The proposal, published in the journal Discover Biotechnology, builds on a growing body of work in plant-derived edible vaccines. The idea is deceptively simple: genetically engineer a plant to produce an antigen, a harmless fragment of a pathogen that the immune system can learn to recognize, and then have people or animals eat the plant tissue. When the antigen reaches the gut, it encounters the gut-associated lymphoid tissue, or GALT, a dense network of immune cells that guards one of the body’s main entry points for pathogens. Studies in both mice and humans have shown that plant-derived antigens delivered orally can stimulate antigen-specific mucosal IgA antibodies as well as serum IgG, the systemic antibody class measured after conventional immunization. That dual response matters, because mucosal immunity is the first line of defense against the respiratory and intestinal infections that cause enormous global disease burden.

Plant-based delivery also solves some stubborn engineering problems. The plant cell wall acts as a natural capsule, shielding antigenic proteins from the acidic environment of the stomach so they survive long enough to reach immune tissue. Even more striking, freeze-dried plant material expressing vaccine antigens has been shown to maintain antigen integrity at ambient temperatures, eliminating the need for refrigeration during storage and transport. For regions where electricity is unreliable and cold-chain logistics are prohibitively expensive, a vaccine that can sit on a shelf as dried powder is a fundamentally different proposition from one that must be kept chilled at every step.

Among the many plants tested as vaccine factories, duckweeds—tiny aquatic flowering plants of the family Lemnaceae—stand out. They pack protein at up to 40 percent of their dry weight, grow at remarkable speed on inexpensive byproduct substrates, and, crucially for vaccine consistency, are so small and anatomically uniform that antigen levels should be even between individual plants. That uniformity addresses one of the biggest weaknesses of edible vaccines in general: dosage. When a vaccine is eaten, the amount of antigen consumed can vary depending on which part of the plant is eaten and how much, leading to inconsistent immune responses. Researchers are countering this with genetic engineering strategies that drive uniform antigen expression in specific tissues, and duckweed’s near-homogeneous body plan gives it a natural head start.

The evidence in animal models is encouraging. Duckweed engineered to express Interleukin-17B has been used as a mucosal adjuvant against infectious bronchitis virus in chickens. When the M2e peptide of the H5N1 avian influenza virus—a sequence so conserved it appears across essentially all influenza strains—was expressed in duckweed and fed to mice, the animals produced anti-M2e antibodies detectable in blood serum. And in an aquaculture demonstration, zebrafish fed transgenic duckweed carrying the LamB antigen from Vibrio alginolyticus were protected against fish vibriosis: when challenged with five times the lethal dose of the pathogen, 63 percent of the vaccinated fish survived, compared with complete mortality in the unvaccinated control group.

So why has no one scaled this up? The answer lies in duckweed’s biology. Because the plants are aquatic, they need vast expanses of water to grow, and in water-scarce regions that requirement can outweigh the benefits of the vaccine itself. Artificial ponds would have to be built, consuming capital and competing with agriculture and urban development for land. Open-air ponds are also vulnerable to contamination by microalgae and fungi, which can render entire batches unusable and impose heavy financial losses. Finally, harvesting delicate, millimeter-scale plants is logistically awkward, and ponds are often located far from the end users, forcing complex delivery chains that erode the cost advantages that made duckweed attractive in the first place.

The research team’s answer is a vertical farming and recirculation system. Instead of spreading duckweed across horizontal ponds, the design stacks multiple layers of cultivation trays, with the liquid medium held at a shallow depth of roughly five centimeters—enough for duckweed, which floats at the surface, to thrive. Water is pumped to the top tray and flows gravitationally through the lower trays back to a reserve basin at the bottom, continuously recirculating and dramatically cutting water use. According to the authors, this vertical arrangement could raise production yield per unit area by a factor of ten to twenty compared with conventional cultivation. Biomass is collected with a filtration-based harvester that returns the supernatant to the basin, minimizing waste.

Vertical farms have a well-known Achilles’ heel: trays lower in the stack are shaded by those above. The proposed solution is elegantly mechanical. The trays would be made of transparent material and mounted on retractable mechanisms along both horizontal axes, with a programmable algorithm adjusting the retraction amplitude and frequency in response to real-time light sensors, so each layer of duckweed gets its optimal share of sunlight. Solar panels integrated into the structure would help offset the energy costs of pumping and automation. The team also proposes siting these systems on livestock and poultry farms, where animal wastewater could serve as the growth medium—turning a disposal problem into a nutrient source while the duckweed simultaneously purifies the water. Settling ponds can reduce turbidity and microbial load in the wastewater before use, and prior studies indicate that duckweed grown on wastewater does not suffer unsafe microbial contamination. Because the system is enclosed, it also limits environmental contamination and gene flow, aligning with global biosafety regulations; regular monitoring for heavy metals in the waste streams would be needed, with quality control applied across the value chain to meet Good Manufacturing Practice standards.

The envisioned value chain runs from molecular bioengineering to the dinner bowl. A gene encoding a pathogenic antigen is introduced into duckweed, the transformed plants are cultivated at scale in the retractable vertical trays, and the harvested biomass is dried and ground into a powder that can be mixed into food or feed—immunizing and nourishing the consumer at the same time. The capital costs of such a system, especially when fitted with solar panels, sensors, and automated retraction, exceed those of traditional greenhouse production, but they are far lower than bioreactor-based manufacturing, and operating expenses can be trimmed by optimizing light regimes. The authors argue that high yields and low downstream processing costs could give the approach a decisive edge in overall unit economics, with lighting costs and protein yield as the two variables that will ultimately determine competitiveness.

Significant hurdles remain before duckweed vaccines reach the main course. Purification steps are still required before the material can be used as a vaccine, and the regulatory pathway for an edible, plant-grown immunization is uncharted territory in most jurisdictions. Yet the convergence of advances in plant biotechnology—improved promoter optimization, enhanced expression systems, and synthetic biology tools—with a cultivation system designed for scale suggests that the gap between laboratory proof and global health impact may finally be closable. If powdered duckweed vaccines can be grown beside the farms and villages that need them, stored without refrigeration, and eaten rather than injected, one of medicine’s oldest tools could take on one of its most persistent inequities.

Subject of Research: Vertical farming of transgenic duckweed for scalable production of edible vaccines

Article Title: Vertical farming of duckweed: advancing edible vaccine production for global health

Article References: Grieš, M., Rosputinský, M., Mećava, M., & del Valle, A. C. (2025). Vertical farming of duckweed: advancing edible vaccine production for global health. Discover Biotechnology, 2(1), Article 14. https://doi.org/10.1007/s44340-025-00018-x

Image Credits: AI Generated

DOI: 10.1007/s44340-025-00018-x

Keywords: duckweed, edible vaccines, vertical farming, mucosal immunity, transgenic plants, Lemnaceae, cold chain, wastewater, antigen expression, global health, plant biotechnology, aquaculture

The biological foundation of this promise lies in duckweed’s extraordinary body plan. The family comprises five genera, Spirodela, Landoltia, Lemna, Wolffiella, and Wolffia, forming an evolutionary gradient from the rooted, structurally complex Spirodela to the rootless, millimeter-scale Wolffia, the smallest flowering plant known. This simplification is the product of reductive evolution: as ancestral land plants returned to water, they progressively shed roots, extensive vascular tissue, and woody structures. What remains is a leaf-like frond that reproduces clonally every one to three days, driven by meristematic activity in budding pouches at the frond base. That doubling rate, among the fastest of any vascular plant, translates directly into short production cycles and high volumetric yields in a biomanufacturing context.

Duckweeds also display remarkable developmental plasticity. Under nutrient starvation, crowding, or shortening days, many species switch from rapid vegetative growth to producing turions, dense dormant propagules packed with starch and lipids. Abscisic acid signaling initiates this program, cell division ceases, and storage compounds accumulate massively; breaking dormancy requires prolonged cold followed by warming and light, after which stored reserves fuel a new frond. Light quality offers another tuning dial: red versus blue light differentially steers biomass toward starch or protein, a lever that could let producers tailor output for biofuels, animal feed, or protein-rich products. Even the plant’s elemental composition shifts with its body plan, as rootless species show markedly lower tissue calcium and magnesium than their rooted relatives.

The genomic era has decoded the logic behind this minimalism. Chromosome-scale assemblies for Spirodela polyrhiza and Lemna minor, and a highly complete genome for Wolffia australiana, reveal a genus-by-genus contraction of gene families tied to lost structures, including lignocellulose biosynthesis, root development, and stomatal function. Yet reduction has been selective: Spirodela shows tandem expansions of disease-resistance genes and antimicrobial peptide genes, while an expanded flavonoid pathway supports ultraviolet protection at the water surface. Cytogenomic surveys of all 36 duckweed species have cataloged a complex history of whole-genome duplication, hybridization, and polyploidy, with triploid hybrids surprisingly common because the genetic pathways enforcing reproductive isolation appear weakened.

Perhaps the most consequential discovery for engineers is duckweed’s radically simplified epigenome. Spirodela polyrhiza has lost key components of the canonical RNA-directed DNA methylation pathway, resulting in very low levels of 24-nucleotide small interfering RNAs and drastically reduced cytosine methylation in gene bodies and repeats. Degenerated transposable elements are instead marked by alternative heterochromatin modifications such as H3K9me1 and H3K27me1, while only intact, potentially active elements retain a focused residual silencing mechanism. For biotechnologists, this matters enormously: reduced gene-silencing machinery lowers the risk that an introduced transgene will be epigenetically shut down, promising more predictable and stable expression of engineered traits than in conventional plant platforms.

Single-cell and metabolomic studies are filling in the remaining blueprint. Single-nucleus and single-cell RNA sequencing of Wolffia australiana resolved just four principal cell clusters, aquatic and aerial parenchyma plus epidermis, with remarkably few genes defining tissue specialization, confirming its status as a streamlined organism. A preliminary atlas of Lemna minuta highlighted mesophyll cells rich in elemental transport genes, consistent with the genus’s phytoremediation prowess. Meanwhile, a genome-wide association study of 137 Spirodela genotypes across 42 metabolites exposed a fundamental growth-metabolism trade-off: biomass correlates positively with free amino acids but negatively with specialized metabolites like flavonoids. The authors propose a two-phase cultivation strategy, first maximizing biomass, then triggering production pathways, mirroring approaches long used in microbial fermentation.

Genetic tooling has advanced just as dramatically. Early Agrobacterium-mediated protocols in Lemna gibba and Lemna minor relied on slow callus cultures, exemplified by an Indian isolate protocol that took 11 to 13 weeks and achieved only 3.8 percent transformation frequency. The Frond Transformation System changed the calculus by bypassing callus entirely, cutting stable line generation from eight or nine months to roughly three and extending compatibility to previously recalcitrant genotypes. CRISPR-Cas9 editing arrived in Lemna aequinoctialis in 2019 with a five-to-six-week cycle and a 14.3 percent biallelic mutant rate. More recently, a so-called duckweed dip method uses plasmid DNA wrapped around carbon nanotubes that plants absorb directly from their medium, and optimized platforms for Spirodela now report efficiencies exceeding 90 percent at every stage, completed in weeks. Endogenous promoters such as LpSUT2 from Landoltia punctata address another chronic problem, maintaining robust expression under stress conditions where the viral 35S promoter becomes methylated and silenced.

These tools are already yielding functional products. Duckweed has been engineered to express the Porcine Epidemic Diarrhea Virus spike protein, the conserved M2e peptide of avian influenza H5N1 at up to 1.96 percent of total soluble protein, and chicken interleukin-17B, which acted as an effective oral mucosal vaccine adjuvant in poultry. A duckweed-based edible vaccine recently conferred complete protection against avian infectious bronchitis virus by inducing robust mucosal and systemic immunity. Transient viral-vector systems achieve yields above one milligram per gram fresh weight within days. Compared with tobacco, the incumbent plant chassis, duckweed offers distinct advantages: it is naturally edible and free of alkaloid contaminants, its cell walls are low in lignin, simplifying extraction, and its obligate aquatic, rarely flowering habit provides built-in biological containment that mitigates transgene escape.

Traditional applications reinforce the platform’s credentials. Duckweed cover on irrigated paddies can almost entirely offset ammonia volatilization induced by water-saving irrigation, through a tripartite mechanism of physical gas blocking, direct ammonium uptake, and reduced water temperature. Replacing up to 15 percent of wheat and soybean meal in laying hen diets with Lemna minor maintained egg production while enhancing yolk color and showing hepatoprotective signs. Under combined nutrient limitation and elevated carbon dioxide, Landoltia punctata accumulated starch to more than 72 percent of dry weight at 10.4 grams per square meter per day, while mixotrophic bioreactor cultivation has reached growth rates of 152.3 grams per square meter per day, projecting yields near 50 tonnes of dry biomass per hectare annually. Duckweed systems also remove over 80 percent of chemical oxygen demand, over 90 percent of total phosphorus, and over half of total nitrogen from wastewater streams.

Significant hurdles remain before duckweed becomes an industrial workhorse. Large-scale cultivation must solve self-shading in dense mats, oxygen limitation under mixotrophic conditions, contamination in open water, and the fragility of fronds during harvesting, where mechanical skimming achieves 60 to 80 percent recovery and filtration exceeds 90 percent but clogs easily. Long-term transgene stability across hundreds of clonal generations lacks empirical data, and regulatory pathways for recombinant products from a novel aquatic host remain uncharted. The review’s authors call for integrated omics databases, universal genetic toolkits with standardized reporting, and scalable bioreactor designs to bridge the gap from proof of concept to production. If those pieces come together, the world’s smallest flowering plants may carry a disproportionate share of the sustainable manufacturing burden ahead.

Subject of Research: Duckweed biology and genetic engineering as a sustainable plant chassis for biotechnology

Article Title: Duckweeds: from fundamental biology to a sustainable plant chassis for biotechnology

Article References: Yin, G.-M., Yang, L., Li, S., & Zhang, Y. (2026). Duckweeds: from fundamental biology to a sustainable plant chassis for biotechnology. Advanced Biotechnology, 4(2), Article 16. https://doi.org/10.1007/s44307-026-00110-1

Image Credits: AI Generated

DOI: 10.1007/s44307-026-00110-1

Keywords: duckweed, Lemnaceae, plant chassis, molecular farming, CRISPR-Cas9, epigenome, phytoremediation, biopharmaceuticals, synthetic biology, genomics, starch production, sustainable biotechnology