Archive for the ‘Nematodes’ Category


DNA barcodes decode the world of soil nematodes

To understand soil ecosystems and contribute to advanced agriculture





The research team of Professor Toshihiko Eki of the Department of Applied Chemistry and Life Science (and Research Center for Agrotechnology and Biotechnology), Toyohashi University of Technology used a next-generation sequencer to develop a highly efficient method to analyze soil nematodes by using the 18S ribosomal RNA gene regions as DNA barcodes. They successfully used this method to reveal characteristics of nematode communities that inhabit fields, copses, and home gardens. In the future, the target will be expanded to cover all soil-dwelling organisms in agricultural soils, etc., to allow investigations into a soil’s environment and bio-diversity. This is expected to contribute to advanced agriculture.


Similar to when the UN declared 2015 to be the International Year of Soils, there have recently been many efforts worldwide to raise awareness of the importance of the soil that covers our Earth and its conservation. Diverse groups of organisms such as bacteria, fungi, protists, and small soil animals inhabit the soil, and together they form the soil ecosystem. Nematodes are a representative soil animal; they are a few millimeters long and have a shape resembling a worm. They play an important role in the cycling of soil materials. Many soil nematodes are bacteria feeders, but they have a wide variety of feeding habits, such as feeding on fungi, plant parasitism, or being omnivorous. In particular, plant parasitic nematodes often cause devastating damage to crops. Therefore, the classification and identification of nematodes is also important from an agricultural standpoint. However, nematodes are diverse, and there are over 30,000 species. Additionally, because nematodes resemble one another, morphological identification of nematodes is difficult for anyone but experts.

The research team focused on “DNA barcoding” to identify the species based on their unique nucleotide sequences of a barcode gene, and they established a method using a next-generation sequencer that can decode huge numbers of nucleotide sequences. They used this to analyze nematode communities from different soil environments. Initially, four DNA barcode regions were set for the 18S ribosomal RNA genes shared by eukaryotes. The soil nematodes used for analysis were isolated from an uncultivated field, a copse, and a home garden growing zucchini. The PCR was used to amplify the four gene fragments from the DNA of the nematodes and determine the nucleotide sequences. Additionally, the nematode-derived sequence variants (SVs) representing independent nematode species were identified, and after taxonomical classification and analysis of the SVs, it was revealed that plant parasitizing nematodes were abundant in the copse soil and bacteria feeders were abundant in the soil from the home garden. It was also determined that predatory nematodes and omnivorous nematodes were abundant in the uncultivated field, in addition to bacteria feeders.

This DNA barcoding method using a next-generation sequencer is widely used for the analysis of intestinal microbiota, etc., but analyses of eukaryotes such as nematodes are still in the research stage. This research provides an example of its usefulness for the taxonomic profiling of soil nematodes.

Development Background

Research team leader Toshihiko Eki stated, “Through genetic research, I have been working with nematodes (mainly C. elegans) for around 20 years. As a member of our university’s Research Center for Agrotechnology and Biotechnology, I came up with this theme while considering research that we could perform that is related to agriculture. As a test, we isolated nematodes from the university’s soybean field and unmanaged flowerbed and analyzed the DNA barcode for each nematode. Bacteria feeders were abundant in the soybean field, and that was used for comparison with the flowerbed, where weed-parasitizing nematodes and their predator nematodes were abundant. This discovery was the start of our research (Morise et al., PLoS ONE, 2012). If that method using one-by-one DNA sequencing was the first generation, the current method using the next-generation sequencer is the second generation, and we were able to clarify characteristics of nematode communities representing the three ecologically different soil environments according to expectations.”

Future Outlook

Currently, the research team is developing the third-generation DNA barcoding method which involves purifying DNA directly from the soil and analyzing the organisms in the whole soil instead of isolating and analyzing any particular soil-dwelling organisms. They are currently analyzing the soil biota of cabbage fields, etc. They are aiming to precisely analyze how communities of soil-dwelling organisms including microbes change with crop growth, clarify the effects that cultivated plants have on these organisms, and investigate biota closely related to plant diseases. If this research moves forward, crops can be cultivated and managed logically based on biological data in agricultural soils, and it can contribute to advancing smart agriculture in Japan, such as in the prominent Higashi-Mikawa agriculture region and beyond.


This research was performed with the support of the Takahashi Industrial and Economic Research Foundation.


Harutaro Kenmotsu, Masahiro Ishikawa, Tomokazu Nitta, Yuu Hirose and Toshihiko Eki (2021). Distinct community structures of soil nematodes from three ecologically different sites revealed by high-throughput amplicon sequencing of four 18S ribosomal RNA gene regions.
PLoS ONE, 16(4): e0249571.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

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Nigeria can attain sustainable food security using biological pesticides – Don

ByNaija247news Media, New YorkJune 23, 2021 010 Share

ood Security

June 24, 2021 

June 24, 2021 Naija247news Media, New Yorkhttps://www.naija247news.com/Naija247news is an investigative news platform that tracks news on Nigerian Economy, Business, Politics, Financial and Africa and Global Economy.

By Akeem Abas
Ibadan, June 18, 2021 A Professor of Nematology, Prof. Timothy Olabiyi, says sustainable food security can be attained through the use of biological pesticides.
Olabiyi disclosed this on Friday while delivering the 45th inaugural lecture of Ladoke Akintola University of Technology (LAUTECH), Ogbomoso.
He said that the only sustainable food security measure is the use of non-synthetic chemicals.
He noted that the world population is increasing on daily basis and many have suffered ill-health as a result of food poison and toxin which are also increasing.
“Sustainable food security can only be attained through the use of biological pesticides that are ecologically friendly and bio-degradable with no chemical residues leading to safe-to-eat food.
“Mass production of biological pesticides and making it available to farmers is germane to disease management and sustainable food security in Nigeria,” he said.
The university don called on Federal Government to establish Biological Pesticide Production Industries that could produce adequate and required biological pesticides.

“Such industries will provide jobs for the youth aside from the fact that the teaming population will have the right to eat safe food,” he said.

He said that the presence of farmer’s hidden enemy is inevitable, adding that they are present everywhere and all year round.

Olabiyi said that sustainable management of these disease-causing micro-organisms is our best option.

According to him, “my target is to produce biological nematicide for farmers in Nigeria.

“I am almost at the point of patenting those products, so that farmers can get to the shop and buy it for their farms.
“At the moment, I have supplied so many farmers nationwide, even in the North East and West.

“They have used it effectively and have given me very good report that it is good and we can use it to replace the synthetic nematicide,” he said.

He called for support to set up an industry for the production of biological nematicide for farmers in Nigeria.
A nematicide is a type of chemical pesticide used to kill plant-parasitic nematodes.

The varsity don said that the issue of farmers-herders’ clashes was due to climate change, saying he could not blame either of the parties.


Expert calls for healthy food cultivation in Nigeria

By Chidinma Ewunonu-Aluko Ibadan, Oct. 16, 2020 Dr Abayomi Olaniyan, Executive Director, National Horticultural Research Institute, Ibadan, says it is imperative for the country to increase agricultural productivity by cultivating healthy food that is diverse in nature. Olaniyan made the remark in an interview with newsmen on Friday in Ibadan…October 16, 2020

In “General Interest”

The Right to Agricultural Technology by Henry I. Miller

May 15, 2017

In “General Interest”

GM cowpea can boost Nigeria’s production by 20%- Expert

November 2, 2020

In “General Interest”

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To develop the research and educational capacity in Sub-Sahara Africa in the field of nematology, or the study of roundworms, a joint Erasmus+ KA2 project was recently launched. The Erasmus+ project, Capacity Building in Higher Education (CBHE): Nematology Education in Sub-Sahara Africa (NEMEDUSSA), is a joint effort by a consortium of Universities from Sub-Sahara Africa and Europe.

This three-year project (2021-2023) is co-funded by the European Union (Erasmus+ KA2 CBHE) and VLIR-UOS, and is linked to the objectives of the Erasmus+ Programme. The aims are to encourage cooperation between the EU and Partner Countries and support eligible Partner Countries in addressing challenges in the management and governance of their higher education institutions.

Specifically, NEMEDUSSA aims to increase awareness of nematodes and expand educational and research capacities in higher education and other institutions in Sub-Sahara Africa in this field. Nematodes or roundworms cause significant damage and yield loss to a wide variety of crops often together with other pathogens. Unfortunately, nematodes are often overlooked or misdiagnosed, resulting in the unnecessary use of unhealthy agro-chemicals. Nematodes can also be used as bio-control agents against insect pests and/or as bio-control agents for environmental health and biodiversity.

Despite the profound adverse impact plant-parasitic nematodes have on productivity worldwide, it is striking how concealed the discipline of nematology has remained, particularly in Sub-Sahara Africa. This project aims to address the need for increased capacity and specialised training in handling these pathogens, so that plant-parasitic nematodes are managed correctly and beneficial nematodes can be implemented as biocontrol organisms.

To achieve this, the project focuses on 6 core activities:

  1. Developing Curricula. Develop curricula in nematology on BSc and MSc level for the integration into existing educational programmes in English and French, for both lecturers and students.
  2. Training Staff. Improve the nematological expertise of academic and technical staff to enhance teaching capacity.
  3. Upgrading lab facilities. Increase the number of student microscopes, lab and demonstration equipment to augment hands-on training.
  4. Nematology digital learning platform. Develop an open-access platform to share and disseminate nematological knowledge, develop curricular modules, knowledge clips, etc.
  5. Nematology Network. Enhance cooperation between nematologists in Sub-Sahara Africa by providing networking tools, workshops on relevant topics in nematology and sharing good practices in education, promoting collaboration with a focus on young nematologists.
  6. Creating awareness. Facilitate dissemination activities and involve a range of different stakeholders such as farmers, extension service workers, policy makers, students and private and public sector.

Ghent University (Belgium) coordinates NEMEDUSSA, in cooperation with:

  • University Abomey-Calavi, Benin
  • University of Parakou, Benin
  • Haramaya University, Ethiopia
  • Jimma University, Ethiopia
  • Kenyatta University, Kenya
  • Moi University, Kenya
  • Ahmadu-Bello University, Nigeria
  • University of Ibadan, Nigeria
  • North West University, South Africa
  • Stellenbosch University, South Africa
  • Makerere University, Uganda
  • Muni University, Uganda
  • University Côte d’Azur, France

The work of this project is further supported by 36 associated partners from the private and public sectors in Sub-Sahara Africa.

For more information about the NEMEDUSSA project, please see www.nemedussa.ugent.be or contact us at nemedussa@ugent.be.  

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WSU researchers combat parasitic worm

Plants that fight back

So small it can’t be seen with the naked eye, a parasitic worm called the root-knot nematode causes mammoth problems for Northwest farmers. But potatoes, grapes and other crops could gain a new, nature-based way to fight back, thanks to Cynthia Gleason and Jennifer Watts, scientists at WSU.

Notorious thieves
Nematodes cause billions of dollars in crop losses nationwide every year. In Washington, they cause significant losses to crops such grapes, onions, garlic and the state’s $734 million potato industry.

“Root-knot nematodes are a huge problem for farmers,” said Gleason, plant pathologist with WSU’s College of Agricultural, Human and Natural Resource Sciences (CAHNRS). The soilborne parasites move into the roots of crops, “then just sit there and feed on the plant. They’re stealing nutrients and water.”

Nematodes don’t kill the plants, but they leave them stunted, wilted from lack of water, and more susceptible to other pathogens, ultimately reducing farmers’ yields.

Chemical-free weapon pursued
“Plants don’t have many natural resistances to root-knot nematodes, so we need a way to combat them,” Gleason said. Traditionally, farmers have used anti-nematode pesticides -nematicides- to eliminate the tiny worms.

“But there aren’t many chemical options left, and they’re very expensive,” she said. “I’m looking for new, chemical-free controls that help growers move on.”

Acid stops nematodes
To help, Gleason is using a new $47,400 Emerging Research Issues grant from the CAHNRS Office of Research to seek genetic defenses that help crops like potatoes and tomatoes fight back against the persistent pest. “I’m developing plants that are basically toxic to nematodes,” she said.

Jennifer Watts, researcher in the School of Molecular Biosciences, discovered that a dietary fatty acid stops parasites from multiplying. Partnering with Jennifer Watts, researcher in the College of Veterinary Medicine’s School of Molecular Biosciences, Gleason is adding genes that tell plants to secrete a specific fatty acid that stops the nematode reproductive cycle.

Watts and her team of student researchers discovered that a certain fatty acid, referred to as DGLA (20:3n-6), stops egg production in a cousin species of the root-knot nematode.

“These fatty acids aren’t normally produced in plant tissue,” says Watts. “My team and I are working with Cynthia to introduce genes into plants so they can make them. If it works, it could be a new, chemical-free method to control nematodes.”

While the fatty acid is not known to be toxic to people or animals at low levels, the researchers plan to only express it in cover crops and plant tissues that aren’t normally eaten.

Future pest fighters
Farmers could one day plant a seed, Gleason said, that grows into a cover or cash crop with its own natural pest control. As nematodes feed on the plants, their populations will fall — leading to healthier plants, bigger crops and an improved food supply.

“Usually, the study of nematodes and the challenges they bring is about new chemicals and pesticide controls,” said Gleason. “This is a new and different approach, one that’s chemical free.

“By working across colleges, mine and Jennifer’s teams are discovering and accomplishing much more than we could individually,” she added. “We can use that information to fight parasites, help Washington farmers, and grow more food. It’s a collaboration that benefits everyone.”

For more information:

Washington State University
Cynthia Gleason
Department of Plant Pathology
Tel.: +1 509-335-3742
Jennifer Watts
School of Molecular Biosciences
Tel.: +1 509-335-8554


Publication date: 6/21/2018


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If you’re an ag retailer and you’re reading this report, I’d guess it’s fair to assume you’ve at least considered adding biopesticide products to your crop protection lineup.

My assumption is part idealism, part result of our 2017 CropLife® Biological Product Market Survey, which was sent to 29,000 ag retailers and other industry members nationwide. In the survey 67% of respondents said they plan to “increase the percentage of biological products” they sell/distribute in the future. Additionally, nearly half (49%) affirmed that their customers apply biologicals as “both seed treatments and topicals.”

Advanced Biological Marketing (ABM) is one such company finding success with seed-applied biological products. Dan Custis, CEO of the Van Wert, OH-based company, has been involved in the biologicals segment of the industry for almost 18 years now. He says that when the company first started marketing biologicals back in 2000 there was “very little adoption at all. Very little.”

“A lot of the types of products that we manufacture were referred to as kind of a bathtub mixture, or ‘Foo-foo Dust’,” Custis fondly recalls. “As we really got into it, we as a company put a lot of science and knowledge behind it.”

Ah yes, another aspect of biological products addressed in the survey. By far the top consensus among those surveyed was that biological products engender a “lack of trust around product performance” while a sizeable 72% of retailers responded that biopesticide products need “more research that demonstrates product effectiveness.”

At ABM, Custis says the company has research that shows about a seven bushel-per-acre yield increase over a five-year average on corn, and in soybeans that number is around two-and-a-half bushels per acre. Its top biopesticide, the seed-applied SabrEx (two strains of Trichoderma) is typically either applied downstream at the retailer, or on-farm by the grower. The company does work with some seed manufacturers as well, such as local Ohio seed company Rupp.

“We know that maybe we get six weeks of benefit at most from a chemical seed treatment depending on weather, unless it’s a systemic,” Custis says. “What biologicals bring to the table is the extension of that plant health beyond the six weeks. Biologicals are a living organism, they should be able to live on the root system of that plant up through flowering.”

ABM’s SabrEx is distributed via the traditional crop input retail channels, through well-known players such as Crop Production Services, WinField Uni­ted, Wil­bur-Ellis, and KOVA of Ohio. Production and formulation take place in Van Wert, while research & development is housed in the Finger Lakes region of Western New York in Geneva.

“Right now in R&D we’re taking a look at nematode control in soybeans and corn, that’s one of the products that we have committed to EPA for approval right now,” Custis shares. “That (product) would be a first, and we’ve certainly got other things in the pipeline that I’m not able to talk about at the moment.”

Where do others see the biopesticide industry headed in the next couple years? Again, we consult our survey responses, and with nearly three-fourths (72%) saying their customers prefer to apply biologicals not as one-off standalones, but actually in conjunction with conventional products. Well-known Iowa State University seed treatment expert Allison Robertson agrees.

“There has been quite a lot of work looking at biologicals, not as stand-alone treatments, but in partnership with treatments that address pathogens in the field,” she shared back in August. “In addition, nematicides have been developed recently to help fight off soybean nematodes.”

Which provides a perfect segue to discuss post-patent giant Albaugh and its intriguing BIOst system, which Director of Global Proprietary Products Chad Shelton describes as “the first complete biological seed treatment platform.”

“What’s really exciting for retailers,” he continues. “Is our BIOst 100 nematicide, which can be combined with synthetic chemistries to give both insect and nematode protection. This is the first biological nematicide registered for control of both soil dwelling pests, along with activity on nematodes. And when we combine that with a neonic seed treatment it’s giving the grower a better return-on-investment (ROI).”

That’s a trend Shelton is seeing play out more and more in the row crop biologicals space in the last couple years, shifting the deployment of biopesticides from one-off products to more integrated usage with conventional hard chemistries.

“It’s no longer about having one mode of action, or a specific agronomic response in the marketplace. To me that’s the biggest change,” he shares. “When you have biopesticides in combination with synthetics at a reduced rate you’re going to get enhanced performance plus ROI.”

Another area that Albaugh is focusing attention is developing products with what Shelton describes as “customization based on microclimate.”

“Our goal today is to customize seed treatment technologies based on micro climate and (regional) needs,” he adds.



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Deciphering plant immunity against parasites

April 13, 2017

Deciphering plant immunity against parasites
These researchers are from the Department of Molecular Phytomedicine at the University of Bonn. Credit: Molekulare Phytomedizin/Uni Bonn

Nematodes are a huge threat to agriculture since they parasitize important crops such as wheat, soybean, and banana; but plants can defend themselves. Researchers at Bonn University, together with collaborators from the Sainsbury Laboratory in Norwich, identified a protein that allows plants to recognize a chemical signal from the worm and initiate immune responses against the invaders. This discovery will help to develop crop plants that feature enhanced protection against this type of parasites. The work is published in the current issue of PLoS Pathogens.


Plant-parasitic nematodes are microscopic worms that parasitize their to withdraw water and nutrients. The feeding process seriously damages the host plant. Nematode infection distorts root and shoot structure, compromises the plant´s ability to absorb nutrients from soil, and eventually reduces crop yield. Yearly losses exceed ten percent in important such as wheat, soybean, and banana. In addition to causing direct damage, nematode infection also provides an opportunity for other pathogens to invade and attack the host plants.

Until now, near to nothing was known about the general innate of plants against nematodes. A team of researchers at the University of Bonn, in cooperation with scientists from the Sainsbury Laboratory in Norwich, has now identified a gene in thale cress (Arabidopsis thaliana), called NILR1, that helps plants sense nematodes. “The NILR1 is the genetic code for a receptor protein that is localized to the surface of plant cells and is able to bind and recognize other molecules,” says Prof. Florian Grundler, chair at the Department of Molecular Phytomedicine at the University of Bonn. “NILR1 most probably recognizes a molecule from nematodes, upon which, it becomes activated and immune responses of plants are unleashed.”

NILR1 recognizes a broad spectrum of nematodes

Although a few receptors, so-called resistance genes, providing protection against specific types of plant-parasitic nematodes have already been identified, NILR1 recognizes rather a broader spectrum of nematodes. “The nice thing about NILR1 is that it seems to be conserved among various and that it provides protection against many nematode species,” says group leader Dr. Shahid Siddique. “The discovery of NILR1 also raises questions about the nematode derived molecule, whose recognition is thought to be integral to this process.” Now that an important receptor is discovered, the scientists are working to find the molecule which binds to NILR1 to switch on the immune responses. The two first authors, PhD students at the department share tasks in the project. Whereas Mary Wang´ombe focuses on the receptor protein and its function, Badou Mendy concentrates on isolating the signal molecule released by the nematodes.

New options for breeding resistant crop plants

The findings of the University Bonn Scientists open new perspectives in making crops more resistant against nematodes. They could already show that important crop plants such as tomato and sugar beet also possess a functional homologue of NILR1 – an excellent basis for further specific breeding. Once the nematode signal is characterized, a new generation of natural compounds will be available that is able to induce defense responses in thus paving the way for safe and sustainable control.

Explore further: Researchers discover a new link to fight billion-dollar threat to soybean production

More information: Mendy, B., Wang’ombe, M.W., Radakovic, Z., Holbein, J., Ilyas, M., Chopra, D., Holton, N., Zipfel, C., Grundler, F.M.W., and Siddique, S.: Arabidopsis leucine-rich repeat receptor-like kinase NILR1 is required for induction of innate immunity to parasitic nematodes, PLoS Pathogens, Internet: doi.org/10.1371/journal.ppat.1006284

Read more at: https://phys.org/news/2017-04-deciphering-immunity-parasites.html#jCp

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When Jon Eisenback, professor of plant nematology at Virginia Tech’s College of Agriculture and Life Sciences, conducted nematode surveys on vegetables and rice in Cambodia this past August, one of the most surprising things he encountered in the vegetable fields was, in a word, nothing.

“One of the biggest finds from that trip was almost completely sterile soil,” Eisenback said of the surveys he and postdoctoral associate Paulo Viera conducted in vegetable farms near Siem Reap.

They visited farms growing cucumbers, sweet melons, eggplants, tomatoes, and cantaloupes to assess whether any of them were suffering from nematode invasions, but they found that all the crops were grown under plastic with drip irrigation. They had been covered with so many pesticides that there was nearly nothing living – the soil was essentially ruined.


Jon Eisenback, second from right, professor of plant nematology at Virginia Tech’s College of Agriculture and Life Sciences, testing soil in the fields of Cambodia with postdoctoral associate Paulo Viera, second from left.

Plant parasitic nematodes are microscopic roundworms that cause significant damage to many crops. In Cambodia, a country with nearly half of its labor force in agriculture, nematodes can create big problems for food production.

To control the pest, Eisenback and Viera traveled to Cambodia to survey nematodes for two IPM Innovation Lab Projects: Rice IPM for Cambodia and Vegetable crops and mango IPM in Asia.

Because of our program’s focus on biocontrol and biopesticides to alleviate agricultural pest problems, Eisenback said that the vegetable IPM project would increase chances that vegetable farmers in Cambodia would stop the soil-killing overuse of pesticides.

After surveying the vegetable fields in the north, Eisenback and Viera traveled to the south of the country to conduct nematode surveys on rice. Given the dearth of scientific literature published on nematodes in Cambodia relating to rice, Eisenback and Viera weren’t sure what to expect. However, they found that the rice fields they surveyed showed a significant loss of production caused by the rice root nematode.

“Every root we looked at had lesions,” Eisenback said. The culprit was a parasitic nematode called Hirschmanniella mucronata. “Rice roots should be creamy white. These were speckled with brown and orange lesions.”

Eisenback expects that these nematodes could cause a 20 to 30 percent crop loss of rice in affected fields.

The next step is field demonstrations; to undertake them, half the fields should be treated with nematicide to measure the effect. Eisenback also said he hopes to continue the survey to see what other nematodes are there.

“I would suspect that there are other fields with other nematode problems.”

As for the vegetable fields with the sterile soil near Siem Reap, Eisenback offered a recommendation for them as well: Don’t use so many toxic pesticides.

With IPM IL’s projects up and running in the region, that should soon become less of a problem.

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A juvenile root-knot nematode, Meloidogyne incognita, penetrates a tomato root. Once inside, the juvenile, which also attacks cotton roots, causes a gall to form and robs the plant of nutrients. Photo by William Wergin and Richard Sayre. Colorized by Stephen Ausmus.

19th Biennial Group Meeting of the “All India Coordinated Research Project (AICRP) on Nematodes in Cropping Systems”

 At the 19th Biennial Group Meeting of the “All India Coordinated Research Project (AICRP) on Nematodes in Cropping Systems” recently held at University of Agricultural and Horticultural Sciences, Shivamogga (Karnataka) India; experts from the country conveyed that an aggressive (with high reproduction rate, more damage to host plants and wide host range) root knot nematode, Meloidogyne enterolobii,  got introduced and established through guava root stocks from Chhattisgarh, is causing huge losses in Dindigul, Coimbatore, Villupuram, Dharampuri and Krishnagiri districts of Tamil Nadu.  The group emphasized that there is an urgent need to strengthen and enforce domestic quarantine mechanism to suspend spread of plant parasitic nematodes with vegetative propagules, especially through seed potatoes and rooted plants – along with soil, from nurseries/ sick plots/ hot-spot areas to disease free niches. In their opinion, presently nurseries in the country are having a field day and incorrigible for spreading pests without meeting any cleanliness standards or phytosanitary regulations. To break the pathway,  it was suggested to enforce registration and licensing of plants and horticultural nurseries.

The recommendation from the Biennial Workshop is immensely important for reducing crop losses of horticultural crops in the country. Horticulture plant nurseries are extremely complex agricultural systems, recorded as pathways for several pests and diseases. Dr. Rajan said that the situation has become further cumbersome with ‘on line’ availability and sale of live ornamental and horticultural plants in the country. As disease management in nurseries/ green houses require specialisation; nematologists from the group ventured a draft road map – with details of detection, exclusion, risk analysis, critical control points for nursery stocks, infrastructure required for prophylactic measures, and costs involved for a prophylactic holistic system approach for registration/ certification for Nurseries and Green Houses.

In the address, Dr. D. J. Patel (Former Dean, Anand Agriculture University) and Dr. P. P. Reddy (Former Director, Indian Institute of Horticulture Research), well known experts in the subject expressed deep concerns about new nematode diseases in pomegranate, guava, coconut, banana, spices and vegetables all over the country through propagules. There is urgent need for policy support from Indian Council of Agricultural Research (ICAR), Department of Agriculture and Cooperation as well as Horticulture Mission for framing mandatory regulatory provisions for registration, licensing and certification of protected cultivation houses, nurseries and green houses especially for pest / quarantine requirements.

Dr. R. K. Walia, Project Coordinator (Nematodes), presented a brief history, background and the salient achievements of the AICRP on nematodes and overall scenario Plant Nematology research in India. He expressed serious concerns about the losses in crops due to nematode diseases and urged upon the nematologists to devise integrated approaches to manage root knot nematode (Meloidogyne spp.) problem in recently established poly-houses (for promoting cultivation of vegetables and ornamental) all over the country.

New publications “Pictorial guide on important nematode diseases of Karnataka”, “Comprehensive monograph of rice root-knot nematode (Meloidogyne graminicola)”, “Status of plant nematode diseases in Karnataka – a review”, and “Compendium of new plant parasitic nematode diseases of Karnataka”, along with a number of bulletins on serious issues were also launched on the occasion.


Principal Scientist (Plant Protection)

Crop Science Division,

Indian Council of Agricultural Research,

Krishi Bhawan, New Delhi 110001, India

email: rajan.newdelhi@gmail.com

Telefax: 011-23382385

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Nematode pheromone ascr#18 has been shown to alert plants to the presence of plant-parasitic nematodes and to activate their immune responses.

Nematodes, or roundworms, are the most numerous animals on earth, parasitizing most plants and animals. These infections are responsible for many of the most common neglected tropical diseases, causing significant morbidity and mortality. Soil-dwelling nematodes also put food security at risk by attacking agriculturally important plants. While the human response to dealing with parasite infection has been thoroughly researched; it has only recently been discovered that plant-parasitic nematodes not only activate defensive responses in plants, but also provide nematode-mediated immunity to subsequent attack by pathogens and viruses.

Numerous nematodes

Root-knot nematode galls on plant roots. Source: commons wikimedia
Root-knot nematode galls on plant roots. Source: commons wikimedia

Despite more than 4,100 species of plant-parasitic roundworms being identified, two major groups of nematodes are responsible for most agricultural plant damage. The root-knot nematodes, Meloidogyne spp. damage plants by producing galls on roots; whereas, the cyst nematodes, Heterodera and Globodera spp., by the formation of root cysts.

Soil-dwelling nematodes are ubiquitous and rich arable soil may contain up to 3 billion worms per acre. It therefore comes as no surprise that infected crops result in over $100 billion worth of agricultural damage globally per annum. For British crops alone, damage by cyst nematodes, Globodera rostochiensis and G. pallida, account for an estimated  £50 million damage each year.

Cyst nematodes damage to potato roots. Source: commons wikimedia

Cyst nematodes damage to potato roots. Source: commons wikimedia

Nematode control therefore is a serious business; however, following the current tightening of legislation, withdrawal from use of inorganic pesticides (the primary source of pest and disease management over the past decades) and a lack of resistant plant varieties, there is an urgent need to understand more about plant natural defenses to promote resistance to nematodes and other invaders.

Plant defenses against pathogens

Plant defenses can be broadly grouped into constitutive (continuous) defenses and inducible defenses. Toxic chemicals or defense-related proteins are typically only produced after pathogens are detected due to the high energy costs associated with their production and maintenance. To allow detection of, and rapid response to, potentially harmful pathogens plants have evolved several layers of highly developed surveillance mechanisms to try and circumvent serious damage.

The first line of defense consists of inducible defenses, which are mounted when plant cells recognize microbe-associated molecular patterns (MAMPs), such as lipopolysaccharides, flagellin, peptidoglycan and other compounds commonly found in microbes. Plant cells then become fortified against attack, conferring protection from the invading pathogen. Although MAMP’s have been well characterized, up until recently, it remained unclear as to whether plants could detect conserved molecular patterns derived from plant-parasitic animals, such as soil-dwelling nematodes.

‘Nematode-associated molecular patterns’

A number of studies have previously shown that, in response to plant-parasitic nematode infection, plants quickly activate defense pathways similar to those induced by other pathogens. Although these findings were very promising, what the nematode-derived signals actually were remained a mystery.

Following the discovery that non-parasitic soil nematodes can also induce plant defenses, a conserved nematode signature molecule appeared to be a likely trigger for activating the plant defense response. Ascarosides are pheromones exclusive to nematodes that are used to regulate development and social behaviours. Ascarosides represent an evolutionarily conserved family of signalling molecules, of which more than 200 different ascaroside structures from over 20 different species have been identified. Due to the highly conserved nature of these molecules, it seemed plausible that plant hosts and nematode-associated microorganisms may have evolved the means to detect and respond to this ancient nematode molecule. A recent study published in Nature Communications investigated whether ascarosides can be detected by plants, and whether detection of the molecules induced the plant-defence response.

(a) Examples of ascarosides previously identified. (b) HPLC-MS analysis of nematode exo-metabolome samples, showing seven detected ascarosides. (c) Chemical structures of identified ascarosides and relative quantitative distribution. Source: http://www.nature.com/ncomms/2015/150723/ncomms8795/fig_tab/ncomms8795_F1.html
(a) Examples of ascarosides previously identified. (b) HPLC-MS analysis of nematode exo-metabolome samples, showing seven detected ascarosides. (c) Chemical structures of identified ascarosides and relative quantitative distribution. Source: http://www.nature.com/ncomms/2015/150723/ncomms8795/fig_tab/ncomms8795_F1.html

Profiles of ascarosides from adult and juvenile stages of a number of agriculturally relevant species of plant-parasitic nematodes were characterised using mass spectrometry (MS) to analyse the metabolome excreted into media supernatant. MS analysis of exo-metabolome samples revealed excretion of similar sets of ascarosides in all analysed species; however, ascr#18 was identified in all plant-parasitic nematodes as the most abundant molecule.

In order to determine whether ascr#18 could be perceived by plants and influence plant-defensive responses to different pathogens, the ascaroside was applied in various concentrations to Arabidopsis roots 24 h prior to leaf innoculation with pathogens. By monitoring expression of MAMP-triggered immunity (MTI) markers and defense-related genes in leaves at different time points after root treatment with ascr#18, characteristic defense responses such as MAMP-triggered immunity were shown to be induced. Interestingly, local and systemic defenses were also shown to be activated by ascr#18 application to leaves.

Detection of ascr#18 by plants increased resistance to viral, bacterial, oomycete, fungal and nematode infections in Arabidopsis, as well as tomato, potato and barley. Additionally, three other ascarosides applied to different plants showed defense responses were induced by structurally diverse ascarosides, but that this varied in a structure- and species-dependent manner.


A comparison of experimental wheat lines showing different levels of resistance to the disease spot blotch. Source: https://www.flickr.com/photos/cimmyt/6508078617
A comparison of experimental wheat lines showing different levels of resistance to the disease spot blotch.                                                                                                                                                                                                                                                                            Source: https://www.flickr.com/photos/cimmyt/6508078617

Plant crops suffer  considerable damage every year from parasites and pathogens, putting food security at great risk. The ability to activate plant immune responses as and when required by using signalling molecules, such as ascarosides, is an exciting discovery that could contribute to improving the economic and environmental sustainability of agriculture. One potential application could be spraying of ascr#18 on crop leaves; as although plants primarily encounter ascarosides via their roots, leaf exposure to low ascr#18 concentrations was also effective at inducing the defense responses to confer fortification against attack.

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Ubaldo Sagastume in his coffee field

Partnering for Innovation
Country: Honduras
Award period:April 2015 – January 2017
Website: http://www.zamorano.edu
With foreign markets requiring reductions in the use of chemicals, there is great demand for biological solutions to pest management. Zamorano University will promote the use of beneficial nematodes instead of traditional pesticides to control insect infestations in select horticultural crops. Through scale-up of their biocontrol laboratory, Zamorano will produce and sell 20 times as many doses of beneficial nematodes over the previous year. Small producers will be able to access this biocontrol at a much lower cost than a synthetic chemical product throughout the western departments of Honduras.

Outcome: 9,000 hectares of smallholder land will use biological pest control. In addition, Zamorano will sell through a commercial partner to build a sustainable distribution channel in the country.

See: http://partneringforinnovation.org/program-zamorano-university.aspx

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