The government often has to deal with difficult problems, and ash dieback disease has been no exception. Ash Dieback is a fungal disease likely to have arrived in the UK from a mixture of infected planting material and spores blown over from infected trees in continental Europe.
The pathogen causing this disease, Hymenscyphus fraxineus, was not formally identified until after it began seriously affecting trees in Eastern Europe in the early 1990s. Even then little was known about the pathogen that might help develop management strategies. Meanwhile, the disease continued to spread across Europe before being identified in East Anglia in 2012. Its arrival and the subsequent public interest demonstrates that trees, woodlands and forests hold a special place in our nation’s hearts.
There are an estimated 126 million ash trees in British woodlands over half a hectare in size, and many more in our parklands, hedgerows and cities. Ash is the 3rd most prevalent broadleaved species in GB woodlands, at 9%, and the fifth most prevalent of all trees at 4%. The economic benefit of forests is estimated to be £1bn to the UK economy, with even greater environmental and social benefits. As one of our native trees, ash is an important part of the forest ecosystem, supporting a huge range of biodiversity from lichens and mosses to invertebrates and birds. Forty-six species are only found on ash trees. So protecting ash trees is about more than just protecting a single species.
After the disease was discovered, Defra worked with the Biotechnology and Biological Sciences Research Council, to establish two research projects to improve our understanding of it. The experience in Europe showed that some trees were more susceptible to the disease, developing symptoms and dying more quickly, while others were less affected. This gave hope that some of the trees in the UK might be tolerant to the disease and their identification became one of Defra’s commitments in response to the disease.
The Nornex project, which published its final report last Friday (22 April) used molecular approaches to improve not only our understanding of the disease, but of the ash tree itself. The research has meant we have been able to develop genetic markers that signal tolerance to the disease, just as quality of plumage can signal biological fitness in birds. The tolerance was assessed using a selection of 182 Danish ash trees, scored for visual signs of disease which was then assessed against the extent to which specific genes were active. Three genetic characteristics appear to be important signals of resistance. Variability in susceptibility may be caused by how two genes interact.
This new knowledge is a great step forward and illustrates the benefits that cutting-edge science can bring to real-life problems, made all the more impressive considering the project ran for only about two years. One of the huge advances that has made this possible is the reduced time needed to sequence a genome, from years to hours and at a fraction of the cost; and the open and collaborative approach taken by the research team.
The project also made use of a Facebook game, Fraxinus, designed to use human pattern recognition skills to identify DNA sequence variations. The game was played more than 63,000 times and resulted in many reliable new sequence variants.
The research, led by Professor Allan Downie from the John Innes Centre in Norwich, was delivered by a consortium including: the University of York; the Genome Analysis Centre at the University of Exeter; Fera Science Ltd; the University of Copenhagen; Forest Research; the Sainsbury Laboratory; East Malling Research; the Forest and Landscape Institute Norway; and the University of Edinburgh.
The Nornex project’s research report can be found here: http://oadb.tsl.ac.uk/?page_id=964