Unlike other plants, sweet potato plants do not have spines or poisons to defend themselves. Some of them have, however, something else that lets hungry herbivores know that they are not an all-you-can-eat buffet, a new study finds.
When one leaf is injured, it produces a chemical that alerts the rest of the plant—and its neighbors—to make themselves inedible to bugs. Sweet potato breeders could potentially engineer plants to produce the chemical as an all-natural pest defense.
Plant ecologists led by Axel Mithöfer of the Max Planck Institute for Chemical Ecology in Jena, Germany, started to look into sweet potato (Ipomoea batatas) defenses after they noticed something interesting about two varieties of the plant grown in Taiwan: The yellow-skinned, yellow-fleshed Tainong 57 is generally herbivore-resistant, but its darker orange cousin, Tainong 66, is plagued by insect pests.
To find out why, the team offered up Tainong 57 and 66 plants to hungry African cotton leafworm caterpillars. Both plants released at least 40 airborne compounds as the caterpillars snacked on their leaves. But Tainong 57 produced a lot more of a chemical called DMNT, which has a very distinct odor, the team details this month in Scientific Reports. (“The smell is not nice,” Mithöfer says. “You wouldn’t want it as a perfume.”)
The chemical DMNT causes the exposed plants to produce a protein called sporamin in their leaves, which makes caterpillars unwell when they eat the leaves.
Find out more about this over at Science.
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