[JshWright]

It actually is pretty "simple" in this case (the tree needs to produce a single chemical, oxalate oxidase). There is a program that has done this very successfully, and it just working through the regulatory process before wider distribution can happen. They have thousands of trees in (controlled) forest plots, including three generations of offspring.

[empyrrhicist]

That's the genetic engineering approach, but the Chinese ones have a different, more complex, less well understood, and potentially complementary resistance mechanism.

[JshWright]

Right, the genetic engineering approach is what this reply thread is about…

[culi]

That's very interesting. The video I linked showed that blight resistant trees had a very specific response to grow extra tissue around the infection site to stop it from spreading further so I assumed it was more of a multi-pronged defense

[empyrrhicist]

Yes - the Asian ones that evolved with the fungus have a more complex strategy, making a purely breeding-based program challenging. Separately, some clever genetic engineering allows the trees to break down oxalic acid, which prevents the fungus from being able to efficiently attack the plant cells.

Two separate things.

[pfdietz]

These two approaches could be combined, and probably will be naturally if both varieties are introduced to the wild.

[JshWright]

Indeed, part of the work being done by the team working on the genetic engineering approach is breeding Darling 58 with the Chinese backcrossed version.