John Coykendall, renowned seed saver and farmer, talks about the difference between commercial and organic tomatoes. John is the master gardener at the mountain retreat Blackberry Farm in his native Tennessee. (See NPR story.) Dr. Howard Conyers, a rocket scientist at NASA, interviews John on his show Nourish for PBS Digital Studios. John has collected more than 500 varieties of seeds gathered from small farmers and backyard gardeners from around the world. He’s been doing this long before GMOs became a concern.