Scientists find genes to save ash trees from deadly beetle

An international team of scientists have identified candidate resistance genes that could protect ash trees from the Emerald Ash Borer (EAB), a deadly pest that is expected to kill billions of trees worldwide.

Researchers from Queen Mary University of London and the Royal Botanic Gardens, Kew, sequenced the genomes of 22 species of ash tree (Fraxinus) from around the world and used this information to analyse how the different species are related to each other.

Meanwhile, collaborators from the United States Department of Agriculture Forest Service in Ohio tested resistance of over 20 ash tree species to EAB by hatching eggs attached to the bark of trees, and following the fate of the beetle larvae. Resistant ash trees generally killed the larvae when they burrowed into their stems, but susceptible ones did not.

The research team observed that several of the resistant species were more closely related to susceptible species than to other resistant species. This meant the UK-based genome scientists were able to find resistance genes, by looking for places within the DNA where the resistant species were similar, but showed differences from their susceptible relatives.

Using this novel approach, the scientists revealed 53 candidate resistance genes, several of which are involved in making chemicals that are likely to be harmful to insects. The findings suggest that breeding or gene editing could be used to place these resistance genes into ash species currently affected by EAB.