- Author: Kathy Keatley Garvey
How do they know?
Molecular biologist Adam Steinbrenner, an assistant professor of biology at the University of Washington, will explain his research at a UC Davis Department of Entomology and Nematology seminar on Wednesday, Feb. 23.
His public seminar, titled "Plant Immune Recognition of Insect Herbivores," will be both in-person and virtual. It begins at 4:10 p.m. (Pacific Time) in 122 Briggs Hall. The Zoom link is https://ucdavis.zoom.us/j/99515291076.
Steinbrenner and his team were the first to identify an immune recognition mechanism that sounds the alarm against chewing insects.
"From the moment of initial encounter with an insect herbivore, a suite of inducible plant defenses are triggered; however, the molecular mechanisms for recognition and response are not highly studied," Steinbrenner writes in his abstract. "Specific molecular patterns from insects can serve as elicitors of defense responses on host plants, but precise receptors mediating such responses have remained elusive. We recently identified a cell surface receptor, Inceptin Receptor (INR), which detects a set of ubiquitous peptide fragments found in the oral secretions of Lepidopteran larval herbivores. INR is specific to select legume species and may structure insect host range across this plant family. We hypothesize that INR serves as a recently evolved and highly potent mechanism to perceive a specific danger signal, above and beyond cues associated with generic tissue damage. I will discuss our recent transcriptiomic characterization of inceptin responses in bean and cowpea, highlighting strong anti-herbivore defense outputs which occur after inceptin treatment but not wounding alone. I will also compare plant responses to herbivory with well-characterized pathways mediating recognition of microbial pathogens.".
The Steinbrenner lab studies the molecular bases of plant immunity to pathogens and pests. "We are specifically interested in recognition and signaling functions of cell surface receptors and evolutionary processes driving novel immune specificity," he says on his website. He holds a bachelor of science degree in biology from Tufts University (2010) and a doctorate from UC Berkeley in plant biology (2015). He was awarded a Howard Hughes Medical Institute Postdoctoral Fellowship of $180,000 in 2016 and studied with Eric Schmelz at UC San Diego.
Steinbrenner served as the lead author of a paper published Nov. 23, 2021 in the Proceedings of the National Academy of Sciences on how cowpea plants detect that they're being eaten by caterpillars. In the article, A Receptor-Like Protein Mediates Plant Immune Responses to Herbivore-Associated Molecular Patterns, scientists from the University of Washington and UC San Diego reported that the cowpea plants harbor receptors on the surface of their cells that can detect a compound in caterpillar saliva and initiate anti-herbivore defenses.
"Despite chemical controls, crop yield losses to pests and disease generally range from 20-30 percent worldwide," Steinbrenner related in a University of Washington news release. "Yet many varieties are naturally resistant or immune to specific pests. Our findings are the first to identify an immune recognition mechanism that sounds the alarm against chewing insects.”
Wrote UW science writer James Urton: "The team showed that, in response to both leaf wounds and the presence of a protein fragment specific to caterpillar saliva, the cowpea's INR protein boosts the production of ethylene, a hormone that plants often produce in response to munching by herbivores and other types of environmental stress. The protein fragment in caterpillar spit that elicited this response, Vu-IN, is actually a fragment of a cowpea protein, which gets broken down by the caterpillar as it dines on cowpea leaves." (See full article.)
Nematologist Shahid Siddique, assistant professor, UC Davis Department of Entomology and Nematology, coordinates the Wednesday seminars. For any Zoom technical issues, contact him at ssiddique@ucdavis.edu.
- Author: Kathy Keatley Garvey
As part of the UC Davis Biodiversity Museum Month, the Santiago Ramirez lab, UC Davis Department of Evolution and Ecology, has created a 10-page Plant-Insect Interactions Coloring Book. If you access the pre-recorded programs activities section, you can download it for free, in either English or Spanish! (Or both!)
The coloring book is the work of Ramirez lab team members Molly Barber, Fernanda Guizar, Collin Gross and Jasen Liu. As you may know, Ramirez is a global expert on orchid bees (see Bug Squad blog) and a Chancellor's Fellow. His postdoctoral researcher Nick Saleh earlier presented a UC Davis Biodiversity Museum talk on the social behavior of bees, focusing on orchid bees.
But back to the coloring book. It's engaging. It's informative. It's entertaining. And it's a good opportunity to learn more about the science of plant-insect interactions and practice your coloring skills. You can stay within the lines or slip out a bit! It's your book!
The Ramirez team explains that orchids "are a big family with many, many plant species. Most of them have beautiful flowers that attract all kinds of pollinators. Some orchid flowers produce perfumes. The scent of these flowers attracts pollinators such as orchid bees. However, scent can also attract herbivores!"
For instance, the authors post an illustration of a weevil and explain: "This type of weevil is herbivorous, meaning it feeds on plant matter. Here you can see a weevil larva, the form the weevil takes just after they have hatched out of their egg. This larva is currently feeding on the inside of the Gongora orchid flower bud. Yummy!"
Another page: "Here you can see an example of a male and female weevil from this species. If you look closely, you will see that they have different looking trunks, also known as rostrums. This is an example of dimorphism, where individuals of the same species may follow one of two variations in body shape, size or color In this case, the male weevil has a shorter rostrum, while the female's rostrum is much larger. But I think both are equally cute!"
The authors point out that not all flowers reward their pollinators. They note that the California pipevine attracts fungus gnats by producing a smell similar to that of mushrooms.
You'll learn that flowers have "evolved ways to make sure that their pollinators are the only ones that can visit them. For example, nectar spurs (hollow modified petals) have evolved in many plant species that allow only pollinators with proper adaptations, such as long beaks or tongues, to reach the nectar at the bottom of the spurs."
Insects are the primary pollinators but they aren't the only ones. The authors draw attention to hummingbirds and bats. They provide an illustration of a Marcgravia. "The bats drink nectar from bowl-like nectaries hanging underneath the flowers and transfer pollen from their foreheads while they do so. The cup-shaped leaves above the flowers reflect the sonar of bats, allowing for them to easily hone in on the plants."
About UC Davis Biodiversity Museum Month
The 10th annual UC Davis Biodiversity Museum Month program is all virtual this year via live talks and demonstrations, and pre-recorded presentations. It's being celebrated throughout the month of February. The science-based event traditionally occurs on only one day--the Saturday of Presidents' Weekend, when families and friends gather on campus to learn first-hand about the UC Davis museums and collections. The 2020 event drew more than 4000 to the campus.
This year's biodiversity event is featuring 12 museums or collections:
- Anthropology Museum
- Arboretum and Public Garden
- Bohart Museum of Entomology
- Botanical Conservatory
- California Raptor Center
- Center for Plant Diversity
- Häagen-Dazs Honey Bee Haven
- Nematode Collection
- Marine Invertebrate Collection
- Museum of Wildlife and Fish Biology
- Paleontology Collection
- Phaff Yeast Culture Collection
For more information and the schedule, access these two formats on the UC Davis Biodiversity program website: (1) live talks and demonstrations and (2) pre-recorded talks and activities. Information on the biodiversity museum events also appear on social media, including Facebook, Instagram, and Twitter, @BioDivDay.
To help support the Biodiversity Museum event, contributions are being accepted through a month-long crowdfunding campaign program at https://crowdfund.ucdavis.edu/project/24310.
- Author: Kathy Keatley Garvey
But more about that later.
Community ecologist Laura Burkle, associate professor in the Department of Ecology, Montana State University, Bozeman, is keenly interested in plant-insect interactions, especially floral volatile organic compounds (VOCs).
She'll discuss her research on “The Implications of Variation in Floral Volatiles for Plant-Pollinator Interactions" at the UC Davis Department of Entomology and Nematology seminar from 4:10 to 5 p.m., Wednesday, Jan. 30 in 122 Briggs Hall, UC Davis campus. Hosts are pollination ecologist Neal Williams, professor in the UC Davis Department of Entomology and Nematology, and doctoral student Maureen Page of the Williams lab.
“One understudied pathway by which environmental conditions and climate change may influence plant-pollinator interactions is via shifts in floral scent and pollinator attraction,” Burkle says in her abstract. “We sampled the floral volatile organic compounds (VOCs), phenologies, and pollinator visitors from naturally growing plants in a montane meadow over three seasons. With these data, we aim to acquire a base understanding of the variation in floral VOCs within and among species and how floral VOCs and other plant traits may structure plant-pollinator interactions across the growing season and across years.”
How did Burkle interested in bees and pollination? “At the Rocky Mountain Biological Lab in Colorado,” she says.
“To be honest, in college I was enamored with marine biology, until I realized that I didn't like being continuously wet while doing field work. Plants I liked because they stayed put for observation (unless eaten by a deer or something)...my interest in bees followed later. Bees and pollination are great fair-weather friends, literally :) And I'm fascinated by the complexity of their interactions with each other.”
Burkle received her bachelor of science degree in biology and environmental studies in 2000 from Bowdoin College, Brunswick, Maine, and then headed to Hanover, N.H., for her doctorate in biology in Dartmouth College's Ecology and Evolution program. Her dissertation: “Bottom-up Effects of Nutrient Enrichment on Plants, Pollinators and Their Interactions.”
Burkle served as a postdoctoral research associate in the Department of Biology at Washington University, St. Louis, from 2008 to 2010, and then joined the Department of Ecology at Montana State University as an assistant professor in 2011. She advanced to associate professor in 2017. At Montana State University, Burkle has taught Principles of Biological Diversity, Plant Ecology, Community Ecology, Ecological Networks and Disturbance Ecology.
She has published her work in Plant Ecology, New Phytologist, Biological Reviews, and Nature Ecology and Evolution, among others. She was the lead author of the technical publication, "Climate Change and Range Shifts" in the North American Bumble Bee Species Conservation Planning Workshop Final Report, published in 2011.
Her 2019 publications include “Checklist of Bees (Hymenoptera: Apoidea) from Small Diversified Vegetable Farms in Southwestern Montana” in the Biodiversity Data Journal; “Dryland Organic Farming Increases Floral Resources and Bee Colony Success in Highly Simplified Agricultural Landscapes” in Agriculture, Ecosystems and Environment; and “The Effects of Post-Wildlife Logging on Plant Reproductive Success and Pollination in Symphoricarpos albus,” a fire-tolerant shrub, published in Forest Ecology and Management.