Plant cell receptor balances signals from food and foe

Salk Institute plant biologists discover a receptor called SRF3 restores cellular iron balance and prevents immune overreaction, offering insights with potential applications in animal biology

Salk Institute

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

image: 

Wolfgang Busch (left) and Matthieu Pierre Platre (right) discovered a receptor called SRF3 restores cellular iron balance and prevents immune overreaction, offering insights with potential applications in animal biology.

view more 

Credit: Salk Institute

LA JOLLA (October 14, 2026)—Energy production in our cells, oxygen traveling in our blood, and immune cells fighting infection all depend on iron, an essential mineral that enters the food chain when plants absorb it from soil. But iron is often scarce—likely increasingly so as global weather and temperatures continue to change—and we aren’t the only ones that need it.

Microbes that live on and around plants also need iron. Plants are then forced to strike a delicate balance between using iron to defend themselves against microbes and retaining it to maintain health. New Salk research reveals a dual-purpose protein called SRF3, which both restores iron balance after microbial invasion and simultaneously ensures that the plant’s immune response is just right.

The study, published in Science Advances on October 14, 2026, and funded by both federal research grants from the National Institutes of Health and private philanthropy, provides crucial insights into plant resilience that could shape future agricultural efforts to feed a growing global population with nutritious crops.

Why are iron and immunity connected?

“Because plants are the main entry point for iron into our food supply, understanding how they control iron is important not only for plant health but also for agriculture and human nutrition,” says co-corresponding author Wolfgang Busch, PhD, a professor and holder of the Hess Chair in Plant Science at Salk.

Busch, alongside co-corresponding author Matthieu Pierre Platre, PhD, have been studying how plants control iron for a while. The two published a paper together in Nature Communications in 2022, in which they first identified SRF3 as mediating plant responses to microbes.

SRF3 lives on the surface of plant cells. There, it is firmly anchored in the plasma membrane, the cell’s outermost wall, where it can receive environmental cues and signals. The 2022 Salk study revealed that SRF3 could sense iron levels and direct root growth accordingly and suggested that the SRF3 protein is also involved in nutritional immunity responses.

“It became very interesting because microbes and plants are fighting for limited iron in the soil,” explains Busch. “So, microbes start invading plants to steal iron from their cells, while plants are forced to defend themselves and protect their iron stores. We were really interested in this tug of war.”

What was really happening on the molecular level and the mechanisms behind SRF3’s involvement remained unknown—until now.

How do plants balance immune defense and iron retention?

The researchers started with Arabidopsis thaliana, a small flowering plant that is easy to grow and acts as a popular laboratory stand-in for other plants, including important crops like wheat or corn. Through a series of experiments—from flagging and tracking iron levels in cells to visualizing the movement of SRF3 to removing SRF3 completely and observing the consequences—they laid out the mechanism by which SRF3 balances immune defense and iron maintenance.

First, SRF3 detects an invading microbe and promotes the generation of reactive oxygen species, molecules that can be used to fight the microbe. While helpful in attacking microbes, the creation of reactive oxygen species eats up cellular iron stores.

As iron levels fall in the cell, SRF3 starts moving around: SRF3 reorganizes itself, receives a key molecular tag called ubiquitin, and is pulled into the cell. Once SRF3 is inside the cell, the creation of new reactive oxygen species that depletes iron and fights microbes stops, and balance is restored.

"What makes this study special is that we explain the mechanism from the single molecule scale to the full organism, providing a level of mechanistic integration that is rarely achievable in other biological systems,” says Platre, a former staff scientist in Busch’s lab and current research associate at the Institute for Plant Sciences of Montpellier.

Could this change future agricultural practices and biological research?

The implications are two-fold: First, there are the plant-specific findings that could be used to create more nutrient-rich, resilient crops; then, there are the molecular biology findings about surface protein dynamics that could fundamentally change how scientists understand cellular communication.

“In the future, this knowledge could help guide the development of crops that resist disease, grow well, and provide nutritious food,” says Busch. “It also suggests that plants use their membranes as sort of computers—turning all these moving molecules out in the environment into actionable signals.”

“This idea that cell surfaces are sort of computational hubs was proposed in mammalian cells at first,” adds Platre, “and now we are seeing it happening in plant cells. Also, our study is the first to show that ubiquitin molecular tags, which are among the most used protein tags in cells, can be used to reorganize proteins on cell surfaces and change how they respond to their environment.”

Future research will explore this “membrane computer” concept further, with the aim of understanding how cells integrate information. The researchers also hope to identify proteins and genes that SRF3 interacts with. By understanding more deeply how plants respond to environmental cues, the findings can help scientists design crops resilient to extreme weather and changing soil nutrition.

Other authors and funding

Other authors include co-first authors Lukas Brent and Matias Gleason of Salk; Preyanka Mehta, Ling Zhang, Olivier Kaakeh, Laura Martins, and Julie Law of Salk; Laia Armengot and Marc Valls of Centre for Research in Agricultural Genomics and Universitat Autònoma de Barcelona; Julie Neveu and Grégory Vert of University of Toulouse; Min Cao of Salk and Fudan University; Santosh Satbhai of Indian Institute of Science Education and Research; and Nuria Coll of Centre for Research in Agricultural Genomics and Consejo Superior de Investigaciones Científicas.

The work was supported by the National Institutes of Health (R01GM127759, P30 CA014195, P30 AG068635, S10 OD021815), Human Frontier Science Program Organization (LT000340/2019 L), Natural Science Foundation of Shanghai (24ZR1404000), Fudan University, Helmsley Center for Genomic Medicine, Chapman Foundation, and Helmsley Charitable Trust.

This press release was written by Isabella Davis.

About the Salk Institute for Biological Studies

The Salk Institute is an independent, nonprofit research institute founded in 1960 by Jonas Salk, developer of the first safe and effective polio vaccine. The Institute’s mission is to drive foundational, collaborative, risk-taking research that addresses society’s most pressing challenges, including cancer, Alzheimer’s, and agricultural vulnerability. This foundational science underpins all translational efforts, generating insights that enable new medicines and innovations worldwide. Learn more at www.salk.edu.

A plant cell with computer circuitry integrated into its plasma membrane illustrates the “membrane computer” concept, where cell surfaces act as computational hubs that turn the external world into actionable signals.

Credit

Salk Senior Illustrator Amy Cao

SRF3 molecules show dynamic movement in Arabidopsis [VIDEO] 

Individual SRF3 molecules are shown as spots, with their trajectories across the plasma membrane color-coded according to time. The tracks reveal distinct mobility behaviors, with some molecules showing dynamic movement and others remaining relatively immobile.

Credit

Salk Institute

---

Journal

Science Advances

DOI

10.1126/sciadv.aeh4671

Article Title

SRF3 Couples Cellular Iron Homeostasis and Defense Responses Through Ubiquitin-Dependent Nano-organization

Article Publication Date

14-Oct-2026

 

Corn farming sustained large pre-colonial villages in the Brazilian savanna

For the first time, research reveals the food subsistence strategies of these communities, which involved sophisticated land use practices that incorporated various species

Fundação de Amparo à Pesquisa do Estado de São Paulo

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

image: 

MAE-USP researcher Eliane Chim (with her back to the camera) examines a human skeleton found in a rock shelter in the municipality of Iuiu, Bahia 

view more 

Credit: Adriano Espinola Filho

According to a study published in the journal Science Advances, corn cultivation was essential for the subsistence and development of large villages inhabiting the Cerrado – Brazil’s savanna biome – between the 9th and 17th centuries. The research, led by archaeologists from the University of São Paulo and supported by FAPESP, reveals the subsistence strategies of these densely populated communities for the first time. They employed sophisticated land-use practices involving the cultivation of various species (polyculture), with a special emphasis on corn. Previously, scientists considered these communities to be either predominantly mobile hunter-gatherers or monoculture farmers.

In addition to contributing to our understanding of the history of human influence on one of the most biodiverse tropical savannas on the planet, the study sheds light on the food production and land use strategies that shaped the landscapes of the Cerrado as we know them today.

The study also highlights the importance of the biome in understanding the biotechnological innovations used by pre-colonial indigenous Brazilian societies, such as adapting corn to the environmental conditions of the Brazilian savanna, which differ greatly from the plant’s place of origin. Previous research had already addressed the characterization and dispersal of corn in Latin America, showing that it arrived in Brazil via the southwestern Amazon rainforest at least 6,000 years ago. It originated in Mexico, where it first appeared 9,000 years ago, and was subsequently spread to other regions.

The conclusions of the study are based on the analysis of minute chemical variations preserved in human bones and teeth. This analysis made it possible to identify the types of plants and other foods consumed, providing a sort of “record” of diet throughout life.

“I often say that humans are what they eat, and that’s recorded in the chemical composition of their bones and teeth. Through that, we were able to identify corn consumption comparable to that of Mayan or Andean populations – something completely unexpected in this context. We also detected variability between two distinct societies, that is, archaeological traditions with markedly different diets, corroborating social and cultural diversity,” Eliane Chim, a researcher at the University of São Paulo’s Museum of Archaeology and Ethnology (MAE-USP) and the lead author of the article, which is part of her doctoral dissertation, told Agência FAPESP.

“For over a century, Brazilian archaeology has debated the role of corn in pre-colonial societies, especially those with high population densities and more elaborate pottery. This is the first time that its central role in the subsistence of those populations has been demonstrated in Brazil. Just as in the Andes and Mesoamerica, corn cultivation here is associated with societies that had larger populations and left more evident marks on the landscape,” notes André Strauss, project coordinator and Chim’s advisor. Strauss is an archaeologist and a professor at MAE-USP and is one of the corresponding authors of the article, along with Patrick Roberts of the Max Planck Institute in Germany.

The researchers consider the study to be a milestone in Brazilian archaeology because it was published in a high-impact journal with Brazilian authors listed first and last. FAPESP funded the research through a Young Investigators grant awarded to Strauss, fellowships awarded to Chim and other group members (20/04402-0, 23/06749-5, 22/05420-7, and 20/06729-6 ), and two projects, including one that funded publication in the journal (19/15914-4 and 26/12048-8).

The “value” of bones

The scientists analyzed the stable isotopes of carbon, nitrogen, and oxygen in the teeth and bones of more than 100 individuals from 37 archaeological sites in the Cerrado, Caatinga (a semi-arid biome in northeastern Brazil), and the Atlantic Forest. The samples, which date from a period between 1,100 and 400 years ago, were obtained from excavations conducted by the research group and from archaeological collections assembled since the 1970s.

Isotopes are natural variants of each chemical element that differ in the number of neutrons they contain. In the case of carbon, they indicate which types of plants predominated in the diet. For example, they can distinguish corn from other fruits and plants typical of the Cerrado. Nitrogen helps estimate the amount of animal protein consumed and the individuals’ position in the food chain. Oxygen, on the other hand, provides data related to water consumption and environmental conditions.

Since different foods have distinct isotopic signatures, these signatures are “recorded” in body tissues and can be used to reconstruct the diets of ancient populations. This makes it possible to determine whether their diet was primarily based on corn or other foods and whether they consumed animal protein.

Additionally, the scientists performed radiocarbon dating on the collagen of approximately 40% of the bones that still contained protein. This technique determines the age of organic remains. The scientists also used paleoecological records to reconstruct the diets. These records consist of natural remains, such as seeds, sediments, and plant and animal remains, that provide insight into vegetation, climate, and the environment during different periods.

The samples come from the villages of two populations: the Aratu, who lived in the open, and the Una, one of the earliest pottery-making horticulturalists of the Cerrado, who frequented rock shelters, usually near riverbeds or ponds.

Among the Aratu populations, bone collagen and dental enamel from the oldest individuals revealed evidence of corn consumption. Additionally, other studies documented wear marks on ceramic vessels that are consistent with the fermentation of alcoholic beverages. This finding suggests a broader role for cultivated plants in the daily lives of these villages. These findings suggest that corn may have been a dietary staple and possibly used in communal or ritual practices.

“We don’t hear much about them, but these Aratu groups had a unique presence in the Cerrado,” Strauss points out. According to Strauss, Aratu villages had as many as 2,000 inhabitants, a population comparable to that of most European towns of the same era.

In contrast, the rock-shelter populations of the Una culture had a more diverse diet with lower corn intake. Since these groups occupied similar environments to those of the Aratu, the scientists conclude that the differences cannot be explained solely by ecology. Rather, they indicate that distinct cultural traditions and economic strategies coexisted within the biome. Both practiced polyculture, but corn was a primary source of subsistence for the more populous Aratu communities.

Collective effort

The project has been underway for more than ten years. It brought together 31 researchers from 10 Brazilian universities in collaboration with the Max Planck Society and institutions in Portugal, Poland, and the United States.

“Archaeology operates on a different timeline. You can’t accomplish much in six months. You have to go into the field, excavate, return to the lab, and curate the finds. Only then can the analytical phase of the work begin. We also use this as a mechanism for training personnel, and Eliane [Chim] is a prime example of that,” says Strauss.

For Chim, one of the challenges of conducting this type of study is preserving the archaeological material, especially when analyzing collagen. More than 270 artifacts were evaluated to obtain the sample used in the study.

“We intend to resume field research at those archaeological sites and try to locate the farmlands where people cultivated crops. We know the cemeteries, the urn fields, and the size of some villages, but we need to find the other areas occupied by those people,” Chim adds, outlining the future of the research.

About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

 

---

Journal

Science Advances

DOI

10.1126/sciadv.aef70

Article Title

Maize-based polyculture, not monoculture, sustained precolonial societies in the Brazilian Cerrado

 

Engineers make quality, low-cost carbon fiber from coproducts of paper, energy production

Iowa State University

Facebook

MessageWhatsAppEmail

image: 

Iowa State engineers are turning the low-value ingredients in these beakers into the high-value carbon fiber on the lab bench. Left to right are Tannon Daugaard next to spools of carbon fiber; Abdulrahman A. B. A. Mohammed holding a beaker of bio-oil; and Xianglan Bai holding a beaker of lignin.

view more 

Credit: Iowa State University/Christopher Gannon.

AMES, Iowa – Xianglan Bai illustrates her development of biobased carbon fiber with two beakers in researchers’ hands.

 

The first contains low-cost, low-value and plentiful softwood kraft lignin, the tough stuff that strengthens and waterproofs the cell walls of trees and plants. The natural binder is a coproduct of paper production.

 

The second contains a low-value, watery fraction of bio-oil, a liquid fuel produced by a thermochemical process called fast pyrolysis. The process uses heat to break down corn stalks, wood chips and other biomass to produce a bio-oil for heating that can be divided into fractions with various properties and performance characteristics. (The process also produces a solid biochar that can be used as fertilizer.)

 

“We’re taking lignin, considered a low-value byproduct of the paper and pulp industry, and aqueous bio-oil, also considered to be a low-value product, and putting them together to come up with a high-value product,” said Bai, an Iowa State University professor of mechanical engineering and an associate director of Iowa State’s Bioeconomy Institute.

 

“This is where chemistry and materials science beautifully meet,” she said.

 

‘Real-world solutions’

Carbon fiber is a strong and ultra-lightweight material used in aerospace, transportation, wind energy and infrastructure applications. You’ll also find it in sport and performance industries such as high-end bicycles and motorsports.

 

It is typically manufactured using petroleum-based materials. But the high costs of those precursors are raising the costs of carbon fiber and limiting its use to premium applications.

 

The U.S. National Science Foundation, as part of its Translation to Practice program, which aims to “turn scientific discoveries into real-world solutions,” is supporting further development of Bai’s biobased carbon fiber with a four-year, $2 million grant.

 

It’s the ‘thermo-mechanochemistry’

Bai and her research group have been researching the production of biobased carbon fiber since 2015, with much of the work focused on lignin as a potential source material.

 

This wasn’t a new idea. Japanese researchers started looking at lignin for carbon fiber back in the 1960s. But the performance of the resulting carbon fiber was inferior to petroleum-based versions.

 

Even after decades of trying, the biobased carbon fibers didn’t have the performance levels required for use in cars and other performance-critical industries.

 

With the support of several grants from the U.S. Department of Agriculture, Bai and her research team have developed several patented and patent-pending technologies “that enable the production of low-cost, lignin-based carbon fibers with exceptional performance properties,” Bai said.

 

One example is introducing “thermo-mechanochemistry” of lignin, a new material chemistry her group recently discovered. The process heats lignin and puts the spun fiber under increasing mechanical stress, fundamentally changing its chemical transformation and the evolution of its material structures. The result is much stronger carbon fiber while maintaining costs below $5 per pound.

 

Researchers measured a tensile strength, or stretching, up to 2.45 gigapascals in the biobased carbon fiber and a tensile modulus, or stiffness, up to 236 gigapascals. That easily meets U.S. Department of Energy carbon fiber recommendations for the auto industry of 1.72 for tensile strength and 172 for tensile modulus while keeping costs from $5 to $7 per pound.

 

Another example of innovation in Bai’s lab is using watery bio-oil to modify non-softening lignin into melt-spinnable precursors. The modified lignin reduced the stabilization time for spun fiber from tens of hours to two to four hours, reducing production bottlenecks and costs.

 

Commercial production

The new grant will allow Bai, her research group and industry collaborators to move from batch production in a lab to commercially relevant continuous production.

 

Additional leaders working on that transition include Tannon Daugaard, an engineer and faculty member for the Bioeconomy Institute and a co-founder of Rise Energy, an Ames-based startup; and Ryan Smith, deputy director of the Bioeconomy Institute, also a co-founder of Rise Energy, which is supplying bio-oil to the project. 

 

Major collaborators include Harper International of New York state, Latis Materials of Maine and Rise Energy.

 

The result could boost the value of paper and bio-oil production while providing the country with a domestic source of high-performance, biobased carbon fiber.

 

“Commercializing this breakthrough technology could significantly reduce manufacturing costs,” the researchers wrote in a project summary, “while securing a reliable domestic supply of a critical structural material, thereby strengthening U.S. economic competitiveness.”

 

  

Lignin, bio-oil and carbon fiber.

Credit

Iowa State University/Christopher Gannon.

 

Worcester Polytechnic Institute researchers identify bamboo as fuel alternative

Bamboo-derived biofuel could rival gasoline and diesel on price, emissions; replace corn ethanol fuel production

Peer-Reviewed Publication

Worcester Polytechnic Institute

FacebookXLinkedInWeChatBlueskyMessageWhatsAppEmail

image: 

Worcester Polytechnic Institute Professor Michael Timko 

view more 

Credit: Worcester Polytechnic Institute

A new study from researchers, including those in Worcester Polytechnic Institute’s Department of Chemical Engineering, has found the fastest-growing plant on Earth may offer a sustainable and cost-effective alternative to petroleum-derived transportation fuels.

The researchers, including Michael Timko, the William B. Smith Professor of chemical engineering and head of the department, and Timothy Woodard, MS’23, PhD ’26, have demonstrated that bamboo could serve as a highly promising raw material for the production of sustainable liquid fuels to power vehicles, planes, and trains. The team’s study, published in the journal Sustainable Energy & Fuels, finds that bamboo can be turned into fuel at a production cost that is competitive to conventional petroleum fuels and with substantially lower greenhouse gas emissions. The study combined laboratory experiments measuring bamboo-to-biocrude conversion efficiency with economic and life-cycle assessment modeling.

“Our study suggests bamboo has a role to play in the future of fuel,” says Timko. “I think this research is especially timely and important because fuel prices are high and the transportation sector produces more greenhouse gas emissions in the U.S. than any other. Bamboo would use different land than we are using for food production, so there is no food versus fuel trade-off. Farmers win, consumers win.”

Key factors in the study are the hydrothermal liquefaction (HTL) technology that converts biomass to fuel and the choice of feedstock. Using bamboo for fuel can reduce greenhouse gasses in two ways: The process to convert it into biocrude is more efficient than when using other feedstocks, and bamboo itself captures and stores large amounts of carbon both above and below ground. Because of the plant’s fast growth even in poor soil conditions, the study finds that converting bamboo into fuel through HTL could match the level of corn-ethanol production in the U.S. while also using roughly 13% as much cultivated land. Unlike annual crops used for many biofuels, bamboo is a perennial grass that can produce large amounts of biomass with relatively low agricultural inputs. And, compared with other perennial grasses, bamboo has very low ash content (less than 1% by dry weight), meaning that the conversion process generates negligible waste.

Economic modeling indicates that bamboo-based fuel could sell for as little as $2.75 per gasoline-gallon equivalent under mature commercial-scale conditions, accounting for the money required to build and operate the fuel plant, suggesting strong economic competitiveness as the renewable-fuel industry expands.

The team’s analysis also finds that using bamboo as a fuel source creates a level of greenhouse gas emissions 26 times lower than those of conventional petroleum diesel fuel: A life-cycle assessment, considering the ability of bamboo to store large amounts of carbon in its underground rhizomes , finds producing fuel from bamboo and its use would generate a greenhouse gas intensity of 3.5 grams of carbon dioxide-equivalent per megajoule of energy.

In addition, the study suggests bamboo as a strong choice as a fuel source because it can grow faster and on smaller plots of land than other fuel feedstocks. “The U.S. has enormous land area under cultivation for corn ethanol, a fuel which is often blended into gasoline,” says Timko. “Freeing up at least some of that land could allow for more food production and reduce the burden on the environment.” The researchers also point out that bamboo can be cultivated on former industrial land or heavily farmed properties where other crops and vegetation may struggle to grow. 

“Bamboo may eventually offer industry a way to generate low-carbon liquid fuels at scale,” says Timko. “With further research and development, bamboo could be a compelling option for decarbonization in sectors that are difficult to electrify, including heavy-duty transport and aviation fuel supply chains.”

Timko and Woodard co-authored the research study with Charles Cai, associate professor in the Department of Bioproducts and Biosystems at Aalto University in Finland, and James Walters, CEO of Avos BioEnergy.

Using a reactor like the one seen in the background, bamboo can be processed into a biocrude.

Credit

Worcester Polytechnic Institute

---

Journal

Sustainable Energy & Fuels

DOI

10.1039/d6se00296j