Ash Trees in the UK Evolving Resistance to Ash Dieback Disease

Ash trees in the UK are showing signs of rapidly evolving resistance to ash dieback disease, as revealed by DNA sequencing of hundreds of trees. This discovery brings hope for the survival of these trees, although complete resistance may still require human intervention through breeding programs.

The Threat of Ash Dieback Disease

Ash dieback, caused by the fungus Hymenoscyphus fraxineus, poses a significant threat to ash trees in the UK. The disease, which originated in Asia, disrupts the trees’ water transport system and has been spreading across Europe since the 1990s, reaching the UK in 2012. The consequences of ash dieback include the release of carbon dioxide, habitat loss for various species dependent on ash trees, and the risk of falling trees endangering people and property.

Evidence of Evolutionary Response

Researchers, including Richard Buggs from the Royal Botanic Gardens, Kew, conducted genome comparisons of 128 adult European ash trees and 458 saplings at a site in Surrey. The study identified genetic variants associated with resistance, with a higher prevalence in young trees, suggesting a natural selection process favoring resistant individuals. While these variants offer only partial resistance, they demonstrate ongoing evolutionary changes within the ash tree population.

Challenges and Solutions

Despite the promising signs of resistance, the long-term survival of ash trees remains uncertain, especially with the potential threat of the emerald ash borer in North America. To address these challenges, Buggs suggests the need for proactive measures such as breeding programs and creating hybrid trees with increased resistance to combat the evolving threats from pests and diseases.

Global Perspectives on Tree Health

The global movement of pests and pathogens poses a growing risk to tree populations worldwide. Buggs emphasizes the importance of maintaining genetic diversity and implementing strategies to protect trees from new epidemics. By understanding the genetic mechanisms underlying tree resistance, researchers and conservationists can work towards preserving tree species in the face of evolving threats.

Source: Richard Buggs