Plant-Derived Exosomes: Isolation Techniques, Characterization Methods and Agricultural Research Applications

Plant-derived exosomes are nanoscale extracellular vesicles (EVs) naturally secreted by plant cells, typically ranging from 30 to 150 nm in diameter. These vesicles carry bioactive components including proteins, lipids, RNAs, and secondary metabolites, and participate in critical physiological processes such as cell-to-cell communication, stress response, and growth regulation.

In recent years, plant exosomes have emerged as a novel research hotspot in agricultural biotechnology, crop science, and plant physiology. Unlike animal or microbial exosomes, plant-derived exosomes show good biocompatibility, low toxicity, and unique biological activities, making them highly valuable for agricultural applications.

This article reviews the mainstream isolation and characterization methods for plant-derived exosomes, as well as their key research and application prospects in modern agriculture.

1. Isolation Techniques for Plant-Derived Exosomes

Isolation efficiency and purity directly affect the reliability of downstream experiments. Plant samples such as leaves, roots, fruits, seeds, and saps often contain polysaccharides, polyphenols, pigments, and cell debris, which increase the difficulty of exosome extraction.

Ultracentrifugation

Ultracentrifugation is the most traditional and widely used method for exosome isolation. It separates vesicles based on density and size via high-speed centrifugation steps.

l Advantages: Mature protocol, suitable for most plant tissues, low reagent interference.

l Disadvantages: Time-consuming, high equipment cost, relatively low purity.

Polymer-based Precipitation

This method uses water‑solvent polymers to aggregate and precipitate exosomes from plant homogenates.

l Advantages: Fast operation, no need for ultra‑high‑speed centrifuges, high yield.

l Disadvantages: Easy to co‑precipitate impurities, may affect downstream analysis.

Size‑exclusion Chromatography

Size‑exclusion chromatography separates particles by molecular weight and diameter, providing high‑purity exosomes.

l Advantages: High purity, mild conditions, maintains vesicle structure.

l Disadvantages: Low processing volume, time‑consuming, requires pre‑treatment.

Immunoaffinity Capture

This technique uses specific antibodies or ligands to bind surface markers of plant exosomes, enabling highly selective enrichment.

l Advantages: Ultra‑high purity, suitable for precise functional studies.

l Disadvantages: High cost, limited by unclear plant exosome markers.

Comparison of Common Plant Exosome Isolation Methods

2. Characterization Methods for Plant-Derived Exosomes

Standardized exosomes characterization is essential to confirm exosome identity, morphology, size, and purity.

Morphological Observation

Transmission electron microscopy (TEM) is used to visualize the typical cup‑shaped or spherical morphology of exosomes. It is the most intuitive method to verify vesicle structure.

Particle Size and Concentration Analysis

Nanoparticle Tracking Analysis (NTA) and Dynamic Light Scattering (DLS) measure the diameter distribution and concentration of exosomes. Plant exosomes generally range from 30 to 150 nm.

Biomarker Detection

Although specific plant exosome markers are still being identified, common detection indicators include:

l Plant‑specific proteins

l Lipid components

l Small RNAs

Western blotting, proteomics, and gene expression analysis are often used for identification.

Density Detection

Sucrose density gradient centrifugation measures the buoyant density of exosomes. Plant exosomes typically show a density range of 1.10–1.19 g/mL.

3. Agricultural Research Applications of Plant-Derived Exosomes

Plant exosomes have broad application potential in agricultural production and scientific research.

Plant Growth and Development Regulation

Plant exosomes mediate signal transmission between cells and tissues, participating in the regulation of seed germination, root development, leaf growth, and fruit ripening. They provide new targets for improving crop yield and quality.

Crop Stress Resistance

Exosomes help plants respond to drought, salt, low temperature, heavy metals, and pathogenic microorganisms. By transporting functional RNAs and proteins, they enhance disease resistance and environmental adaptability. 

Plant–Microbe Interaction

Plant exosomes participate in communication between plants and beneficial microbes such as rhizobia, mycorrhizal fungi, and probiotics. They also regulate defense responses against pathogens. This mechanism supports the development of eco‑friendly biocontrol agents.

Delivery Systems for Agricultural Biomolecules

Due to their stable structure and high biocompatibility, plant exosomes can be used as natural nanocarriers.

Potential applications include:

l Delivery of small RNAs for gene regulation

l Delivery of natural antimicrobial compounds

l Development of environmentally friendly pesticides

Biomarkers for Crop Health Monitoring

Exosome composition changes under different growth conditions or stress treatments. They can serve as non‑invasive biomarkers for evaluating crop health, nutritional status, and disease infection.

4. Current Challenges in Plant Exosome Research

Despite rapid progress, several challenges remain in agricultural exosome research:

l Lack of universal and specific protein markers for plant exosomes

l Low extraction efficiency from complex plant tissues rich in polysaccharides and polyphenols

l Unclear mechanisms of exosome biogenesis and secretion in plants

l Limited application examples in actual agricultural production

5. Future Prospects

With the development of nanotechnology, omics, and agricultural synthetic biology, plant‑derived exosomes will show greater value:

l Establishment of standardized isolation and identification systems

l Discovery of more functional components in crop exosomes

l Development of exosome‑based biostimulants and biopesticides

l Application in precision agriculture and intelligent crop management

Plant exosomes represent a new frontier connecting cell biology, nanotechnology, and agricultural innovation.

Conclusion

Plant-derived exosomes are important extracellular vesicles with critical roles in plant growth, stress resistance, and cell communication. Standardized isolation and characterization methods are the foundation of agricultural exosome research.

As a novel biological resource, plant exosomes provide new strategies for crop improvement, disease control, environmental stress adaptation, and sustainable agricultural development. Further in‑depth research will strongly promote their application in modern agriculture.