The groundcherry might look at first like a purely ornamental plant. A member of the genus Physalis, it bears papery, heart-shaped husks that resemble Chinese lanterns. (The plant popularly known as the Chinese lantern is a close cousin.) Within each groundcherry casing is a small, tart, edible fruit, similar in appearance to a cherry tomato, that is sometimes sold at farmer’s markets.
The fruit might be more common in supermarkets were it not so difficult to grow in large quantities. Groundcherry bushes sprawl untidily and can drop their fruits early, and the plants possess other undesirable traits. Diminishing these traits through selective breeding would take years.
On Monday, however, a team of researchers reported that, by removing certain portions of the plant’s DNA using common gene-editing techniques, they’ve produced a groundcherry with a larger fruit and a more ordered bush, greatly speeding the process of domestication. Their work, which appeared in the journal Nature Plants, is part of a scientific initiative called the Physalis Improvement Project.
[Like the Science Times page on Facebook. | Sign up for the Science Times newsletter.]
Groundcherries are related to tomatoes, which have a well-studied genome. Joyce Van Eck, a plant geneticist at Cornell University and an author of the paper, and her colleagues had already discovered that, using Crispr, a gene-editing technique that can snip out portions of the genome, they could alter a specific tomato gene and produce plants that produced flowers more quickly.
The scientists wondered whether the groundcherry could be similarly altered, to help fast-track the domestication process. They examined the groundcherry genome for analogues of known tomato genes, and found one: an analogue of a gene called “SELF-PRUNING” or SP, that in tomatoes controls the shape of the plant.
Using Crispr, the team removed a small portion of SP from the groundcherry genome. The resulting plants, when they grew, arranged themselves into more compact bushes. The team performed similar experiments with genes that influence flower number and fruit size.
“Sure enough, when we got those fruit off, they were larger than the parent groundcherry,” Dr. Van Eck said. “Close to 25 percent more weight in the fruit.”
Heartened by these successes, the researchers are working to see whether they can control the shape of groundcherry bushes with more precision. They are also keen to find a solution to the problem of fruit dropping off the bush.
“That can really complicate harvesting,” Dr. Van Eck said.
Tomatoes are known to carry a gene that influences the formation of a weak point on the stem of the fruit. Perhaps modulating this gene in the groundcherry will make possible a variety that keeps a firmer grip on its fruits.
It took around two years to complete the experiments. In the future, changes could take less time, or more, depending on how much work is necessary to adjust a given trait.
Still, Dr. Van Eck estimates that with conventional breeding techniques, addressing such traits can often take at least five years. And that’s if the trait breeders want to encourage is already present in some plants. If the trait isn’t readily available, then they face a much more difficult task of trying to track it down, then beginning the breeding process.
Because Crispr involves only the removal of DNA, not the addition of new material, the resulting produce isn’t considered genetically modified organisms in the U.S. or Canada, Dr. Van Eck said.
The researchers suggest that this technique could be helpful in bringing plants that aren’t grown widely into greater circulation. The groundcherry, with its unusual look and enticing taste, could be a good first candidate.
