown in 137 countries, accounting for 80% of global sugar production. It supports the livelihood of more than 100 million people and up to 25% of the rural population in some countries. Plant-parasitic nematodes are one significant constraint in sugarcane production and can lead to a loss of up to 30% in productivity. More than 300 species of parasitic nematodes have been discovered in sugarcane soil. Owing to limited data, the potential damage to sugarcane crops caused by parasitic nematodes is often underestimated. The main nematodes present in sugarcane fields are root-lesion (Pratylenchus spp.), spiral (Helicotylenchus spp.), root-knot (Meloidogyne spp.), dagger (Xiphinema spp.), stunt (Tylenchorhynchus spp.), ring (Criconemella spp.), and stubby (Paratrichodorus spp.). Among these, Meloidogyne javanica and Pratylenchus zeae are the most damaging nematode species. Management of nematodes is a challenging task as there are no clear symptoms of their presence, and they often come in multiple species with varying levels of pathogenicity. Moreover, the management options available are not always effective. Integrated nematode management is a sustainable strategy for controlling nematode infestations. It involves using all possible methods to suppress the parasitic nematode population in a compatible manner and reduce it below economic threshold levels. This article focuses on the challenges of managing nematodes in sugarcane and highlights the opportunity for implementing a sustainable nematode management strategy.

Influence of Cropping Sequence and Tillage System on Plant-Parasitic Nematodes and Peanut (Arachis hypogaea) Response to Fluopyram Applied at Planting

Crop sequence and tillage can affect the yield of peanut (Arachis hypogaea L.) and other crops. Research was conducted from 2006 through 2022 to determine the response of peanut to previous crop sequences including corn (Zea mays L.) and cotton (Gossypium hirsutum L.) planted in continuous conventional tillage (e.g., disking, field cultivating, and bedding with in-row sub-soiling) or strip tillage (e.g., tilling a 45 cm section on rows spaced 91 cm apart using fluted coulters, rolling baskets, and in-row sub-soiling). In 2013, 2019, and 2022, the entire test area was planted with peanut. In 2019 and 2022, peanut was planted without or with fluopyram applied in the seed furrow at planting. Decreasing the number of years between peanut planting resulted in lower peanut yields compared with fewer years of peanut planting in the rotation sequence. Continuous conventional tillage and strip tillage resulted in similar peanut yields at one location, while the yield was lower at a second location when peanut was planted in continuous strip tillage. Fluopyram did not affect peanut yield regardless of previous crop rotation sequence, the number of years separating peanut plantings, or the tillage system. However, minor differences in the populations of plant-parasitic nematodes in soil were noted when comparing fluopyram treatment. The results from these experiments indicate that while fluopyram can reduce the populations of some plant-parasitic nematodes in soil, the magnitude of reduction does not translate into increases in peanut yield.