When the ancient Americans first engineered the genome of the tomato thousands of years ago, they selected strains of the wild plant that produced bigger fruit.
When geneticists recently edited the same genome, they pushed the plant to produce bigger fruit by growing larger flowers, a simple modification that could be applied to a number of key crops, including corn. Though it’s just one experiment on one crop, the findings could offer a new—and, in a way, time-tested—approach to improve yields.
While many people consider tomatoes a vegetable, botanically speaking, they are a fruit, or seed-bearing structures that are produced when a flower is pollinated. Flowers develop from a specific part of the plant, known as the meristem. In the meristem, a pathway known as CLV regulates flower growth. Messing with that pathway can either limit or encourage certain parts of of that process, making the flowers smaller or larger depending on the modification.
Elizabeth Pennisi, writing for Science, explains further:
Fruit size and other plant traits depend on what happens in the uppermost part of the stem, a growing tip called the meristem. There, unspecialized cells called stem cells divide to make more of themselves or specialize into specific plant parts, like carpels, the flower organs that make seed compartments. Wild tomatoes have two; beefsteaks have eight or more. The scientists discovered a feedback loop involving two genes, one to stimulate stem cell production and the other to hold production in check. A shortage of the latter, a gene called CLAVATA3 [which makes up a portion of the CLV pathway], leads to plumped up beefsteaks.
Earlier studies found that the CLV pathway exists across a wide range of plants, from corn to rice (which represent two very distinct portions of the plant family tree), meaning that our understanding of it could be used to tweak any number of different fruit-producing crops.
The exact mutations used in this study to produce larger tomatoes probably won’t produce massive ears of corn—the genetic sequences will undoubtedly have to be tweaked—but it likely won’t take much more experimentation before scientists can make more fruitful crops.
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