Path found to defeat crop

Aug 16, 2023

Published: August 25, 2023

Crops, News

It’s a mould that causes billions in crop losses every year, infecting berries, tomatoes and most other fruits and vegetables. Now, researchers have found a way to defeat the mould.

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Smoke from northern Ontario and Quebec wildfires was prevalent across Ontario for several weeks in June and early July. While…

If you’ve ever seen a fuzzy gray strawberry, you’ve seen gray mould. It affects more than 1,400 different plant species, and there is no real cure. Control may hinge on the discovery of lipid “bubbles” secreted by the mould cells, which some researchers previously dismissed as insignificant.

New UC Riverside research shows these bubbles are essential for communications between pathogens and their hosts, including many types of fungi, as well as bacteria and mammals. In this case, researchers found that gray mould has learned how to use the bubbles to achieve successful infections.

“Because they are hard to isolate and study, the important functions of these lipid bubbles, also called extracellular vesicles, have been overlooked for decades,” said Hailing Jin, professor of microbiology and plant pathology, who led the research project.

READ MORE: How a parasitoid wasp might address fruit fly pest issue

“Now we know the mould, just like its plant hosts, also uses extracellular vesicles to protect and deliver what amount to weapons — small RNA molecules that silence genes involved in plants’ immune systems,” Jin said.

This finding is detailed in the journal Nature Communications, where researchers not only show that gray mould secretes virulent RNA in these lipid-based bubbles, but that a particular protein is key to the mould’s ability to produce the bubbles.

The protein, tetraspanin, appears on the surface of the bubbles. Researchers found that if they eliminated the mould’s ability to make tetraspanin, the mould’s ability to secrete and deliver the bubbles was largely reduced.

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Previously, the same research team identified genes that allow the fungus to produce small RNA molecules. Knocking out those genes, as well as the ones that allow the fungus to make tetraspanin, would enable a new generation of “RNA fungicides” that inhibit grey mould disease.

“Everything has RNA in it, and it is easily digested by humans and animals. RNA can be degraded quickly in the environment and wouldn’t leave any toxic residues,” Jin said.

Fungicides are the main treatments for gray mould at present.

Gray mould is the second most damaging fungus for food crops in the world, preceded only by the rice pathogen Magnaporthe. An eco-friendly fungicide based on RNA, which attacks the ability to secrete extracellular vesicles, may also be effective against Magnaporthe and other fungal pathogens.

“With the climate changing so fast, many fungal infections can get worse. We are excited to develop new eco-friendly methods of protecting the global food supply that may be so widely applicable,” Jin said.

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