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By far the most interesting part of the discussion, and perhaps the more optimistic, was identifying how we might rise to the challenge of making our precious trees and woods more resilient in the face of these on going and inevitable threats. With the input of renowned woodland ecologist, Keith Kirby from University of Oxford, the group considered how the natural and cultural history of our woods has shaped them – and what we can do to give nature a helping hand.

This cannot be a ‘one size fits all’ approach and there is no simple template that all woodland owners and managers should follow – in fact the tendency to try and manage all of our woods in the same way in the past or previous suddenly shifts in management resulting from pursuit of narrow theories has probably made them more vulnerable today. A vulnerability compounded by the continuing gradual loss of woodland and the fragmentation of woods and other habitats, leaving them disconnected and isolated.

But some key principles are emerging. Our woods will be more resilient if they contain a wider range of native species, and have a more diverse structure too – so that we have a good mix of types of trees and a range of young, established and older trees.

Prof Erik Kjaer from the University of Copenhagen, confirmed that a small proportion (around 2%) of ash may be naturally resistant or tolerant to chalara. There are also good signs that this characteristic can be passed on to progeny of those surviving trees.

http://wtcampaigns.wordpress.com/2013/06/28/making-our-woods-more-resilient-tapping-in-to-the-insight-of-experts/

See what we are doing: The Natural Ash Nursery –

http://worldwidewood.wordpress.com/2013/06/17/natural-ash-nursery-cleared-and-ready-for-the-deer-fence/

The genetic insights could eventually be used to cross Tree 35 with breeding stock from our native ash population. Tree 35 is predominantly female and the genetic make-up could help identify a predominantly male UK tree with resistance to make a breeding pair. Or it could be used to identify both female and male UK trees with similarly low susceptibility to the fungus. A combination of crosses might be needed for a lasting comeback from the epidemic.

Ash trees are almost always fertilised by pollen from another ash tree rather than by self-pollination. This generates two copies of each chromosome in the resulting seeds. Although very similar, the chromosomes tend to have many differences when you look at the detail. This ‘heterozygosity’ makes it difficult to generate a genome sequence because in effect you have to put two genomes together at the same time.

Tree 35 has been identified as highly heterozygous.

http://www.tgac.ac.uk/home/news/54/68/Genome-sequence-for-mother-of-ash-dieback-survival/

The scientists are extremely hopeful that, having determined the tree’s complete set of genetic material – through a process known as genome sequencing – they have paved the way to identify those genes which might be connected to its ability to withstand the fungus.

Although the breakthroughs have raised hopes that a new breed of ash will be able to grow and survive in the face of the fungus, they will do nothing to protect Britain’s 80m existing ash trees, which are all under threat.

Adult clones of tree 35 grown from cuttings taken from the original trees in the 1930s were recently discovered on the Danish island of Sealand. [However] just planting this variety of Ash in the UK would result in a narrow genetic base making the species vulnerable to future diseases, experts said, adding that the latest breakthroughs still represented a giant step forward for the long-term prospects of the tree in this country.

http://www.independent.co.uk/news/uk/home-news/genetic-secrets-of-resistant-tree-gives-new-hope-over-ash-dieback-disease-8660992.html

Dutch elm disease is a tragic thing to watch, but we shouldn’t be too gloomy. Woody vegetation responds, adapts, regroups. What emerges in its recovery stage may not be the same as before, but it will always be a vital, dynamic, arboreal community.

The fungus, now known as Chalara fraxinea, is biologically mysterious, an entirely new organism of uncertain origins. It probably evolved in eastern Asia, where it appears to be harmless to native ash species. Its ancestor is a benign and widespread leaf fungus called Hymeno­scyphus albidus, native even in the UK. But at some recent date, this threw up a mutant, Hymenoscyphus pseudoalbidus, with slight genetic differences but a terrible virulence.

Natural resistance is likely to be the best hope for the survival of a core population of ashes in the UK. Isolated from the continent for nearly 8,000 years, our trees may be more genetically diverse than those in Poland.

For their part, ordinary rural people were mystified by the need for plantations, having lived for thousands of years with woods that renewed themselves spontaneously and indefinitely by seeding, or by regrowth from cut coppice stools and pollards. In place of this system of natural regeneration came the notion of trees as artefacts, biddable machines for the production of timber, programmed at every stage of their lives from planting to cutting.

The fundamental grammar of our relationship with them had been changed. Previously, “growing” had been an intransitive verb in the language of woods. Trees grew, and we, in a kind of subordinate clause, took things from them. In the forest-speak of the Enlightenment, “growing” became a transitive verb. We were the subject and trees the object. We were the cause of their existence in particular places on the earth.

Now, in the extremities of ash dieback, we can see that decades of well-intentioned planting have been not only often unnecessary, but, quite possibly, dangerous. Runtish saplings, often mislabelled and of unknown provenance, are shoved into the ground, regardless of whether they might be vectors for disease, or whether the soil is right and the site appropriate.

The existence of a large population of indigenous ashes is our best safeguard for the future and makes rather baffling the Forestry Commission’s experiment, initiated early in May, of planting out trial plots with 150,000 saplings of “15 different varieties”. The intention is to discover whether a few may be resistant and eventually propagate from them. But as 80 million ashes from probably ten times that number of genotypes are already engaged in just such an experiment across Britain, it is hard to see this as much more than a PR exercise – one that fits tidily in to our long, hubristic belief that the salvation of trees lies with us and our superior arboreal intelligence only.

http://www.newstatesman.com/sci-tech/2013/06/our-ash-trees-are-dying-dont-despair-catastrophes-are-natural-events-lives-trees

See also: http://worldwidewood.wordpress.com/2013/06/17/natural-ash-nursery-cleared-and-ready-for-the-deer-fence/

Scientists have sequenced the genome of a type of ash tree with resistance to the deadly fungal disease sweeping the UK.

The development could be the starting point for breeding a strain of ash to replace thousands expected to succumb to ash die-back in the next few years.

All the data is being put on a crowd sourcing website OpenAshDieBack to enable experts from around the world to help identify genes that might be connected to the trees’ ability to withstand the fungus.

These genes could then be part of a breeding programme for resistant trees.

The samples for the latest research came from so-called “tree 35”, a strain of ash from Denmark originally bred nearly 100 years ago, which has shown an ability to tolerate the fungal disease, when virtually all its Danish relatives were wiped out.

Prof Allan Downie of the John Innes Centre believes this genetic understanding of both the lethal fungal infection and the surviving strain could help fill the impending gap in the canopy.

“We’re trying to give nature a bit of a helping hand by identifying the right kind of (native) trees to do the appropriate crosses,” he said.

http://www.bbc.co.uk/news/science-environment-22913111

The Genome Analysis Centre (TGAC) has worked fast to sequence and assemble the valuable genome of the survivor “tree 35” from the recent Ash Dieback outbreak that have caused devastating damage to the Danish Ash woodlands and that now threatens the UK trees.

This information will be useful to those that are trying to find the trees that would offer at least a partial resistance and can be used to replace the now empty woodlands and remediate the damage.

This work contributes to the Nornex consortium, part of the Biotechnology and Biological Sciences Research Council (BBSRC) and Defra funded bioscience response to ash dieback (Chalara fraxinea). Prof. Erik Dahl Kjær and his group have been instrumental in the success of this project, read more about his work on this here.

“The genome sequence of this ash will be an essential tool that can help us to follow the inheritance of the ability of some ash trees to tolerate and to inhibit the growth of the Chalara fraxinea pathogen. Such knowledge will help generate new varieties of ash trees that can withstand attack by the fungus,” said Prof. Allan Downie at the John Innes Centre.

http://www.tgac.ac.uk/news/52/68/Unravelling-the-genetic-code-of-the-Ash-Dieback-survivor-tree-35/

The images were obtained using cryo scanning electron microscopy, where the sample is plunged into liquid nitrogen to freeze it and imaged using the electron microscope.

The benefit of this method is that the sample is imaged in as close to its natural state as possible, providing the best quality 3D view of an organism.

http://news.jic.ac.uk/2013/05/close-up-images-of-chalara-fraxinea/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+NewsFromTheJohnInnesCentre+%28News+from+the+John+Innes+Centre%29

 

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