- Author: Kathy Keatley Garvey
The open-access journal Nature Communications, published the peer-reviewed research Oct. 19.
“Plant-parasitic nematodes are a threat to crop production,” said Siddique, an assistant professor in the UC Davis Department of Entomology and Nematology. “We used a combination of genomic, genetic, and biochemical approaches to show that the plant pathogen cyst nematode possesses an incomplete vitamin B5 synthesis pathway, of potential prokaryotic origin, which is complemented by its plant host. This approach has identified new targets for future development of nematode-resistant crops.”
The 33-member research team included scientists from universities in Germany, France, The Netherlands, Poland, and the United Kingdom, as well as scientists from three universities in the United States: Iowa State University, Ames; and the University of Tennessee, Knoxville; and UC Davis.
The article is titled “The Genome and Lifestage-Specific Transcriptomes of a Plant-Parasitic Nematode and its Host Reveal Susceptibility Genes Involved in Trans-Kingdom Synthesis of Vitamin B5.”
“The scarcity of classical resistance genes highlights a pressing need to find new ways to develop nematode-resistant germplasm,” the scientists wrote in their abstract. “Here, we sequence and assemble a high-quality phased genome of the model cyst nematode Heterodera schachtii to provide a platform for the first system-wide dual analysis of host and parasite gene expression over time, covering all major parasitism stages. Analysis of the hologenome of the plant nematode infection site identified metabolic pathways that were incomplete in the parasite but complemented by the host. Using a combination of bioinformatic, genetic, and biochemical approaches, we show that a highly atypical completion of vitamin B5 biosynthesis by the parasitic animal, putatively enabled by a horizontal gene transfer from a bacterium, is required for full pathogenicity. Knockout of either plant encoded or now nematode-encoded steps in the pathway significantly reduces parasitic success. Our experiments establish a reference for cyst nematodes, further our understanding of the evolution of plant parasitism by nematodes, and show that congruent differential expression of metabolic pathways in the infection hologenome represents a new way to find nematode susceptibility genes. The approach identifies genome-editing-amenable targets for future development of nematode-resistant crops.”
Corresponding authors are Florian Grundler of the Rheinische Friedrich-Wilhelms-University of Bonn, Germany, and Sebastian Eves-van den Akker of the Crop Science Centre, Department of Plant Sciences, University of Cambridge, UK.
Research in the Siddique lab focuses on basic as well as applied aspects of interaction between parasitic nematodes and their host plants. “Plant-parasitic nematodes are destructive pests causing losses of billions of dollars annually,” Siddique said. “The long-term object of our research is not only to enhance our understanding of molecular aspects of plant–nematode interaction but also to use this knowledge to provide new resources for reducing the impact of nematodes on crop plants in California.”
- Author: Kathy Keatley Garvey
Filipa Rijo-Ferreira, a UC Berkeley School of Public Health (BPH) assistant professor who specializes in parasitology and circadian rhythms, will present a UC Davis Department of Entomology and Nematology seminar at 4:10 p.m., Wednesday, Oct. 19 on "Circadian Rhythms in Parasitic Diseases" in 122 Briggs Hall.
Her seminar also will be virtual. The Zoom link is https://ucdavis.zoom.us/j/95882849672. Host is molecular geneticist and physiologist Joanna Chiu, professor and vice chair of the UC Davis Department of Entomology and Nematology.
"Malaria's main symptom is the periodic fevers experienced by patients, fevers that ‘come and go' at certain times of the day and are a consequence of synchronized parasite rhythms," Rijo-Ferreira says in her abstract. "In humans, circadian clocks regulate multiple aspects of physiology, including sleep-wake cycles, metabolism, and immune defense. Circadian biology leads to body rhythms experienced by the pathogens that infect humans. In addition to sensing host rhythms, we recently discovered that parasites which cause devastating health burdens such as malaria and sleeping sickness diseases also have their own intrinsic clocks. The clocks of parasites regulate core biological functions from metabolism to the cell cycle, and the discovery of the existence of their clocks serves as an opportunity to access the molecular mechanisms regulating their rhythmic biology."
Rijo-Ferreira, trained in infectious diseases and neuroscience, joined the UC Berkeley faculty in January 2022. A native of Lisbon, Portugal, she holds a bachelor's degree in molecular and cellular biology from Nova University of Lisbon, and her master's degree in 2009 in molecular genetics and biomedicine from Imperial College, London. She received her doctorate in 2016 at the University of Porto, Portugal, where she completed her studies in basic and applied biology, molecular parasitology, and neuroscience. Postdoctoral training followed at the University of Texas Southwestern Medical Center, Dallas.
"Our lab is interested in parasitic infections and we study them under the lenses of time of day," she wrote on her lab website. "Our rhythmic world has been a driving force for organisms to evolve a molecular clock to anticipate such daily rhythms. Similarly, our own circadian biology leads to physiological rhythms that parasites experience.We study the single-celled parasites Plasmodium spp. that causes malaria, and Trypanosoma brucei that causes sleeping sickness. We employ technical approaches spanning from next-generation sequencing, to cellular and behavioral assays to investigate the interactions of these parasites with their hosts.Our work seeks to understand how circadian rhythms modulate host-parasite-vector interactions and identify opportunities in their rhythmic biology to treat parasitic infections
In an interview with BPH staff writer Eliza Partika, published in February 2022, she commented: "I am fascinated about our day and night cycles and how organisms evolved to anticipate them. I find it incredible that parasites, such as the ones that cause malaria, show a coordinated rhythmic pattern themselves, which underlies periodic fevers in infected individuals. Our research is aimed at understanding how this phenomenon is regulated molecularly, and how we can disrupt these rhythmic patterns to offset the infection."
"At BPH, we aim to set up a framework where we can explore the relationships between parasites, hosts, and the mosquitoes that serve as the vector of disease transmission, based on the time of day," Rijo-Ferreira related. "We hypothesize that the circadian rhythms of these three organisms need to be aligned in order for the parasite to cause an efficient infection. In fact, when rhythms are misaligned, there is a reduction in parasite levels. Thus, identifying the molecular players from host, parasite, and mosquito is essential to understanding this phenomenon and creating alternative strategies to manage deadly infections like malaria and sleeping sickness."
Rijo-Ferreira said she seeks to "bring to the attention the circadian aspect of infectious diseases and bring awareness of the potential benefits of time of day vaccination and drug treatment."
Emily Meineke, assistant professor of urban landscape entomology, UC Davis Department of Entomology and Nematology, coordinates the department's seminars for the 2022-23 academic year. All 11 seminars will take place both person and virtually at 4:10 p.m. on Wednesdays in Room 122 of Briggs Hall except for the Nov. 9th and Dec. 7th seminars, which will be virtual only, she said. (See list of seminars)
For further information on the seminars or to resolve any technical difficulties with Zoom, contact Meineke at ekmeineke@ucdavis.edu.
- Author: Kathy Keatley Garvey
Their work, “Insect Herbivory Within Modern Forests Is Greater than Fossil Localities,” appears in the Oct. 10th edition of the Proceedings of the National Academy of Sciences (PNAS). The first-of-its-kind study compares insect herbivore damage of modern-era plants with that of fossilized leaves dating as far back as 67 million years ago.
“Our work bridges the gap between those who use fossils to study plant-insect interactions over deep time and those who study such interactions in a modern context with fresh leaf material,” said lead researcher and ecologist Lauren Azevedo-Schmidt, formerly of the Department of Biology, University of Wyoming and now a postdoctoral research associate with the Climate Change Institute, University of Maine. “The difference in insect damage between the modern era and the fossilized record is striking.”
No stranger to UC Davis, Currano presented a UC Davis Department of Entomology and Nematology seminar, hosted by Meineke, on "Ancient Bug-Bitten Leaves Reveal the Impacts of Climate and Plant Nutrients on Insect Herbivores" on April 28, 2021.
“Plants and insects are the most diverse lineages on earth, but their interactions in the face of climate and other global changes are poorly understood…despite insect declines, insect damage to plants is elevated in the modern era compared with other time periods represented in the fossil record,” they wrote. “Plants today are experiencing unprecedented levels of insect herbivory, with unknown consequences for plant fitness and evolution.”
The scientists presented estimates for damage frequencies and diversities on fossil leaves from the Late Cretaceous (66.8 million years ago) through the Pleistocene (2.06 million years ago) and compared these estimates with recent (post-1955) leaves collected via paleobotanical methods from three modern ecosystems, including Harvest Forest, a 3000-acre ecological research area in managed by Harvard University and located in Petersham, Mass. The site, in operation since 1907, is one of North America's oldest managed forests.
Other ecosystems: the Smithsonian Environmental Research Center (SERC) of Chesapeake Bay, a 2,650-acre campus spanning forests, wetlands, marshes and 15 miles of protected shoreline, and the 3953-acre La Selva Research Station, Costa Rica, a private forest reserve.
The scientists advocate more research to determine the precise causes of increased insect damage to plants, but related that a “warming climate, urbanization and introduction of invasive species likely have had a major impact.”
“We hypothesize that humans have influenced (insect) damage frequencies and diversities within modern forests, with the most human impact occurring after the Industrial Revolution,” the researchers wrote. “Consistent with this hypothesis, herbarium specimens from the early 2000s were 23 percent more likely to have insect damage than specimens collected in the early 1900s, a pattern that has been linked to climate warming.”
“This research suggests that the strength of human influence on plant-insect interactions is not controlled by climate change alone but, rather, the way in which humans interact with the terrestrial landscape,” the researchers concluded.
Meineke, who joined the UC Davis faculty in 2020, served as a postdoctoral fellow at Harvard University Herbaria from 2016 to 2019, including a National Science Foundation-sponsored fellowship there in 2017. She holds a doctorate in entomology from North Carolina State University (2016), Raleigh, where she wrote her dissertation on “Understanding the Consequences of Urban Warming for Street Trees and Their Pests.”
Meineke helped spearhead the newly created Harvard Museum of Natural History's “In Search of Thoreau's Flowers: An Exploration of Change and Loss," hailed as an examination of the natural world and climate change at the intersections of science, art and history. The exhibit opened to the public May 14, 2022.
- Author: Kathy Keatley Garvey
Miridae is working with pollination ecologist Neal Williams, professor, and urban landscape entomologist Emily Meineke, assistant professor. Also on the team is assistant professor Haven Kiers of the Department of Human Ecology, who specializes in landscape architecture and environmental design.
"This year we are collaborating with UC Davis entomologists who will use these seed piles to learn about how certain urban conditions impact native bee species," Krimmel said.
Those who live in the Sacramento area (including Davis) and the East Bay, are invited to participate. Krimmel explains:
- You sign up here
- You get 3 free packets of native wildflower seeds
- You drop them somewhere in your neighborhood or commute
- You DO NOT water or maintain them
- You monitor them once a month until May using the Miridae app and "tell us what you see"
"We encourage folks of all ages to participate, and we provide resources such as seedling identification guides to help you identify the species in your seed piles," Krimmel said. "This is a great project for school classes and scout troops in addition to individuals."
It works like this: "Community participants to drop small piles of local, California native seeds in urban areas where they live or work, then monitor the results through repeated observations," Krimmel said. "Using data from participants on the conditions under which certain species of these locally adapted seeds spread, survive, or die, we can gain a better understanding of which native species to incorporate into the built environment and where to put them for the greatest ecological benefit and resilience."
"The basic goal is to learn which species can thrive in human-occupied spaces, especially transportation corridors," said Krimmel, who studied native plant-insect interactions at UC Davis with major professor Jay Rosenheim, distinguished professor of entomology. He received his doctorate in ecology in January, 2015.
A kickoff gathering is set from 4 to 7 p.m., Thursday, Nov. 17 at the Jackrabbit Brewing in West Sacramento where participants can pick up their seed packets, meet other participants, and perhaps buy a native plant and/or beverage. "There will be other pickup options as well," he said.
Krimmel founded the company, located at 1385 Terminal St., West Sacramento, with the intention of “creating habitat for native species within human-occupied areas and engaging people with the species interactions occurring in these habitations.” Its mission: "To strengthen connections between people, native plants, and wildlife through design, construction, outreach and research."
The name, Miridae, is Latin for a family of insects known as “plant bugs,” or mirids, which Krimmel researches. One of the most well-known mirid is the lygus bug, a serious pest of cotton, strawberries and alfalfa.
Miridae won the highly competitive 2020 Award of Excellence for Communication from the American Society of Landscape Architects (ASLA) for its Seed Bank Living Wall at DPR Construction, Sacramento. The ASLA awards, judged by a jury of professionals, honor the best in landscape architecture from around the globe.
Of his company, Krimmel says: “We create habitat for, and engage people with, native plants and the wildlife they support. We do this by tying together design, science, and high-quality construction to create landscapes that are beautiful, resilient, and ecologically powerful.” His goal, with each project, is to “come one step closer to creating a network of habitat gardens and migration corridors to support resilient populations of native species.”
Krimmel may be reached via his website www.miridae.com or on Instagram.
- Author: Kathy Keatley Garvey
The Bohart Museum is located in Room 1124 of the Academic Surge Building, 455 Crocker Lane. The event is free and family friendly.
Among artists represented will be UC Davis graduate student Srdan Tunic; undergraduate students Allen Chew, Francisco Basso and Brittany Kohler; and UC Davis alumna Megan Ma; plus the work of the late scientific illustrator Mary Foley Benson (1905-1992), who worked for the U.S. Department of Food and Agriculture, the Smithsonian before retiring and moving to Davis. She also worked for UC Davis entomologists.
Tunic, a UC Davis candidate for a master's degree in art history, will present a seminar on Benson from 11 a.m. to noon, Oct. 15, in Room 1010 of the TLC Teaching and Learning Complex, 482 Hutchison Drive. (See separate news story on Tunic and see research story on Mary Foley Benson by forest entomologist Malcolm Furniss)
"I will focus on the visual material, and start by saying a few words about the museum, and then talk about Mary's life and art chronologically, paying special attention to her work at UC Davis," Tunic said. "At some point I will briefly touch on scientific illustration and how artists make this sort of work, and near the end, mention other illustrators I encountered during this process, and wrap up motivating people to dive into their local collections."
The family arts-and-crafts activity at the open house will be to "create your own Pokemon card," said Lynn Kimsey, director of the Bohart Museum and a UC Davis distinguished professor of entomology. Also planned: eating insects, creating gall ghosts (from oak galls), learning about cochineal dyes, and showing off insect tattoos.
"We would love to have folks come and show off their insect tattoos," Kimsey said.
The UC Davis museum, founded in 1946 by noted entomologist Richard M. Bohart (1913-2007), is dedicated to teaching, research and service. It is the home of a global collection of eight million insect specimens. The collection is now the seventh largest in North America and includes terrestrial and fresh water arthropods. The museum is also home of the California Insect Survey, a storehouse of the insect biodiversity of California's deserts, mountains, coast, and the Great Central Valley. In addition, the Bohart features a live "petting zoo" (Madagascar hissing cockroaches, walking sticks and tarantulas) and an insect-themed gift shop, stocked with T-shirts, hoodies, jewelry, posters, books and insect-collecting equipment.
The Bohart is open to the public year-around (except for holidays) Monday through Thursday from 9 a.m. to noon and from 1 to 5 p.m. It is closed to the public on Friday to enable research activities. Admission is free. For more information, access the website or contact the museum at bmuseum@udavis.edu.
