Heidi Ledford, Nature News 18 May 2017, https://www.nature.com/news/fixing-the-tomato-crispr-edits-correct-plant-breeding-snafu-1.22018
Tomatoes have been bred for their large fruit over thousands of years. To prevent the tomato from dropping mature fruit, breeders in the 1950s crossed the modern tomato with a wild variety discovered in the Galapagos that lacked the weak region of the stem responsible for fruit dropping. While this trait functioned in the new cross, it also resulted in extra branches that produced flowers, draining the plants resources. By sequencing many tomato varieties, scientists have now identified the genes responsible for both traits and are using CRISPR to modify the tomato for better yields and fruit retention.