How Plants Use Scent to Help Each Other Resist Pests
Plants may seem to have no consciousness, but they also help each other. A Japanese research team has found that when the leaves of some plants are eaten by pests, they release a specific scent that prompts nearby companions to produce compounds that hinder pest growth, thereby avoiding being eaten by pests. This discovery is expected to lead to the development of new pesticides that enhance plant resistance.
After some plants suffer pest damage, nearby companions mount self-defense responses and strengthen their resistance to pests, but scientists had not been clear about the detailed mechanism.
Researchers from Kyoto University and Yamaguchi University in Japan reported on the 28th in the online edition of the US journal Proceedings of the National Academy of Sciences that they let moth larvae eat the leaves of a tomato plant, and let another tomato plant that had not been eaten sense the scent released by the first tomato plant. They found that after the moth larvae began eating the second tomato plant, their survival rate dropped by about 20{bf} compared with when they ate the first one.
This scent is the smell you notice when mowing the lawn. After investigating more than 7,000 components in the scent released by the first tomato plant, the research team found that a compound called leaf alcohol increased significantly in its leaves. After the other tomato plant senses leaf alcohol, it causes the leaf alcohol to combine with sugar in its own leaves, producing a toxic compound that curbs larval growth, thereby lowering the larvae's survival rate.
Junji Takabayashi, a professor at Kyoto University who led the research, pointed out that tomatoes do not produce toxins in advance; instead, they adopt an "energy-saving" defense strategy. Only after coming into contact with the scent released by nearby companions do they begin absorbing leaf alcohol as the raw material for the toxin, which then combines with sugar in their bodies to produce toxic compounds that resist pests. Plants such as rice, eggplant and cucumber all possess the same mechanism.