To help me with my tomato experiment, I spent all my free time yesterday reading about tomato breeding and genetics. Wow. There are a ton of genes that they know about (and that link is just a sample). I learned some interesting facts, not all of them about tomatoes either.
The most important fact was that unlike most modern tomatoes, the Sungold plant has long stigmas that stick out from the cone of the anthers. Most modern tomatoes hold the stigma inside the anther cone, so the modern tomato is always self-pollinating. Well Sungolds aren't always, nor are some old Heirlooms and wild tomatoes. They are free to cross with any tomato close to them, though still often cross with themselves. I had two other tomatoes in my garden - Aussie and Orange Blossom. Did they cross with my Sungolds? I did have bumble bees working the tomatoes last year.
I read that sometimes you want to select plants that have some traits that you like then recross them back with the origianal plants. I'm not going to do that. To do that you have to isolate the flower and strip it of its anthers before the pollen is viable, then hand cross it. Nah. Maybe some year. Right now I'm just going to let them grow and see what I get. I'll pick the best and save seed from those.
I learned that the Mi gene gives resistance to the root knot nematode (along with some aphids and whiteflys), but it works much better as a hybrid. If it carrys two copies of the gene (which an open pollinated plant would), it doesn't work as well. Too bad. I'd love to have that resistance in an OP tomato.
The most shocking thing I found out was not about tomatoes at all. Brassicas are self-incompatable for pollination. I knew that apples and blueberries need different pollinators, but figured all the garden vegetables have been bred in the past to be open pollinated homezygous plants that would breed true from themselves. Brassicas actually don't like being homozygous. Even if you cheat and bud pollinate them (a technique where you polinate the stigma while the flower is just in bud) they oftens still don't like to grow because they like their genetic diversity.
With all this new knowledge, I'm still going to do just what I was before. Plant them; see how they grow; save the ones I like. I would love to learn more however. The subject of plant breeding is really enthralling. I've followed Daughter of the Soil this year in her amatur plant breeding of peas and was facinated. I've been looking at books too. I'm thinking Breed Your Own Vegetable Varieties: The Gardener's & Farmer's Guide to Plant Breeding & Seed Saving would be a good introduction. It is an older book and some of the story line is a little out of date, but the breeding and saving parts are still up to date.