To make cassava plants resistant to ‘mosaic virus’, which can cause almost total loss of these plants in an epidemic, Australian researchers tried to “recombine the virus’s DNA” by genome editing, using CRISPR-Cas9.
Both frightening and unexpected results were obtained. The modified cassava plants did not develop any resistance to mosaic virus. On the contrary, the intervention encouraged viruses to “evolve faster”. “We have seen a mutant virus resistant to our procedure appear in the laboratory,” explained Devang Mehta, a postdoctoral fellow at the University of Alberta (Canada).
The researchers have therefore called for “laboratory tests be carried out in the future to detect possible viral mutations before launching field trials“.