NUS scientists create microneedle system to deliver biofertiliser directly into plants, boosting growth with less waste
A dissolving patch delivers beneficial microbes into leaves and stems, speeding growth in vegetables while using over 15 per cent less biofertiliser than soil application
National University of Singapore
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Dr Arya Gopinath Madathil Pulikkal (left) and Assistant Professor Andy Tay (right) in front of a small greenhouse containing Choy Sum plants. Their team developed dissolving microneedles patches that deliver biofertiliser directly into plant tissue, boosting plant growth while using over 15 per cent less biofertiliser than conventional soil inoculation.
view moreCredit: College of Design and Engineering, National University of Singapore
Researchers at the National University of Singapore (NUS) have developed dissolving microneedle patches that deliver living “biofertiliser” straight into plant tissue. In greenhouse tests, Choy Sum and Kale grew faster — by shoot biomass, leaf area and height — while using over 15 per cent less biofertiliser than standard soil inoculation.
The approach points to more precise fertiliser delivery, less waste and potentially lower off-target environmental impact, with near-term fit for urban and vertical farms and for high-value crops that benefit from controlled dosing.
Biofertiliser, which contain beneficial bacteria and fungi that help crops absorb nutrients and tolerate stress, are usually added to soil. There, they must compete with native microbes and can be hindered by acidity and various other conditions. Much of the input never reaches the roots. By placing beneficial bacteria or fungi directly into leaves or stems, the new method developed by the NUS team bypasses those hurdles and accelerates early gains.
“Inspired by how microbes can migrate within the human body, we hypothesised that by delivering beneficial microbes directly into the plant’s tissues, like a leaf or stem, they could travel to the roots and still perform their function, but much more effectively and be less vulnerable to soil conditions,” said Assistant Professor Andy Tay from Department of Biomedical Engineering at the College of Design and Engineering at NUS, and Principal Investigator at the Institute for Health Innovation & Technology (iHealthtech), who led the work.
The study was published in Advanced Functional Materials on 13 September 2025.
Gentle delivery
The team fabricated plant-tuned microneedles from polyvinyl alcohol (PVA), a biodegradable, low-cost polymer. For leaves, a 1 cm by 1 cm patch carries a 40 by 40 array of pyramids about 140 μm long, while a short row of roughly 430-μm needles suits thicker stems. Microbes are blended into the PVA solution, cast into tiny moulds and locked in the needle tips. Pressed by the thumb or with a simple handheld applicator that spreads force evenly, the needles slip into plant tissue and dissolve within about a minute, releasing their microbial cargo.
In laboratory tests, the patch barely disturbed plant tissue or function. Shallow indentations in leaves faded within two hours; chlorophyll readings remained stable; and stress-response gene expression, which briefly rose after insertion, returned to baseline within 24 hours. The patches maintained high microbial viability after storage for up to four weeks – this means the patches can be prepared in advance – and importantly, loading concentration translated to delivered dose, which enables controlled application that is difficult to achieve in soil. A 3D-printed applicator provided uniform insertion across large leaf areas and could become an integral component in future robotic automation.
Proving the approach
The NUS team demonstrated that delivering a plant growth-promoting rhizobacteria (PGPR) cocktail of Streptomyces and Agromyces-Bacillus through leaves or stems improved growth in Choy Sum and Kale compared to untreated controls and gave better results than soil treatments with microbes. PGPR is commonly used to improve nutrient uptake and stimulate growth hormones in plants.
Additionally, the plants grew more as the researchers loaded more microbes into each patch, up to an effective ceiling. Beyond that, extra microbes did not help the plants grow further. This lets growers determine the lowest effective dose, which in turn cuts costs and waste.
“Our microneedle system successfully delivered biofertiliser into Choy Sum and Kale, enhancing their growth more effectively than traditional methods while using over 15 per cent less biofertiliser,” Asst Prof Tay said. “By faster growth we refer to higher total plant weight, larger leaf area and higher plant height.”
The team tracked the bacteria as they moved from the injected leaves to the roots within days. At the roots, the bacteria nudged the root microbiome towards a more beneficial mix without throwing it out of balance. Plant chemical readouts showed that the main energy-production cycle (involves cells turning sugars into usable energy) was working harder, nitrogen was used more efficiently and compounds needed for growth were synthesised at a higher rate. The team also observed stronger antioxidant capacity, a sign the plants were better prepared for stress and growth.
The team extended the approach to beneficial fungi. Patches loaded with a Tinctoporellus strain (AR8) promoted Choy Sum growth and adjusted phytohormones levels – the signalling molecules that guide how plants grow, develop, and respond to their surroundings – helping to keep plant growth hormones in balance. “This work is the first to demonstrate that root-associated biofertiliser can be directly delivered into a plant’s leaves or stems to enhance growth,” Asst Prof Tay added. “With this finding, we introduced a new concept of ‘microneedle biofertiliser’ that overcomes significant challenges of soil inoculation.”
The researchers see early applications in urban and vertical farms where precise dosing matters, as well as in slow-growing, high-value crops such as medicinal herbs. Looking ahead, Asst Prof Tay added, “A major focus is scalability. We plan to explore integrating our microneedle technology with agricultural robotics and automated systems to make it feasible for large-scale farms. We will also test this across a wider variety of crops, such as strawberry, and investigate how these microbes migrate effectively from the leaf to the root.”
A microneedle patch containing biofertiliser is pressed onto the back of the leaf or along the stem of the plant using the thumb or a simple handheld applicator. Within a minute, the microneedles dissolve, releasing beneficial microbes directly into the plant tissue.
Credit
College of Design and Engineering, National University of Singapore
The microneedle patches are made using polyvinyl alcohol (PVA), a biodegradable, low-cost polymer, and infused with a plant growth-promoting rhizobacteria (PGPR) cocktail of Streptomyces and Agromyces-Bacillus. A 1 cm by 1 cm microneedle patch (shown in the petri dish on the right) carries a 40 by 40 array of 140-μm pyramids for application on leaves, while a short row of roughly 430-μm needles (shown in the petri dish on the left) suits thicker stems.
Credit
College of Design and Engineering, National University of Singapore
2025 1209 Microneedles for plant growth 4 [VIDEO]
Researchers at the College of Design and Engineering at NUS have created a innovative dissolving microneedle patch that delivers living biofertilisers directly into plant tissue. The system helps vegetables grow faster while using over 15 per cent less fertiliser than soil application. Watch how this new approach could benefit urban farms, vertical agriculture and high-value crops.
Credit
College of Design and Engineering, National University of Singapore
Journal
Advanced Functional Materials
Article Title
Microneedle-Based Biofertilizer Delivery Improves Plant Growth Through Microbiome Engineering
Rice resists change: Study reveals viral tools fall short
Two widely used virus-based tools for probing gene function fail in rice
Rothamsted Research
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Graphic showing the different effect of viral tools on wheat samples compared to rice.
view moreCredit: Rothamsted Research
Researchers from Rothamsted Research and the Federal University of Rio Grande do Sul tested two popular viral vectors - barley stripe mosaic virus (BSMV) and foxtail mosaic virus (FoMV) - to see if they could temporarily switch genes on or off in rice (Oryza sativa). These virus-enabled reverse genetics (VERG) techniques are regularly used in plants to study gene function without permanent genetic modification. These methods have worked well at Rothamsted in wheat and blackgrass producing clear results: plants turn white when a chlorophyll gene is silenced, or glow green when a fluorescent protein is expressed. In rice, no such changes occurred. Despite extensive optimisation across six rice cultivars, the team found no evidence that these VERG techniques work in rice.
“Although we don’t know why they didn’t work, it’s clear they don’t,” said Guilherme Turra, lead author and PhD student at the Federal University of Rio Grande do Sul. “Rather than chase every possible explanation, we focused on rigorously testing variations of established protocols and inoculation methods across different rice types. By using robust scientific methods and clear visual phenotypes, we can be confident these tools simply don’t deliver in rice.”
Building on that point, Dr Dana MacGregor, senior author at Rothamsted, said: “It’s important to trust robust data, even when it challenges your original hypothesis. As scientists, we need to stay open to the possibility that our approach or assumption was wrong. We assumed what works in wheat would work in rice, but our data clearly show otherwise. By sharing these results, we hope to help others avoid the same pitfalls.”
The findings, now peer-reviewed and published in Annals of Applied Biology, underscore the species-specific nature of VERG and the importance of sharing negative results to guide future research. By publishing these data, the team hopes to prevent others from repeating unsuccessful experiments and to encourage innovation in viral systems tailored to rice.
The work was supported by the UK’s Biotechnology and Biological Sciences Research Council (BBSRC), Rio Grande do Sul State’s Research Support Foundation (FAPERGS) and Brazil’s CAPES programme.
Journal
Annals of Applied Biology
Article Title
Insights from controlled, comparative experiments highlight the limitations of using BSMV and FoMV for virus-enabled reverse genetics in rice
Article Publication Date
8-Dec-2025
Pioneering plant biologist Masatsugu Toyota wins 9th Okazaki Award
International award honors discovery that plants smell danger and warn their neighbors within minutes.
Grant and Award Announcementimage:
Professor Masatsugu Toyota from Saitama University received the 9th Tsuneko & Reiji Okazaki Award at Nagoya University on November 27, 2025, for his pioneering research on plant communication systems.
view moreCredit: ITbM, Nagoya University
The 9th Tsuneko & Reiji Okazaki Award was presented to Professor Masatsugu Toyota of Saitama University on November 27, 2025, at Nagoya University. The international honor recognizes Professor Toyota’s research on how plants sense and respond to touch and chemical signals. The award ceremony took place during the 11th International Symposium on Transformative Bio-Molecules.
The Okazaki Award, established in 2015, honors early-career scientists who make significant contributions to biology through innovative approaches or transformative technologies.
Professor Toyota was born in Marugame, Kagawa Prefecture, the only son in a family with four sisters. As a child, he dreamed of becoming a physicist. He graduated from Nagoya University’s Department of Physics before moving to the Graduate School of Medicine to pursue his PhD in medical science.
His mentor, Professor Sokabe Masahiro, introduced him to plant science and encouraged him to build custom research equipment. This shaped his unique research approach that combines physics with biology.
How plants warn their leaves and their neighbors
Professor Toyota’s most important discovery involves glutamate receptor channels—proteins found in both human brains and plants. In humans, they help us learn and remember. “We also have a glutamate receptor channel in the brain, and plants have these same proteins that they use to sense insect attacks,” he said.
When an insect bites a leaf, these channels trigger calcium signals that move through the plant at one millimeter per second. This alerts distant leaves to prepare their defenses. Professor Toyota’s work with the carnivorous plant, Venus flytrap, and the sensitive plant, Mimosa pudica, shows that plants can move and protect themselves in surprisingly sophisticated ways.
He also discovered that plants “smell” danger through airborne chemicals released by damaged neighbors and prepare their own defenses before an attack occurs. These findings challenge the traditional view of plants as passive organisms and reveal advanced sensory networks that rival animal nervous systems.
Professor Toyota’s unique background in biophysics allows him to build custom microscopes and imaging systems that show plant behavior invisible to the naked eye.
“If you don’t have a device, you can make it,” he said, explaining his approach to research challenges. His centrifuge microscope and other inventions have opened new windows into the lives of plants.
Professor Toyota’s work has important implications for agriculture, specifically the development of biostimulants—chemicals that protect plants by activating their natural defenses rather than killing insects.
“We are creating new types of biostimulants to protect plants and these aren’t pesticides, so this method solves the problem of insects becoming resistant to traditional pesticides,” he explained.
His research demonstrates that plants possess rapid communication systems that coordinate complex responses across their entire structure, despite their lack of nerves or brains.
Honoring accomplished scientists—past and present
The award commemorates the legacy of Professors Tsuneko and Reiji Okazaki, who discovered “Okazaki fragments,” short DNA segments that form during cell replication. Their breakthrough work in the 1960s solved a fundamental mystery about how cells copy genetic information.
Past recipients of the Okazaki Award include distinguished scientists from institutions such as MIT, Stanford University, Princeton University, and the University of Zurich.
Nagoya University faculty members, including those from the Institute of Transformative Bio-Molecules (ITbM), select recipients through a rigorous review process that evaluates both scientific achievement and future potential in the field of biology.
When asked about the secret to his success, Professor Toyota emphasized curiosity and persistence. “You should keep your curiosity from childhood,” he advised young scientists. Rather than seeing obstacles as roadblocks, he views them as opportunities. “I’m always very happy to face limitations or problems, because this is when big discoveries happen,” he said.
Calcium waves move through an Arabidopsis plant being attacked by a caterpillar [VIDEO]
Calcium waves move through an Arabidopsis plant being attacked by a caterpillar at nearly one millimeter per second. The bright fluorescence reveals the plant’s rapid communication system responding to a threat, similar to how nerve signals work in animals.
Credit
Toyota et al., 2018
Real-time calcium signals in Dionaea muscipula (Venus flytrap) responding to ants on its leaves. The green glow shows calcium signals moving through the plant as it senses the insects and reveals how plants transmit danger signals throughout their bodies.
Credit
Suda et al., 2025
Mimosa pudica leaves fold within seconds of being wounded. This rapid defensive movement is triggered by electrical and calcium signals that travel through the plant and protect it from further insect damage.
Credit
Hagihara et al., 2022
