Bigger Peppers, Borrowed Genes: How People Change Traits

The Seed Library Pepper Project

1The public library in Millbrook runs a seed library. Gardeners borrow seeds in the spring and bring back seeds from their own plants in the fall. In 2019, eighth grader Tobias Eklund and the library's garden club set a goal: grow a sweet pepper with heavier fruit. They started with one batch of seeds of a single variety. Even within that batch the plants were not all alike. Some plants gave peppers of about 90 g, others gave peppers of about 150 g, and the average was 120 g.

2The club split the seeds into two lines and grew both in the same raised beds. Each line had 40 plants each summer, the same soil mix and the same watering schedule. In the selected line, the club weighed every ripe pepper and saved seeds only from the 5 plants with the heaviest average fruit. In the control line, they saved seeds from 5 plants picked at random by drawing numbers from a cup. They covered the flowers of all parent plants with mesh bags so bees could not bring in pollen from other plants. A pepper plant lives for one summer here, so each year's plants grew from seeds saved the fall before. Table 1 shows the average pepper mass in each line.

3Each fall, Tobias typed the results into a shared spreadsheet so other gardeners could follow the project. He also noted that plants in the two lines looked alike in height and leaf color, and that both lines got the same weekly checks for pests.

4At a library talk, plant scientist Dr. Kwame Osei described a second technology, genetic engineering. Scientists copy a specific gene from one organism and insert it into the DNA of another organism, which can belong to a very different species. The changed organism can then make the protein that the gene codes for, and it can pass the gene to its offspring. Table 2 lists three examples. The insulin example began in the early 1980s; before then, most insulin for people with diabetes came from the pancreas of cows and pigs.

5Dr. Osei also described rice. Rice plants make beta-carotene in their green leaves, but the grain people eat makes almost none. The body uses beta-carotene to make vitamin A. Breeders searched many rice varieties and did not find plants whose grain made it. People debate both technologies, he added, including their cost, how they are safety tested and how many crop varieties farmers keep growing.