The nine-member research team, led by Frank Schroeder, a BTI professor and also a professor in Cornell University's Department of Chemistry and Chemical Biology, detailed how plants speak “roundworm language” for self-defense. The work is published Jan. 10 in the journal Nature Communications.
The researchers studied chemicals called ascarosides, which the worms produce and secrete to communicate with each other. Williamson helped analyze the data and helped make some key insights toward the paper's conclusions, the BTI scientists related.
The team found that plants “talk” to nematodes by metabolizing ascarosides and secreting the metabolites back into the soil.
“It's not only that the plant can ‘sense' or ‘smell' a nematode,” Schroeder said in a BTI news release. “It's that the plant learns a foreign language, and then broadcasts something in that language to spread propaganda that ‘this is a bad place.' Plants mess with nematodes' communications system to drive them away.”
The study built on the team's previous work showing that plants react to ascr#18 – the predominant ascaroside secreted by plant-infecting nematodes – by bolstering their own immune defenses, thereby protecting them against many types of pests and pathogens.
In those earlier studies, “We also saw that when ascr#18 was given to plants, the chemical disappears over time,” according to lead author Murli Manohar, a senior research associate at BTI.
That observation, along with published literature suggesting plants could modify pest metabolites, led the team to hypothesize that “plants and nematodes interact via small molecule signaling and alter one another's messages,” Schroeder said.
To probe that idea, the team treated three plant species – Arabidopsis, wheat and tomato – with ascr#18 and compared compounds found in treated and untreated plants. They identified three ascr#18 metabolites, the most abundant of which was ascr#9.
The researchers also found Arabidopsis and tomato roots secreted the three metabolites into the soil, and that a mixture of 90% ascr#9 and 10% ascr#18 added to the soil steered nematodes away from the plant's roots, thereby reducing infection.
The team hypothesized that nematodes in the soil perceive the mixture as a signal, sent by plants already infected with nematodes, to “go away” and prevent overpopulation of a single plant. Worms may have evolved to hijack plant metabolism to send this signal. Plants, in turn, may have evolved to tamper with the signal to appear as heavily infected as possible, thereby fooling would-be invaders.
“This is a dimension of their relationship that no one has seen before,” said Manohar. “And plants may have similar types of chemical communication with other pests.”
Although the mixture of ascr#9 and ascr#18 could serve as a crop protectant, Schroeder said there should be no detriment to using straight ascr#18 on crops, as described in the team's earlier research.
“Ascr#18 mainly primes the plant to respond more quickly and strongly to a pathogen, rather than fully inducing the defensive response itself,” he said. “So there should be no cost to the plant in terms of reduced growth, yield or other problems.”
The team also showed that plants metabolize ascr#18 via the peroxisomal β-oxidation pathway, a system conserved across many plant species.
“This paper uncovers an ancient interaction,” Schroeder said. “All nematodes make ascarosides, and plants have had millions of years to learn how to manipulate these molecules.”
He added: “Plants aren't passive green things. They are active participants in an interactive dialog with the surrounding environment, and we will continue to decipher this dialog.”
These discoveries are being commercialized by a BTI and Cornell University-based startup company, Ascribe Bioscience, as a family of crop protection products named PhytalixTM.
Scientists affiliated with four institutions--BTI, Cornell, UC Davis and the USDA's Robert W. Holley Center for Agriculture and Health--co-authored the paper. Grants from USDA and the National Institutes of Health funded the research.
Moreau is the Moser Professor of Biosystematics and Biodiversity, Departments of Entomology and Ecology and Evolutionary Biology at Cornell University, Ithaca, N.Y. and the curator of the Cornell University Insect Collection.
"Moreau and colleagues were the first to establish the origin of the ants at 140 million years ago using molecular sequence data (40 million years older than previous estimates), and that the diversification of the ants coincided with the rise of the flowering plants (angiosperms)," according to an entry in Wikipedia. "In addition, Moreau and Charles D. Bell showed that the tropics have been and continue to be important for the evolution of the ants. Moreau and colleagues have demonstrated the importance of gut-associated bacteria in the evolutionary and ecological success of ants through targeted bacterial and microbiome sequencing, including showing that bacterial gut symbionts are tightly linked with the evolution of herbivory in ants."
Her honors are many. In 2018 she was elected a fellow of the American Association for the Advancement of Science. Also in 2018, she was featured in National Geographic as a "Woman of Impact." In 2015, she was included in "15 Brilliant Women Bridging the Gender Gap in Science."
A native of New Orleans, Moreau holds degrees (bachelor and master's) from San Francisco State University and a doctorate in biology from Harvard University (2007). At Harvard, she studied with major professors E. O. Wilson and Naomi Pierce. Wilson featured her in his 2013 book, Letter to a Young Scientist.
"There was no bravado in Corrie, no trace of overweening pride, no pretension," Wilson wrote. "The story of Corrie Saux Moreau's ambitious undertaking is one I feel especially important to bring to you. It suggests that courage in science born of self-confidence (without arrogance!), a willingness to take a risk but with resilience, a lack of fear of authority, a set of mind that prepares you to take a new direction if thwarted, are of great value – win or lose."
Moreau will cover diverse topics in her talk. "To fully understand the macro evolutionary factors that have promoted the diversification and persistence of biological diversity, varied tools and disciplines must be integrated," she says in her abstract. "By combining data from several fields, including molecular phylogenetics/phylogenomics, comparative genomics, biogeographic range reconstruction, stable isotyope analyses, and microbial community sequencing to study the evolutionary history of the insects, we are beginning to understand the drivers of speciation and the interconnectedness of life. Comparative phylogenetic analysis reveals the interconnectedness of ants and plants and that ants diversified after the rise of the angiosperms. Comparative genomics has permitted the exploration of the role of symbiosis on genome evolution and behavioral gene evolution demonstrating that Red Queen dynamics are at play in obligate mutualisms..."
"Microbial contributions to ants are not limited to diet enrichment," she says, "and we find evidence for their role in cuticle formation. These multiple lines of evidence are illuminating a more complete picture of ant evolution and providing novel insights into the role that symbiosis plays to promote biological diversity."
UC Davis graduate student Marshall McMunn of the Phil Ward lab is the host. Community ecologist Rachel Vannette, assistant professor (email@example.com), coordinates the weekly seminars. See seminar schedule.
The award, given by ESA's Systematics, Evolution and Biodiversity Section, recognizes outstanding research by a doctoral student who has completed a research thesis or dissertation in arthropod morphology, systematics, taxonomy, or evolution. The prize is a $500 cash award and an invited talk at ESA. She'll speak on "Unraveling the Evolution of Spider flies (Diptera, Acroceridae): Progress and Possibilities" at the ESA's annual meeting, set Nov. 17-20 in St. Louis, Mo.
Gillung is the first UC Davis student to receive the award, which was first presented in 1992. Her dissertation, “Systematics and Phylogenomics of Spider Flies (Diptera, Acroceridae),” focused on the evolution, conservation, biology, and taxonomy of spider flies, a group of spider natural enemies.
Awarded her doctorate in entomology in December 2018, Gilllung studied with major professor Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology, UC Davis Department of Entomology and Nematology. She also studied with mentor Shaun Winterton, insect biosystematist, California Department of Food and Agriculture, and collaborated with ant specialist and taxonomist Phil Ward, professor, UC Davis Department of Entomology and Nematology.
Gillung's dissertation, involving genomics, phylogenetics, systematics, and comparative analyses, “has increased our understanding of the biological patterns and processes that have shaped our planet's biodiversity,” Kimsey wrote in her letter of nomination. Her taxonomic work included identification keys and morphology-based diagnoses of species using modern techniques of cybertaxonomy—the application of the internet, digital technologies, and computer resources to increase and speed up the discovery and cataloging of new species, Kimsey wrote in her letter of nomination.
“Using cybertaxonomic tools, Jessica described 25 new spider fly species herself, and in collaboration with fellow entomologists, three fossil species from Baltic amber, described in her first dissertation chapter," Kimsey wrote. "Cybertaxonomy is a powerful tool that allows researchers and citizen scientists to collaborate in real time and across great distances to increase the speed and efficiency of biodiversity discovery.”
Kimsey noted that “Jessica unraveled the functional and ecological implications of key morphological traits, as well as their distribution across the Tree of Life," and "established new homologies for the wing venation of spider flies. She conducted detailed and assiduous dissections of male reproductive structures (i.e., genitalia) to understand homologies, demonstrating that morphological traits are dynamically evolving systems useful for both classification and inference of evolutionary history.”
While at UC Davis, Gillung drew more $120,000 in grants and awards for her multifaceted research on genomics, bioinformatics, phylogenetics, plant-pollinator interactions, and biodiversity discovery. She compiled a near straight-A academic record, published 11 refereed publications in top journals, and engaged in public service and outreach programs that reached more than 20,000 people at UC Davis-based events.
Gillung was a key member of the UC Davis Linnaean Games Team that won the ESA national championship in 2015. The Linnaean Games are lively question-and-answer, college bowl-style competitions on entomological facts played between university-sponsored student teams.
The UC Davis-trained entomologist earlier received
- The 2019 Marsh Award for Early Career Entomologist, sponsored by the Royal Entomological Society. That involved a $1624 cash award and an invitation to the society meeting, Aug. 20-22 at the London School of Hygiene and Tropical Medicine.
- The 2019 Early Career Award from the Pacific Branch, Entomological Society of America (PBESA). PBESA encompasses 11 western states, U.S. territories and parts of Canada and Mexico.
- The 2018 Student Leadership Award from PBESA
- The “Best Student Presentation Award” at the ninth annual International Congress of Dipterology, held in 2018 in Windhoek, Namibia.
At Cornell, Gillung is researching Apoidea (stinging wasps and bees) phylogenomics, evolution and diversification in the Brian Danforth lab.
(Editor's Note: This seminar initially set for Wednesday, May 2 at 4:10 p.m. in 122 Briggs Hall has been cancelled.)
Tory Hendry, an assistant professor of microbiology at Cornell University, Ithaca, New York, will present a seminar on bacteria that infect and kill pea aphids at 4:10 p.m., Wednesday, May 2 in 122 Briggs Hall, as part of the weekly spring seminars hosted by the UC Davis Department of Entomology and Nematology.
Her seminar is titled “Life and Death in the Phyllosphere: Epiphytic Bacteria Influence Aphid Survival and Behavior.”
“She will be talking about some of her new and very cool work on insect vision and pathogen avoidance,” said co-seminar coordinator Rachel Vannette, assistant professor of entomology. “Her website is here, but briefly, she works on bacterial genome evolution and plant-microbe-insect interactions, and other microbial symbioses.”
In her abstract, Henry writes: “Several diverse strains of plant epiphytic bacteria, such as Pseudomonas syringae, are able to infect and kill pea aphids. P. syringae can be pathogenic to plants, but is also widespread in the environment and a common eipipye. We have found the P. syringae can easily infect aphids and be highly virulent to insects. This interaction is fairly broad, both across P. syringae strains and across hemipteran insect species, suggesting that infection by these bacteria may be common in nature. Aphids may use varied non-immunological defenses against bacterial infection, in particular they are able to avoid feeding when highly virulent bacteria are present on a leaf. We found that up to 80 percent of aphids avoid leaves painted with epiphytic bacteria in favor of feeding on control leaves."
"This interaction is fairly broad, both across P. syringae strains and across hemipteran insect species, suggesting that infection by these bacteria may be common in nature. Aphids may use varied non-immunological defenses against bacterial infection, in particular they are able to avoid feeding when highly virulent bacteria are present on a leaf. We found that up to 80 percent of aphids avoid leaves painted with epiphytic bacteria in favor of feeding on control leaves."
However, says Hendry, "aphids do not avoid all strains, rather avoidance is correlated with strain virulence such that mainly highly virulent strains are avoided. We determined that production of the fluorescent siderophore pyoverdine by P. syringae was necessary for aphid avoidance, and the evidence suggests that aphids use vision to detect the fluorescence of this molecule. Pyoverdine is not responsible for virulence itself, but aphids may use it as a reliable cue of virulence.”
Hendry received her doctorate in ecology and evolutionary biology from the University of Michigan. She held a postdoctoral appointment at the University of Arizona, working with David Baltrus, and was a fellow with USDA's National Institute of Food and Agriculture, working with Nicholas Mills and Steven Lindow at the UC Berkeley.
Co-coordinator of the weekly seminars are Brendon Boudinot, doctoral candidate in the Phil Ward lab, and Extension apiculturist Elina Lastro Niño.
Thaler will be honored at a reception from 3:30 to 4:15 on Thursday, Feb. 9 at the International House, located at 10 College Park, Davis. Following the reception, she will present a seminar in the International House conference room from 4:15 to 5 p.m. on "Tritrophic Interactions and the Ecology of Fear."
Her areas of expertise are population and community ecology, plant-insect interactions, tri-trophic interactions and chemical ecology.
"I study the ecological interactions between plants, herbivores, and carnivores in wild and agricultural Solanaceous plant species," she says. "My approach focuses on understanding behavioral and phytochemical mechanisms of such tri-trophic interactions, testing theory on the organization of multi-trophic communities, and generating novel strategies to control insect pests."
Thaler received her bachelor of science degree in biology, cum laude, from Wellesley College in 1993 and her doctorate in entomology from UC Davis with major professor Rick Karban in 1999.
After receiving her doctoral degree, she worked as a postdoctoral researcher for a year at Wageningen Agricultural University, the Netherlands, and then served at the University of Toronto as an assistant professor of botany from 2000 to 2004. She joined the Cornell University faculty in 2004 as an assistant professor, advancing to associate in 2006, and to full professor in 2015.
Thaler was named a Cornell Center for Sustainable Future Faculty Fellow in 2011 and continues to serve in that position. Among her other honors and awards:
- Excellence in Ecological Entomology, Royal Entomological Society's Awards for Scientific Writing, runner up (2003)
- Premiers Research Excellence Award, Government of Ontario (2000)
- American Society of Naturalists Young Investigators Award (2000)
- Entomological Society of America, second prize for oral presentation (1998)
The professor is a member of the Entomological Society of America, the Ecological Society of America and the International Society of Chemical Ecology.
She presented a invited seminar at the 2017 Gordon Research Conference on "Plant-Herbivore Interactions, Tritrophic Interactions and the Ecology of Fear" and a presentation on Predator-Prey Interactions: Chemical Ecology of Tri-Trophic Interactions" at the 2016 Gordon Research Conference. The Gordon Research Conferences, founded in 1931 and headquartered in Rhode Island, organizes international scientific conferences dedicated to advancing the frontiers of scientific research in the biological, chemical, and physical sciences, and their related technologies.
Thayer has also presented seminars at the 2014 Entomological Society of America meeting in Portland Ore. on "Non-Lethal Effects of Predators in Arthropod Food Webs" and at the 2013 Ecological Society of America meeting in Minneapolis on "Ecophysiological Consequences of Predation Risk," among many others.
The Leigh Alumni Award memorializes cotton entomologist Thomas Frances Leigh (1923-1993) and his wife Nina. Leigh was an international authority on the biology, ecology and management of arthropod pests affecting cotton production. During his 37-year UC Davis career, he was based at the Kern County Shafter Research and Extension Center, also known as the U.S. Cotton Research Station. He researched pest and beneficial arthropod management in cotton fields, and host plant resistance in cotton to insects, mites, nematodes and diseases. Leigh joined the UC Davis Department of Entomology in 1958, retiring in 1991 as an emeritus professor, but he continued to remain active in his research and collaboration until his death on Oct. 26, 1993.
At Shafter, Leigh focused his research on the biology, ecology, host plant resistance, control and management of insects and spider mites on cotton. He stood at the forefront of Integrated Pest Management (IPM) of cotton pests, according to an article in the summer 1994 edition of American Entomologist. He taught courses on cotton IPM and host plant resistance.