Spraying leaves from barley plants with a liquid containing long RNA molecules helps them to fend off fungal infection.
A mechanism called RNA interference (RNAi) uses double-stranded RNA molecules to shut down the expression of specific genes. Karl-Heinz Kogel of the Justus Liebig University in Giessen, Germany, and his colleagues used RNAi to silence three genes that fungi require to make ergosterol, a compound needed for fungal growth. The team found that when the RNA is sprayed directly onto barley leaves, it is taken up by the fungal pathogen Fusarium graminearum and inhibits its growth in those leaves. Even unsprayed leaf parts are protected from the fungus, because the RNA molecules are absorbed and transported by the leaves before being taken up by the pathogen.
The approach could open the door to a new generation of fungicides, the authors note.