Simon "Niels" Groen, assistant professor of evolutionary systems biology, UC Riverside, will present a UC Davis Department of Entomology and Nematology seminar on "Plant Toxins and the Evolution of Host-Parasite Interactions" on Wednesday, Feb. 2.

He will speak in person at 4:10 p.m. in 122 Briggs Hall. For those unable to attend, his lecture also will be on Zoom; link to https://ucdavis.zoom.us/j/99515291076.

"Plants interact with incredibly diverse groups of animals including plant-feeding insects and nematodes as well as their natural enemies," Groen says in this abstract. "These interactions are influenced by toxic defensive chemicals that plants make. In my talk, I will focus on how plants evolved variation in production of these defensive chemicals and how animal parasites in turn evolved mechanisms enabling them to handle such toxins."

He recently authored an article in the journal Current Biology on "Convergent Evolution of Cardiac-Glycoside Resistance in Predators and Parasites of Milkweed Herbivores."

From EurekaAlert: "Scientists now understand how certain animals can feed on picturesque, orange monarch butterflies, which are filled from head to abdomen with milkweed plant toxins. In high enough concentrations, milkweed can kill a horse, or a human. To be able to eat this plant, monarchs evolved a set of unusual cellular mutations. New UC Riverside research shows the animals that prey on monarchs also evolved these same mutations. A Current Biology journal article describes the research that revealed these mutations in four types of monarch predators — a bird, a mouse, a parasitic wasp, and a worm."

Groen, who joined the UC Riverside faculty in July 2021 following his postdoctoral research position (2014 to 2021) in the Noah Whiteman laboratory, Department of Ecology and Evolutionary Biology, University of Arizona, focuses his research on "understanding molecular mechanisms of adaptation in the context of species interactions and fluctuating environmental conditions." 

A native of the Netherlands, he received his bachelor's degree and masters degree  in biology from Wageningen University,  Netherlands, and his doctorate in plant sciences from the University of Cambridge, UK.

Groen served as a visiting researcher from 2007 to 2008 in the Department of Multi-Trophic Interactions, Netherlands Institute of Ecology, and as a visiting researcher from 2008 to 2012 in the Department of Organismic and Evolutionary Biology, Harvard University. 

"Growing up in The Netherlands, I became fascinated with plants and their responses to ever-changing environmental conditions while working as a 'ziekzoeker' in tulip fields outside of school hours," he writes in an author profile on the American Society of Plant Biologists website. The site featured him as the first author of “Evolutionary Systems Biology Reveals Patterns of Rice Adaptation to Drought-Prone Agro-Ecosystems," published Nov. 15, 2021 in the journal Plant Cell.

"A 'ziekzoeker' looks for diseased plants and I searched in particular for variegated white and red tulips--the ones you'd recognize from a golden-age Dutch still life painting," Groen related. "I learned how these tulips are infected with an aphid-transmitted virus and during my PhD in the group of John Carr at the University of Cambridge, I would further investigate the molecular mechanisms of how virus infections would change plant interactions with aphids and pollinators. I was gripped by the role that plant defensive chemicals play in shaping species interactions and I continued to study these as a postdoc with Noah Whiteman at the University of Arizona and the University of California, Berkeley.'

On the author page, he chronicled his previous work on the interactions between milkweeds and the monarch butterfly "and found out how the monarch evolved resistance to the cardenolide toxins that milkweeds make. While this work mostly revolved around a single gene of large effect, typically several or many genes are involved in organisms' evolutionary responses. As a Gordon and Betty Moore Foundation fellow in the group of Michael Purugganan at New York University, I learned about the latest developments in evolutionary genomics and systems biology while investigating patterns of natural selection on gene expression in rice populations that we grew under wet and dry field conditions with our collaborators at the International Rice Research Institute in The Philippines."

"The current paper (Plant Cell) is a culmination of this research," Groen related. "We found that under field drought rice plants do not just respond to changes in water availability, but also to concomitant changes in abundance of soil microbes that they interact with. As assistant professor in the Department of Nematology at the University of California, Riverside, I will continue to study rice and milkweed as well as plants from the nightshade family and look at the complex evolutionary tug-of-war between these plants and parasitic nematodes. Combining laboratory and field experiments, we will zoom in on the central role that plant chemicals play by using approaches from evolutionary and systems biology like the ones we describe in our paper."

Nematologist Shahid Siddique, assistant professor in the Department of Entomology and Nematology, coordinates the winter quarter seminars. He may be reached at ssiddique@ucdavis.edu for any technical issues involving the Zoom connection.

UC Davis second-year doctoral student Alison Coomer is now a global champion.

Coomer, a member of the laboratory of nematologist Shahid Siddique of the UC Davis Department of Entomology and Nematology, just won a world-wide competition sponsored by the International Federation of Nematology Societies (IFNS) for her three-minute thesis on root-knot nematodes.

She delivered her video presentation virtually on “Trade-Offs Between Virulence and Breaking Resistance in Root-Knot Nematodes.” She will be awarded a busary and plaque at the 7th  International Congress of Nematology (ICN), set May 1-6 in Antibes, France. 

Coomer earlier was selected one of the nine finalists in the 22-participant competition, vying against eight other graduate students from the University of Idaho, Moscow; and universities in England, Australia, Brazil, Ireland, Kenya, Belgium and South Africa. 

"Our entire lab is glad for Alison winning this award," said Siddique. "This is an outstanding performance and Alison has really been working hard for that. I feel proud about it. I am also looking forward to Alison's presentation at ICN."

Judges announced that Rhys Copeland of Murdoch University, Australia, won second, and Laura Sheehy of Liverpool John Moores University England,  scored third. They also will receive busaries and plaques at the 7th  International Congress of Nematology. (See the nine finalists' presentations on this site.)

Copeland discussed "Determining the Spatial Distribution of Pratylenchus quasitereoides/Pratylenchus curvicauda in the WA Wheatbelt, and Understanding How They Find Host Roots."

Sheehy's topic: Improving the Biological Control of Slugs: Understanding the Genome of Parasitic Nematode Phasmarhabditis hermaphrodita."

IFNS hosts the competition, IFNS 3-Minute Thesis, "to cultivate student academic and research communication skills, and to enhance overall awareness of nematodes and the science of nematology."

The competition began with 22 participants. Each was required to present only a single static slide, and not use any props or sound-effects. In the finals, a panel of judges--six nematologists and three non-experts from other areas of plant sciend science--scored them on the quality of their research presentation, ability to communicate research to non-specialists, and the 3MT slide. 

In her presentation, Coomer began with: “Root-knot nematodes, specifically the MIG-group, consisting of Meloidogyne incognita, javanica, and arenaria, are the most damaging of the plant parasitic nematodes causing severe yield loss in over 2,000 different plant species including tomatoes. The Mi-gene, which is a resistance gene in tomato, has been used in commercial farming and has been praised for its effectiveness towards the MIG group. This gene has been cloned but the mechanisms of how it's resistance works is still unknown.” 

“We do know that with the presence of the MI gene, plants are more durable and will restrict infection and reproduction, by inducing an immune response within the plant,” Coomer pointed. “Although this resistance gene has been reliable for many decades, resistance breaking strains of root-knot nematodes have emerged threatening the tomato industry.” 

Coomer related that her research “compares two strains of the root-knot nematode M. javanica. One strain is the wildtype, which has been isolated from fields, we will refer to it as VW4. This nematode can infect tomato plants, but when the MI gene is present, the nematode is blocked from successfully infecting. The other strain is a naturally mutated version of VW4. This strain breaks the resistance provided by the MI gene and therefore infects plants that contain the MI gene. I have labeled this strain as VW5. With the help of research like mine we can stay ahead of the resistance breaking strains and prevent major crop loss in the future.” 

“Sequencing the entire genome of VW5 when compared to VW4, we can see that there is a large deletion in its genome, but we have yet to find out what genes were deleted and how important they are when it comes to infecting other plants,” she continued. “My research is focusing on what happens when we infect the resistance breaking strain, VW5 on plants not containing the MI gene.” 

In detailing her research, she said “My infection assays have been designed as displayed by the flow chart. Tomato and cucumber were used since neither variety contained the MI gene. 500 J2s were inoculated and at 34 days post inoculation, roots were harvested, and eggs were collected. After staining, galls were dissected, and nematode stage development was recorded for juveniles and females; comparisons between the two roots were made. As displayed by the graph and image, consistently, we see a reduction in the number of eggs produced in plants infected with VW5 than with VW4. The image also shows significant reduction in galls for VW5s as well. Two main objectives remain for this project: How does VW5 break MI resistance and why is VW5 less fit on plants that do not contain the MI gene. With the help of further infection assays and genomic data regarding gene presence and transcription analysis we hope to shed light on this process, identify candidate genes in action, and overall identify how the mechanism of the MI gene works.”

Coomer, a doctoral student in plant pathology with an emphasis on nematology and advised by Siddique, is working on her dissertation, "Plant Parasitic Nematode Effectors and Their Role in the Plant Defense Immune System."

Coomer, originally from the St. Louis, Mo., area, received two bachelor degrees--one in biology and the other in chemistry--in May 2020 from Concordia University, Seward, Neb., where she won the Outstanding Graduate Student in Biology Award. She served as a biology lab assistant and taught courses in general biology and microbiology. 

As a biological science aide/intern, Coomer did undergraduate research in the Sorghum Unit of USDA's Agricultural Research Service. Lincoln, Neb.  Her work included collecting, prepping and analyzing DNA, RNA and proteins to identify genes that contribute to an under- and over-expression of lignin in sorghum plants. 

The UC Davis Department of Nematology's winter quarter seminars will  take place on Wednesdays at 4:10 p.m., beginning Jan. 5 and continuing through March 9, announced seminar coordinator and nematologist Shahid Siddique, assistant professor.  

Both in-person and virtual seminars will be broadcast via Zoom at https://ucdavis.zoom.us/j/99515291076. The in-person seminars will be in 122 Briggs Hall.

For technical issues, Siddique may be reached at ssiddique@ucdavis.edu.

The schedule: