"Target-site insensitivity (TSI) is an important mechanism of animal resistance to toxins," says nematologist Adler Dillman of the University of California, Riverside. "TSI evolved in parallel in the monarch butterfly and other insects that specialize on milkweeds and is thought to have facilitated sequestration of cardiac glycosides that may protect these insects from predation and parasitism."

Dillman, professor and chair of the UCR Department of Nematology,  will share his research in a presentation titled "Nematode Parasitism of Insects with Toxic Cardenolides," hosted by the UC Davis Department of Entomology and Nematology at 4:10 p.m., Monday, Jan. 8.  

His seminar will be in Room 122 of Briggs Hall and also will be on Zoom. The Zoom link: https://ucdavis.zoom.us/j/95882849672. Associate professor and nematologist Shahid Siddique of the Department of Entomology and Nematology is the host. 

Dillman holds a bachelor's degree in microbiology from Brigham Young University (2006) and a doctorate in genetics (2013) from the California Institute of Technology.

The abstract of his UC Davis seminar:  

Known as an excellent investigator and teacher, Dillman won the 2022 UCR Chancellor's Award for Excellence in Undergraduate Research and Creative Achievement; the 2021 Award for Excellence in Teaching from the Society of Nematologists, and a 2020 Outstanding Investigator Award, Maximizing Investigators' Research Award (MIRA).

Check out his lab page that details his research and his guest spot on an episode on the podcast Something Offbeat. He he discussed a scientific article on a case of Ophidascaris robertsi infection in a human brain.

Seminar coordinator is Brian Johnson, associate professor, UC Davis Department of Entomology and Nematology. For Zoom technical issues, he may be reached at brnjohnson@ucdavis.edu. The complete list of winter seminars will be posted soon. 

Congrats to the lab of nematologist Shahid Siddique, UC Davis Department of Entomology and Nematology, for excellent presentations at the 62nd annual meeting of the Society of Nematologists (SON), held July 9-14 in Columbus, Ohio:

• Alison Coomer Blundell, who will be a fourth-year doctoral candidate in Plant Pathology this fall, won first place in the three-minute student competition with her presentation on “Trade Offs Between Resistance Breaking and Fitness Cost in Root-Knot Nematodes.” She received a $250 award and a plaque.
  
  
• Ching-Jung Lin, who will be a fourth-year doctoral student this fall, won second place in the 12-minute category with her presentation on "Elucidating the Role of MigPSY Peptides in Interactions Between Plants and Root-Knot Nematodes." She received a $250 prize.
  
  
• The six-member Siddique lab team, "Meloidogyne Gang Gang," which included Blundell, Lin, third-year doctoral student Pallavi Shakya, and second-year doctoral student Veronica Casey, tied for second place in the Cobb Bowl, a jeopardy-like competition that can include both students and postdoctoral fellows on the teams.

The University of Idaho team, one of six teams competing, won the Cobb Bowl. The study material is based on six decks of nematode trading cards created by Jon Eisenback, professor in  Virginia Tech's School of Plant and Environmental Sciences. He also hosted the game as "SmartAlex EisenTrebeck." He asked questions in the form of an answer, such as:  

• Question: "The Guava root-knot nematode."
  Answer: "Meloidogyne enterolobii"
• Question: "First report of root-knot nematodes."
  Answer:"Who is Miles Joseph Berkeley?"

"The most difficult question, said team member Veronica Casey was: "The color of the first edition of the Journal of Nematology."

"The answer was simply, 'What is orange?' but many teams thought it was green," Casey related. "Another difficult question was 'The full species name of the Beech Leaf disease nematode.' The answer: "What is Litylenchus crenatae mccannii?"

Also at the SON meeting, Siddique participated in a session titled "Nematology Faces of the Future." In his five-minute self-introduction, he displayed a map showing how far he has traveled. A native of Multan, Pakistan, he 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. After serving as a research group leader for several years at the University of Bonn, Germany, he joined the UC Davis Department of Entomology and Nematology faculty in 2019 as an assistant professor and advanced to associate professor this year.

"Plant-parasitic nematodes are destructive pests causing losses of billions of dollars annually," Siddique says on his website. "Economic, health, and environmental considerations make natural host plant resistance a preferred strategy for nematode control, but there are limitations to this approach. In many cases, the resistance conferred by resistance genes is partial, and some of the nematodes are able to survive. Similarly, nematode resistance genes are often effective against only one or a few species, whereas plants are exposed to several pathogens in the field. Another concern is the emergence of pathotypes that can overcome resistance. In view of all these limitations, it is important to identify additional mechanisms and tools that can be used to develop novel and sustainable approaches to the management of nematodes."

The Siddique lab focuses its research "on basic as well as applied aspects of interaction between parasitic nematodes and their host plants. 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."

Perfect timing.

Today, during the 62nd annual international conference of the Society of Nematologists, being held July 9-14 in Columbus, Ohio, The Proceedings of the National Academy of Sciences (PNAS) published a UC Davis research team's important--and exciting--research paper on root-knot nematodes.

It's online at “Root-Knot Nematodes Produce Functional Mimics of Tyrosine-Sulfated Plant Peptides."

Basically, the researchers discovered that “both a harmful plant bacterium and a parasitic worm can mimic a plant peptide hormone to enhance their ability to infect plants.”

It's a joint project of nematologist Shahid Siddique, an associate professor in the Davis Department of Entomology and Nematology, and Siddique and UC Davis distinguished professor Pamela Ronald, a plant pathologist and geneticist in the Department of Plant Pathology and the Genome Center. They are the corresponding authors. Joint first-authors are Henok Zemene Yemer, formerly of the Siddique lab and now with Gingko Bioworks, Emeryville, and Dee Dee Lu of the Ronald lab.

It's like hijacking plant development to facilitate parasitism, according to Siddique.  “This finding showcases an amazing case of convergent evolution across three different types of organisms, revealing how diverse life forms can develop similar strategies for survival.”

The root-knot nematode, which threatens global food security, is a small worm-like organism that is a highly evolved obligate parasite, or an organism that cannot survive without its host. It is known to infest some 2000 crops worldwide. “These parasites have a remarkable ability to establish elaborate feeding sites in roots, which are their only source of nutrients throughout their life cycle,” the authors wrote.

“Root-knot nematodes are a major threat to various crops, including fruit trees and vegetables,” Siddique said. “In California, tomatoes, almonds, and walnuts are among the major hosts susceptible to root-knot nematode infection.”

Siddique and UC Davis distinguished professor Pamela Ronald, a plant pathologist and geneticist in the Department of Plant Pathology and the Genome Center, are the joint corresponding authors. Joint first-authors are Henok Zemene Yemer, formerly of the Siddique lab and now with Gingko Bioworks, Emeryville, and Dee Dee Lu of the Ronald lab.

Plant-parasitic nematodes (PPNs) are among the most destructive plant pathogens, causing an annual economic loss of $8 billion to U.S. growers and more than $100 billion worldwide, the authors said.

The team also included emerita professor Valerie Williamson of the former Department of Nematology; Maria Florencia Ercoli, postdoctoral fellow in the Ronald lab; Alison Coomer Blundell, a doctoral candidate in the Siddique lab; and Paulo Vieira of the USDA's Mycology and Nematology Genetic Diversity and Biology Laboratory, Beltsville, Md.

“Plant peptides containing sulfated tyrosine (PSY)-family peptides are peptide hormones that promote root growth via cell expansion and proliferation,” the authors explained. “A PSY-like peptide produced by a bacterial pathogen has been shown to contribute to bacterial virulence. Here, we discovered that PSY-like peptides are encoded by a group of plant-parasitic nematodes known as root-knot nematodes. These nematode-encoded PSY mimics facilitate the establishment of parasitism in the host plant. Our findings are an example of a functional plant peptide mimic encoded by a phytopathogenic bacterium (prokaryote) and a plant-parasitic nematode (an animal).”

The research involved gene expression analysis and parasitism of tomato and rice plants.

The project drew financial support from a collaborative grant awarded to Siddique and Ronald from the National Science Foundation's Division of Integrative Organismal Systems.

Siddique, a member of the UC Davis faculty since 2019, focuses his research on basic as well as applied aspects of interaction between parasitic nematodes and their host plants. “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.”

Ronald, noted for her innovative work in crop genetics, especially rice, is recognized for her research in infectious disease biology and environmental stress tolerance. Thomson Reuters named her one of the world's most influential scientific minds and Scientfic American recognized her as among the world's 100 most influential people in biotechnology. In 2022 Ronald received the Wolf Prize in Agriculture.

The next steps? “Currently, we are working to understand the mechanism by which these peptides contribute to the nematode infection,” Siddique said. “This entails the characterization of receptors involved and gaining insights into transcriptional changes.”

Ever heard of Carey's Equality?

Do you know who discovered it?

That would be UC Davis distinguished professor James R. Carey of the Department of Entomology and Nematology, who will present a departmental seminar at 4:10 p.m.  Wednesday, May 25, on "The Conceptual Sweep of a Mathematical Discovery in Insect Biodemography: From Medfly Populations to the U.S. Congress."

You can attend the seminar in person at 122 Briggs Hall, UC Davis campus, or access it via Zoom. The Zoom link is https://ucdavis.zoom.us/j/99515291076.

"Twenty years ago while attempting to develop a new concept for studying insect aging in the wild, I discovered a previously unknown mathematical identity now referred to in the formal demography literature as the eponym Carey's Equality—the age distribution of a stationary population equals the distribution of lifetimes yet to come," Professor Carey says in his abstract. "In this seminar I will present my attempts at both operationalizing the concept for study of populations of insects and other non-human species, and generalizing it for applications to groups with fixed numbers of members and where renewal involves birth and death processes."

"These general applications include data from a British cemetery, the National Basketball Association, the Baltimore Longitudinal Health Study, the U.S. Congress (both chambers) and the world population," said Carey, a member of the UC Davis Department of Entomology and Nematology faculty since  1980.  "After discussing implications and extensions of the identity, I will wrap up with descriptions of five simple but important demographic relations that all entomologists should know."

Highly honored for his research, teaching and public service, Carey served as the principal investigator of a 10-year, $10 million federal grant on “Aging in the Wild,” encompassing 14 scientists at 11 universities. 

Biodemography Textbook. In 2020, he and Deborah Roach, professor and chair of the University of Virginia's Department of Biology, co-authored a 480-page textbook, Biodemography: An Introduction to Concepts and Methods, published by Princeton University Press  and hailed as the “definitive textbook for the emerging field of biodemography, integrating biology, mathematics and demography.” Carey recently created a free-access, video guidebook with a playlist of 175 separate presentations, subtitled in 300 different languages. He storyboarded the script, turned graphs, schematics, tables and equations into animated slides,  and then with teleprompter assistance, narrated and video-recorded the 175 presentations, which span 12 hours of viewing. It appears on UC Berkeley Population Sciences website at https://bit.ly/3FTge7u.

An internationally recognized teacher, Carey won a 2018 global award in the Robert Foster Cherry Award for Great Teaching Program, an academic competition sponsored every two years by Baylor University, Waco, Texas. He received the 2015 Distinguished Achievement in Teaching Award from the Entomological Society of America (ESA) and the 2014 Distinguished Teaching Award from the Pacific Branch of ESA. The UC Davis Academic Senate honored him as the recipient of its 2014 Distinguished Teaching Award, given to internationally recognized professors who excel at teaching.

Carey is a fellow of four organizations: American Association for the Advancement of Science, Entomological Society of America, California Academy of Science and the Gerontological Society of America. He holds a doctorate in entomology (1980) from UC Berkeley, and two degrees from Iowa State University: a bachelor of science degree in animal biology (1973) and a master's degree in entomology (1975).

Nematologist Shahid Siddique, assistant professor, UC Davis Department of Entomology and Nematology, coordinates the spring seminars. He may be reached at ssiddique@ucdavis.edu for any technical issues regarding Zoom. (See complete list of spring seminars.)