Host: The Japanese Society of Toxicology
Name : The 47th Annual Meeting of the Japanese Society of Toxicology
Date : 2020 -
Plants are constantly exposed to the threat of herbivorous insects, and many of them produce toxic substances in response to insect damage. In particular, insect species that have not evolved their detoxification mechanisms will be killed when they eat up their food plants. However, if insects can detect and avoid toxins quickly, they are more likely to survive. Therefore, like humans, in order to avoid toxins, they developed a taste reception and/or recognition mechanism that perceives toxic substances as bitter taste substances. Until around 2000, little had been known about the bitter taste receptor of insects. We and an Italian research group functionally identify the bitter taste receptor cell in the fly taste organs almost simultaneously. Indeed, our study, which noticed the involvement of gustatory odorant-binding protein (gustatory OBP) in a toxic substance reception by the bitter taste receptor cell, was the first to elicit an urgent vomiting response in the detection of oral toxin. In addition, the olfactory mechanism for recognizing the odor of the same substance also plays a role in the toxin detection. It has also been found that odor memory maintains appetite decrease for a lifetime. This appetite decrease may seem unhealthy for the fly, but it may be a beneficial reaction if the insect takes toxins to death. If so, plants no longer need to kill insects with lethal toxins until they have eaten themselves. Otherwise, plants can have another defense strategy targeting insect sensory mechanism for toxin detection with only a little bite and bitterness. Some plants have shifted to such a mild defense strategy. In the second half, I would like to add the story of such a plant species that has evolved a new defense strategy.
