The science behind plant breeding

Kids tend to look like their moms and dads, and the same rule applies to plants.

The passing of traits from generation to generation is called heredity. And the field of science that focuses on the rules of heredity is genetics. For thousands of years, farmers and gardeners have taken advantage of the rules of heredity to create new plants with bigger and sweeter fruits and with greater resistance to disease, drought and insects. Scientists who do this are called plant breeders.

These scientists use pollen from the best male plants to fertilize the best female plants. They have brought us big, juicy ears of corn (varieties from several hundred years ago were about the size of your thumb) and blackberry bushes that don’t have thorns.

In recent years, scientists have learned how to make new plant varieties even more efficiently by genetic engineering. They insert or delete pieces of DNA, the genetic material that is in a plant’s chromosomes. Among their results: corn plants that make insect-killing chemicals in their leaves, so farmers don’t have to spray them, and soybeans that will not die when farmers accidentally splash them with weed killers.

But those advances bring new concerns, too. Pollen from some of these plants has spread accidentally to nearby weeds, making those weeds stronger. Scientists are now developing ways to keep new plant traits from spreading accidentally.