Thread: GM to save chestnut from extinction?

Reference : New Scientist, 7 June 2014, page 15

The American chestnut (Castanea dentata) is threatened with extinction. At one stage, it was a quarter of all hardwood trees in the USA, with 4 billion specimens. Then, around 1900, someone brought in Chinese chestnut speciments, which were carriers of a fungus disease. By 1950, the vast stands of native chestnut were gone.

There are two approaches to saving the tree. One is to inter-breed it with the Chinese chestnut, to try to breed in a degree of resistance to the disease. This approach works, but the final result is no longer genetically an American chestnut, with about 6% of its genes alien.

The second approach is to insert one single gene to impart fungus resistance. A gene from wheat does the job, and seeds are now available. The latest GM strains are more resistant than the Chinese tree, or the hybrid.

The next stage is to plant these trees once more in the wild, to restore some of the great old chestnut forests. The question is whether to use the hybrid, with 6% alien genes, or to use the GM tree with less than 0.01% alien genes.

Surely this is the prime example of an "all of the above" approach.

If it were up to me, I'd be planting a few, largish stands of the hybrid trees in key areas where chestnuts used to be common, while maintaining sizable nurseries for all three options.

Give it 5-10 years and see how they go and do more experimental work on the current options and any new ones that emerge anyway.

Presuming that they're OK and that they've not negatively affected the forests into which they've grown, try out the GM ones in other areas and similar areas.

Eventually, I'd think that using a mix of the hybrids and the GM in selected large plantings should be tried. With any luck, nature will do its thing and more natural hybrids will turn up in the seeds and one or several of those could turn out to be an even better option.

How to maintain a healthy source of the original species is a bit of a challenge, but I'd presume there are quarantinable stands of these still extant. Planting any of the Chinese and/or hybrid Chinese trees in or near or downwind of any such groups of trees would obviously have to be prohibited, but that's not a huge issue I would have thought.

I have several surviving American chestnuts trees. The fungus only kills the trunk and leaves the roots alone. So the roots send up shoots that may get to 10 to 15 foot height before they die. Generally this is too short a life span to produce any fruit. The GM idea sounds good I may buy a tree to plant. What sounds to me like a better approach would be gene tayloring a predator for the fungus. I don't know that anyone has tried to do that.

As I understand it, both approaches are under way, and stands of both hybrid and GM variety will be planted and monitored. There is little doubt that the GM option is better in terms of minimising genetic change and in terms of maximising disease resistance. However, because these things are likely to be very political, it is likely that the American people will make the final decision. Will they act on anti-GM prejudice, or permit the better option?

Don't think most Americans will care since chestnuts haven't been on their menu for more than half a century. GMO is the obvious choice here.