Peptide Imitation Is the Sincerest Form of Plant Flattery
Plant biologists at the Salk Institute are proposing a new solution to help kick agriculture’s unsustainable fertilizer habit. The researchers identified a key molecule produced by plant roots, a small peptide called CLE16, that encourages plants and beneficial soil fungi to interact with each other. They say boosting this symbiotic relationship, in which the fungi provide mineral nutrients to the plants through CLE16 supplementation, could be a more natural and sustainable way to encourage crop growth without the use of harmful artificial fertilizers. The findings were published in The Proceedings of the National Academy of Sciences.
“Industrial breeding techniques have dampened many symbiosis traits in our modern-day crops and cemented their dependence on chemical fertilizers,” said senior author Lena Mueller. “By restoring the natural symbiosis between plant roots and fungi, we could help crops get the nutrients they need without the use of harmful fertilizers.”
In this mutually beneficial relationship, soil-borne arbuscular mycorrhizal fungi supply plants with water and phosphorus, which the plants accept in exchange for carbon molecules. These exchanges occur by specialized symbiotic fungal tendrils, called arbuscules, burying themselves into plant root cells. Around 80 percent of plants can trade resources with fungi in this way. However, the traits that support this symbiosis have been weakened over centuries of agricultural plant breeding that prioritized creating crops with the biggest yields.
Salk scientists say new crop varieties could be bred to strengthen these traits again.
To begin discovering and strengthening these traits, Mueller’s lab started by growing a species of arbuscular mycorrhizal fungus together with Medicago truncatula, a small Mediterranean legume. Once the two had formed a symbiotic relationship, the researchers looked to see what genes were supporting this interaction.
The legumes had started to express large amounts of a small signaling molecule called CLE16 — a member of the CLE family of peptides. These small signaling molecules are present in many plant species yet have been relatively understudied. Until CLE16, the only plant CLE peptides scientists had studied were working against symbiosis.
To confirm that CLE16 was promoting the symbiotic relationship, the researchers added excess CLE16 to the soil to see what would happen. The extra dose of CLE16 caused the fungal arbuscules to become more robust and live longer, ultimately increasing the abundance of these nutrient-trading structures in the roots. The result was a self-amplifying pro-symbiosis signal: the more the beneficial fungus expanded inside the roots, the more CLE16 was produced by the plant, which then promoted even more fungal colonization.
The team then did a series of experiments to understand how CLE16 was encouraging this interaction between plants and beneficial fungi. Their findings revealed that CLE16 promotes the symbiosis via the signaling protein CORYNE (CRN), a component of the CLAVATA receptor complex known for its roles in plant responses to the environment.
As a plant becomes stressed, it enters a heightened immune state to protect itself from any further threats. However, this also inadvertently makes the plant less receptive to surrounding fungi. Mueller predicts that when CLE16 binds to the CRN-CLAVATA receptor complex, this reduces the plants’ stress levels and immune reactivity, allowing the beneficial fungus to enter the plant roots and begin the nutrient exchange.
Importantly, Mueller’s team showed that many arbuscular mycorrhizal fungi also produce their own CLE16-like peptides, which also promoted symbiosis when added to the soil. The researchers think that these fungal peptides imitate the plants’ own CLE16 peptides, thus enabling the beneficial fungus to amplify symbiosis by binding to the same plant CRN-CLAVATA receptor complexes.
With validation that both plant CLE16 and fungal CLE16-like peptide supplementation improved symbiosis, a similar supplementation on farmland may be the solution to kick-starting the growth of fungal networks that benefit crops year after year.
Future work will validate whether CLE16 peptides or fungal CLE16-like peptide mimics also promote symbiosis in important crops, like soy, corn or wheat. If they do, harnessing these molecules to replace unsustainable, polluting chemical fertilizers with beneficial fungi will begin.
Trying to Fix a Problem We Created: Pollen-Replacing Food for Honeybees
(Washington State University)
Scientists have unveiled a new food source designed to sustain honeybee colonies indefinitely without natural pollen.
Published in the journal Proceedings of the Royal Society B, the research from Washington State University and APIX Biosciences NV in Wingene, Belgium, details successful trials where nutritionally stressed colonies, deployed for commercial crop pollination in Washington state, thrived on the new food source.
The food, which resembles the human-made diets fed to livestock and pets, contains all the nutrients honeybees need. The researchers hope it becomes a potent strategy for combating the escalating rates of colony collapse and safeguarding global food supplies reliant on bee pollination.
The newly developed food source resembles human “Power Bars.” These are placed directly into honeybee colonies, where young bees process and distribute the essential nutrients to larvae and adult bees. They address one of the growing challenges faced by honeybees: lack of adequate nutrition in their environment.
“Changes in land use, urban expansion, and extreme weather all negatively impact nutrition for honeybees and other pollinators,” said Brandon Hopkins, a co-author of the paper.
A critical discovery within the research is the role of isofucosterol, a molecule found naturally in pollen that acts as a vital nutrient for honeybees. Colonies fed with isofucosterol-enriched food survived an entire season without pollen access, while those without it experienced severe declines, including reduced larval production, adult paralysis, and colony collapse. The new feed also contains a comprehensive blend of the other nutrients honeybees require.
To validate the efficacy of the new food source under real-world conditions, WSU conducted field trials with nutritionally stressed colonies in blueberry and sunflower fields, both known for poor pollen quality for bees. Compared to colonies receiving standard commercial feed or no supplementation, those fed the new food source thrived, demonstrating increased survival and colony growth.
Whether bees should be fed a human-lab-created diet — rather than working to increase the nutrient density of the plants they naturally feed on — remains an open question, though.
First New Plant Tissue Discovered in 160 Years Boosts Crop Yields
A research group led by Nagoya University in Japan has discovered a new tissue in plants that is essential for seed formation. Published in the journal Current Biology, their discovery represents the first new plant tissue discovered in 160 years. Their findings open a new field for research and have already demonstrated practical applications, with the team increasing yields of important crops, including rice.
Scientists have long known that fertilization is necessary for the seed body, known as the hypocotyl, to receive nutrients from the “mother” parts of the plant. Understanding how plants detect successful fertilization is important for maximizing yields from crop species during breeding.
The research group led by Ryushiro Kasahara and Michitaka Nodaguchi made the discovery of the new tissue by chance. Kasahara had been staining seeds to track the deposition of callose, a waxy substance commonly studied because of its association with fertilization, to verify findings from a previous study.
While examining the stained areas, Kasahara noticed something unexpected. “Plants fertilize by the insertion of a pollen tube, so most scientists are only interested in the place where this occurs. However, we found signals on the opposite side too,” he said. “Nobody was looking where I was looking. I remember being surprised, especially when we realized that this signal was particularly strong when fertilization failed.”
Further analysis revealed a distinctive rabbit-shaped tissue structure that functions as a gateway. This structure, named the “Kasahara Gateway” in honor of its discoverer, represents the first new plant tissue identified since the mid-19th century.
The signal Kasahara observed resulted from callose deposition, which blocks the flow of nutrients and hormones into unfertilized seeds. Closure of the gateways led to the seeds not receiving nutrients and dying. The researchers termed this the “closed state.” On the other hand, when fertilization occurs, the hypocotyl detects this success and dissolves the callose, allowing nutrients to flow into the seed and enabling growth. The researchers called this the “open state.”
“When the flow of nutrients was compared between successfully fertilized and unsuccessful embryos, it was found that the inflow of nutrients was observed only in the successful embryos, whereas it was completely blocked in the unsuccessful ones,” Kasahara explained. “This limits the amount of resources wasted on unviable seeds.”
The gateway’s ability to switch between open-and-closed states suggested genetic regulation. The researchers examined fertilized plant hypocotyls to identify potential genetic controls.
They identified a gene called AtBG_ppap that was upregulated exclusively in fertilized hypocotyls and identified its role in dissolving callose. When they modified hypocotyls to overexpress AtBG_ppap, the gateway remained permanently in the open gate state, increasing nutrient uptake.
“This led us to the realization that keeping the gateway permanently open could enlarge seeds,” Kasahara said. “When we tested this theory with rice seeds, we made seeds that were 9 percent bigger. With seeds from other species, we succeeded in increases of as much as 16.5 percent.”
Their findings represent a significant advancement in seed enhancement in plant breeding. Maintaining a permanently open state could substantially increase yields of important crops.
Whether altering the design of plants to increase yield is wise, though — what other important natural roles does the Kasahara Gateway play? — is an open question, though.
Intuition Guides Farmers Toward Better Decision-Making, But Remains a Taboo
In Finland, farmers who have transitioned to regenerative agriculture perceive intuition as something that leads to better decision-making, a new study from the University of Eastern Finland shows. However, intuition also remains a taboo — a topic that is avoided and rarely discussed.
Published in Journal of Rural Studies, the new study explores the role and manifestations of intuition in regenerative farmers’ decision-making processes. The study involved 84 farmers involved in the Carbon Action Project implemented by the Finnish Meteorological Institute and the Baltic Sea Action Group.
Farmers participating in the study described intuition as certain and reliable, and relevant to the person experiencing it. Intuition is future-oriented, always prompting action or inaction. However, many factors, such as stress, haste, fatigue, strong emotions, over-analysis and too much factual information, can interfere with the interpretation of intuition, leading to intuitive cues being easily overlooked or misinterpreted.
“In the analytical process, intuition acts as a summarizing and guiding ‘decision-making assistant,’” said researcher Soja Sädeharju. “It is constantly present in decision-making, particularly at the beginning and end stages. Since intuition was perceived as leading to the right and good outcome, it may be linked to what is generally known as the ‘voice of reason’.”
Farmers participating in the study felt that intuition stemmed from both internal and external sources. In particular, input from nature influenced farming decisions.
