MU scientists show that parasitic nematodes hijack vascular stem cell pathways to attack their hosts
Invisible to the naked eye, cyst nematodes are a major threat to agriculture, causing billions of dollars in global crop losses every year. A group of plant scientists, led by University of Missouri researchers, recently found one of the mechanisms cyst nematodes use to invade and drain life-sustaining nutrients from soybean plants. Understanding the molecular basis of interactions between plants and nematodes could lead to the development of new strategies to control these major agricultural pests and help feed a growing global population.
A nematode (the oblong object on the left) activates the vascular stem cell pathway in the developing nematode feeding site (syncytium) on a plant root.
Credit: Xiaoli Guo, Division of Plant Sciences and Bond Life Sciences Center, University of Missouri; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
Soybeans are a major component for two-thirds of the world's animal feed and more than half the edible oil consumed in the United States, according to the U.S. Department of Agriculture (USDA). Cyst nematodes jeopardize the healthy production of this critical global food source by "hijacking" the soybean plants' biology.
"Cyst nematodes are one of the most economically devastating groups of plant-parasitic nematodes worldwide," said Melissa Goellner Mitchum, a researcher in the Bond Life Sciences Center and an associate professor in the Division of Plant Sciences at MU. "These parasites damage root systems by creating a unique feeding cell within the roots of their hosts and leeching nutrients out of the soybean plant. This can lead to stunting, wilting and yield loss for the plant. We wanted to explore the pathways and mechanisms cyst nematodes use to commandeer soybean plants."
About 15 years ago, Mitchum and colleagues unlocked clues into how nematodes use small chains of amino acids, or peptides, to feed on soybean roots.
Using next-generation sequencing technologies that were previously unavailable, Michael Gardner, a graduate research assistant, and Jianying Wang, a senior research associate in Mitchum's lab, made a remarkable new discovery -- nematodes possess the ability to produce a second type of peptide that can effectively "take over" plant stem cells that are used to create vital pathways for the delivery of nutrients throughout the plant. Researchers compared these peptides with those produced by plants and found that they were identical to the ones the plants use to maintain vascular stem cells, known as CLE-B peptides.
"Plants send out these chemical signals to its stem cells to begin various functions of growth, including the vascular pathway that plants use to transport nutrients," Mitchum said. "Advanced sequencing showed us that nematodes use identical peptides to activate the same process. This 'molecular mimicry' helps nematodes produce the feeding sites from which they drain plant nutrients."
To test their theory, Xiaoli Guo, a post-doctoral researcher in Mitchum's lab and first author of the study, synthesized the CLE-B nematode peptide and applied it to the vascular cells of Arabidopsis, a model plant system used in plant research. They found that the nematode peptides triggered a growth response in Arabidopsis much in the same way as the plants' own peptides affected development.
Next, the team "knocked out" the genes Arabidopsis plants use to signal to their own stem cells. Here, the nematodes didn't do as well because the parasites were unable to signal to the plant and the nematode's feeding site was compromised, Guo says.
"When a nematode attacks the root, it selects vascular stem cells that are located along the root," Mitchum said. "By knocking out that pathway, we reduced the size of the feeding site that nematodes use to control the plant. This is the first time we've been able to show that the nematode is modulating or controlling the vascular plant pathway. Understanding how plant-parasitic nematodes modulate host plants to their own benefit is a crucial step in helping to create pest-resistant plants. If we can block those peptides and the pathways nematodes use to overtake the soybean plant, then we can enhance resistance for this very valuable global food source."
The study "Identification of cyst nematode B-type CLE peptides and modulation of the vascular stem cell pathway for feeding cell formation," recently was published by PLOS Pathogens. This work was supported by grants from the National Science Foundation (IOS-1456047), the U.S. Department of Agriculture (2012-67013-19345) and Huazhong Agricultural University Scientific and Technological Self-Innovation Foundation (Program No. 2016RC004). The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies.
Editor's Note: For more on the story please see: https:/
Jeff Sossamon | EurekAlert!
Filling intercropping info gap
16.11.2017 | American Society of Agronomy
Climate change, population growth may lead to open ocean aquaculture
05.10.2017 | Oregon State University
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses