The bacterial community structure dynamics in Meloidogyne incognita infected roots and its role in worm-microbiome interactions

AbstractBackgroundPlant parasitic nematodes such as Meloidogyne incognita have a complex life cycle, occurring sequentially in various niches of the root and rhizosphere. They are known to form a range of interactions with bacteria and other microorganisms, that can affect their densities and virulence. High throughput sequencing can reveal these interactions in high temporal, and geographic resolutions, although thus far we have only scratched the surface. We have carried out a longitudinal sampling scheme, repeatedly collecting rhizosphere soil, roots, galls and second stage juveniles from 20 plants to provide a high resolution view of bacterial succession in these niches, using 16S rRNA metabarcoding.ResultsWe find that a structured community develops in the root, in which gall communities diverge from root segments lacking a gall, and that this structure is maintained throughout the crop season. We detail the successional process leading toward this structure, which is driven by interactions with the nematode and later by an increase in bacteria often found in hypoxic and anaerobic environments. We show evidence that this structure may play a role in the nematode’s chemotaxis towards uninfected root segments. Finally, we describe the J2 epibiotic microenvironment as ecologically deterministic, in part, due to active bacterial attraction of second stage juveniles.ConclusionsHigh density sampling, both temporally and across adjacent microniches, coupled with the power and relative low cost of metabarcoding, has provided us with a high resolution description of our study system. Such an approach can advance our understanding of holobiont ecology. Meloidogyne spp., with their relatively low genetic diversity, large geographic range and the simplified agricultural ecosystems they occupy, can serve as a model organism. Additionally, the perspective this approach provides could promote the efforts toward biological control efficacy.

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Bacterial Community Structure Dynamics in Meloidogyne incognita-Infected Roots and Its Role in Worm-Microbiome Interactions

mSphere ◽

10.1128/msphere.00306-20 ◽

2020 ◽

Vol 5 (4) ◽

Author(s):

Timur M. Yergaliyev ◽

Rivka Alexander-Shani ◽

Hana Dimerets ◽

Shimon Pivonia ◽

David McK. Bird ◽

...

Keyword(s):

Community Structure ◽

Life Cycle ◽

High Resolution ◽

Meloidogyne Incognita ◽

Complex Life Cycle ◽

Crop Season ◽

Root Knot Nematodes ◽

Second Stage ◽

Root Segments ◽

Bacterial Succession

ABSTRACT Plant parasitic nematodes such as Meloidogyne incognita have a complex life cycle, occurring sequentially in various niches of the root and rhizosphere. They are known to form a range of interactions with bacteria and other microorganisms that can affect their densities and virulence. High-throughput sequencing can reveal these interactions in high temporal and geographic resolutions, although thus far we have only scratched the surface. In this study, we have carried out a longitudinal sampling scheme, repeatedly collecting rhizosphere soil, roots, galls, and second-stage juveniles from 20 plants to provide a high-resolution view of bacterial succession in these niches, using 16S rRNA metabarcoding. Our findings indicate that a structured community develops in the root, in which gall communities diverge from root segments lacking a gall, and that this structure is maintained throughout the crop season. We describe the successional process leading toward this structure, which is driven by interactions with the nematode and later by an increase in bacteria often found in hypoxic and anaerobic environments. We present evidence that this structure may play a role in the nematode’s chemotaxis toward uninfected root segments. Finally, we describe the J2 epibiotic microenvironment as ecologically deterministic, in part, due to the active bacterial attraction of second-stage juveniles. IMPORTANCE The study of high-resolution successional processes within tightly linked microniches is rare. Using the power and relatively low cost of metabarcoding, we describe the bacterial succession and community structure in roots infected with root-knot nematodes and in the nematodes themselves. We reveal separate successional processes in galls and adjacent non-gall root sections, which are driven by the nematode’s life cycle and the progression of the crop season. With their relatively low genetic diversity, large geographic range, spatially complex life cycle, and the simplified agricultural ecosystems they occupy, root-knot nematodes can serve as a model organism for terrestrial holobiont ecology. This perspective can improve our understanding of the temporal and spatial aspects of biological control efficacy.

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Molecular cloning and life stage expression pattern of a new acetylcholinesterase gene from the plant-parasitic nematode Meloidogyne incognita

Nematology ◽

10.1163/156854103767139707 ◽

2003 ◽

Vol 5 (2) ◽

pp. 213-217 ◽

Cited By ~ 8

Author(s):

Jean-Baptiste Laffaire ◽

Marie-Noëlle Rosso ◽

Stéphanie Jaubert ◽

Pierre Abad

Keyword(s):

Meloidogyne Incognita ◽

Life Stage ◽

Distinct Group ◽

Catalytic Triad ◽

Pcr Analysis ◽

Parasitic Nematodes ◽

Reading Frame ◽

C Elegans ◽

Second Stage ◽

Before And After

AbstractA new cDNA, named Mi-ace-2, encoding an acetylcholinesterase, was isolated from Meloidogyne incognita. The full-length cDNA, carrying the trans-spliced SL1 leader sequence, was 2122 bp long with an open reading frame of 2058 bp. The predicted protein shared 32.3% identity with the previously identified MI ACHE and 49.1% identity with the C. elegans ACE-2. The conserved motifs involved in the catalytic triad, the choline binding site and 11 aromatic residues lining the catalytic gorge were present in the MI-ACE-2 deduced protein. RT-PCR analysis showed that Mi-ace-2 is transcribed in second stage juveniles before and after hatching, in females and in males. Phylogenetic analysis showed that MI-ACE-2 and ACE-2 were clustered in a distinct group closely related to the acetylcholinesterases secreted by animal-parasitic nematodes.

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Toxicity of ethanol solutions and vapours against Meloidogyne incognita

Nematology ◽

10.1163/15685411-00003046 ◽

2017 ◽

Vol 19 (3) ◽

pp. 271-280 ◽

Cited By ~ 6

Author(s):

Julio C.P. Silva ◽

Vicente P. Campos ◽

Eduardo S. Freire ◽

Willian C. Terra ◽

Liliana E. Lopez

Keyword(s):

Root System ◽

Meloidogyne Incognita ◽

Parasitic Nematodes ◽

Infested Soil ◽

Large Reduction ◽

Plant Parasitic Nematodes ◽

Second Stage ◽

Plant Parasitic

Ethanol (EtOH) is less harmful to humans than currently available nematicide molecules. This study evaluated the efficacy of EtOH in controlling Meloidogyne incognita in vitro and in lettuce plants under glasshouse conditions. Aqueous EtOH solutions (5-70% volume) and their vapours caused an acute nematicidal effect in vitro in second-stage juveniles (J2) of M. incognita and reduced hatching of J2. There was a large reduction of galls and eggs in the root system when 40 ml of EtOH was applied to M. incognita-infested soil at concentrations of 40 and 70%. Water exposed to EtOH vapours for 1 h became toxic, and a 12-h exposure caused 100% J2 mortality. Use of a plastic cover did not increase the efficiency of EtOH in controlling M. incognita in lettuce plants. The observed EtOH effects indicate its prospective use in controlling plant-parasitic nematodes, especially in glasshouses.

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Chemoreception of Meloidogyne incognita and Caenorhabditis elegans on botanical nematicidals

10.1101/274092 ◽

2018 ◽

Author(s):

Robert Sobkowiak ◽

Natalia Bojarska ◽

Emilia Krzyżaniak ◽

Karolina Wągiel ◽

Nikoletta Ntalli

Keyword(s):

Caenorhabditis Elegans ◽

Meloidogyne Incognita ◽

Plant Secondary Metabolites ◽

Model Organism ◽

Nematode Species ◽

Sublethal Concentration ◽

Parasitic Nematodes ◽

Small Molecular Weight ◽

C Elegans ◽

Aldehydes And Ketones

AbstractPlant–parasitic nematodes cause serious damage to various agricultural crops worldwide, and their control necessitates environmentally safe measures. Plant secondary metabolites of botanical origin are tested here–in to study their effect in Meloidogyne incognita locomotion, being this an important factor affecting host inoculation inside the soil. We compare the effect to the respective behavioral responses of the model organism Caenorhabditis elegans. The tested botanical nematicidals, all reported of activity against Meloidogyne sp. in our previous works, belong to different chemical groups of small molecular weight molecules encompassing acids, alcohols, aldehydes and ketones. Specifically we report on the attractant or repellent properties of trans–anethole, (E,E)–2,4–decadienal, (E)–2–decenal, fostiazate, and 2–undecanone. The treatments for both nematode species were made at sublethal concentration levels, namely 1mM (<EC50), and the chemical control used for the experiment was the commercial nematicide fosthiazate and oxamyl. According to our results, trans–anethole, decenal, and oxamyl act as C. elegans attractants. 2–undecanone strongly attracts M. incognita. These findings can be of use in the development of nematicidal formulates, contributing to the disruption of nematode chemotaxis to root systems.

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Chia: Host Status for Meloidogyne incognita and Activity of Plant Extracts

Plant Disease ◽

10.1094/pdis-10-19-2171-re ◽

2020 ◽

Vol 104 (11) ◽

pp. 2979-2985

Author(s):

Susan L. F. Meyer ◽

Margaret H. MacDonald ◽

Nathan D. Reetz ◽

Mihail R. Kantor ◽

Lynn K. Carta ◽

...

Keyword(s):

Meloidogyne Incognita ◽

Egg Production ◽

Animal Feed ◽

Parasitic Nematodes ◽

Plant Parasitic Nematodes ◽

Plant Parts ◽

Second Stage ◽

Host Status ◽

Cucumber Roots ◽

Salvia Hispanica L

Chia (Salvia hispanica L.) seeds are used for food, drinks, oil, and animal feed, and all plant parts are employed in traditional medicine. The growing demand for the seed has created a need for improved disease management. Plant-parasitic nematodes have been found on other Salvia spp., but none have been reported from S. hispanica. Chia has also not been tested for production of compounds active against these nematodes. Therefore, aqueous extracts from shoots and roots of six chia lines, Brad’s Organic, Cono, E2, G3, G5, and W13.1, were tested in laboratory assays. Some concentrations of all extracts were nematotoxic, killing about one-third of Meloidogyne incognita (Kofoid & White) Chitwood second-stage juveniles (J2s) in shoot extracts and up to nearly half of J2s in root extracts. Hatch was generally not affected by the extracts. In greenhouse trials, all six chia lines were hosts of M. incognita. Chia line G3 had approximately two times or more eggs per gram of root than Brad’s Organic or Cono. When cucumber seedlings were transplanted into soil amended with chopped chia shoots (2.3 or 2.5% weight of fresh shoots/weight of dry soil), galling and egg production on cucumber roots were not suppressed. To our knowledge, this is the first report that chia is a host to M. incognita (or any phytoparasitic nematode) and that chia shoots and roots produce compounds active against a nematode.

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Advanced Treatment of Coking Wastewater by Oxidation Process Using Pyrite and Hydrogen Peroxide

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.726-731.2521 ◽

2013 ◽

Vol 726-731 ◽

pp. 2521-2525

Author(s):

Zhi Yong Zhang ◽

De Li Wu

Keyword(s):

Hydrogen Peroxide ◽

Oxidation Process ◽

Low Cost ◽

Oxygen Demand ◽

Utilization Efficiency ◽

Advanced Treatment ◽

Coking Wastewater ◽

Second Stage ◽

Potential Alternative ◽

High Utilization

Coking wastewater is a kind of recalcitrant wastewater including complicate compositions. Advanced treatment of coking wastewater by Fenton-Like reaction using pyrite as catalyst was investigated in this paper. The results show that the chemical oxygen demand (COD) of coking wastewater decreased significantly by method of coagulation combined with two-stage oxidation reaction. COD of wastewater can decrease from 250mg/l to 45mg/l after treatment, when 2g/L pyrite was used in each stage oxidation and the dosage of hydrogen peroxide (H2O2) is 0.2ml/l for first stage treatment, 0.1ml/l for second stage treatment respectively. The pyrite is effective to promote Fenton-Like reaction with low cost due to high utilization efficiency of H2O2, moreover, catalyst could be easily recovered and reused. The Fenton-Like reaction might be used as a potential alternative to advanced treatment of recalcitrant wastewater.

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Fabrication and Compressive Behavior of a Micro-Lattice Composite by High Resolution DLP Stereolithography

Polymers ◽

10.3390/polym13050785 ◽

2021 ◽

Vol 13 (5) ◽

pp. 785

Author(s):

Chow Shing Shin ◽

Yu Chia Chang

Keyword(s):

High Resolution ◽

Lattice Structure ◽

Low Cost ◽

Hierarchical Structures ◽

Dip Coating ◽

Unit Cell ◽

Digital Light Processing ◽

Unit Cell Size ◽

Wide Range ◽

And Performance

Lattice structures are superior to stochastic foams in mechanical properties and are finding increasing applications. Their properties can be tailored in a wide range through adjusting the design and dimensions of the unit cell, changing the constituent materials as well as forming into hierarchical structures. In order to achieve more levels of hierarchy, the dimensions of the fundamental lattice have to be small enough. Although lattice size of several microns can be fabricated using the two-photon polymerization technique, sophisticated and costly equipment is required. To balance cost and performance, a low-cost high resolution micro-stereolithographic system has been developed in this work based on a commercial digital light processing (DLP) projector. Unit cell lengths as small as 100 μm have been successfully fabricated. Decreasing the unit cell size from 150 to 100 μm increased the compressive stiffness by 26%. Different pretreatments to facilitate the electroless plating of nickel on the lattice structure have been attempted. A pretreatment of dip coating in a graphene suspension is the most successful and increased the strength and stiffness by 5.3 and 3.6 times, respectively. Even a very light and incomplete nickel plating in the interior has increase the structural stiffness and strength by more than twofold.

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Allelopathy: a possible mechanism of suppression of plant-parasitic nematodes by entomopathogenic nematodes

Nematology ◽

10.1163/156854199508766 ◽

1999 ◽

Vol 1 (7) ◽

pp. 735-743 ◽

Cited By ~ 32

Author(s):

Parwinder S. Grewal ◽

Edwin E. Lewis ◽

Sudha Venkatachari

Keyword(s):

Meloidogyne Incognita ◽

Entomopathogenic Nematodes ◽

Galleria Mellonella ◽

Steinernema Feltiae ◽

Symbiotic Bacteria ◽

Parasitic Nematodes ◽

Plant Parasitic Nematodes ◽

Tomato Roots ◽

Xenorhabdus Nematophilus ◽

Plant Parasitic

Abstract A possible mechanism of suppression of a plant-parasitic nematode Meloidogyne incognita by entomopathogenic nematodes is described. Heat-killed entomopathogenic nematodes Steinernema feltiae and S. riobrave temporarily suppressed penetration of the root-knot nematode M. incognita into tomato roots, but live nematodes had no effect. Infective juvenile M. incognita were repelled from all entomopathogenic nematode treatments that included their symbiotic bacteria. They were repelled by Galleria mellonella cadavers infected with S. carpocapsae, S. feltiae, and S. riobrave and from cell-free culture filtrates of the symbiotic bacteria Xenorhabdus nematophilus, X. bovienii, and Xenorhabdus sp. "R" from the three nematode species, respectively. Cell-free filtrates from all three Xenorhabdus spp. were toxic to M. incognita infective juveniles causing 98-100% mortality at 15% concentration. Cell-free filtrate of Xenorhabdus sp. "R" also reduced the hatch of M. incognita eggs. Application of formulated bacterial cell-free filtrates temporarily suppressed M. incognita penetration into tomato roots in a greenhouse trial. The short-term effects of cell-free bacterial filtrates, namely toxicity and repellency, were almost entirely due to ammonium. These results demonstrate allelopathic interactions between plant-parasitic nematodes, entomopathogenic nematodes and their symbiotic bacteria. The likely role of allelopathy in the suppression of plant-parasitic nematodes by innundative applications of entomopathogenic nematodes is discussed. Allelopathie: Ein moglicher Mechanismus zur Unterdruckung pflanzenparasitarer Nematoden durch insektenpathogene Nematoden - Es wird ein moglicher Mechanismus zur Unterdruckung des pflanzenparasitaren Nematoden Meloidogyne incognita durch insektenpathogene Nematoden beschrieben. Durch Hitze abgetotete insektenpathogene Nematoden Steinernema feltiae und S. riobrave underdruckten das Eindringen des Wurzelgallenalchens M. incognita in Tomatenwurzeln, lebende Nematoden hatten keine Wirkung. Infektionsjuvenile von M. incognita wurden von allen Behandlungen mit insektenpathogenen Nematoden abgestossen, die auch die symbiontischen Bakterien einschlossen. Sie wurden durch die Kadaver von Galleria mellonella abgestossen, die mit S. carpocapsae, S. feltiae und S. riobrave infiziert waren sowie durch zellfreie Kultursubstrate der symbiontischen Bakterien Xenorhabdus nematophilus, X. bovienii und Xenorhabdus sp. "R" aus den drei genannten Nematodenarten. Zellfreie Kultursubstrate von allen drei Xenorhabdus spp. waren giftig fur die Infektionsjuvenilen von M. incognita und verursachten in einer Konzentration von 15% Abtotungsraten von 98-100%. Zellfreie Kultursubstrate von Xenorhabdus sp. "R" vermiderten ausserdem das Schlupfen von M. incognita-Eiern. In einem Gewachshausversuch unterdruckten formulierte zellfreie Bakterienfiltrate vorubergehend das Eindringen von M. incognita in Tomatenwurzeln. Die Kurzzeitwirkungen von zellfreien Bakterien filtraten, namentlich Giftigkeit und Abstossung, waren nahezu ganz bedingt durch Ammoniak. Diese Ergebnisse zeigen das Vorhandensein von allelopathischen Wechselwirkungen zwischen pflanzenparasitaren Nematoden, insektenpathogenen Nematoden und deren symbiontischen Bakterien. Die wahrscheinliche Rolle von Allelopathie bei der Unterdruckung pflanzenparasitarer Nematoden durch eine Massenanwendung insektenpathogener Nematoden wird diskutiert.

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A HIGH-RESOLUTION 2D IMAGING LASER RADAR FOR OCCLUDED HARD TARGET VIEWING AND IDENTIFICATION

International Journal of High Speed Electronics and Systems ◽

10.1142/s0129156408005424 ◽

2008 ◽

Vol 18 (02) ◽

pp. 393-400 ◽

Cited By ~ 1

Author(s):

ROBERT J. GRASSO ◽

JOHN C. WIKMAN ◽

DAVID P. DROUIN ◽

GEORGE F. DIPPEL ◽

PAUL I. EGBERT

Keyword(s):

High Resolution ◽

Target Identification ◽

Low Cost ◽

System Size ◽

Operating Conditions ◽

Array Technology ◽

Diode Pumped ◽

Target Ranging ◽

2D Imaging ◽

Gated Imaging

BAE SYSTEMS has developed a Low Cost Targeting System (LCTS) consisting of a FLIR for target detection, laser-illuminated, gated imaging for target identification, laser rangefinder and designator, GPS positioning, and auto-tracking capability within a small compact system size. The system is based upon BAE Systems proven micro-bolometer passive LWIR camera coupled with Intevac's new EBAPS camera. A dual wavelength diode pumped laser provides eyesafe ranging and target illumination, as well as designation; a custom detector module senses the return pulse for target ranging and to set the range gates for the gated camera. Trials show that the current detectors offer complete extinction of signals outside of the gated range, thus, providing high resolution within the gated region. The images have shown high spatial resolution arising from the use of solid state focal plane array technology. Imagery has been collected in both the laboratory and the field to verify system performance during a variety of operating conditions.

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