Dorothy Hinshaw Patent
Nature’s Animal Ambassador
If you’d been strolling through a tropical forest in New Guinea thousands of years ago and reached up to pluck a wild banana snack, you wouldn’t have wanted to eat it. The banana ancestors had big hard seeds surrounded by a small amount of sweet flesh, not worth peeling. Sometimes, however, plants appeared with fruit that had no seeds. Over time, people cherished these seedless fruits and grew the plants for their own use.
The banana plant sends up a central stalk surrounded by very large leaves, then flowers at the tip. The flowers produce a heavy load of bananas without being pollinated. Then the stalk dies. Meanwhile, the stalk sends out side shoots that become new plants. That’s a form of cloning, meaning that all of a banana plant’s progeny are genetically identical, both to their parent and to one another.
The ancestors of the modern banana could reproduce in the usual way, so their seeds contained mixtures of DNA from the mother plant and DNA from another plant’s pollen. This “sexual reproduction” allows for the genes of the plants to be combined in new ways. If a disease came along, it might kill most of the plants, but some others could have natural resistance and survive.
Because it lacks seeds, the banana has gotten into trouble. Back in the 1950s, an especially sweet and tasty variety called the Gros Michel was the commercial banana. But a devastating fungus came along and killed the plants and contaminated the soil. Growers then chose another variety, Cavendish, which resisted the disease. But now a wilt called Panama disease has shown up that kills the Cavendish plants. And because bananas lack genetic diversity and because they don’t develop seeds that mix up their genes, the Cavendish has no way of defending itself. Banana growers are doing what they can to stop the spread of the disease, however, and up to now they have been successful. But don’t be surprised if in a few years the bananas you buy look and taste different. Luckily, there are other varieties out there, like small “finger” bananas and larger red-skinned fruits, that you can already buy in places like Hawaii.
Dorothy Hinshaw Patent is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.
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