I devoured this article earlier tonight:
The Plant Journal(2014)77,727–736
Restoring pistil-side self-incompatibility factors recapitulatesan interspecific reproductive barrier between tomato species Alejandro Tovar, Aruna Kumar, Katsuhiko Kondo, Amy Ashford, You S. Baek, Lillian Welch,Patricia A. Bedinger and Bruce A. McClure
It basically says that there are two genes that affect self incompatibility in tomatoes. One is expressed in the pistil, and one in the pollen. And that self-incompatibility can be restored by re-introducing both genes. Whew!!!! Good thing, since that's been the whole basis of my Beautifully Promiscuous and Tasty Tomato project.