The whole system wilts, however, if good resistance does not appear in a variety of the crop. Grasses related to wheat and corn, for example, have supplied defensive genes against deadly viruses. But related species don't always cross. And that was the problem facing Helgeson in 1994, when late blight struck a field of spuds he was testing for resistance to another disease. Because the two plants would not cross-breed, Helgeson turned to protoplast fusion.
More chemicals weaken the remaining cell membrane, allowing the two cells to fuse.
You're left with one cell with a double copy of all the organelles inside. Eventually, the nuclei also fuse, the cells begin dividing, and form a gob of undifferentiated cells called a callus. Using tissue culture, you grow some of these cells into full-size plants. And that is exactly what Helgeson has done, as you can see from the photo above. It just doesn't allow the fungus to grow very fast, so it does not take over the plant and reduce it to nothing.