Novel bioassays to examine the host-finding ability of plant-parasitic nematodes

Nematology ◽  
2011 ◽  
Vol 13 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Johnathan J. Dalzell ◽  
Rachel Kerr ◽  
Matthew D. Corbett ◽  
Colin C. Fleming ◽  
Aaron G. Maule
Keyword(s):  
Concentration Gradient ◽  
Host Finding ◽  
Globodera Pallida ◽  
Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Water Control ◽  
Validation Data ◽  
Central Trough ◽  
The Impact ◽  
Plant Parasitic

Abstract We present two novel bioassays to be used in the examination of plant-parasitic nematode host-finding ability. The hostfinding 'pipette-bulb assay' was constructed from modelled Pasteur pipette bulbs and connecting barrels using parafilm fastenings. This assay examines the direction of second-stage juvenile (J2) migration in response to a host seedling, through a moistened sand substrate, which underlies terminal upward-facing 'seedling bulbs', one containing a host seedling in potting compost, the other with only potting compost. An equal watering regime through both upward-facing seedling bulbs creates a directional concentration gradient of host diffusate chemotactic factors. Positive chemotactic stimuli cause the J2 to orientate and migrate towards the host plant. We present validation data collected from assays of the root-knot nematode, Meloidogyne incognita, and the potato cyst nematode, Globodera pallida, which indicate a highly significant positive attraction of J2 of both species to respective host plants. This represents a simple, quick and inexpensive method of assessing host-finding behaviour in the laboratory. We consider that the pipette-bulb assay improves on previous host-finding/chemo-attraction assays through creating a more biologically relevant environment for experimental J2; analysis is quick and easy, allowing the straightforward interpretation of results. In addition, we have developed an 'agar trough' sensory assay variant which we believe can be used rapidly to ratify nematode responses to chemical gustatory or olfactory cues. This was constructed from a water agar substrate such that two counting wells were connected by a raised central trough, all flooded with water. Two small water agar plugs were dehydrated briefly in an oven and then hydrated in either an attractant, repellent or water control; these plugs were then placed in the terminal counting wells and subsequently leached the attractant or repellent to form a concentration gradient along the central trough, which contained the initial J2 innoculum. Our data show that both M. incognita and G. pallida J2 are positively attracted to host diffusates. In addition, they displayed a strong repulsion in response to 1 M NaCl2. J2 of M. incognita displayed a mild aversion to a non-host oak root diffusate, whereas G. pallida J2 displayed a strong aversion to the same non-host diffusate; neither species responded to a compost leachate. We believe that the agar trough assay improves on previous methods by facilitating rapid diffusion of attractant or repellents. Both of the aforementioned assays were designed as tools to assess the impact of RNAi-based reverse genetics screens for gene targets involved in chemosensory orientation.

The role of plant-parasitic nematodes in reducing yield of sugarcane in fine-textured soils in Queensland, Australia

2007 ◽  
Vol 47 (5) ◽  
pp. 620 ◽  
Author(s):  
B. L. Blair ◽  
G. R. Stirling
Keyword(s):  
Growth And Yield ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Population Densities ◽  
Lesion Nematode ◽  
Yield Responses ◽  
The Impact ◽  
Stalk Length ◽  
Plant Parasitic

Damage to sugarcane caused by root-knot nematode (Meloidogyne spp.) is well documented in infertile coarse-textured soils, but crop losses have never been assessed in the fine-textured soils on which more than 95% of Australia’s sugarcane is grown. The impact of nematodes in these more fertile soils was assessed by repeatedly applying nematicides (aldicarb and fenamiphos) to plant and ratoon crops in 16 fields, and measuring their effects on nematode populations, sugarcane growth and yield. In untreated plant crops, mid-season population densities of lesion nematode (Pratylenchus zeae), root-knot nematode (M. javanica), stunt nematode (Tylenchorhynchus annulatus), spiral nematode (Helicotylenchus dihystera) and stubby-root nematode (Paratrichodorus minor) averaged 1065, 214, 535, 217 and 103 nematodes/200 mL soil, respectively. Lower mean nematode population densities were recorded in the first ratoon, particularly for root-knot nematode. Nematicides reduced populations of lesion nematode by 66–99% in both plant and ratoon crops, but control of root-knot nematode was inconsistent, particularly in ratoons. Nematicide treatment had a greater impact on shoot and stalk length than on shoot and stalk number. The entire community of pest nematodes appeared to be contributing to lost productivity, but stalk length and final yield responses correlated most consistently with the number of lesion nematodes controlled. Fine roots in nematicide-treated plots were healthier and more numerous than in untreated plots, and this was indicative of the reduced impact of lesion nematode. Yield responses averaged 15.3% in plant crops and 11.6% in ratoons, indicating that nematodes are subtle but significant pests of sugarcane in fine-textured soils. On the basis of these results, plant-parasitic nematodes are conservatively estimated to cost the Australian sugar industry about AU$82 million/annum.

The impact of management strategies on the development and status of potato cyst nematode populations in Switzerland: An overview from 1958 to present

Plant Disease ◽  
2021 ◽  
Author(s):  
Andrea Caroline Ruthes ◽  
Paul Dahlin
Keyword(s):  
Integrated Management ◽  
Abiotic Factors ◽  
Management Strategies ◽  
Monitoring Program ◽  
Cyst Nematode ◽  
Globodera Pallida ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
The Impact ◽  
Plant Parasitic

Globodera rostochiensis and Globodera pallida are some of the most successful and highly specialized plant-parasitic nematodes, and appear among the most regulated quarantine pests globally. In Switzerland, they have been monitored by annual surveys since their first detection in Swiss soil, in 1958. The dataset created was reviewed to give an overview of the development and actual status of PCN in Switzerland. Positive fields represent 0.2% of all the samples analyzed, and currently their distribution is limited to central-west and western Switzerland, suggesting that new introduction of PCN and the spread of the initial introduced PCN populations did not occur. In this way, the integrated management used in Switzerland appears to be effective. However, the increasing availability of potato varieties with resistance to G. rostochiensis and the limited availability of varieties with resistance to G. pallida, together with other biotic and abiotic factors promoted changes in the dominance of either species. Consequently, an extended monitoring program would be of interest to Swiss farmers, to avoid favoring virulent traits that could be present within Swiss Globodera populations.

scholarly journals Pathogenicity and Metabolites of Endoparasitic Nematophagous Fungus Drechmeria coniospora YMF1.01759 against Nematodes

2021 ◽  
Vol 9 (8) ◽  
pp. 1735
Author(s):  
Juan Wan ◽  
Zebao Dai ◽  
Keqin Zhang ◽  
Guohong Li ◽  
Peiji Zhao
Keyword(s):  
Secondary Metabolites ◽  
Nematophagous Fungus ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Active Metabolites ◽  
Water Control ◽  
Egg Hatching ◽  
Fermentation Products ◽  
Plant Parasitic

Plant parasitic nematodes cause severe damage to crops. Endoparasitic nematophagous fungi (ENF) are a type of important biocontrol fungi, which can cause disease or kill nematodes by producing various spores. As a major ENF, Drechmeria coniospora displays certain potential for controlling plant-parasitic nematodes. In this study, the pathogenicity and secondary metabolites of the endoparasitic fungus D. coniospora YMF1.01759 were investigated. The strain D. coniospora YMF1.01759 had high infection efficiency against nematodes. The process of infecting nematodes by the strain was observed under an electron microscope. Here, 13 metabolites including one new compound 4(S)-butoxy-3-(butoxymethyl)-2-hydroxycyclopent-2-en-1-one (2) were isolated and identified from the fermentation products of D. coniospora YMF1.01759 cultured in a SDAY solid medium. Furthermore, a bioassay showed that 5-hydroxymethylfuran-2-carboxylic acid (1) is toxic to the root knot nematode Meloidogyne incognita and affects the hatching of its egg. Thereby, the nematicidal mortality attained 81.50% at 100 μg/mL for 48 h. Furthermore, egg hatching was inhibited at the tested concentrations, compared with water control eggs. This is the first report on the secondary metabolites of the ENF D. coniospora. The results indicated that D. coniospora could infect nematodes by spores and produce active metabolites to kill nematodes. The biological control potential of D. coniospora against nematodes was expounded further.

scholarly journals Belowground Chemical Interactions: An Insight Into Host-Specific Behavior of Globodera spp. Hatched in Root Exudates From Potato and Its Wild Relative, Solanum sisymbriifolium

2022 ◽  
Vol 12 ◽  
Author(s):  
Joanna Kud ◽  
Syamkumar Sivasankara Pillai ◽  
Gabriel Raber ◽  
Allan Caplan ◽  
Joseph C. Kuhl ◽  
...  
Keyword(s):  
Root Exudates ◽  
Root Exudate ◽  
Globodera Pallida ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Chemical Interactions ◽  
Susceptible Host ◽  
The Impact ◽  
Plant Parasitic ◽  
Solanum Sisymbriifolium

Understanding belowground chemical interactions between plant roots and plant-parasitic nematodes is immensely important for sustainable crop production and soilborne pest management. Due to metabolic diversity and ever-changing dynamics of root exudate composition, the impact of only certain molecules, such as nematode hatching factors, repellents, and attractants, has been examined in detail. Root exudates are a rich source of biologically active compounds, which plants use to shape their ecological interactions. However, the impact of these compounds on nematode parasitic behavior is poorly understood. In this study, we specifically address this knowledge gap in two cyst nematodes, Globodera pallida, a potato cyst nematode and the newly described species, Globodera ellingtonae. Globodera pallida is a devastating pest of potato (Solanum tuberosum) worldwide, whereas potato is a host for G. ellingtonae, but its pathogenicity remains to be determined. We compared the behavior of juveniles (J2s) hatched in response to root exudates from a susceptible potato cv. Desirée, a resistant potato cv. Innovator, and an immune trap crop Solanum sisymbriifolium (litchi tomato – a wild potato relative). Root secretions from S. sisymbriifolium greatly reduced the infection rate on a susceptible host for both Globodera spp. Juvenile motility was also significantly influenced in a host-dependent manner. However, reproduction on a susceptible host from juveniles hatched in S. sisymbriifolium root exudates was not affected, nor was the number of encysted eggs from progeny cysts. Transcriptome analysis by using RNA-sequencing (RNA-seq) revealed the molecular basis of root exudate-mediated modulation of nematode behavior. Differentially expressed genes are grouped into two major categories: genes showing characteristics of effectors and genes involved in stress responses and xenobiotic metabolism. To our knowledge, this is the first study that shows genome-wide root exudate-specific transcriptional changes in hatched preparasitic juveniles of plant-parasitic nematodes. This research provides a better understanding of the correlation between exudates from different plants and their impact on nematode behavior prior to the root invasion and supports the hypothesis that root exudates play an important role in plant-nematode interactions.

scholarly journals Plant parasitic nematodes and their management in the Maritime provinces of Canada

2005 ◽  
Vol 71 (2) ◽  
pp. 45-54 ◽  
Author(s):  
J. Kimpinski ◽  
L.S. Thompson
Keyword(s):  
Crop Yields ◽  
Nematode Species ◽  
Parasitic Nematodes ◽  
Meloidogyne Hapla ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Maritime Provinces ◽  
Management Procedures ◽  
The Impact ◽  
Plant Parasitic

This paper presents a review of the plant parasitic nematodes that are of concern in New Brunswick, Nova Scotia, and Prince-Edward-Island, and the approaches used to manage them. The root lesion nematode (Pratylenchus penetrans) is the only nematode species in the region that regularly reduces crop yields. The northern root-knot nematode (Meloidogyne hapla) occasionally causes damage to carrots (Daucus carota), but population levels of this nematode species usually are very low. The clover cyst nematode (Heterodera trifolii) is widespread, but has not caused any damage to crops in the region. Management procedures used to reduce the impact of plant parasitic nematodes in the Maritime provinces, e.g. crop rotations, nematicide treatments, enforcement of quarantine regulations, and tillage practices are discussed. A nematode advisory service is also considered.

scholarly journals Toward genetic modification of plant-parasitic nematodes: delivery of macromolecules to adults and expression of exogenous mRNA in second stage juveniles

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
Olaf Kranse ◽  
Helen Beasley ◽  
Sally Adams ◽  
Andre Pires-daSilva ◽  
Christopher Bell ◽  
...  
Keyword(s):  
Food Security ◽  
Genetic Modification ◽  
The Body ◽  
Forward Genetics ◽  
Heterodera Schachtii ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Cyst Nematodes ◽  
Plant Parasitic

Abstract Plant-parasitic nematodes are a continuing threat to food security, causing an estimated 100 billion USD in crop losses each year. The most problematic are the obligate sedentary endoparasites (primarily root knot nematodes and cyst nematodes). Progress in understanding their biology is held back by a lack of tools for functional genetics: forward genetics is largely restricted to studies of natural variation in populations and reverse genetics is entirely reliant on RNA interference. There is an expectation that the development of functional genetic tools would accelerate the progress of research on plant-parasitic nematodes, and hence the development of novel control solutions. Here, we develop some of the foundational biology required to deliver a functional genetic tool kit in plant-parasitic nematodes. We characterize the gonads of male Heterodera schachtii and Meloidogyne hapla in the context of spermatogenesis. We test and optimize various methods for the delivery, expression, and/or detection of exogenous nucleic acids in plant-parasitic nematodes. We demonstrate that delivery of macromolecules to cyst and root knot nematode male germlines is difficult, but possible. Similarly, we demonstrate the delivery of oligonucleotides to root knot nematode gametes. Finally, we develop a transient expression system in plant-parasitic nematodes by demonstrating the delivery and expression of exogenous mRNA encoding various reporter genes throughout the body of H. schachtii juveniles using lipofectamine-based transfection. We anticipate these developments to be independently useful, will expedite the development of genetic modification tools for plant-parasitic nematodes, and ultimately catalyze research on a group of nematodes that threaten global food security.

scholarly journals Peach Root-knot Nematode

EDIS ◽  
2018 ◽  
Vol 2018 (4) ◽  
Author(s):  
Mary Ann D. Maquilan ◽  
Ali Sarkhosh ◽  
Donald W. Dickson
Keyword(s):  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
The Subject ◽  
Plant Parasitic

One of the production issues that peach growers in Florida must contend with is plant-parasitic nematodes. One such species is the more recently discovered peach root-knot nematode, Meloidogyne floridensis, which is the subject of this 5-page publication. Written by Mary Ann D. Maquilan, Ali Sarkhosh, and Donald Dickson and published by the UF/IFAS Horticultural Sciences Department, July 2018. http://edis.ifas.ufl.edu/hs1320

scholarly journals Biochemical Analysis Based on Zinc Uptake of Chickpea (Cicer arietinum L.) Varieties Infected by Meloidogyne incognita

2021 ◽  
pp. 186-192
Author(s):  
Pranaya Pradhan ◽  
Dhirendra Kumar Nayak ◽  
Manaswini Mahapatra
Keyword(s):  
Cicer Arietinum ◽  
Zinc Content ◽  
Cost Effective ◽  
Zinc Uptake ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Cicer Arietinum L ◽  
Chickpea Plant ◽  
Plant Parasitic

The significant constraints in Chickpea (Cicer arietinum L.) production hampers a bit more than 14% global yield loss due to plant-parasitic nematodes. Root-knot nematode (Meloidogyne sp.) is an endoparasite and a significant species affecting the chickpea plant. So, the chemical basis of management is more cost-effective, and pest resurgence building is enhanced in the pathogen. So, ecological-based nematode management is requisite, which also is got hampered due to breeding for resistance against such plant-parasitic nematodes. This was the primary reason to conduct this experiment to enhance resistance in the chickpea plants based on Zinc uptake by using bioagent, Pseudomonas fluorescens alone or in combination. where Different treatments including nematode, bacterium, and chemicals were used sustaining the enhancement of disease resistance in chickpea cultivars, RSG 974, GG 5, GNG 2144. Zinc content of chickpea variety GNG 2144 was found the highest in treatment, when only bacterium (P. fluorescens) was inoculated, i.e., 3.14 mg/100g of root followed by GG 5, i.e., 2.79 mg/100g of root and RSG 974 was, i.e., 2.35 mg/100g of root respectively in a descending order. Application of P. fluorescence combined or alone gradually increased the Zn concentration in roots of chickpea plants compared to healthy check followed by chemical treated plants.

scholarly journals Short-Term Effects of Sublethal Doses of Nematicides on Meloidogyne incognita

2019 ◽  
Vol 109 (9) ◽  
pp. 1605-1613 ◽  
Author(s):  
Catherine L. Wram ◽  
Inga A. Zasada
Keyword(s):  
Population Density ◽  
Meloidogyne Incognita ◽  
Cultivated Plants ◽  
Parasitic Nematodes ◽  
Initial Population ◽  
Plant Parasitic Nematodes ◽  
Water Control ◽  
Effective Doses ◽  
Sublethal Doses ◽  
Plant Parasitic

Meloidogyne species are one of the most important groups of plant-parasitic nematodes globally because of their ability to damage most cultivated plants. Although they are widespread and economically important, there are limited control measures to combat these nematodes. New nonfumigant nematicides have been discovered that have the potential to be widely utilized for the management of plant-parasitic nematodes. Because of the longer half-lives in soil and lower toxicity of new nematicides compared with traditional fumigant and nonfumigant nematicides, understanding how nematodes respond to sublethal doses of nematicides is imperative to understanding whether nematicide resistance has the potential to develop. Characterizing responses of nematodes to sublethal doses will provide the foundation for future work, such as gene expression studies. In this study, the nematicides oxamyl (Vydate), fluazaindolizine (Salibro), fluensulfone (Nimitz), and fluopyram (Velum), were evaluated to understand how sublethal doses affect the fecundity and mobility of Meloidogyne incognita second-stage juveniles (J2). Using a microwell assay system, dose-response curves for each nematicide were established for M. incognita J2. Fluopyram was the most toxic nematicide, with effective doses up to 230 times lower than that of other nematicides. The other nematicides had predicted ED50 values (effective doses that resulted in 50% of the population becoming inactive) of 89.4, 131.7, and 180.6 ppm for oxamyl, fluensulfone, and fluazaindolizine, respectively. The 24-h ED50 of each nematicide was then used in both motility and infectivity assays. The motility and activity of M. incognita J2 exposed to ED50 doses of fluazaindolizine and fluensulfone was significantly reduced, with nematodes initially being motile but eventually becoming inactive. However, the motility of M. incognita J2 exposed to ED50 doses of fluopyram and oxamyl was not different from a water control. In a pot assay, M. incognita J2 exposed to ED50 doses of fluazaindolizine, oxamyl, and fluensulfone were unable to reproduce on tomato, with reproduction factors (RF = final population density/initial population density) of 0 to 0.03. Fluopyram did not reduce reproduction of M. incognita, with a mean RF of 38.7 ± 4.5, which was similar to the RF of 46.3 ± 4.6 for the water control. This study is the first comprehensive evaluation of M. incognita activity, motility, and fecundity after exposure to the traditional nematicide, oxamyl, as well as three new nematicides, fluazaindolizine, fluopyram, and fluensulfone.

Population dynamics of plant parasitic nematodes in Queensland pineapple fields and the effects of these nematodes on pineapple production

1993 ◽  
Vol 33 (2) ◽  
pp. 197 ◽  
Author(s):  
GR Stirling ◽  
A Nikulin
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Ratoon Crop ◽  
Original Population ◽  
Ethylene Dibromide ◽  
Nematode Population Density ◽  
Plant Parasitic

Twelve pineapple fields with various densities of root-knot nematode were selected during a ratoon crop. Nematode populations were monitored regularly after the crop was ploughed out. Regardless of the original population density, rootknot nematodes were almost nondetectable at the end of the subsequent 3-6-month fallow intercycle period. In the absence of nematicide treatment there were marked differences between sites in the manner in which rootknot nematodes increased in the newly planted crop. At some sites, they were detectable 9-15 months after planting, whereas at other sites, nematodes were not observed at 15 months. Increases in ratoon crop yield following application of ethylene dibromide or fenamiphos were related to root-knot nematode population density. Significant increases in yield were not obtained at sites where the nematode was not detectable at 15 months. The results suggest that some pineapple growers are needlessly applying nematicides and that nematode diagnostic services should be developed to provide growers with advice on their nematode management programs.

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