Nav: Home

Illinois study identifies a key to soybean cyst nematode growth

March 28, 2019

URBANA, Ill. - The soybean cyst nematode, one of the crop's most destructive pests, isn't like most of its wormy relatives. Whereas the vast majority of nematodes look like the microscopic worms they are, the female soybean cyst nematode shape-shifts into a tiny lemon after feeding on soybean roots. In a new EvoDevo article, a University of Illinois research team explains how it happens and why.

"We think the soybean cyst nematode has evolved this body shape so that they can produce a lot more offspring," says Nathan Schroeder, assistant professor in the Department of Crop Sciences at the University of Illinois and corresponding author on the new study. "If you compare the most closely related species that stay long and skinny, they have a lot fewer babies than this lady does."

The round shape allows female soybean cyst nematodes to retain about two-thirds of their fertilized eggs inside their bodies. As embryos develop, the mother's body hardens to become a protective cyst. Schroeder says these adaptations have allowed the soybean cyst nematode to become as successful as it is.

From previous research with a different species, the scientists suspected seam cells were responsible for the shift from long and skinny to fat and round. Seam cells, which have stem-cell-like properties, run the length of these worms and divide to enlarge the epidermis every time the worms molt.

"Normally, there's one division for each molt, creating one new set of nuclei in the multinucleated epidermis. We found that with soybean cyst nematode, they divide multiple times after infection, molt, divide even more times, molt, divide even more times. You have exponential growth which leads to this fat, round beast that has lots and lots of these epidermal nuclei," Schroeder explains. "Between the last juvenile phase, which is long and skinny, and the reproductive adult phase, the number of nuclei increase forty-fold."

The research team also investigated the division pattern in other plant-parasitic nematodes and found similar seam cell proliferation in several others, despite not being closely related to soybean cyst nematodes. Essentially, they found evidence of convergent evolution, or the appearance of similar traits to meet the same needs in distantly related species. The common example is wings in butterflies and bats, but now nematode body shape can be added to the list.

"The larger question is how do you get new body shapes in biology? How do new shapes arise? In this case, we're suggesting that these organisms are using mechanisms of stem cell proliferation to generate new body shapes, which is pretty interesting," Schroeder says.

The discovery could also have potential management implications down the road. If researchers could disrupt the proliferation of these seam cells at a certain stage, it might be possible to keep female nematodes from becoming quite so round, with room for so many babies.

"From my perspective, it's a combination of interesting biology and practical implications with an economically important pest causing yield loss throughout the Midwest," Schroeder says. "If we can find some new target strategies that will affect it but not the other thousands of beneficial nematode species in the soil, that would be a game-changer."
-end-
The article, "Convergent evolution of saccate body shapes in nematodes through distinct developmental mechanisms," is published in EvoDevo [DOI: 10.1186/s13227-019-0118-5]. Authors include Sita Thapa, Michael Gates, Ursula Reuter-Carlson, Rebecca Androwski, and Nathan Schroeder. The research was supported by the Schlumberger Foundation, the USDA NIFA Hatch program, and the NIH National Institute of General Medical Sciences.

University of Illinois College of Agricultural, Consumer and Environmental Sciences

Related Nematodes Articles:

Parasitic nematodes that cause greatest agricultural damage abandoned sex
The nematode worms that cause the world's most devastating crop losses have given up on sexual reproduction and instead rely on their large, duplicated genomes to thrive in new environments.
Drug-delivery method holds promise for controlling crop parasites
Nematodes cause $157 billion in crop damage annually, largely because traditional pesticides fail to reach plant roots, where the round worms do their damage.
Using venomous proteins to make insect milkshakes
In a just-published paper in the journal PLOS Pathogens, Adler Dillman, an assistant professor at the University of California, Riverside and several collaborators found that nematodes secrete a deadly cocktail of proteins to kill many insects that damage crops.
Deciphering plant immunity against parasites
Nematodes are a huge threat to agriculture since they parasitize important crops such as wheat, soybean, and banana; but plants can defend themselves.
Researchers profile symbiotic relationship between bacteria and filarial nematodes
Filarial nematodes -- microscopic, thread-like roundworms -- currently infect up to 54 million people worldwide and are the leading cause of disability in the developing world.
More Nematodes News and Nematodes Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Teaching For Better Humans
More than test scores or good grades — what do kids need to prepare them for the future? This hour, guest host Manoush Zomorodi and TED speakers explore how to help children grow into better humans, in and out of the classroom. Guests include educators Olympia Della Flora and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#534 Bacteria are Coming for Your OJ
What makes breakfast, breakfast? Well, according to every movie and TV show we've ever seen, a big glass of orange juice is basically required. But our morning grapefruit might be in danger. Why? Citrus greening, a bacteria carried by a bug, has infected 90% of the citrus groves in Florida. It's coming for your OJ. We'll talk with University of Maryland plant virologist Anne Simon about ways to stop the citrus killer, and with science writer and journalist Maryn McKenna about why throwing antibiotics at the problem is probably not the solution. Related links: A Review of the Citrus Greening...