“We won’t be able to solve the whole problem in the life of this collaboration. However, we aim to use new technologies to help tree breeders select the best trees to cross-fertilise. We hope to generate the knowledge needed to understand why this fungus has become such a problem. That knowledge will catalyse further research around the world.”

It will be the first time that some advanced genetic techniques such as ‘associative transcriptomics’ are used in trees. This is where the expressed genes of plant varieties are compared to identify markers for traits. These can be used to speed up marker assisted breeding.

The scientists will focus part of their ash research on ‘Tree 35’, a tree in Denmark that has stayed healthy during the epidemic that has damaged most ash trees in the country. By mapping the genomes of ‘Tree 35’ and other trees with low susceptibility, they will be able to establish the genetic basis of resistance.

Ash is highly variable because mother trees can have multiple partners. If, within this variation, different types of ash show some resistance, the scientists will be able to recommend building stronger resistance based on multiple crosses. Different crosses for different environments will also need to be suggested, to breed resistant trees adapted to specific conditions.