plant immune system

#IAmScience: Mengran Yang

April 29, 2022 By Penquite, Cara (MU-Student) in #IAmScience Tags: Arabidopsis, plant immune system, plant science

By Cara Penquite | Bond LSC

Mengran Yang sat perched on a stool too tall for the cart of lush green tobacco plants in front of her. Behind towering shelves of lab equipment, she hunched over the plants and steadily pricked each leaf with a syringe.

Yang works with Arabidopsis and tobacco plants to learn about plant immune systems as a postdoctoral fellow in the Gary Stacey lab. Her research focuses on signals plant cells send to coordinate a fight against pathogens.

“I think it’s very interesting to see how plants can defend against the pathogens,” Yang said.

20220421_YangIAmScience_1 — Mengran Yang infiltrates the leaves of tobacco plants with a syringe. While her work mostly focuses on Arabidopsis plants, Yang also uses tobacco plants as a tool in her research since it is convenient to express the correct target proteins in their leaves. Photo by Cara Penquite | Bond LSC

Just like humans have immune cells that fight germs, plants have a network of cells and signals to deal with harmful microbes. This system is particularly important for plants since they are rooted in place and cannot avoid the attackers in their environment.

The plant immune system protects it both inside and outside its cells. Proteins inside the cell can recognize molecules from invaders and trigger an immune response, and the second — the part Yang’s research focuses on — uses receptors on the surface of the cells to recognize molecular patterns from microbes to signal for the plant to get rid of the pathogen.

“Our lab is focused on the extracellular ATP signaling pathway,” Yang said. “ATP, as maybe everyone knows, is an energy source, but we found it can also be a signal when it is released to the extracellular matrix, where it is referred to as extracellular ATP.”

Yang’s work with the lab started when she moved from China to Columbia for her postdoctoral research at Mizzou. Although originally drawn to the lab because of Stacey’s prominence in the field of plant immunity and signaling, Yang stays because of the community within the lab.

“Our lab is very international — some people are from China, Korea, Brazil, Vietnam and India,” Yang said. “A lot of the same-aged girls will go out for fun.”

This community stems from Stacey’s emphasis on the team’s collective success.

“You try to develop an esprit de corps in the lab where people care about each other’s success,” Stacey said. “They’re taking care of themselves, but at the same time, they care about other people’s success.”

Becoming a good researcher started with strong academics, and Yang remembers being the top of her class in biology, physics and math in middle school and high school. When she started her studies at the university level she followed her growing interest in biology.

Growing up with her twin sister in China, Yang recalls societal pressures to fill any spare time with more study. Her parents thought her teachers gave too much homework and pushed back on this expectation.

“My father thinks this kind of education is not good, he thinks you need to promote your efficiency and not just work hard,” Yang said. “You need to study smart, not just hard, and I think my dad influenced us a lot.”

Yang applies this mentality to her research and is supported by Stacey who encourages her to plan experiments and life goals.

“While I was a Ph.D. student, I spent the most time in the lab for fun,” Yang said. “But now I’m good at scheduling stuff, so I schedule my experiments at least a week ahead.”

DSC_9057 copy — Mengran Yang shows a dish with Arabidopsis plants. Yang’s work primarily focuses on studying extracellular ATP in Arabidopsis plants. Photo by Cara Penquite | Bond LSC

Stacey works with Yang to ensure her future impact as a researcher. When picking a project, Stacey guides his researchers towards projects with lots of potential.

“That’s the kind of discussion I have with people, what’s the best project for them where they have the chance to make an impact,” Stacey said.

With her lab mates and other research labs, Yang collaborates to strengthen each other’s weaknesses. If she does not have experience with an experiment, Yang asks other postdoc students with more experience for help with her project. When she publishes her research, she makes sure to give credit to the other students who helped her.

“In Chinese, ‘shuangying’ means ‘good to both sides,” Yang said. “That’s very common. You will read a paper, and you can also see most [papers] have a lot of authors there. That’s the cooperation.”

After finishing her research in the U.S., Yang plans to return to China to continue doing what she loves — research.

“I want to have my own lab in China,” Yang said. “It’s difficult, I know, but it’s my dream.”

Defense or growth: a complicated balance

April 7, 2021 By Lauren Hines in Research Tags: gene expression, plant immune system, plant science, TOPLESS gene family

By Lauren Hines | Bond LSC

The plant immune system isn’t active all the time. Plants must decide to either defend against disease or grow, but not simultaneously.

The reason behind this process is not fully understood, and the Walter Gassmann lab at Bond Life Sciences Center is searching for answers.

The lab recently found a link between members of the TOPLESS gene family, the immune receptor SNC1 and a negative regulator SRFR1. The relationship revealed when members of the gene family are absent in a plant, the immune system intensifies, and growth is stunted. The findings were published in February in the journal PLoS Genetics.

“As scientists, we try to simplify a model but sometimes the more we know, the more complicated we realize it to be,” said Jianbin Su, a research scientist in the Gassmann lab.

The study focused on TPR2 and TPR3, two genes within the TOPLESS family.

After studying these two genes, Gassmann said they did not act as he expected when partnered with SNC1. It turns out the genes act as “brakes” so then the immune system doesn’t go on forever.

“If you were to keep stimulating a plant with pathogens, you would see reduced growth over the long term,” said Gassmann, director of Bond LSC. “Plants have to balance whether they grow or if they defend, but we can artificially remove genes in the repertoire of a plant so that the immune system is on all the time from the get-go, and that manifests itself as stunted growth.”

This balance is the main obstacle facing researchers who want to increase crop yield and resistance to disease. Technically, researchers could increase the level of resistance in plants today but increasing the defense system often costs too much growth and yield.

Instead, the Gassmann lab proposes to modify the natural regulation of the plant’s immune system and bypass artificially increased resistance like pesticides.

“In the end, we would like to be able to generate crop plants that are more resistant to a wide swath of pathogens once we understand their regulatory system better,” Gassmann said.

Now, all the Gassmann lab needs to do is figure out how the system works. Easier said than done.

However, there are theories as to why the plant must choose between growth and defense. Previous theories believe there isn’t enough energy for plants to defend and grow at the same time. Gassmann said the theory doesn’t make a lot of sense to him. Even though the plants at Bond LSC are “pampered” and live in a “luxurious environment,” they stop growing whenever their immune systems are stimulated.

“I think evolutionarily, it is an advantage for plants to have a genetic circuit that makes them decide whether to grow or to defend themselves,” Gassmann said. “So, it’s not an energy limitation. It is genetic pathways that we can study to understand how that recognition works. And if there’s a genetic circuit, then we can tweak it and improve on it.”

Even with these theories, there’s more to this system than just genetics. While TPR2 and TPR3 interact with the immune receptor SNC1 and a negative regulator SRFR1 — a molecule that puts a stop or pause on a cellular process — that doesn’t mean their proteins interact in the cell.

“In terms of protein-protein interaction, many people think, ‘Oh it’s just as we interact physically,’ but actually, the cell is alive,” Su said. “In microscopes, they are moving. Sometimes the protein interaction needs a trigger to induce the protein-protein interaction.”

This interaction at the protein level still needs to be further analyzed, but it can explain why both SRFR1 and TPR2 must be absent for the plant to stop growing and be smaller.

“We think they actually work at different points in the circuit, and that’s why you get an additive effect on plant growth,” Gassmann said. “We’d be really interested to find out what those points are exactly, so there’s always more work to be done.”

While the Gassmann lab has found a new interaction revealing a bit more of the plant immunity process, there is still more to understand.

“Knocking out SRFR1 causes smaller plants, but the more accurate mechanism is still, I think, largely unknown,” Su said. “These genetic interactions with TPR2 are just one part of SRFR1 as a negative regulator in plant immunity.”

Bond LSC Researchers Named Most Highly Cited for 2020

January 26, 2021 By Lauren Hines in Research Tags: Highly Cited Researchers, plant immune system, reactive oxygen species

Bing Yang and Ron Mittler — Bond Life Sciences Center principal investigators Bing Yang (left) and Ron Mittler (right) are pictured above. | photos by Erica Overfelt, Bond LSC.

By Lauren Hines | Bond LSC

Building onto previous knowledge is a pillar of the scientific process, and citations in research do just that.

This makes recognition of Bond Life Sciences Center principal investigators Ron Mittler and Bing Yang, as well as Mizzou biochemistry professor Shuqun Zhang in the Highly Cited Researchers list for 2020, an important acknowledgment.

“I’m glad to have this, and this is the second year [I have been on the list],” Yang said. “If you have your paper widely read by other researchers and actually cited, it’s relevant to the rest of the field, or to the community. We always talk about the impact of your research to the community and the impact of the research on science.”

Yang studies the resilience and susceptibility of disease in crops, specifically rice. The Bing Yang lab also strives to develop genome editing technology to discover and improve traits in rice, like disease resistance.

“It’s significant because we create some useful tools and develop technology, so then other people or the community can use it,” Yang said. “We also work on the bacteria and disease, which can help the small farmer, help the grower of the rice to fight the disease and make the rice more productive.”

On the other hand, Mittler’s research focuses more on how reactive oxygen species (ROS) helps regulate systemic signaling in plants. ROS are reactive molecules that perform chemical reactions easily. While these molecules destroy cells with these reactions, they can also send widespread messages and regulate many essential processes.

Understanding ROS – and building upon the knowledge of ROS – can help researchers genetically modify crops to withstand more environmental stresses in the future.

With some luck and most of 2021 ahead, Mittler, Yang, Zhang and others will continue their pursuit of discovery and expand the shared knowledge base of science for the future.

To learn more, read some of Bing Yang and Ron Mittler’s most cited work. The Highly Cited Researchers List is compiled by Clarivate’s Web of Science.

Bond LSC Alumnus Celebrates Black Botanists Through Social Media Initiative

January 22, 2021 By Lauren Hines in Research Tags: #BlackBotanistsWeek, plant immune system

By Lauren Hines | Bond LSC

It seems most people grow out of bombarding their parents with millions of questions. However, plant biologist Morgan Halane never could shake the habit.

Such boundless curiosity could not be contained to just one man. Halane has reached out to other Black students and botanists through cofounding the social media initiative #BlackBotanistsWeek.

However, his path didn’t begin until he was an undergraduate at the University of Missouri when he found a subject that had more questions than he could ask.

“I was really close to joining an HIV lab, actually,” Halane said. “Then, Walter Gassmann at the Bond Life Sciences Center sent me an email, and we were talking about plant immunity and plant immune systems. It was something that I hadn’t really thought about, and I wanted to learn more… I was thinking more about the human immune systems like cold, flu, HIV and those diseases, but wasn’t really thinking that much about a plant getting sick.”

While Halane left Mizzou after receiving his Ph.D. in 2017, he’s recently spent time spreading his curiosity and the gospel of botany. Shortly after a confrontation in Central Park in New York between Christian Cooper and Amy Cooper in May 2020, a social media initiative called #BlackBirdersWeek emerged.

Halane’s friend Tanisha Williams and he decided to adapt the idea to highlight their passion.

Williams and Halane cofounded their own initiative called #BlackBotanistsWeek. From July 6 to July 11, the initiative encouraged people of color in botany to post about their work and stories about needing diversity in the field.

“It was basically a way to make Black botanists more visible to the world,” Halane said. “I got a lot of emails and messages, and we were really happy to get that support.”

However, Halane’s outreach work didn’t stop in July. In November, he hosted an online lecture in partnership with the Ohio Holden Gardens, which touched on topics from navigating nontraditional scientific careers to being Black in the field of science and the systemic racism and unconscious bias that comes with it.

Halane started in botany at Mizzou when he joined the Walter Gassmann lab as a freshman in 2012. During that time, he analyzed how the immune system of the model plant Arabidopsis functions and is regulated.

“That’s where he really excelled, and he is just very conscientious and precise and meticulous in how he does things,” said Gassmann, interim director of Bond LSC. “He had a whole project to himself that ended up being in a paper in Science fairly quickly, so that’s a huge success by our standards. He stood out as being just really a good student and quick learner.”

After Bond LSC, Halane took a more nontraditional career track, opting to follow wherever his curiosity took him. After working in labs in Korea and California, he worked in the public and private sectors of science with the National Parks Service and a non-profit called Aanika Biosciences.

In the Holden lecture, Halane discussed how the traditional scientific career path is defined by white scientists and the belief that non-conformity to the traditional path disproportionally harms Black scientists.

Halane encourages white scientists in leadership positions to help solve systemic racism in academia instead of appointing Black scientists to do the work. Halane also says these leaders should amplify Black scientists’ concerns and not minimize them. White leaders in science should also understand that a single Black scientist is not representative of Black people as a whole.

“A lot of things that are happening with systemic racism and unconscious biases in the scientific community are also happening in our society in general,” Halane said. “If we can focus on solving those problems in our bubble, I think that will positively affect the other bubbles out there in society also. Doing what we can here will then hopefully ripple out.”

After finishing his most recent project with the National Parks Service, Halane is unsure of what his next steps are. His next position though, whether it’s in academia or the non-profit sector, will have to be challenging enough to keep him asking questions.

“Sometimes just being a Black person doing science in a visible way is actually [outreach] even though you’re not actively focused on outreach,” Halane said.

Contributors to #BlackBotanistsWeek include Tanisha M. Williams, Nokwanda P. Makunga, Georgia Silvera Seamans, Rupert Koopman, Maya Allen, Morgan Halane, Brandi Cannon, Jade Bleau, Natasza Fontaine, Beronda L. Montgomery, Tatyana Soto and Itumeleng Moroenyane.

Morgan Halane is just one alumnus from Bond LSC. If you want to highlight other alumni, email Roger Meissen at meissenr@missouri.edu.

#IAmScience Leland Cseke

January 15, 2021 By Becca Wolf in #IAmScience Tags: plant immune system, plant science

By Becca Wolf | Bond LSC

In a cluttered basement in Dearborn, Michigan, one could find Leland Cseke conducting amateur plant tissue culture experiments on his family’s pool table as a child. These attempted experiments consisted of whatever he could find around the house, such as gelatin mix, items from his mother’s bathroom, and motors from his step-father’s work.

Now Cseke is the research lab manager in the Gassmann lab at Bond Life Sciences Center and has an actual lab to work in, with all the supplies he needs.

“I look back in amusement that I’m still kind of doing the same thing,” Cseke said. “I think I knew early on I was going to study plant sciences.”

Cseke’s passion for plant science grew in high-school, and after a short stint in community college, he went to Michigan Technical University (MTU) for his undergraduate degree.

“It is all the way up in the forests in the upper peninsula of Michigan,” Cseke said. “That’s where I met my first really influential advisor, Gopi Podila. He had a lab there and he was interested in environmental issues dealing with how soil fungi interact with trees — how trees develop and how humans use them — which made a real impact on me.”

After he graduated from MTU, Cseke went on to receive his graduate degrees from the University of Michigan in plant physiology and molecular biology. Here, he studied how the activation or deactivation of a single scent gene over evolutionary time controls what pollinators come to flowers.

For his postdoc, he decided to go to the University of Arizona, to experience a different climate and to study plant post-transcriptional gene silencing. He used methods in plant transformation in dicots and monocots, which helped lead to new RNAi technologies.

RNAi is the biological process that dials down the level of a protein that evolved to protect cells from viruses.

Despite this, Cseke felt like something was missing.

“I had a great learning experience in Arizona, but their forests are not what we typically think of because they’re all thorny. Everything has thorns, even the softest looking plant is grabbing at you. I had a longing to get back to a ‘real’ forest. So, I decided to give Gopi Padilla a call,” Cseke said.

Turns out, Podila had a position for Cseke: assistant research professor. Along with teaching molecular biology and chemical principles of biology, Cseke conducted research on the molecular biology of aspen tree wood and flower development.

A few years later, Podila decided to move to the University of Alabama in Huntsville (UAH) and asked Cseke to follow.

“I went from the great white north to heat and humidity. At the time, I really thought that I would more likely end up living in Alaska more than Alabama, but Gopi asked me to go with him to run his lab,” Cseke said.

Alabama ended up being where Cseke laid down his roots. He spent more than 15 years teaching classes, conducting research, and authoring papers and books there. He even started a community garden to bring applied learning to more people.

“The community garden became a hands-on research plot for my class ‘People, Plants, and Environment.’ Students in biology and earth system sciences could come and learn about plant and soil biology through hands-on experiences. It was really helpful for the students to be out of the classroom to actually see the biology rather than just talk about it,” Cseke said.

Cseke and his graduate students worked on many environmental molecular biology projects dealing with beneficial plant/microbe interactions. He worked extensively with the USDA and the Department of Energy as well as the Argonne and Brookhaven National Laboratories.

Cseke’s interests have taken him to all seven continents, from Washington DC to work with government policies to Antarctica to see first-hand the effects of climate change.

Soon, Cseke became interested in permaculture. Unlike permafrost, permaculture does not have anything to do with frozen dirt. Permaculture is an environmental design science that is based on principles at work in nature to develop ecosystem solutions that result in regenerative systems that will last for centuries.

“When things are bad, you don’t want to talk about being sustainable. You always want to talk about the regenerative way to go,” Cseke said, “That term, ‘regenerative,’ is what motivates me.”

Cseke helped form a group of engineers interested in permaculture and correctly portraying the science behind regenerative design. They are developing a framework for designers to create systems that are biocompatible.

“We want the design framework to not only benefit humans, but the entire surrounding environment and ecosystems,” he said.

His work on regenerative design helped lead to the creation of the Institute for Integrated Regenerative Design, where Cseke remains a collaborator on weekly Zoom calls.

The move to Missouri and Bond LSC came in 2018 when he sensed a need to be closer to family. He now works on how plant pathogens interact with a plant’s immune system.

“Throughout my career, I’ve kept my ears and eyes open for where people are doing good science but also having a good life,” Cseke said. “Overall, I think that Mizzou is a great place and has a good community of not just plant scientists, but scientists across the board.”

He is excited about his future here.

“I am a lifelong student. I don’t like to assume that I truly understand anything because that inhibits learning,” Cseke said. “There’s so much complexity on the pathogen side that I didn’t even realize I didn’t know, and this makes me even more excited to pursue science.”

Plant vs. Pathogen

October 7, 2020 By Lauren Hines in Research Tags: plant immune system

Research scientist Jianbin Su studies the immune system in lettuce on the third floor of the Bond Life Science Center.

By Lauren Hines | Bond LSC

Scientist Jianbin Su’s research lately took him outside to look at patches of grass and cracks in sidewalks around Mizzou’s campus, searching for a subject in the wild. He found his subject in the form of wild lettuce.

That search can potentially help Su — a research scientist in the Walter Gassmann lab at Bond Life Sciences Center — better understand the immune system of lettuce and therefore protect it against diseases like Downy Mildew and Xanthomonas, which would increase lettuce crop yield.

Su’s paper under review about how the pathogen effector protein, AvrRps4, interacts with lettuce’s immune system will hopefully soon be accepted in the journal Molecular Plant-Microbe Interactions.

“Scientists in Florida are still focusing on lettuce resistance to Xanthomonas,” Su said. “If we can find a mechanism where lettuce recognizes our protein, this finding can be applied to make lettuce immune to Xanthomonas.”

Xanthomonas causes bacterial leaf spots and is a serious seed-borne disease that results in significant losses for the lettuce industry

To infect a plant successfully, the bacterium must inject 30 to 40 protein effectors, like AvrRps4, in the cell and interact with multiple plant cell functions at once to overcome the host. Effectors for a pathogen can bind to proteins that affect the biological activities of the plant, letting the disease invade the plant, suppress its immune system and allow Xanthomonas to survive.

However, when the plant cell’s receptors recognize the pathogen, it can trigger its immune response. To stop the pathogen from growing, the plant cell initiates a hypersensitive response by killing itself. If the plant can’t stop the pathogen, it will multiply and affect much larger areas of the leaf. This will ultimately destroy the plant tissue and cause the characteristic round, brown dead spots on the lettuce leaves.

“Plants can afford the hypersensitive response because their developmental program isn’t set in stone like in most animals,” said Walter Gassmann, interim director for Bond Life Sciences Center. “They can adjust their growth in real-time…so losing a leaf is not a big deal to a plant, not like us, losing a limb or something like that.”

Wild Lettuce Found on Campus — While studying lettuce immunity, research scientist Jianbin Su took photos of wild lettuce growing on campus. | photo contributed by Jianbin Su.

Once AvRrps4 enters the plant cell, it splits up into two parts: AvRrps4-C and AvRrps4-N. Some plants like flowers, tomatoes and melons only recognize the C part, but lettuce only recognizes the N part of the effector.

“The C part of AvrRps4 has been studied by many labs, and they’ve already found some mechanisms,” Su said. “The C part attacks a group of important proteins that are required for plant immunity. That’s the function of the C part, but the function of the N part is not clear. That’s what I’m focusing on in lettuce.”

Recognition is important because, without it, plant cells can’t respond to fight off the pathogen.

Su is studying lettuce not only because it hasn’t been studied as much, but so far, it’s the only plant that requires recognition of both parts to initiate immunity.

This means lettuce evolved to recognize and attack AvRrps4-C. In turn, the effector evolved by adding a second part to prevent recognition by plants.

This evolutionary choice, if you will, is odd. Instead of getting around the immune response by getting rid of the protein that is recognized, the protein added a second part to itself. This means AvRrps4-N, the original part, must possess a vital function for the pathogen worth keeping.

“That’s why we think this effector arose in nature,” Gassmann said. “It’s because the first part triggered a very strong immune response, something else got tacked on to it to weaken that immune response to give the pathogen a leg up.”

This evolutionary battle can be seen in Mizzou’s very own backyard. Su found five different types of wild lettuce. After testing if the types were able to recognize the N part of the effector, he found two of the five did.

Since some did and others did not, Su thinks the receptor for recognizing the effector has been lost in some wild lettuce types due to evolution and the absence of the pathogen in certain areas.

“We haven’t found the lettuce receptor but based on this information we can narrow it down,” Su said. “Right now, we have 36 candidates. We are already sure that among the 36, there’s 99.999% that there is one receptor that recognizes our protein.”

Su still has much work left to do but, for now, he resubmitted his paper Oct. 5.

“Once we identify the receptors that recognize our protein, our research will go into the next direction, and maybe have some application purpose for our research,” Su said.

#IAmScience Christopher Garner

July 18, 2017 By Mary Jane Rogers in #IAmScience Tags: plant immune system, plant science

Emilia Asante #IAmScience — Christopher Garner, Ph.D, moments before his sucessful dissertation defense. | Photo by Mary Jane Rogers, Bond LSC

By Mary Jane Rogers | Bond LSC

“#IAmScience because I believe that the collective pursuit of scientific knowledge is what moves us forward as a species.”

In the time leading up to Christopher Garner’s dissertation defense, you never would have known if he was nervous. He was confident and composed, and the conference room at Bond LSC was completely filled with his professors, friends and well-wishers. Dr. Walter Gassmann gave a complimentary introduction to the dissertation, saying, “I don’t know if I’ve ever seen a student so prepared.” Needless to say, Garner passed with flying colors.

Garner completed his undergraduate degree at the University of Missouri, St. Louis. After graduating, he went to work on a small R & D team at a St. Louis company. That was his first experience with research and his mentor was influential in persuading Garner to go to graduate school. During graduate school at MU, Garner worked in Gassmann’s lab at Bond LSC, researching the inner workings of the plant immune system. His favorite part of working in the lab was constantly conducting new experiments.

“It’s really satisfying to make a prediction and then see it come true,” said Garner. “It can be equally exciting to see things are radically different than what you predicted.”

His dissertation – “Should I slay or should I grow? Transcriptional repression in the plant innate immune system” – focused on the tradeoffs between growth and defense that plants face when mounting an immune response. While the immune response is essential for the survival of plants in the face of pathogen infection, expression of defense-related genes can interfere with growth and development and must therefore be kept under tight control. His research identified a protein involved in preventing an overshoot of the immune system after it has been activated, thereby contributing new information to the field.

“If there is some way in which I can contribute to the pursuit of scientific knowledge, be it through research or teaching others about science, then I feel like I have done something worthwhile,” said Garner.

Congratulations on a successful defense, Chris!