Scientists find genes to save ash trees from deadly beetle

Scientists find genes to save ash trees from deadly beetle - Queen Mary University London

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.

Scientists find genes to save ash trees from deadly beetle. Credit: USDA Forest Service photo by Jennifer Koch.

In the new study, published today (Monday 25 May) in Nature Ecology & Evolution, 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.

Dr Laura Kelly, an academic visitor at Queen Mary, Research Leader in Plant Health at the Royal Botanic Gardens, Kew and first author of the study, said: “Ash trees are key components of temperate forest ecosystems and the damage caused by EAB also puts at risk the many benefits that these forests provide. Our findings suggest that it may be possible to increase resistance in susceptible species of ash via hybrid breeding with their resistant relatives or through gene editing. Knowledge of genes involved in resistance will also help efforts to identify trees that are able to survive the ongoing threat from EAB, and in turn, could facilitate restoration of ash woodlands in areas which have already been invaded.”