My reading of the article suggests they modified the genomes of multiple trees, and the “winners” that got into the field happened to have ancestors that had moved the target gene to a different chromosome.
They’re simultaneously trying to make precision modifications to the genome and also trying to preserve hundreds of wild strains.
If they succeed, the required technological advances will probably be broadly applicable.
"Upon further and additional independent investigation, scientists confirmed that the trees they had been researching were in fact *descendants of a different event in the Darling line* in which the OxO gene had been inserted into a coding region, causing a deletion in a known gene. "