They are a major threat to global food security, says Sebastian Eves-van den Akker of the Department of Plant Sciences, University of Cambridge, UK.
Eves-van den Akker will speak on "Effector Gene Birth in Plant-Parasitic Nematodes: Furnishing the Immunity and Development-Altering 'Tool Box' " at the Wednesday, Jan. 22th seminar of the UC Davis Department of Entomology and Nematology. His seminar is from 4:10 to 5 p.m. in 122 Briggs Hall, off Kleiber Hall Drive, UC Davis campus. Host: nematologist Shahid Siddique, assistant professor, UC Davis Department of Entomology and Nematology.
In a recent publication in PLOS Genetics titled "Effector Gene Birth in Plant Parasitic Nematodes: Neofunctionalization of a Housekeeping Glutathione Synthetase Gene," Eves-van den Akker noted that "Plant parasitism has arisen four times independently within the phylum Nematoda, resulting in at least one parasite of every major food crop in the world. Some species within the most economically important order (Tylenchida) secrete proteins termed effectors into their host during infection to re-programme host development and immunity. The precise detail of how nematodes evolve new effectors is not clear."
He and his colleagues reconstructed the evolutionary history of a novel effector gene family. They showed that "during the evolution of plant parasitism in the Tylenchida, the housekeeping glutathione synthetase (GS) gene was extensively replicated. New GS paralogues acquired multiple dorsal gland promoter elements, altered spatial expression to the secretory dorsal gland, altered temporal expression to primarily parasitic stages, and gained a signal peptide for secretion. The gene products are delivered into the host plant cell during infection, giving rise to 'GS-like effectors.'"
"Our results demonstrate the re-purposing of an endogenous housekeeping gene to form a family of effectors with modified functions," Eves-van den Akker wrote. "We anticipate that our discovery will be a blueprint to understand the evolution of other plant-parasitic nematode effectors, and the foundation to uncover a novel enzymatic function."
Eves-van den Akker studied biology at the University of Leeds from 2007 to 2019. During his final year, in the lab of Professor P. E. Urwin, he became interested in plant-pathology, and "the fascinating and potentially useful abilities of plant-parasitic nematodes." From 2010 to 2014, he studied for a doctorate in plant-nematode “effectors,” jointly appointed between the University of Leeds and The James Hutton Institute.
In 2015, he was awarded a three-year Anniversary Future Leaders Fellowship from the Biotechnology and Biological Sciences Research Council (BBSRC), part of UK Research and Innovation, a non-departmental public body funded by a grant-in-aid from the UK government. His fellowship was designed to understand the structural and molecular detail of nematode effector function.
That led to a discovery that provided what he calls "the first tangible insight into the regulatory processes underlying plant-nematode parasitism," and that in turn, resulted in his five-year BBSRC David Phillips Fellowship in 2018. With this second fellowship, he established a research group at the University of Cambridge and was elected Fellow of King's College.
Community ecologist Rachel Vannette, assistant professor, is coordinating the winter quarter seminars, all held on Wednesdays at 4:10 p.m. in 122 Briggs Hall. The remaining schedule:
Wednesday, Jan. 29
Elizabeth Crone, Tufts University, Medford, Mass.
Topic: "Why Are Monarch Butterflies Declining in the West?"
Hosts: Neal Williams, professor; Rachel Vannette, assistant professor
Wednesday, Feb. 5
Andrew Young, postdoctoral scholar at California Department of Food and Agriculture, Pest Diagnostic
Topic: Syrphids (title to be announced)
Host: Lynn Kimsey, professor and director of the Bohart Museum of Entomology
Wednesday, Feb. 12
Kevin Rice, University of Missouri, Columbia
Topic: "Lasers, Drones, and Growth Promoting Fungus: New Technologies for IPM"
Host: Ian Grettenberger, assistant professor
Wednesday, Feb. 19
Mercedes Burns, University of Maryland,Baltimore County
Topic: (pending) She studies evolutionary ecology of reproductive traits and behaviors, sexual conflict, reproductive polymorphism, arthropod biology
Host: Jason Bond, professor and Schlinger Chair in Insect Systematics
Wednesday, Feb. 26:
Faculty Flash Talks (featuring series of faculty members, including Rachel Vannette, Ian Grettenberger, Shahid Siddique, Geoffrey Attardo, Jason Bond)
Wednesday, March 4
Brendon Boudinot, doctoral candidate, Phil Ward lab, exit seminar
Topic: "Morphology and Evolution of the Insects, and the Ancestors of the Ants"
Host: Phil Ward, professor
Nine speakers are booked for the fall quarter seminars sponsored by the UC Davis Department of Entomology and Nematology. The seminars begin Wednesday, Sept. 25 and continue through Wednesday, Dec. 5.
Coordinated by assistant professor and community ecologist Rachel Vannette, the seminars will take place at 4:10 p.m., every Wednesday in Room 122 of Briggs Hall except on Nov. 20 (no seminar due to the Entomological Society of America meeting in St. Louis, Mo).
James Nieh, professor, Section of Ecology, Behavior and Evolution, Department of Biological Sciences, UC San Diego
Topic: "Animal Information Warfare: How Sophisticated Communication May Arise from the Race to Find an Advantage in a Deadly Game Between Honey Bees and their Predators" (See lab website)
Host: Brian Johnson, associate professor, Department of Entomology and Nematology
Nathan Schroeder, assistant professor, Department of Crop Sciences, University of Illinois, Urbana-Champaign
Topic: "Stem Cells and Neurobiology of Nematodes"
Host: Shahid Saddique, assistant professor, Department of Entomology and Nematology
John Mola, doctoral candidate, Neal Williams lab, Graduate Group in Ecology
Exit seminar: "Bumble Bee Movement Ecology and Response to Wildfire." Mola specializes in bee biology, pollinator ecology and population genetics.
Host: Neal Williams, professor, Department of Entomology and Nematology
Rebecca Irwin, professor, applied ecology, North Carolina State University, Raleigh, N.C.
Topic: (to be announced; she specializes in the ecology and evolution of multiple-species interactions, pollination biology, and species invasions)
Host: Rachel Vannette, assistant professor, Department of Entomology and Nematology
Julián Hillyer, director of the program in career development and associate professor of biological sciences, Vanderbilt Institute for Infection, Immunology and Inflammation, Nashville, Tenn.
Topic: "Not So Heartless: Functional Integration of the Immune and Circulatory Systems of Mosquitoes"
Host: Olivia Winokur, graduate student, Chris Barker lab
Takato Imaizumi, professor, Department of Biology, University of Washington, Seattle
Topic: Circadian Timing Mechanisms in Plant-Pollinator Interaction"
Host: Joanna Chiu, associate professor and vice chair of the Department of Entomology and Nematology
Brock Harpur, assistant professor, Department of Entomology, Purdue University
Topic: "Caste Differentiation in Honey Bees from the Bottom Up"
Host: Santiago Ramirez, associate professor, UC Davis Department of Evolution and Ecology, College of Biological Sciences
Allison Hansen, assistant professor, Department of Entomology, UC Riverside
Topic: Insect Herbivore-Microbe Interactions
Host: Clare Casteeel, assistant professor, UC Davis Department of Plant Pathology
No seminar (meeting of Entomological Society of America in St. Louis, Mo.)
Jackson Audley, doctoral candidate, Louie Yang lab and Steve Seybold lab
Exit seminar (topic to be announced). Audley studies the walnut twig beetle, Pityophthorus juglandis, which in association with the fungus, Geosmithia morbida, causes the insect-pathogen complex known as thousand cankers disease.)
Host: Steve Seybold, lecturer, forest entomology, UC Davis Department of Entomology and Nematology and forest entomologist and chemical ecologist with the Pacific Southwest Research Station, USDA Forest Service, Davis
The seminars are free and open to all interested persons. Some will be recorded for later viewing on YouTube. More information on the fall seminars or schedule is available from Vannette at email@example.com.
And it has a University of California, Davis, connection.
An international team of 10 scientists, led by plant nematologist Shahid Siddique, a former research group leader at the University of Bonn, Germany, and now an assistant professor in the UC Davis Department of Entomology and Nematology, has discovered the role of a plant's endodermal barrier system in defending against plant-parasitic nematodes.
“We discovered that the integrity of the endodermis—a specialized cell layer that surrounds the vascular system and helps regulate the flow of water, ions and minerals--is important to restrict nematode infection,” said Siddique, who joined the UC Davis faculty in March after serving several years at the University of Bonn.
“We found that having defects in endodermis make it easier for parasites to reach the vascular cylinder and establish their feeding site. Although, this finding is a result of basic research, it opens new avenues to for breeding resistance against cyst nematodes in crops.”
The research, “Root Endodermal Barrier System Contributes to Defence against Plant‐Parasitic Cyst and Root‐Knot Nematodes,” is published in the July 19th edition of The Plant Journal.
Siddique collaborated with scientists from Germany, Switzerland and Poland: Julia Holbein, Rochus Franke, Lukas Schreiber and Florian M. W. Grundler of the University of Bonn; Peter Marhavy, Satosha Fujita, and Niko Geldner of the University of Lasuanne, Switzerland; and Miroslawa Górecka and Miroslaw Sobeczak of the Warsaw University of Life Sciences, Poland.
“Plant-parasitic nematodes are among the most destructive plant pathogens, causing agricultural losses amounting to $80 billion annually in the United States,” said Siddique. “They invade the roots of almond, tomato, beets, potato or soybeans and migrate through different tissues to reach the central part—the vascular cylinder--of the root where they induce permanent feeding sites.”
“These feeding sites are full of sugars and amino acids and provide the parasite all the nutrients they need,” Siddique explained. “A specialized cell layer called the endodermis surrounds the vascular system and helps regulates the flow of water, ions and minerals into and out of it. However, the role of endodermis in protecting the vascular system against invaders such as nematodes had remained unknown.”
In their abstract, the scientists noted that plant-parasitic nematodes (PPN) “cause tremendous yield losses worldwide in almost all economically important crops. The agriculturally most important PPNs belong to a small group of root‐infecting sedentary endoparasites that includes cyst and root‐knot nematodes. Both cyst and root‐knot nematodes induce specialized long‐term feeding structures in root vasculature from which they obtain their nutrients.”
“A specialized cell layer in roots called the endodermis, which has cell walls reinforced with suberin deposits and a lignin‐based Casparian strip (CS), protects the vascular cylinder against abiotic and biotic threats,” the researchers explained. “Until now, the role of the endodermis, and especially of suberin and the CS, during plant–nematode interactions was largely unknown.”
The research was funded by a grant from the German Research Foundation.
(Note: The Plant Journal is a peer-reviewed scientific journal of plant science published by Wiley-Blackwell for the Society for Experimental Biology. Established in 1991, the journal is published twice a month. Editor Lee Sweetlove says that the journal "provides a dynamic forum for the ever-growing international plant sciences research community and publishes in all key areas of plant biology.")
And you ought to be interested in the exciting research that Shahid Masood Siddique, a new member of the UC Davis Department of Entomology and Nematology faculty, is doing.
Plant-parasitic nematodes are microscopic worms that extract water and nutrients from such host plants as wheat, soybeans, sugar beets, citrus, coconut, corn, peanuts, potato, rice, cotton and bananas. (See more from a list compiled by the Agricultural Research Services of the U.S. Department of Food and Agriculture or USDA-ARS.)
“They're one of the most destructive agricultural pests,” says Siddique, an assistant professor who joined the UC Davis Department of Entomology and Nematology last March. “The agricultural losses due to plant-parasitic nematodes reach an estimated $80 billion. The high impact of plant parasitic nematodes in economically important crops is not only due to the direct damage but also because of the role of some species as virus vectors.”
“In fact, a recent expert-based assessment of crop health lists nematodes among the most damaging pests and pathogens in different crops. In particular for soybeans, nematodes are the most damaging pests in the United States and around the world.”
Siddique, who served as a research group leader for several years at the University of Bonn, Germany, before joining the UC Davis faculty, says nematodes are troubling in other ways as well. “Although nematode-resistance varieties are available for various crops, there is an emergence of resistant-breaking population throughout the world. An example is the recent arrival of peach root-knot nematode in California, which has the potential to seriously harm many of region's important crops including almonds, peaches, eggplants, sugar beets and cucumber.”
Siddique was among a team of scientists from Bonn University and University of Missouri, who demonstrated the ability of parasitic nematodes to synthesize and secrete a functional plant hormone to manipulate the host system and establish a long-term parasitic interaction. PNAS published the research in August 2015. In a subsequent article headlined “Researchers Discover Key Link in Understanding Billion-Dollar Pests in Agriculture,” Science Daily called nematodes “a huge threat to agriculture, causing billions in crop losses every year …The discovery will help to develop crop plants that feature enhanced protection against this type of parasites.”
Born and reared in Multan, Pakistan, Siddique received two degrees in Multan: his bachelor of science degree from the Government College Bosan Road in 2001 and his master's degree in botany from the Bahauddin Zakariya University in 2004. Then it was off to Vienna, Austria to receive his doctorate in 2009 in agriculture and biotechnology from the University of Natural Resources and Life Sciences.
“His group was working on understanding the molecular aspects of plant-nematode interaction,” Siddique recalled. “In particular, they were using microarrays to study the changes in gene expression in plants upon nematode infection. I found the work very interesting and joined his lab.”
Nematodes did not immediately trigger his interest. “They have a complicated life cycle and infection pattern,” he points out. “Also, it is not yet possible to genetically transform plant-parasitic nematodes. So, I was mostly focusing on plants, which are more amenable to genetic manipulations. Then I gradually started to realize that how fascinating it is to work with nematodes, how they have mastered the ability to manipulate the defense and developmental pathways of their host.”
By the time he completed his doctorate, “I was completely infected by nematodes.” He still is.
What drew him to UC Davis? “High academic reputation in field of agriculture was the main factor that drew me to UC Davis,” Siddique says. “Ethnic diversity and liberal culture of golden state are some of the other factors that contributed to my decision to move to UC Davis.”
“For the next six months, I will be focusing on establishing a state-of-the art nematology lab here at UC Davis. This includes buying equipment, hiring the staff, establishing the protocol, and multiplying the nematode culture. In terms of research, my mid-term goal is understanding the plant immune responses to nematode infections. In long-term, I would like to use this knowledge to produce durable and broad-spectrum resistance in crops.”
“Another area where I will be focusing is development of molecular diagnostic tools for plant-parasitic nematodes from soil,” Siddique says. “I will be particularly focusing on nematodes that are relevant to California agriculture. Lastly, I am highly interested in understanding the mechanism of biocontrol of plant-parasitic nematodes. I expect that this will help in understanding why application of microbial biocontrol is so inconsistent.”
Siddique describes himself as “a result-oriented person and I am comfortable leading a large research team. At the same time, I like to delegate the responsibilities. My working style is collaborative and I believe on open and frank communication.”
In his leisure time, he enjoys cooking, outdoor adventures and watching documentaries. What would people be surprised to know about him? “I am an introvert,” he says. “A couple of other things: I like super spicy food and my favorite game is cricket. And oh, yes, I don't like ice-cold water.”
Siddique is currently seeking “undergraduate and graduate students to work on a number of exciting projects.”
“California is a beautiful place to live,” Siddique says, “and Davis is a perfect place to work on nematodes. So, for those interested in working with nematodes, drop me an email at firstname.lastname@example.org.”
- “Worm Subverts Plant Attack,” The Scientist, April 3, 2014
- “Researchers Discover Key Link in Understanding Billion-Dollar Pests in Agriculture,” Science Daily, Sept. 29, 2015
- “Arabidopsis Leucine-Rich Repeat Receptor–Like Kinase NILR1 Is Required for Induction of Innate Immunity to Parasitic Nematodes,” PLOS Pathogens, April 13, 2017
The U.S. Department of Agriculture's (USDA) Agricultural Research Service (ARS) and Pheronym, a company in Alachua, Fla., that develops and produces nematode pheromones, have announced plans to send nematodes (small round worms) to the International Space Station as early as this year.
The news, announced Feb. 20 on the ARS website, may have been overlooked by many ("What's a nematode?") but not by nematologists and other scientists.
The headline: "Starship Nematode."
"The mission represents a look into the future where food crops will be grown in space," according to writer Sharon Dunham. "The goal is to develop environmentally friendly methods for space travel that are not harmful to humans," she wrote. "This will be the first biological control experiment in space."
She went on to relate that experiment will "test the movement and infection behavior of beneficial nematodes (also called entomopathogenic nematodes or EPNs) that control a wide array of insect pests in agriculture." ARS research entomologist, David Shapiro-Ilan at the Fruit and Tree Nut Research Station in Byron, Ga., is co-project director of the experiment.
Nematodes, Dunham said, are "environmentally friendly alternatives to broad spectrum chemical insecticides and are also safe to humans and other nontarget organisms. One fascinating aspect of the EPN biology is that the nematodes kill their insect pest hosts with the aid of symbiotic bacteria that are carried in the nematode gut."
Nathan Augustus Cobb (1859-1932), the "father of nematology in the United States," had this to say about a world without nematodes.
"In short, if all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes. The location of towns would be decipherable, since for every massing of human beings, there would be a corresponding massing of certain nematodes. Trees would still stand in ghostly rows representing our streets and highways. The location of the various plants and animals would still be decipherable, and, had we sufficient knowledge, in many cases even their species could be determined by an examination of their erstwhile nematode parasites."
In fact, nematodes seem totally destructible.