Researchers Find a New Way To Mitigate Gray Mold in Food Crops
Gray mold affects more than 1,400 different plant species, including berries, tomatoes, and most other fruits and vegetables. There is no real cure for it. Being able to control gray mold might hinge on the discovery of lipid “bubbles” secreted by the mold 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, the researchers found that gray mold 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,” says Hailing Jin, UCR Professor of microbiology and plant pathology, who led the research project.
“Now we know the mold, 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 says.
This finding is detailed in the journal Nature Communications, where the researchers not only show that gray mold secretes virulent RNA in these lipid-based bubbles, but that a particular protein is key to the mold’s ability to produce the bubbles.
The protein, tetraspanin, appears on the surface of the bubbles. The researchers found if they eliminated the mold’s ability to make tetraspanin, the mold’s ability to secrete and deliver the bubbles was largely reduced.
“If we knock out this key component of the vesicles, we can attenuate their ability to deliver the weapons of small RNAs or other molecules that suppress host immunity,” Jin adds.
Previously, the same research team also 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 mold 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 says. Currently the main treatments for gray mold are fungicides and these chemicals can negatively impact human and animal health and our environment.”
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