Nature’s warriors: How rice plants detect and defend against viral invaders
Peking University
Peking University, March 20, 2025: A groundbreaking study led by Li Yi, professor at the School of Life Sciences, was published in Nature on March 12, titled “Perception of viral infections and initiation of antiviral defence in rice”, uncovering a molecular mechanism by which rice cells perceive viral infections and initiate antiviral response, which significantly contributes to understanding of virus-host interactions for further disease resistance breeding.
Why it matters:
Viruses affecting rice, a staple food for more than half of the world population, pose persistent threats to crop production and could severely undermine global food security. Though recent discoveries have revealed how rice plants mitigate such threats by initiating immune responses against insect-borne viruses, the molecular mechanism by which plant hosts perceive viral infections and initiate defense remains elusive.
Key Findings & Methodology:
The research team introduced viruses to rice plants via insect vectors, employing natural infection methods that mimic real-world agricultural conditions to provide more accurate insights into plant-virus interactions.
The study uncovered a complete antiviral immune pathway that sets off the following reactions in the plant’s immune system:
1. Perception and recognition of viral coat proteins mediated by RBRL;
2. Degradation of jasmonic acid(JA) signaling pathway repressors;
3. Activation of RNA silencing core protein AGO18 expression via the jasmonic acid signaling pathway;
4. Upregulation of a synergistic defense mechanism involving AGO18-mediated RNA interference and reactive oxygen species (ROS), which strengthened the plant’s ability to fend off the virus.
Other key findings include:
1. The RING1-IBR-RING2 type ubiquitin ligase(RBRL) in rice can not only recognize the coat protein (CP) of the Rice stripe virus (RSV) but also the coat protein P2 of the Rice dwarf virus (RDV).
2. Further research indicates that the RSV CP not only induces an upregulation of RBRL expression but also activates the ubiquitin ligase activity of RBRL. This, in turn, promotes the ubiquitination and degradation of the jasmonic acid signaling pathway repressor NOVEL INTERACTOR OF JAZ 3 (NINJA3) mediated by RBRL, thereby activating the jasmonic acid signaling pathway in rice.
Significance
The discovery made by Li Yi's team, combined with their previous research findings, has elucidated a core antiviral pathway in rice. This pathway encompasses the entire chain of processes from the perception of viral infection by rice cells to the activation of the antiviral immune mechanisms in rice. This research represents a milestone in plant virology and crop science, bringing researchers closer to developing a multi-target strategy for antiviral breeding of crops.
*This article is featured in PKU News' "Why It Matters" series. More from this series.
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Written by: Yang Yimeng
Edited by: Wu Jiayun, Chen Shizhuo
Source: PKU News (Chinese)
Journal
Nature
Article Title
Perception of viral infections and initiation of antiviral defence in rice
Article Publication Date
21-Mar-2025
Guardians of the vineyard: Canines and chemistry work to combat powdery mildew
American Chemical Society
SAN DIEGO, March 23, 2025 — Dogs have many jobs but one you may not expect is identifying grapevines coated in a destructive and highly contagious fungus. Although dogs can detect serious vine infections by smell, scientists don’t know exactly what odor molecules are triggering the response. Researchers are now analyzing volatile chemicals emanating from grape leaves infected by a fungus called powdery mildew with the goal of improving training for vineyard canines.
Nayelly Rangel, a graduate student at Texas Tech University, will present the team’s results at the spring meeting of the American Chemical Society (ACS). ACS Spring 2025 is being held March 23-27; it features about 12,000 presentations on a range of science topics.
“Powdery mildew is one of the most contagious diseases that affects grapevine plants,” says Rangel. “It reduces plant growth, fruit quality and quantity, and it can lead to a decline in wine quality.”
The current method to identify an infection relies on humans looking for tell-tale patches of grey powder along plant leaves. But, by then, the condition is usually serious and requires large amounts of fungicide to eradicate. Past research showed that dogs can identify powdery mildew by smell. But not much is known about the chemistry of what these animals smell, or whether the plants’ odor profile changes as the infection progresses.
“Our four-legged friends don’t talk, so we’re trying to understand what they are encountering when they’re sniffing,” says Paola Prada-Tiedemann, a professor of forensic science at Texas Tech University who is leading the study. So, the researchers set out to identify which volatile organic compounds, or airborne scents, grapevine leaves give off at different stages of powdery mildew infection.
First, the team needed a technique that would keep leaf samples intact for dog training. So, they placed a leaf inside a vial and inserted a tiny absorptive fiber into the vial to pick up chemicals from the air above a leaf. From there, the researchers characterized the volatile organic compounds (VOCs) stuck to the fiber by inserting it directly into a gas chromatograph-mass spectrometer.
“Our approach is unique because we’re testing the exact location where a canine sniffs the grape leaf,” says Rangel. “So, we’re analyzing the same airspace in both scenarios, whether we’re in the chemistry lab or the canine lab.”
So far, the team has optimized their process from the VOCs emitted from healthy leaves. Initial results from comparisons of healthy and fungus-impacted grapes revealed that the baseline odors emitted from healthy leaves include more acidic odor compounds than sick ones. In fact, healthy leaves released fewer vapors over time, says Rangel, in contrast to sick leaves that expelled more VOCs as the infection grew.
Next, the researchers will analyze the chemical composition of what’s wafting off the leaves at different stages of infection. Once they’ve identified a few key molecules, they will present each one individually to the canines, measure the animals’ responses to each, and test the smallest amount needed for detection. Like how certain scents, such as vinegar’s, are strong in small amounts, the researchers think that dogs may pick up on certain VOCs more easily than others. Using those compounds for training could enable more sensitive and accurate mildew identification, especially early-stage infections.
“The ultimate goal is to move away from the visual diagnosis of mildew to odor diagnosis as the gold standard,” says Prada-Tiedemann. “Even when we can’t see it ourselves, the dog sitting next to a plant can tell you with their nose, ‘uh oh, that vine’s starting to go.’”
By “bridging the canine to chemistry,” as Prada-Tiedemann says, the team wants to find a more efficient solution for protecting grapevines from a widespread and damaging disease. After all, she adds, “We all want good wine!”
The researchers report no external funding for this work.
A Headline Science YouTube Short about this topic will be posted on Sunday, March 23. Reporters can access the video during the embargo period, and once the embargo is lifted the same URL will allow the public to access the content. Visit the ACS Spring 2025 program to learn more about this presentation, “Evaluating chemical odor profiles of Vitis vinifera: Odor profiling for pathogen identification” and other science presentations.
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Title
Evaluating chemical odor profiles of Vitis vinifera: Odor profiling for pathogen identification
Abstract
Powdery mildew is a highly contagious fungal disease that can target a wide variety of plants. Though this disease is rarely fatal, it can severely weaken the plant, reduce growth and fruit yield, and increase susceptibility to other diseases. This pathogen has risen in importance to viticulturists due to its impact on vineyards economy and fruit quality. There is an increasing need to develop more precise methods of disease identification to enhance current mitigation strategies. One such method involves the use of detection dogs. Biological detection dog training must adequately reflect what canines will encounter in the field, and to do so, research must be conducted not just to optimize training methods but to also understand the target odor source composition. Therefore, the goal of this research is to identify grapevine powdery mildew specific volatile organic compounds (VOCs) through the headspace analysis of healthy and infected plant leaves using solid-phase microextraction/gas chromatography-mass spectrometry. Targeted method parameters for headspace diagnostic applications included the optimization of the SPME fiber and extraction time to determine maximum extraction efficiency. Evaluating the VOC profiles of grape leaves as the infection progresses gives insight on characteristic volatile biomarkers, which can aid in canine detection training by providing an objective volatolomic approach on pathogen identification.
Triggering parasitic plant ‘suicide’ to help
farmers
UC Riverside research explores a new way to fight devastating weeds
University of California - Riverside
image:
UCR student Annalise Kane, co-first author of the study.
view moreCredit: Claudia Sepulveda/UCR
Parasitic weeds are ruthless freeloaders, stealing nutrients from crops and devastating harvests. But what if farmers could trick these invaders into self-destructing? Scientists at UC Riverside think they’ve found a way.
Across sub-Saharan Africa and parts of Asia, places already struggling with food insecurity, entire fields of staples like rice and sorghum can be lost to a group of insidious weeds that drain crops of their nutrients before they can grow. Farmers battle these parasites with few effective tools, but UCR researchers may be able to turn the weeds’ own biology against them.
This trick is detailed in the journal Science, and at its heart lies a class of hormones called strigolactones — unassuming chemicals that play dual roles. Internally, they help control growth and the plants’ response to stresses like insufficient water. Externally, they do something that is unusual for plant hormones.
“Most of the time, plant hormones do not radiate externally — they aren’t exuded. But these do,” said UCR plant biologist and paper co-author David Nelson. “Plants use strigolactones to attract fungi in the soil that have a beneficial relationship with plant roots.”
Unfortunately for farmers, parasitic weeds have learned to hijack the strigolactone signals, using them as an invitation to invade.
Once the weeds sense the presence of strigolactones, they germinate and latch on to a crop’s roots, draining them of essential nutrients.
“These weeds are waiting for a signal to wake up. We can give them that signal at the wrong time — when there’s no food for them — so they sprout and die,” Nelson said. “It’s like flipping their own switch against them, essentially encouraging them to commit suicide.”
To understand strigolactone production, the research team led by Yanran Li, formerly at UCR and now at UC San Diego, developed an innovative system using bacteria and yeast. By engineering E. coli and yeast cells to function like tiny chemical factories, they recreated the biological steps necessary to produce these hormones. This breakthrough allows researchers to study strigolactone synthesis in a controlled environment and potentially produce large amounts of these valuable chemicals.
The researchers also studied the enzymes responsible for producing strigolactones, identifying a metabolic branch point that may have been crucial in the evolution of these hormones from internal regulators to external signals.
“This is a powerful system for investigating plant enzymes,” Nelson said. “It enables us to characterize genes that have never been studied before and manipulate them to see how they affect the type of strigolactones being made.”
Beyond agriculture, strigolactones hold promise for medical and environmental applications. Some studies suggest they could be used as anti-cancer or anti-viral agents, and there is interest in their potential role in combating citrus greening disease, which is doing large-scale damage to citrus crops in Florida.
Scientists still have questions about whether the weed suicide strategy will work in real-world fields. “We’re testing whether we can fine-tune the chemical signal to be even more effective,” Nelson said. “If we can, this could be a game-changer for farmers battling these weeds.”
This research was supported by the NSF-funded Plants3D traineeship program, led by distinguished UCR professor and geneticist Julia Bailey-Serres. The program trains students to design original biology and engineering solutions to the projected problem of massive-scale global food insecurity.
“The program is so exciting because it helps students learn to use the most cutting-edge technologies to increase crop yields and nutritional value, while also helping themselves professionally,” Bailey-Serres said.
Journal
Science
Article Title
Evolution of interorganismal strigolactone biosynthesis in seed plants
Scientists witness living plant cells generate cellulose and form cell walls for the first time
In a discovery with potential practical applications, a team of Rutgers biophysicists, bioengineers and plant biologists capture first live images
Rutgers University
image:
Artistic rendering of cellulose biosynthesis with zoomed in view. Individual cellulose chains (dark brown) are synthesized by plasma membrane-bound (purple) cellulose synthase enzyme complexes (cream) and associate into elementary fibrils (light brown) that further assemble into a microfibril network, forming the main scaffold for the cell wall.
view moreCredit: Ehsan Faridi/ Inmywork Studio/ Chundawat, Lee and Lam Labs
In a groundbreaking study on the synthesis of cellulose – a major constituent of all plant cell walls – a team of Rutgers University-New Brunswick researchers has captured images of the microscopic process of cell-wall building continuously over 24 hours with living plant cells, providing critical insights that may lead to the development of more robust plants for increased food and lower-cost biofuels production.
The discovery, published in the journal Science Advances, reveals a dynamic process never seen before and may provide practical applications for everyday products derived from plants including enhanced textiles, biofuels, biodegradable plastics, and new medical products. The research also is expected to contribute to the fundamental knowledge – while providing a new understanding – of the formation of cell walls, the scientists said.
It represents over six years of effort and collaboration among three laboratories from differing but complementary academic disciplines at Rutgers: the School of Arts and Sciences, the School of Engineering, and the School of Environmental and Biological Sciences.
“This work is the first direct visualization of how cellulose synthesizes and self-assembles into a dense fibril network on a plant cell surface, since Robert Hook’s first microscopic observation of cell walls in 1667,” said Sang-Hyuk Lee, an associate professor in the Department of Physics and Astronomy and an author of the study. “This study also provides entirely new insights into how simple, basic physical mechanisms such as diffusion and self-organization may lead to the formation of complex cellulose networks in cells.”
The microscope-generated video images show protoplasts – cells with their walls removed – of cabbage’s cousin, the flowering plant Arabidopsis, chaotically sprouting filaments of cellulose fibers that gradually self-assemble into a complex network on the outer cell surface.
“I was very surprised by the emergence of ordered structures out of the chaotic dance of molecules when I first saw these video images,” said Lee, who also is a faculty member at the Institute for Quantitative Biomedicine. “I thought plant cellulose would be made in a lot more of an organized fashion, as depicted in classical biology textbooks.”
Cellulose is the most abundant biopolymer – large molecules naturally produced by living organisms – on Earth. A carbohydrate that is the primary structural component of plant cell walls, cellulose is widely used in industry to make a range of products, including paper and clothing. It also is used in filtration, trapping large particles more effectively and enhancing flow, and as a thickening agent in foods such as yogurt and ice cream.
“This discovery opens the door for researchers to begin dissecting the genes that could play various roles for cellulose biosynthesis in the plant,” said Eric Lam, a Distinguished Professor in the Department of Plant Biology in Rutgers School of Environmental and Biological Sciences and an author on the study. “The knowledge gained from these future studies will provide new clues for approaches to design better plants for carbon capture, improve tolerance to all kinds of environmental stresses, from drought to disease, and optimize second-generation cellulosic biofuels production.”
The work is the culmination of a childhood dream for Shishir Chundawat, an associate professor in the Department of Chemical and Biochemical Engineering in the Rutgers School of Engineering and an author on the study.
“I have always been fascinated by plants and how they capture sunlight via leaves into reduced carbon forms like cellulose that form cell walls,” Chundawat said, who plans to explore new ways to produce new, sustainable biofuels and biochemicals from diverse feedstocks like terrestrial plants and marine algae. “I remember back in middle school when I had collected many leaves of different shapes, sizes and colors for a science class report, and being very curious about how plants produce all this myriad complexity and diversity in nature. I was inspired by that experience to delve deeper into the fundamental phenomena of biomass production and its utilization using sustainable engineering to produce valuable bioproducts for societal benefit.”
Scientists from each of the three research teams made unique and critical contributions.
When conventional lab microscopes wouldn’t do, providing at best blurry images of the cell wall-building process, the team turned to an advanced super-resolution and minimally invasive technique called total internal reflection fluorescence microscopy. The approach, which captured images only of the underside surface of cells, was sensitive enough to take videos for 24 hours without bleaching and destroying the cells.
Lee, a biophysicist and an expert on using cutting-edge microscopy techniques to study living systems, developed a custom microscope for the project and oversaw the imaging efforts.
Chundawat led a team that pioneered a technique allowing the scientists to tag the emerging cellulose tendrils with fluorescent protein dye.
Chundawat is a bioengineer and expert on protein engineering and glycosciences, the study of complex carbohydrates such as cellulose. To make the cells fluorescent and detectable by the microscope, he and his team developed a probe derived from an engineered bacterial enzyme that binds specifically to cellulose.
Lam, an expert on plant genetics and biotechnology, and his team found a way to remove the cell wall of individual cells of Arabidopsis to create a “blank slate” for new cell walls to be laid down by protoplast cells.
“This provided little to no background cellulose to confound our visualization and tracking of newly synthesized cellulose under optimized conditions,” Lam said.
Other Rutgers scientists on the study included: Hyun Huh, a postdoctoral scientist with the Institute for Quantitative Biomedicine; Dharanidaran Jayachandran, a doctoral student, and Mohammad Irfan, a postdoctoral scientist in the Department of Chemical and Biochemical Engineering; and Junhong Sun, a lab technician in the Department of Plant Biology.
Animations for young students inspired to learn more about plants are available, however, the Rutgers study shows that the process of cellulose synthesis and cell wall formation is much more complex.
Artistic rendering of cellulose regenerating on a plant protoplast cell surface with zoomed out view. Cellulose is synthesized by plasma membrane-bound enzyme complexes (green) and assembles into a microfibril network (brown), forming the main scaffold for the cell wall.
Credit
Ehsan Faridi/ Inmywork Studio/ Chundawat, Lee and Lam Labs
Journal
Science Advances
Method of Research
Observational study
Subject of Research
Cells
Article Title
Time-resolved tracking of cellulose biosynthesis and assembly during cell wall regeneration in live Arabidopsis protoplasts
Article Publication Date
21-Mar-2025
