Plant virus recruited to save crops from root-eating nematodes

Plant parasitic nematodes are microscopic soil-dwelling creatures that damage crops by feeding on their roots. Scientists have now developed a greener and more efficient means of eradicating them, using a modified plant virus.

Currently, farmers fight nematodes by applying pesticides to their crops.

Because those chemicals would otherwise just stay near the soil's surface, large quantities of them have to be applied, often accompanied by lots of water to wash them down to the roots. This means that farmers have to spend a lot of money on pesticides, they have to use a lot of water, plus large quantities of the toxic chemicals enter the environment.

Seeking a less wasteful and more eco-friendly alternative, Prof. Nicole Steinmetz and colleagues at the University of California-San Diego looked to the tobacco mild green mosaic virus. Unlike pesticides, it's naturally adept at making its way down through the soil.

The scientists developed a process which begins with the rod-shaped virus getting mixed with the pesticide ivermectin within a liquid solution. That solution is then heated to over 90 ºC (194 ºF), which causes three things to happen.

"First, the rod 'spits out' its genetic nucleic acid (the infectious part), which is degraded at the high temperature," Steinmetz told us. "Second, the rod turns into a spherical protein ball [a nanoparticle] that, thirdly, contains the pesticide."

In lab tests, the resulting non-infectious pesticide-encapsulating nanoparticles successfully made their way down through 10 cm (3.9 in) of soil. When the particles were recovered from the soil samples and added to a petri dish full of nematodes, their pesticide payload eradicated at least half of the population.

Plans now call for the nanoparticles to be tested on actual nematode-infested crop plants.

"This technology holds the promise of enhancing treatment effectiveness in the field without the need to increase pesticide dosage," said Steinmetz.

A paper on the research was recently published in the journal Nano Letters.

Source: UC San Diego