Common plant viruses engineered into nanoscale agricultural materials that help crops grow
To reduce the harm caused by pests and diseases, farmers apply pesticides appropriately in accordance with the crop growth cycle. Since most pesticides are non-specific, improper application may destroy the food web around farmland and thereby affect the balance of the surrounding ecosystem. With the rise of environmental awareness and the introduction of the concept of safe pesticide use management, in addition to eliminating agricultural pests and regulating the growth of agricultural and forestry crops, the load on the regional environment should also be avoided. For this reason, pesticide application is gradually being managed and practiced toward the thinking of precision agriculture (precision farming). To apply pesticides precisely to farmland and reduce environmental impact, a research team at the University of California, San Diego (University of California San Diego) used plant viruses as pesticide delivery vehicles to develop highly penetrating nanopesticides.
To develop materials with localized slow release and the ability to easily degrade in the environment, the research team focused on the development of nanoscale materials. Unlike previous nanomaterials based mainly on artificial synthesis, the research team used plant virus particles as carriers for delivering agents, selecting tobacco mild green mosaic virus (tobacco mild green mosaic virus, abbreviated TMGMV), cowpea mosaic virus (cowpea mosaic virus, abbreviated CPMV) and Physalis mosaic virus (Physalis mosaic virus, abbreviated PhMV) as research materials, and compared them with common drug delivery systems such as mesoporous silica nanoparticles (mesoporous silica nanoparticles, abbreviated MSNPs) and poly(lactic-co-glycolic acid) (poly(lactic-co-glycolic acid), abbreviated PLGA). The team first measured the mobility (migration rate) of these materials in soil media, and combined computer simulations of data such as the migration depth of the materials, the appropriate application dose and the drug release time, and found that tobacco mild green mosaic virus and cowpea mosaic virus could diffuse into soil 30 cm below the surface and precisely release nematicides slowly, effectively controlling nematodes that harm plant roots. By comparison, synthetic nanomaterials could only migrate to a depth of 12 cm below the soil, making it less able to provide more comprehensive protection for deep-rooted crops.
In the face of the better migration effect, the research team inferred that this may be related to the special geometric structure and chemical composition of the virus surface, enabling the viral materials to easily penetrate soil pores. Among these geometric structures, the long rod-shaped tobacco mild green mosaic virus was superior to other spherical nanomaterials, and in addition its rod-shaped surface possesses a variety of chemical substances, enabling it to interact with different soil media, and for this reason this nanomaterial can perform better in soil.
This research model established by the research team helps advance the development process of other biological materials. With only simple equipment, under computer-aided simulation, research that originally took 1 month was condensed into 4 days. This research likewise makes a major contribution to precision agriculture, pest and disease control management technology and environmental safety.
The research was funded by the U.S. National Science Foundation (National Science Foundation) and the U.S. National Institutes of Health (National Institutes of Health), and the related research results were published in <Nature Nanotechnology>.
