Immunity-boosting silica nanoparticles could replace pesticides

Pesticides may indeed kill plant pathogens, but they're also harmful to the environment. Newly developed nanoparticles may provide a more eco-friendly alternative, as they boost the immune systems of crop plants, then harmlessly dissolve.

Occurring naturally in soil, a compound known as silicic acid has for some time been known to provoke plants' immune response. It's also released by amorphous (non-crystalline) silica nanoparticles, which are found in some crop plants. Such nanoparticles are additionally an ingredient in food-grade silica, which is used as an anti-clumping agent in products like table salt and protein powders.

Silicic acid is already applied to crops in liquid fertilizer form, to help them fight off viruses and problematic bacteria. Unfortunately, though, the sudden and intense dose of the compound can actually stress the plants, plus it may harm beneficial microorganisms living in the soil.

Seeking a gentler approach, scientists at Switzerland's University of Fribourg have created synthetic silica nanoparticles which are rich in silicic acid, but that release it slowly. In lab tests, these were applied to thale cress plants (Arabidopsis thaliana) that were infected with Pseudomonas syringae bacteria. It was found that the acid helped the plants to fight off the microbes, by increasing production of a key defense hormone.